1
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* *
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* FFFFF L U U K K AAA 222 000 000 888 *
* F L U U K K A A 2 2 0 0 0 0 8 8 *
* F L U U K K A A 2 0 0 0 0 8 8 *
* FFFF L U U KK AAAAA === 2 0 0 0 0 888 *
* F L U U K K A A 2 0 0 0 0 8 8 *
* F L U U K K A A 2 0 0 0 0 8 8 *
* F LLLLL UUU K K A A 22222 000 000 888 *
* *
* http://www.fluka.org *
* *
* Copyright (c) 1989-2008 by INFN and CERN *
* *
* All rights reserved *
* Main authors: A.Fasso`, A.Ferrari, J.Ranft, P.R.Sala *
* Contributing authors: G.Battistoni, F.Cerutti, T.Empl, *
* M.V.Garzelli, M.Lantz, A.Mairani, *
* V.Patera, S.Roesler, G.Smirnov, *
* F.Sommerer, V.Vlachoudis *
* *
* 2008 version of the FLUKA code by : *
* *
* Alberto Fasso` - SLAC *
* fasso@slac.stanford.edu *
* *
* Alfredo Ferrari & Paola Sala - CERN/INFN Milan *
* Alfredo.Ferrari@cern.ch, Paola.Sala@mi.infn.it *
* Alfredo.Ferrari@mi.infn.it, Paola.Sala@cern.ch *
* *
* Johannes Ranft - Siegen University *
* Johannes.Ranft@cern.ch *
* *
*====================================================================*
1
26 September 2008
Present (active) authors (since FLUKA89):
A. Fasso`, Stanford Linear Accelerator Center, 2575 Sand Hill Road,
Menlo Park, CA 94025, USA
A. Ferrari, The European Organization for Nuclear Research,
1211 Geneva 23, Switzerland
J. Ranft, Universitaet Gesamthochschule Siegen, Fachbereich Physik,
D-57068 Siegen, Germany
P. R. Sala, Istituto Nazionale di Fisica Nucleare, via Celoria 16,
20133 Milano, Italy
Present contributing authors:
G. Battistoni, Istituto Nazionale di Fisica Nucleare, via Celoria 16,
20133 Milano, Italy
F. Cerutti, The European Organization for Nuclear Research,
1211 Geneva 23, Switzerland
A. Empl, Houston University, Texas, USA
M. V. Garzelli, Universita' degli Studi di Milano, Physics Department
via Celoria 16, 20133 Milano, Italy
M. Lantz, Istituto Nazionale di Fisica Nucleare, via Celoria 16,
20133 Milano, Italy
A. Mairani, Heidelberger Ionenstrahl-Therapie (HIT), Heidelberg,
Germany
V. Patera, Universita' La Sapienza, Roma, and INFN Frascati,
Italy
S. Roesler, The European Organization for Nuclear Research,
1211 Geneva 23, Switzerland
G. Smirnov, The European Organization for Nuclear Research,
1211 Geneva 23, Switzerland
F. Sommerer, The European Organization for Nuclear Research,
1211 Geneva 23, Switzerland
V. Vlachoudis The European Organization for Nuclear Research,
1211 Geneva 23, Switzerland
Other authors who contributed to previous FLUKA versions (from FLUKA82
up to FLUKA92):
P. Aarnio, Helsinki University of Technology, Dept. of Technical
Physics Otakaari 1, SF-02150 ESPOO, Finland
(up to FLUKA87)
J.-H. Moehring, Leipzig University, Germany, Fachbereich Physik,
LEIPZIG, Germany
(up to FLUKA92)
G. R. Stevenson, TIS/RP, CERN, CH-1211 GENEVE 23, Switzerland
(up to FLUKA90)
J. M. Zazula, Institute of Nuclear Physics, CRACOW, Poland
(up to FLUKA90)
1
FLUKA User license, as established by the FLUKA Coordination Committee
Copyright statement and license conditions
Copyright Italian National Institute for Nuclear Physics
(INFN) and European Organization for Nuclear Research (CERN)
("the FLUKA copyright holders"), 1989-2008.
All rights not expressly granted under this license are
reserved.
This software results from work performed by Alberto Fasso`,
Alfredo Ferrari, Johannes Ranft and Paola Sala.
INFN and CERN are the exclusive source of distribution of
the code, bug fixes and documentation of the FLUKA
software. Each official version of FLUKA is identified by a
numbering scheme specifying major and minor releases.
The FLUKA Coordination Committee or its delegates are able
to grant any of the permissions noted in this License
Agreement as requiring a specific consent. Any such consent
may only be granted in writing.
Installation, use, reproduction, display of the FLUKA
software ("FLUKA"), in source and binary forms, are
permitted free of charge on a non-exclusive basis for
internal scientific, non-commercial and non-weapon-related
use by non-profit organizations only. Any exercise of these
rights is subject to the following conditions:
1. Insertion of the FLUKA code, in whole or in part, into
other codes, or its translation into any other computer
language are possible only after obtaining prior written
permission. Modifications of the FLUKA code are permitted
for use by the licensee only, unless authorized in
written.
2. FLUKA is non-transferable, non-sub-licensable and may not
be distributed in any way, without express written
consent, whether in original or modified form. Site-wise
or collaboration-wise conditions can be agreed with the
FLUKA Coordination Committee.
3. Notwithstanding the above, the licensee may modify and
sub-license FLUKA User Routines to third parties in so far
as their purpose is limited to the adaptation of input and
output interfaces of FLUKA and their modification does not
circumvent, replace, add to or modify any of the functions
of FLUKA, or extract specific isolated results from any of
the individual internal physics models embedded within
FLUKA.
4. The licensee shall forthwith license all its modifications
of FLUKA to the FLUKA copyright holders, at no cost and
with no limitation of use. The licensee acknowledges that
the FLUKA copyright holders may insert such modifications
into future releases of FLUKA, subject to appropriate
acknowledgment of the licensee's contribution.
5. Any publication by the licensee with respect to FLUKA or
results obtained from it shall explicitly acknowledge
FLUKA by quoting its set of references and the FLUKA
copyright holders. The licensee shall not without prior
written permission publish documents or results based on a
modified form of FLUKA, unless the modification
exclusively concerns User Routines for the adaptation of
its input and output interfaces which comply with the same
restrictions, as defined in section 3) as those which
apply to sub-licensing. Any publication of documents or
results shall be based only on official FLUKA versions as
obtained from the FLUKA website (http://www.fluka.org) or
from any authorized mirror. Publication here implies any
legal publication to any third party, whether verbal,
electronic, visual, in writing or otherwise.
6. The licensee shall ensure that the FLUKA references,
copyright statement and license conditions are not altered
or removed from FLUKA. Any integration of any portion of
FLUKA, in modified or in unmodified form, into any other
software package must preserve the internal copyright
notices in those portions of FLUKA that have been
employed, and must reproduce such notices within any
additional global notices included along or embedded
within the software into which FLUKA has been
integrated. Any portion of FLUKA so integrated, whether
modified or unmodified shall continue to be subject to
these license conditions.
7. Nothing in this license shall be construed as to grant any
rights in any of the FLUKA versions since 1989. In
addition, users are not permitted to circumvent any
protection in prior distributions of FLUKA that provided
for a preset expiration date of the code
8. Versions or parts of the FLUKA source code, entrusted to
individuals or groups prior to the enactment of the
CERN-INFN Collaboration Agreement, which are listed in
Chapter 5 of Annex 1 of the EP-AB-INFN Scientific
Agreement (19-02-2003), together with the agreed
conditions of use, are subject to this License Agreement
in addition to any other restrictions on the scope of use
that may have been part of the initial use grant.
9. Commercial use of FLUKA, outside the scope of this
license, must be negotiated with the copyright holders
10. DISCLAIMER
THIS SOFTWARE IS PROVIDED BY THE FLUKA COPYRIGHT HOLDERS "AS
IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT
NOT LIMITED TO, IMPLIED WARRANTIES OF MERCHANTABILITY, OF
SATISFACTORY QUALITY, AND FITNESS FOR A PARTICULAR PURPOSE
OR USE ARE DISCLAIMED. THE FLUKA COPYRIGHT HOLDERS AND THE
AUTHORS MAKE NO REPRESENTATION THAT THE SOFTWARE AND
MODIFICATIONS THEREOF, WILL NOT INFRINGE ANY PATENT,
COPYRIGHT, TRADE SECRET OR OTHER PROPRIETARY RIGHT.
11. LIMITATION OF LIABILITY
THE FLUKA COPYRIGHT HOLDERS AND THE AUTHORS SHALL HAVE NO
LIABILITY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL,
CONSEQUENTIAL, EXEMPLARY, OR PUNITIVE DAMAGES OF ANY
CHARACTER INCLUDING, WITHOUT LIMITATION, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES, LOSS OF USE, DATA OR PROFITS,
OR BUSINESS INTERRUPTION, HOWEVER CAUSED AND ON ANY THEORY
OF CONTRACT, WARRANTY, TORT (INCLUDING NEGLIGENCE), PRODUCT
LIABILITY OR OTHERWISE, ARISING IN ANY WAY OUT OF THE USE OF
THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
DAMAGES.
REQUESTS MADE BY THE FLUKA AUTHORS TO ALL USERS
All licensees are requested to report as soon as practical
to the Authors any errors or bugs found in any portion of
FLUKA and its accompanying documentation.
All licensees are requested to forward copies of all
comparisons that they may make between FLUKA results and
data or other codes as soon as practical. The Authors agree
to keep any such communications confidential unless
otherwise notified by the contributing user.
The Authors reserve the right of publishing any benchmarking
and/or comparisons of the distinct separate performance of
the individual internal models that are embedded into FLUKA,
whether the comparisons are with data or with other
codes. The Authors would also like to convey a general
willingness to conduct any such benchmarking efforts either
upon request or in collaboration with interested parties. In
case of doubt please contact the Authors.
Users should exclusively download FLUKA from the official
FLUKA website (http://www.fluka.org) or one of the
authorized mirror sites. Users are invited to regularly
update their FLUKA version to profit for improvements and
bug fixes.
Users are invited to use reasonably updated versions of the
code for publications. Publications of results based on
those FLUKA versions that are declared unsupported and
obsolete on the official FLUKA website shall be avoided.
Users should address any request of consent to one member of
the FLUKA Coordinating Committee, which at present is
composed as follows:
Giuseppe Battistoni Giuseppe.Battistoni@mi.infn.it
(chairman)
Michael Doser Michael.Doser@cern.ch
Roberto Losito Roberto.Losito@cern.ch
Johannes Ranft Johannes.Ranft@cern.ch
Paola Sala Paola.Sala@mi.infn.it
In accordance with the User License, the use of the FLUKA code must be
acknowledged explicitly by quoting the following set of references:
- A. Fasso`, A. Ferrari, J. Ranft, and P.R. Sala,
"FLUKA: a multi-particle transport code",
CERN-2005-10 (2005), INFN/TC_05/11, SLAC-R-773
- G. Battistoni, S. Muraro, P.R. Sala, F. Cerutti, A. Ferrari,
S. Roesler, A. Fasso`, J. Ranft,
"The FLUKA code: Description and benchmarking",
Proceedings of the Hadronic Shower Simulation Workshop 2006,
Fermilab 6--8 September 2006, M. Albrow, R. Raja eds.,
AIP Conference Proceeding 896, 31-49, (2007)
Additional FLUKA references can be added, provided they are relevant
for the FLUKA version under consideration
This set of references is subject to change in time. New ones will be
communicated, when necessary, in the Release Notes of new FLUKA versions.
Note: The "FLUKA User Routines" mentioned at point 3) in the
FLUKA User License are those (and only those) contained
in the directory usermvax, both in the source and binary
versions of the code
For questions/clarifications/problems about the license or in general the
use of FLUKA please contact the chairman of the joint INFN/CERN FLUKA
Coordination Committee:
Prof. Giuseppe Battistoni
INFN - Via Celoria 16 I-20133 Milano (Italy)
Giuseppe.Battistoni@mi.infn.it
or one of the Authors.
1
FLUKA2008 MANUAL
IMPORTANT WARNING FOR THE USERS
This manual is a reference tool for preparing input for the FLUKA
particle transport code. It is not complete and it is not guaranteed to
be free from errors. It is continually evolving just as the code does.
It should not be cited: the proper references to be cited in any recent
work related to FLUKA are listed above (see also the list of References
in 17}). In using the code, the user agrees on the authorship
and copyright and hence is bound to quote the above references.
Please note also that early versions of the FLUKA hadronic event generator
as implemented in other codes (in particular GEANT) should be referenced
as such (e.g. GEANT-FLUKA) and not as FLUKA. They have little in common
with the present version and should be considered virtually obsolete.
The proper reference to GEANT-FLUKA is Fas93a.
Some parts of the manual must be "enriched": output etc.; the part on
auxiliary programs must be updated.
Please refer to fasso@slac.stanford.edu / Alfredo.Ferrari@cern.ch for any
comment or criticism on this manual and/or the code.
Alberto Fasso`, Alfredo Ferrari
1********************************************************************************
Index of the FLUKA manual on-line
(search for string " 1}", " 2}" etc. for quick location)
********************************************************************************
0} What is FLUKA?
1} A quick look at FLUKA's physics, structure and capabilities
2} A FLUKA beginner's guide
3} Installation
4} FLUKA modules (Fortran files)
5} Particle and material codes
6} General features of FLUKA input
7} Description of FLUKA input options
8} Combinatorial Geometry
9} Output
10} Low-energy neutrons in FLUKA
11} Collision tape
12} Generating and propagating optical photons
13} User routines
14} Use of RAY pseudoparticles
15} Examples on the material/compound definitions
16} History of FLUKA
17} References
1********************************************************************************
0} What is FLUKA?
********************************************************************************
FLUKA is a general purpose tool for calculations of particle transport
and interactions with matter, covering an extended range of
applications spanning from proton and electron accelerator shielding to
target design, calorimetry, activation, dosimetry, detector design,
Accelerator Driven Systems, cosmic rays, neutrino physics, radiotherapy
etc.
The highest priority in the design and development of FLUKA has always been
the implementation and improvement of sound and modern physical models.
Microscopic models are adopted whenever possible, consistency among all the
reaction steps and/or reaction types is ensured, conservation laws are enforced
at each step, results are checked against experimental data at single
interaction level. As a result, final predictions are obtained with a minimal
set of free parameters fixed for all energy/target/projectile combinations.
Therefore results in complex cases, as well as properties and scaling laws,
arise naturally from the underlying physical models, predictivity is provided
where no experimental data are directly available, and correlations within
interactions and among shower components are preserved.
FLUKA can simulate with high accuracy the interaction and propagation
in matter of about 60 different particles, including photons and electrons
from 1 keV to thousands of TeV, neutrinos, muons of any energy, hadrons
of energies up to 20 TeV (up to 10 PeV by linking FLUKA
with the DPMJET code) and all the corresponding antiparticles, neutrons down
to thermal energies and heavy ions. The program can also transport polarised
photons (e.g., synchrotron radiation) and optical photons. Time evolution and
tracking of emitted radiation from unstable residual nuclei can be performed
online.
FLUKA can handle even very complex geometries, using an improved version of the
well-known Combinatorial Geometry (CG) package. The FLUKA CG has been designed
to track correctly also charged particles (even in the presence of magnetic or
electric fields). Various visualisation and debugging tools are also available.
For most applications, no programming is required from the user.
However, a number of user interface routines (in Fortran 77) are
available for users with special requirements.
The FLUKA physical models are described in several journal and conference
papers; on the technical
side the stress has been put on four apparently conflicting
requirements, namely efficiency, accuracy, consistency and flexibility.
Efficiency has been achieved by having a frequent recourse to table look-up
sampling and a systematic use of double precision has had a great impact on
overall accuracy: both qualities have benefited from a careful choice of the
algorithms adopted. To attain a reasonable flexibility while minimising
the need for user-written code, the program has been provided with a
large number of options available to the user, and has been completely
restructured introducing dynamical dimensioning.
Another feature of FLUKA, probably not found in any other Monte Carlo
program, is its double capability to be used in a biased mode as well as a
fully analogue code. That means that while it can be used to predict
fluctuations, signal coincidences and other correlated events, a wide choice of
statistical techniques are also available to investigate punchthrough or other
rare events in connection with attenuations by many orders of magnitude.
1********************************************************************************
1} A quick look at FLUKA's physics, structure and capabilities
********************************************************************************
Only a very short summary will be given here of the capabilities and
the limitations of FLUKA, since this is meant to be mainly a practical
guide. More detailed descriptions of the physical models, algorithms
and techniques will be found in cited references and hopefully in a
future more comprehensive Reference Manual.
1.1} Physics
------------
1.1.1} Hadron inelastic nuclear interactions
The FLUKA hadron-nucleon interaction models are based on resonance
production and decay below a few GeV, and on the Dual Parton model above.
Two models are used also in hadron-nucleus interactions. At momenta
below 3--5 GeV/c the PEANUT package includes a very detailed Generalised
Intra-Nuclear Cascade (GINC) and a preequilibrium stage, while at high
energies the Gribov-Glauber multiple collision mechanism is included in
a less refined GINC. Both modules are followed by equilibrium processes:
evaporation, fission, Fermi break-up, gamma deexcitation. FLUKA can also
simulate photonuclear interactions (described by Vector Meson Dominance,
Delta Resonance, Quasi-Deuteron and Giant Dipole Resonance). A schematic
outline is presented below:
* Inelastic cross sections for hadron-hadron interactions are represented by
parameterised fits based on available experimental data [PDG].
* For hadron-nucleus interactions, a mixture of tabulated data and
parameterised fits is used [Bar72,Moh83,She91,Pra98,Pra98a].
* Elastic and charge exchange reactions are described by phase-shift analyses
and eikonal approximation.
* Inelastic hadron-hadron interactions are simulated by different event
generators, depending on energy:
- Momentum < 20 TeV and > 5 GeV/c:
Dual Parton Model (DPM) [Cap94]. The version used in FLUKA has been
derived by A. Ferrari and P.R. Sala [Fer94, Fas95, Fer95, Fer96b] from
the original version by J. Ranft and collaborators [Ran83, Ran83a]. A
description of modifications and improvements can be found in
[Fer96b, Col00]
- Momentum from threshold to 5~GeV/c:
Resonance production and decay model [Fer96b] (Improved version of the
H"anssgen et al. model [Han79, Han80, Han84, Han84a, Han84b, Han86, Han86a])
* Inelastic hadron-nucleus interactions are simulated by different event
generators depending on energy and projectile:
- Momentum < 20 TeV and > 5 GeV/c: Glauber-Gribov multiple scattering
followed by Generalized Intranuclear Cascade (GINC)
- Below 5 GeV/c for nucleons, anti-nucleons and pions; below 1.5 GeV kinetic
for kaons:
Preequilibrium-cascade model PEANUT (Ferrari-Sala) [Fer94, Fas95]
- In between PEANUT and DPM for kaons: H"anssgen K. et al. GINC modified to
take into account correlations among cascade particles and more refined
nuclear effects (Ferrari-Sala).
* All three models include evaporation and gamma deexcitation of the residual
nucleus [Fer96, Fer96a]. Light residual nuclei are not evaporated but
fragmented into a maximum of 6 bodies, according to a Fermi break-up model.
* Treatment of antiparticle capture: antinucleons according to resonance model,
pi-minus, K-minus and mu-minus by the preequilibrium-cascade model.
1.1.2} Elastic Scattering
* Parameterised nucleon-nucleon cross sections.
* Tabulated nucleon-nucleus cross sections [Pra98, Pra98a].
* Tabulated phase shift data for pion-proton and phase-shift analysis for
kaon-proton scattering.
* Detailed kinematics of elastic scattering on hydrogen nuclei and transport
of proton recoils (Ferrari-Sala)
1.1.3} Nucleus-Nucleus interactions
Nuclear interactions generated by ions are treated through interfaces to
external event generators.
* Above 5 GeV per nucleon: DPMJET-II or DPMJET-III, with special
initialisation procedure.
* Between 0.1 and 5 GeV per nucleon: modified RQMD
1.1.4} Transport of charged hadrons and muons
An original treatment of multiple Coulomb scattering and of ionisation
fluctuations allows the code to handle accurately some challenging problems
such as electron backscattering and energy deposition in thin layers even in
the few keV energy range.
1.1.5} Energy loss
* Bethe-Bloch theory [Bet30, Bet32, Bet34, Blo33, Blo33a]
* Optional delta-ray production and transport with account for spin
effects and ionisation fluctuations.
The present version includes a special treatment [Fas97a] which
combines delta-ray production with properly restricted ionisation
fluctuations and includes corrections for particle spin and
electrons/positrons and "distant collision" straggling corrections
(similar to Blunck-Leisegang ones).
* Shell and other low-energy corrections derived from Ziegler [Zie77]
* Density effect according to Sternheimer [Ste84].
* Special transport algorithm, based on Moli\`ere's theory of multiple Coulomb
scattering improved by Bethe [Mol48, Mol55, Bet53], with account of several
correlations:
- between lateral and longitudinal displacement and the deflection angle
- between projected angles
- between projected step length and total deflection
* Accurate treatment of boundaries and curved trajectories in magnetic and
electric fields
* Automatic control of the step
* Path length correction
* Spin-relativistic effects at the level of the second Born approximation
[Fer91a]
* Nuclear size effects (scattering suppression) on option (simple nuclear
charge form factors are implemented, more sophisticated ones can be supplied
by the user)
* Correction for cross section variation with energy over the step.
* Bremsstrahlung and electron pair production at high energy by heavy charged
particles, treated as a continuous energy loss and deposition or as discrete
processes depending on user choice
* Muon photonuclear interactions, with or without transport of the produced
secondaries.
1.1.6} Low-energy neutrons
For neutrons with energy lower than 20 MeV, FLUKA uses its own neutron cross
section libraries (P5 Legendre angular expansion, 260 or 72 neutron energy groups),
containing more than 200 different materials, selected for their interest in
physics, dosimetry and accelerator engineering and derived from the most
recently evaluated data.
* multigroup P5 cross sections with 260 or 72 groups [Cuc91]
* Gamma-ray generation and different temperatures available.
* Doppler broadening for temperatures above 0 K.
Transport:
* Standard multigroup transport with photon and fission neutron
generation.
* Detailed kinematics of elastic scattering on hydrogen nuclei.
* Transport of proton recoils and protons from 14-N(n,p)14-C reaction.
* Capture photons are generated according to the multigroup treatment,
but transported with the more accurate EMF package which performs
continuous transport in energy and allows for secondary electron
generation.
For nuclei other than hydrogen, kerma factors are used to
calculate energy deposition (including from low-energy fission).
For details about the available materials, group structure
etc., see 10}
1.1.7} Electrons
* FLUKA uses an original transport algorithm for charged particles
[Fer91a], including complete multiple Coulomb scattering treatment
giving the correct lateral displacement even near a boundary (see
hadron and muon transport above).
* The variations with energy of the discrete event cross sections and of the
continuous energy loss in each transport step are taken into account exactly.
* Differences between positrons and electrons are taken into account
concerning both stopping power and bremsstrahlung [Kim86].
* The bremsstrahlung differential cross sections of Seltzer and
Berger [Sel85, Sel86] have been extended to include the finite value at
"tip" energy, and the angular distribution of bremsstrahlung photons
is sampled accurately.
* The Landau-Pomeranchuk-Migdal suppression effect [Lan53,Lan53a,
Mig56,Mig57] and the Ter-Mikaelyan polarisation effect in the soft part
of the bremsstrahlung spectrum [Ter54] are also implemented.
* Electrohadron production (only above rho mass energy 770 MeV)
via virtual photon spectrum and Vector Meson Dominance Model
[Moh89]. (The treatment of the latter effect has not been
checked with the latest versions, however).
* Positron annihilation in flight and at rest
* Delta-ray production via Bhabha and M\oller scattering.
Note: the present lowest transport limit for electrons is
1 keV. Although in high-Z materials the Moli\`ere multiple scattering
model becomes unreliable below 20-30 keV, a single-scattering option
is available which allows to obtain satisfactory results in any
material also in this low energy range.
The minimum recommended energy for PRIMARY electrons is about
50 to 100 keV for low-Z materials and 100-200 keV for heavy
materials, unless the single scattering algorithm is used.
Single scattering transport allows to overcome most of the
limitations at low energy for the heaviest materials at the price of
some increase in CPU time.
1.1.8} Photons
* Pair production with actual angular distribution of
electrons and positrons.
* Compton effect with account for atomic bonds through use of
inelastic Hartree-Fock form factors.
* Photoelectric effect with actual photoelectron angular
distribution [Sau31], detailed interaction on six K and L
single sub-shells, optional emission of fluorescence photons
and approximate treatment of Auger electrons.
* Rayleigh effect.
* Photon polarisation taken into account for Compton, Rayleigh
and Photoelectric effects.
* Photohadron production:
- Vector Meson Dominance Model (Ranft [Ran87b]), modified and improved
(Ferrari-Sala) using PEANUT below 770 MeV [Fas95].
- Quasideuteron interactions
- Giant Dipole Resonance
Note: the present lowest transport limit for photons is 1 keV.
However, fluorescence emission may be underestimated at
energies lower than the K-edge in high-Z materials, because of
lack of Coster-Kronig effect.
The mimimum recommended energy for PRIMARY photons is about
5 to 10 keV.
1.1.9} Optical photons
* Generation and transport (on user's request) of Cherenkov,
Scintillation and Transition Radiation.
* Transport of light of given wavelength in materials with user-defined optical
properties.
1.1.10} Neutrinos
* Electron and muon (anti)neutrinos are produced and tracked on option, without
interactions
* Neutrino interactions however are implemented, but independently from
tracking.
1.2} Geometry
-------------
A part of the code where efficiency, accuracy, consistency and
flexibility have combined giving very effective results is the new FLUKA
geometry. Derived from the Combinatorial Geometry package, it has been
entirely rewritten. A completely new, fast tracking strategy has been
developed, with special attention to charged particle transport,
especially in magnetic fields. New bodies have been introduced, resulting
in increased rounding accuracy, speed and even easier input preparation.
* Combinatorial Geometry (CG) from MORSE [Emm75], with additional bodies
(infinite circular and elliptical cylinder parallel to X,Y,Z axis, generic
plane, planes perpendicular to the axes).
* Possibility to use body and region names instead of numbers.
* Possibility of using body combinations inside nested parentheses.
* Distance to nearest boundary taken into account for improved performance.
* Accurate treatment of boundary crossing with multiple scattering and magnetic
or electric fields.
* The maximum number of regions (without recompiling the code) is 10000.
* The tracking strategy has been substantially changed with respect to
the original CG package. Speed has been improved and interplay with
charged particle transport (multiple scattering, magnetic and electric
field transport) has been properly set.
* A limited repetition capability (lattice capability) is available. This
allows to avoid describing repetitive structures in all details.
Only one single module has to be described and then can be repeated as
many times as needed. This repetition does not occur at input stage but
is hard-wired into the geometry package, namely repeated regions are not
set up in memory, but the given symmetry is exploited at tracking time
using the minimum amount of bodies/regions required. This allows in
principle to describe geometries with even tens of thousands regions (e.g.
spaghetti calorimeters) with a reasonable number of region and body
definitions.
* Voxel geometry is available on option, completely integrated into CG.
Special options:
* Geometry debugger
* Plotting of selected sections of the geometry, based on the Ispra PLOTGEOM
program
* Pseudoparticle RAY to scan the geometry in a given direction.
1.3} Transport
--------------
* Condensed history tracking for charged particles, with single scattering
option.
* Time cut-off.
* Legendre angular expansion for low-energy neutron scattering.
* Transport of charged particles in magnetic and electric fields.
Transport limits:
Secondary particles Primary particles
charged hadrons 1 keV-20 TeV (*) 100 keV-20 TeV (*)
neutrons thermal-20 TeV (*) thermal-20 TeV (*)
antineutrons 1 keV-20 TeV (*) 10 MeV-20 TeV (*)
muons 1 keV-1000 TeV 100 keV-1000 TeV
electrons 1 keV-1000 TeV 70 keV-1000 TeV (low-Z materials)
150 keV-1000 TeV (high-Z materials)
photons 1 keV-1000 TeV 7 keV-1000 TeV
heavy ions 10 MeV/n-10000 TeV/n 100 MeV/n-10000 TeV/n
(*) 10 PeV with the DPMJET interface
1.4} Biasing
------------
* Leading particle biasing for electrons and photons: region dependent,
below user-defined energy threshold and for selected physical effects.
* Russian Roulette and splitting at boundary crossing based on region
relative importance.
* Region-dependent multiplicity tuning in high energy nuclear interactions.
* Region-dependent biased downscattering and non-analogue absorption of
low-energy neutrons.
* Biased decay length for increased daughter production
* Biased inelastic nuclear interaction length
* Biased interaction lengths for electron and photon electromagnetic
interactions
* Biased angular distribution of decay secondary particles.
* Region-dependent weight window in three energy ranges (and energy group
dependent for low energy neutrons).
1.5} Optimisation
-----------------
* Optimisation of the step length, user-defined or automatic, by material
and/or by region.
1.6} Scoring
------------
* Star density by producing particle and region.
* Energy density by region, total or from electrons/photons only.
* Star, energy and momentum transfer density in a geometry-independent binning
structure (Cartesian or cylindrical), averaged over the run or event by event.
* Energy deposition weighted by a quenching factor (Birks law).
* Step size independent of bin size.
* Time window.
* Coincidences and anti-coincidences.
* Fluence and current scoring as a function of energy and angle, via
boundary-crossing, collision and track-length estimators coincident
with regions or region boundaries.
* Track-length fluence in a binning structure (Cartesian or cylindrical)
independent of geometry.
* Particle yield from a target or differential cross section with respect to
several different kinematic variables.
* Residual nuclei.
* Fission density.
* Momentum transfer density.
* Neutron balance.
* No limit to the number of estimators and binnings within the total memory
available (but a maximum number must be fixed at compilation time).
* Energy deposition can be scored on option disregarding the particle weights
(useful for studying computer performance, etc.)
* All quantities from radioactive decay of residual nuclei can be scored
according to user-defined irradiation and cooling time profiles.
1.7} Code structure, technical aspects
--------------------------------------
* The whole program, including the numerical constants, is coded in double
precision (at least the versions for 32-bit word machines). The only
exceptions are the low-energy neutron cross sections, which are stored in
single precision to save space.
* Consistent use of the latest recommended set of the physical constant
values [PDG].
* Dynamic memory allocation is implemented as far as possible.
* Extensive use of INCLUDE statements and of constant parameterisation
* 64-bit random number generator [Mar04]
1.8} MAIN DIFFERENCES BETWEEN FLUKA AND EARLIER CODES WITH SAME NAME
--------------------------------------------------------------------
The history of FLUKA, spanning more than 40 years, is narrated in detail in 16}.
It is possible to distinguish three different generation of "FLUKA" codes along
the years, which can be roughly identified as the FLUKA of the '70s (main authors
J. Ranft and J. Routti), the FLUKA of the '80s (P. Aarnio, A. Fasso`,
H.-J. M"ohring, J. Ranft, G.R. Stevenson), and the FLUKA of today (A. Fasso`,
A. Ferrari, J. Ranft and P.R. Sala).
These codes stem from the same root and of course every new ``generation''
originated from the previous one. However, each new ``generation'' represented
not only an improvement of the existing program, but rather a quantum
jump in the code physics, design and goals. The same name ``FLUKA'' has been
preserved as a reminder of this historical development - mainly as a
homage to J. Ranft who has been involved in it as an author and mentor from the
beginning until the present days - but the present code is completely different
from the versions which were released before 1990, and in particular from the last
one of the second generation, FLUKA87 [Aar86, Aar87].
Major changes and additions have affected the physical models used, the code
structure, the tracking strategy and scoring. Important additions, such as a
wider range of biasing possibilities and some specialised tools for calorimeter
simulation, have extended the field of its possible applications.
An exhaustive description of all these changes and new features along the years
is reported in Chap. 16}. However, the best gauge of the program evolution is
probably the widening of the application fields, and the boost of its recognition
and diffusion all over the world.
1.9} Applications
------------------
While FLUKA86-87 was essentially a specialised program to calculate
shielding of high energy proton accelerators, the present version can be
regarded as a general purpose tool for an extended range of applications.
In addition to traditional target design and shielding, applications are
now spanning from calorimetry to prediction of activation, radiation
damage, isotope transmutation, dosimetry and detector studies.
Prediction of radiation damage has always been a traditional field of
application of FLUKA, restricted however in earlier versions to
hadron damage to accelerator components. The new capability to deal with
the low-energy neutron component of the cascade has extended the field of
interest to include electronics and other sensitive detector parts. In
addition, radiation damage calculations and shielding design are not
limited to proton accelerators any longer, but include electron accelerators
of any energy, photon factories, and any kind of radiation source, be it
artificial or natural.
The present version of FLUKA has been used successfully in such diverse
domains as background studies for underground detectors, cosmic ray
physics, shielding of synchrotron radiation hutches, calculation of dose
received by aircraft crews, evaluation of organ dose in a phantom due to
external radiation, detector design for radiation protection as well as
for high energy physics, electron and proton radiotherapy, nuclear
transmutation, neutrino physics, shielding of free-electron lasers,
calculation of tritium production at electron accelerators, energy
amplifiers, maze design for medical accelerators, etc.
The recent addition of the simulation of heavy ion interactions allows also
for applications to hadrotherapy.
1********************************************************************************
2} A FLUKA beginner's guide
********************************************************************************
This Chapter is intended to provide a minimal set of instructions to install
and run FLUKA for a beginner user, going through the different steps required
to run a simple example. References to the relevant chapters of the manual are
given to help the user in finding more detailed information on the different
topics. After describing the installation procedure, instructions are given on
how to build the input file for a simple case. Instructions for running and
accessing the results are also reported. As a further step, the user is
addressed to Chapter 13} to learn how to tailor FLUKA to specific needs by
means of user routines.
2.1} Installing FLUKA
---------------------
A full description of the installation procedure is given in Chapter 3}.
The FLUKA package for LINUX and UNIX platforms is distributed as a tar file
which can be downloaded from the FLUKA Website http://www.fluka.org or other
authorised mirror site.
The user must prepare a directory where the tar file has to be expanded.
Let us suppose that the gzipped tar file, called fluka2006.1-linuxAA.tar.gz,
has been downloaded in a given directory and that it must be expanded in a new
subdirectory called fluka (but any other name is valid). A possible way to
proceed is the following:
mkdir fluka
cd fluka
tar zxvf ../fluka2006.1-linuxAA.tar.gz
An alternative way to expand the tar file is:
gunzip -dc ../fluka2006.1-linuxAA.tar.gz | tar xvf
At this stage, the user must define an environmental variable FLUPRO pointing
to the directory where the distribution tar file has been opened.
This directory is made available as follows:
Bash shell: use the export command C or tc shell: use the setenv command
... ...
cd fluka cd fluka
export FLUPRO=$PWD setenv FLUPRO $PWD
Of course the definition of FLUPRO can be placed once for ever in the login
script.
The FLUKA libraries and most data files will be located in $FLUPRO, the INCLUDE
files in $FLUPRO/flukapro/, the default user routines in $FLUPRO/usermvax/,
compilation and linking scripts (as well as several postprocessing programs to
analyse user scores) in $FLUPRO/flutil/. See details in Chapter 3}.
The user must produce the default FLUKA executable, to be located in the $FLUPRO
directory, by means of the $FLUPRO/flutil/lfluka script:
...
cd $FLUPRO
$FLUPRO/flutil/lfluka -m fluka
The default executable is called flukahp.
2.2} Building a FLUKA input
---------------------------
2.2.1} Generalities about FLUKA input
-------------------------------------
FLUKA reads user input from an ASCII "standard input" file with extension .inp.
The general characteristics and rules of FLUKA input are described in
Chapter 6}.
The input consists of a variable number of "commands" (called also "options"),
each consisting of one or more "lines" (called also "cards" for historical
reasons).
Apart from FLUKA commands, the input file may contain also the description of
the geometry of the simulated set-up. Also this description is provided by
means of specific geometry "command cards" in a special format described in
Chapter 6}.
The geometry description can, on request, be kept in a separate ASCII file:
this feature is especially useful when the same geometry is used in several
different inputs, not only to save space but because modifications can be made
in one single place.
The typical structure of a FLUKA input file is the following:
* Titles and comments for documentation purposes (optional, but recommended)
* Description of the problem geometry (solid bodies and surfaces, combined to
partition space into regions) (mandatory)
* Definition of the materials (mandatory unless pre-defined materials are used)
* Material assignments (correspondence material-region, mandatory)
* Definition of the particle source (mandatory)
* Definition of the requested "detectors". Each of these is a phase space
domain (region of space, particle direction and energy) where the user wants
to calculate the expectation value of a physical quantity such as dose,
fluence, etc. Various kinds of detectors are available, corresponding to
different quantities and to different algorithms used to estimate them
("estimators"). Detectors are optional, but one at least is expected, at
least in the production phase
* Definition of biasing schemes (optional)
* Definition of problem settings such as energy cut-offs, step size, physical
effects not simulated by default, particles not to be transported, etc.
(optional)
* Initialisation of the random number sequence (mandatory if an estimation of
the statistical error is desired)
* Starting signal and number of requested histories (mandatory)
In addition, special commands are available in FLUKA for more advanced problems
involving magnetic fields, time-dependent calculations, writing of history
files (so-called "collision tapes"), transport of optical photons,
event-by-event scoring, calling user-written routines, etc. These options are
expected to be requested only by users having some previous experience with the
more common commands: therefore they will be mostly ignored in this beginner's
guide.
Let's first recall the general structure of the FLUKA command lines (cards).
The geometry commands will be reviewed later. Each card contains:
* one keyword,
* six floating point values (called WHATs),
* one character string (called SDUM)
Some WHATs represent numerical quantities (e.g. energy, coordinates), while
others, converted to integers, are indices corresponding to a material, a
type of particle, a region etc. In this latter case, it is possible to replace
the number by the corresponding name (a character string).
Not necessarily all WHATs and SDUMs are used. In some cases, a command
line can be followed by a line of text (for instance a filename path or a
title). Any line having an asterisk (*) in the first position is treated as a
comment. All lines (commands, text strings and comments) are echoed on
the standard output (the file with extension .out). In case of problems, it is
a good idea to check how every line has been printed in the standard output.
Often, output reveals typing or format errors by showing how the program has
misinterpreted them.
In addition to the simple echo, an "interpreted" feedback to all commands is
provided in the next section of the standard output. Checking this part of the
output is also very useful, because it helps making sure that the user's
intentions have been expressed correctly and understood by the code. See
Chapter 9} on FLUKA output for a detailed description.
If a line contains an exclamation mark (!) all following characters are
replaced by blanks. This feature can be used for short in-line comments which
will not be echoed in output.
The order of input commands is generally free, with only a few exceptions
reported in Chapter 7}. Therefore, the order suggested in the following should
not be considered as mandatory, but only one of the possible ways to write
FLUKA input.
2.2.2} Input alignment
----------------------
Be careful to properly align keywords and numbers. Format is not free, unless a
command is issued at the beginning of input: see option GLOBAL or FREE.
Even in the free format for the input file, the part of the input describing the
geometry can still be written in fixed format (which is different from the
general FLUKA input format, see Chap. 6}). There is the possibility of having
free format also for the geometry part: this can also be activated using the
GLOBAL command.
In fixed format, in order to ensure proper alignment, a comment line showing a
scale can be used anywhere in the input file, for instance:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
In numerical fields, blanks are treated as zero. Therefore, numbers written
with a decimal period and without an exponent (e.g. 1.2345) can be placed
anywhere inside their respective format fields, For instance, the following two
input lines are equally acceptable:
BEAM 200. 0.2 1.5 1.2 0.7 1.0 PROTON
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
BEAM 200. 0.2 1.5 1.2 0.7 1.0PROTON
If a number is written in exponential notation (e.g. 2.3E5) or in integer form
(without decimal point), it must be aligned to the right of the field.
Depending on the platform and the compiler, sometimes the number is correctly
interpreted even if the alignment rule is not respected. However THIS IS NOT
GUARANTEED AND THE RIGHT ALIGNMENT RULE SHOULD ALWAYS BE FOLLOWED.
For instance in:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
BEAM 2.E2 0.2 1.5 1.2 0.7 1. PROTON
the first value might be interpreted as 2.E200. Another case is the following:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
BEAM 200. 0.2 1.5 1.2 0.7 1 PROTON
here the last numerical field would be interpreted as 1000000000. To avoid
mistakes due to this kind of input errors, the present FLUKA versions now
recognise such potential problems and the program is forced to stop. At the
same time a message is printed on the standard output file, as shown here for
the above example:
*** The 6th field 1 of the following input card ***
BEAM 200. 0.2 1.5 1.2 0.7 1 PROTON
*** does not contain a valid formatted fortran real number!!! ***
*** It is ambiguous and it could be read differently on different compilers ***
*** depending how strictly the blank=0 formatted input rule is implemented ***
Keywords (character strings such as BEAM and PROTON) must be aligned to the
left of their field and must be in upper case. An exception is the continuation
character & used in some commands, which can be placed anywhere within its
10-characters field.
Non-numerical values of WHATs ("names") can be aligned anywhere within the
corresponding fixed-format fields. Sometimes a special option requires a region
or a particle number to be entered with a negative sign: in this case the
equivalent name must also be entered preceded by a minus sign.
2.2.3} A simple example
-----------------------
Let us now consider a simple starting application. We want to calculate the
charged pion fluence produced by a monochromatic proton beam of momentum
50 GeV/c impinging on a 5 cm thick beryllium target of simple shape: a small
parallelepiped (20 cm x 20 cm x 5 cm). A further simplification will be made
for the purpose of this example, neglecting all the surrounding environment and
substituting it with ideal vacuum.
We will guide the reader through the different parts of a possible input file
suited for this application. The information which follows is meant to serve as
a guide, but does not cover all the important points. It is recommended that
for each option card selected, the user read carefully the relevant manual
entry, and especially the explanatory notes.
2.2.4} The title
------------------
Typically, an input file begins with a TITLE card followed by one line of text
describing the problem, or identifying that particular run, or providing some
kind of generic information. In our case, for example:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
TITLE
Charged pion fluence inside and around a proton-irradiated Be target
Further information can be provided by comment cards, but the title, because it
is printed at the top of the standard output and of each estimator output, is a
useful reminder of what the corresponding file is about. In addition, the title
is printed in all separate output files (error file, estimator files etc.)
together with the date and time of the FLUKA run, allowing to keep track of
their origin.
Commands such as GLOBAL and DEFAULTS, if needed, must immediately follow. Since
this is intended as a beginner's guide, these can be ignored here (for most
common problems the defaults provided are sufficient). Let us recall that
without specifying a DEFAULT value, the NEW-DEFAults set of FLUKA parameters is
loaded.
2.2.5} Definition of the primary particles
--------------------------------------------
All "events" or "histories" are initiated by primary particles, which in the
simplest case are monoenergetic, monodirectional and start from a single point
in space (pencil beam). The particle energy (or momentum) is defined by option
BEAM, and their starting position and direction by option BEAMPOSit. These two
commands can be used also to define particle beams having a simple angular or
momentum distribution (Gaussian or rectangular), or a simple transverse profile
(Gaussian, rectangular or annular). Isotropic or semi-isotropic angular
emission can be described as a special case of an angular rectangular
distribution.
For particle sources with more complex distributions in energy, space and
direction, the user must write, compile and link a special routine (SOURCE),
following the instructions given in Chap. 13}, and input a card SOURCE.
A summary of the input data concerning primary particles is printed in the
standard output under the title "Beam properties".
The beam definition for our example can be the following (monochromatic,
monodirectional proton beam of momentum 50 GeV/c):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
BEAM 50.E+00 PROTON
In our example, the beam starting point is given by:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
BEAMPOS 0.0 0.0 -50.0
In the cartesian geometry used by FLUKA, the previous card means that the beam
is injected at x, y, z cordinates: 0, 0, -50 cm and is directed along the
positive z axis. Of course, the choice of the point of injection, the
direction, etc., must be coherent with the geometrical description of the
set-up, as discussed in the following section.
2.2.6} The geometry
---------------------
The input for the Combinatorial Geometry (bodies, regions and optional region
volumes) must be immediately preceded by a GEOBEGIN card and immediately
followed by a GEOEND card. These two cards follow the normal FLUKA format. It
is recalled that the format for the geometry has its own special rules,
described in Chap. 8}.
Comment lines in the geometry input have an asterisk in first position as in
the rest of FLUKA input (but on-line comments are not allowed). Body numerical
data can be written in two different formats, a "short" one (field length 10)
and a "long" one (field length 22). The latter one is to be preferred when
higher precision is needed, for instance when using bodies such as truncated
cones, cylinders or planes not aligned with axes. It must be realised that
using too few decimals can cause geometry errors when bodies are combined into
regions (portions of space not defined or doubly defined).
The whole geometry must be surrounded by a region of "blackhole" limited by a
closed body (generally an RPP parallelepiped). It is often a good idea to make
this body much larger than the minimum required size: this makes easier to
introduce possible future extensions. In some cases, as in our basic example,
it is also useful to surround the actual geometry by a region of ideal vacuum,
and to have the blackhole region surrounding the vacuum. This can be useful,
for instance, in order to start the trajectory of the primary particles
outside the physical geometry (a particle may not be started on a boundary).
Both the body input section and the region input section must be ended with an
END card. Optionally, region volumes can be input between the region END card
and the GEOEND card (this option can be requested by setting a special flag in
the Geometry title card, see Chap. 8}). The only effect of specifying region
volumes is to normalise per cm3 the quantities calculated via the SCORE option
(see below): for other estimators requiring volume normalisation the volume is
input as part of the detector definition (USRTRACK, USRCOLL, USRYIELD), or is
calculated directly by the program (USRBIN).
The GEOEND card indicates the end of the geometry description, but can also be
used to invoke the geometry debugger.
The geometry output is an expanded echo of the corresponding input, containing
information also on memory allocation and on the structure of composite regions
made of several sub-regions by means of the OR operator.
A possible realisation of the geometry set up for our basic example can be seen
in the Figure below:
z ^ -----------------------------------
| / ______________________ /|
| / / / / |
| ----------------------------------- |
| | / vacuum (region 2) / | | |
| | ------------------------ | | |
| | | ___________ | | | |
| | | / Be /| | | | |
| | | ------------ | | | | |
| | | | (reg. 4) |/| | | | |
| | | ----------- | | | | |
| | | | (reg. 3) |/ | | | |
+-- | | ------------ | | | |-------->
/ | | ^ | / | | y
/ | | | Beam |/ | |
/ | ------------------------ | /
/ | Blackhole (region 1) |/
/ -----------------------------------
x
Only four bodies are used here: an RPP body (Rectangular Parallelepiped, body
no. 3) to define a volume which will be the Be target region, inside another
larger RPP body (no. 2), which will be filled with ideal vacuum and in turn is
contained inside another larger RPP body (no. 1), to define the blackhole
region. The fourth body, an XYP half-space (defined by a plane perpendicular to
the z axis), will be used to divide the target into 2 different regions: the
upstream half will be defined as the portion of body 3 contained inside the
half-space, and the downstream half as the portion outside it. Therefore,
region "3" (the upstream half of the target) is the part of body no. 3 which is
also inside body 4, while region "4" (downstream half of the target) is the
part of body no. 3 which is not inside body 4. Region "2" (the vacuum around
the target) is defined as the inside of body no. 2 from which body no. 3 is
subtracted. Region "1" is simply the interior of body no. 1 from which body
no. 2 is subtracted.
Note that bodies and regions can be identified by numbers, as described above,
or with names (alphanumeric strings). The latter option is recommended, since
it makes the preparation of the geometry much easier, especially if free
format is also chosen. Here below we will show both possibilities.
The beam starting point has been chosen so that it is in the vacuum, outside
the target region.
The geometry part of the input file can then be written as:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
GEOBEGIN COMBINAT
A simple Be target inside vacuum
RPP 1-5000000.0+5000000.0-5000000.0+5000000.0-5000000.0+5000000.0
RPP 2-1000000.0+1000000.0-1000000.0+1000000.0 -100.0+1000000.0
RPP 3 -10.0 +10.0 -10.0 +10.0 0.0 +5.0
* plane to separate the upstream and downstream part of the target
XYP 4 2.5
END
* black hole
BH1 5 +1 -2
* vacuum around
VA2 5 +2 -3
* Be target 1st half
BE3 5 +3 +4
* Be target 2nd half
BE4 5 +3 -4
END
GEOEND
The same geometry can be described in name-based free format as follows:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
GEOBEGIN COMBNAME
A simple Be target inside vacuum
RPP blakhole -5000000.0 +5000000.0 -5000000.0 +5000000.0 -5000000.0 +5000000.0
RPP vacumbox -1000000.0 +1000000.0 -1000000.0 +1000000.0 -100.0 +1000000.0
RPP betarget -10.0 +10.0 -10.0 +10.0 0.0 +5.0
* plane to separate the upstream and downstream part of the target
XYP cutplane 2.5
END
* black hole
Blckhole 5 +blakhole -vacumbox
* vacuum around
Vacarund 5 +vacumbox -betarget
* Be target 1st half
UpstrBe 5 +betarget +cutplane
* Be target 2nd half
DwnstrBe 5 +betarget -cutplane
END
GEOEND
2.2.7} Materials
------------------
Each geometry region is supposed to be filled with a homogeneous material, or
with vacuum, or with "blackhole". The latter is a fictitious material used to
terminate particle trajectories: any particle is discarded when reaching a
blackhole boundary. Materials can be simple elements or compounds, where an
element can have either natural composition or consist of a single nuclide,
and compound indicates a chemical compound or a mixture or an alloy (or an
isotopic mixture) of known composition.
An element can be either predefined (see list in 5}) or defined by a MATERIAL
card giving its atomic number, atomic mass, density, name and a material
identification number > 2. The material number can be chosen by the user, with
the restriction that all lower numbers must also be defined (but not
necessarily used).
Number 1 is reserved for blackhole and 2 for ideal vacuum. There are 25
predefined materials; but each of the numbers from 3 to 25 can be redefined
freely, overriding the default definition. However, a predefined material
can only be redefined using the same name by assigning to it a number equal
to the original one.
Materials can also be defined with higher numbers, provided no gaps are left in
the numbering sequence. For instance a material cannot be defined to have
number 28 unless also 26 and 27 have been defined.
A compound is defined by a MATERIAL card plus as many COMPOUND cards as needed
to describe its composition. The MATERIAL card used to define a compound
carries only the compound name, density and material number (atomic number and
atomic mass having no meaning in this case).
Materials predefined or defined in the standard input are referred to as "FLUKA
materials", to distinguish them from materials available in the low-energy
neutron cross section library (called "low-energy cross section materials).
When transport of low-energy neutrons (E < 20 MeV) is requested (explicitly
or by the chosen defaults), a correspondence is needed between each elemental
(i.e. not compound) "FLUKA material" and one of the "low-energy cross section
materials" available in the FLUKA low-energy neutron library. The default
correspondence is set by the name: and if more than one material with that name
exist in the neutron library, the first in the list with that name (see
Chap. 10}) is assumed by default. The default can be changed using option
LOW-MAT.
In the case of our example, only Beryllium is necessary, apart from blackhole
and vacuum. In principle, since Beryllium is one of the pre-defined FLUKA
materials, this part could even be omitted. However, for pedagogical reasons
the following card is proposed, where index 5 is assigned to the target
material:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
MATERIAL 4.0 9.0122 1.848 5.0 BERYLLIU
Notice that the chosen name is BERYLLIU and not BERYLLIUM, in order to match
the name in the list of "low-energy cross section materials" for low
energy neutrons (see Chap. 10}), where material names have a maximum length of
8 characters.
The standard output concerning materials is very extended. First a list of
multiple scattering parameters (printed by subroutine MULMIX) is reported for
each material requested. This is mostly of scarce interest for the normal user,
except for a table giving for each requested material the proportion of
components, both by number of atoms (normalised to 1) and by weight (normalised
to material density). The same information is repeated later on in another
table entitled "Material compositions".
If low-energy neutron transport has been requested (explicitly or by a chosen
default), the following section reports the relevant material information: in
particular, a table entitled "Fluka to low en. xsec material correspondence"
specifying which material in the neutron cross section library has been mapped
to each input material. Note that a much more detailed cross section
information can be obtained by setting a printing flag (WHAT(4)) in the
LOW-NEUT command.
The Table "Material compositions" contains information about the requested
materials, those pre-defined by default and the elements used to define
compounds. In addition to effective atomic and mass number, density and
composition, the table shows the value of some typical quantities: inelastic
and elastic scattering length for the beam particles (not valid for electron
and photon beams), radiation length and inelastic scattering length for 20
MeV neutrons.
The next table contains material data related to stopping power (average
excitation energy, density effect parameters, and pressure in the case of
gases) plus information about the implementation of various physical effetcs
and the corresponding thresholds and tabulations.
The last material table is printed just before the beginning of the history
calculations, and concerns the "Correspondence of regions and EMF-FLUKA
material numbers and names".
2.2.8} Assigning materials to regions
---------------------------------------
A material must be associated to each of the geometry regions, except to those
defined as blackhole. This is done in a very straightforward way by command
ASSIGNMAt. Assigning explicitly blackhole to a region is allowed, but is not
necessary (except for region 2) because a region is blackhole by default unless
another material has been associated to it. (Region 2, if not assigned a
material, is COPPER by default).
The table entitled "Regions: materials and fields", in the standard output, can
be consulted to check that material assignment has been done as desired.
For the present example the assignment could be:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
* Be target, 1st and 2nd half
ASSIGNMAT 5.0 3.0 4.0
* External Black Hole
ASSIGNMAT 1.0 1.0
* Vacuum
ASSIGNMAT 2.0 2.0
The same material assignments in a name-based input would be the following
(BLCKHOLE and VACUUM are the predefined names of material 1 and 2):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
* Be target, 1st and 2nd half
ASSIGNMAT BERYLLIU UpstrBe DwnstrBe
* External Black Hole
ASSIGNMAT BLCKHOLE Blckhole
* Vacuum
ASSIGNMAT VACUUM Vacarund
2.2.9} Production thresholds
------------------------------
The implicit NEW-DEFA default setting adopted in the example, sets, among other
things, the production and transport threshold of heavy particles to 10 MeV.
Production thresholds for e+e- and photons must be explicitly set using the
EMFCUT command for all materials in the problem. Let us choose also in this
case a 10 MeV threshold for the single material of the example (previously
marked with material index 5 and name BERYLLIU). Following the instructions
about the EMFCUT option, the card can be written as:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
* e+e- and gamma production threshold set at 10 MeV
EMFCUT -0.010 0.010 1.0 5.0 PROD-CUT
where the first numerical field is the threshold for e+e- (the minus sign
meaning kinetic energy) and the second is for photons. The material number is
given in the fourth numerical field. For details on all other parameters, and
for other possibilities (for example how to introduce a transport cut-off
different from production threshold) the user should accurately consult the
Notes to EMFCUT.
In a name-based input, the above card could be:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
EMFCUT -0.010 0.010 1.0 BERYLLIU PROD-CUT
Production and transport threshold for all other particles can be overwritten
using the PART-THR command.
2.2.10} Estimators and Detectors
---------------------------------
Even though, for setting-up purposes, it is conceivable that no estimator be
requested in a preliminary run, in most cases FLUKA is used to predict the
expectation value of one or more quantities, as determined by the radiation
field and by the material geometry described by the user: for such a task
several different estimators are available. The quantities which are most
commonly scored are dose and fluence, but others are available. Dose equivalent
is generally calculated from differential fluence using conversion
coefficients.
The simplest estimator available to the user is a historical vestige, survived
from the "ancient" FLUKA (pre-1988) where the only possible output quantities
were energy deposition and star density in regions. It is invoked by option
SCORE, requesting evaluation of one to four different quantities. These can be
different forms of energy density (proportional to dose), or of star density
(approximately proportional to fluence of selected high-energy hadrons).
For this estimator, the detectors are pre-determined: the selected quantities
are reported for each region of the geometry. The corresponding results,
printed in the main output immediately after the last history has been
completed, are presented in 6 columns as follows:
region region region first second third fourth
number name volume quantity quantity quantity quantity
1 ...... ...... ........ ........ ........ ........
2 ...... ...... ........ ........ ........ ........
etc.
on a line for each geometry region. The region volumes (in cm3) have the value
1.0, or values optionally supplied by the user at the end of the geometry
description. All other columns are normalised per region volume and per primary
particle.
The input could be as follows:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
* score in each region energy deposition and stars produced by primaries
SCORE 208.0 210.0
The same, in a name-based input:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
SCORE ENERGY BEAMPART
Other estimators are more flexible: the corresponding detectors can be
requested practically in any number, can be written as unformatted or text
files, and in most cases can provide differential distributions with respect to
one or more variables. On the other hand, their output is presented in a very
compact array form and must generally be post-processed by the user. For this
purpose several utility programs are available: but output in text format can
even be exported to a spreadsheet for post-processing.
USRBDX is the command required to define a detector for the boundary-crossing
estimator. It calculates fluence or current, mono- or bi-directional,
differential in energy and angle on any boundary between two selected regions.
The area normalisation needed to obtain a current in particles per cm2 is
performed using an area value input by the user: if none is given, the area is
assumed to be = 1 cm2 and the option amounts simply to counting the total number
of particles crossing the boundary. Similarly if fluence is scored, but in this
case each particle is weighted with the secant of the angle between the
particle trajectory and the normal to the boundary surface at the crossing
point.
This is one of the estimators proposed for our example. We will request two
boundary crossing detectors, one to estimate fluence and one for current, of
particles crossing the boundary which separates the upstream and the downstream
half of the target.
The following group of cards can be inserted:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
* Boundary crossing fluence in the middle of the target (log intervals, one-way)
USRBDX 99.0 209.0 -47.0 3.0 4.0 400. piFluenUD
USRBDX +50.0 +50.0 0.0 10.0 &
*
* Boundary crossing current in the middle of the target (log intervals, one-way)
USRBDX -1.0 209.0 -47.0 3.0 4.0 400. piCurrUD
USRBDX +50.00 +50.0 0.0 10.0 &
The same, in a name-based input:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
USRBDX 99.0 PIONS+- -47.0 UpstrBe DwnstrBe 400. piFluenUD
USRBDX +50.0 +50.0 0.0 10.0 &
*
USRBDX -1.0 PIONS+- -47.0 UpstrBe DwnstrBe 400. piCurrUD
USRBDX +50.00 +50.0 0.0 10.0 &
According to the instructions reported in the description of the USRBDX
command, it can be seen that the combined fluence of pi+ and pi- is requested
only when particles exit region "3" ("UpstrBe", the upstream half of the target)
to enter into region "4" ("DwnstrBe", the downstream half). There is no interest
in the reverse, therefore "one-way scoring" is selected. The scoring of the
first detector will be inverse cosine-weighted, in order to define correctly the
fluence. Results will be written unformatted on unit 47 for both quantities (so
there will be two "Detectors" on the same output unit, but this is not
mandatory). The energy distribution is going to be binned in 50 logarithmic
intervals, from 0.001 GeV (the default minimum) up to 50 GeV. The angular
distribution will be binned into 10 linear solid angle intervals from 0. to 2pi
(having chosen the one-way estimator). The results will be normalised dividing
by the area of the boundary (separation surface between the two regions, in
this case the transverse section of the target), and will provide a double-
differential fluence or current averaged over that surface in cm-2 GeV-1 sr-1.
Other fluence scoring options, based respectively on a track-length and on a
collision estimator, are USRTRACK and USRCOLL which request the estimation of
volume-averaged fluence (differential in energy) for any type of particle or
family of particles in any selected region. The volume normalisation needed to
obtain the fluence as track-length density or collision density is performed
using a volume value input by the user: if none is given, the volume is assumed
to be = 1 cm3 and the result will be respectively the total track-length in
that region, or the total number of collisions (weighted with the mean free
path at each collision point).
Note that if additional normalisation factors are desired (e.g. beam power)
this can be achieved by giving in input the "volume" or "area" value
multiplied or divided by those factors. Options USRTRACK, USRCOLL and
USRBDX can also calculate energy fluence, if the "particle" type is set
= 208 (energy, name ENERGY) or 211 (electron and photon energy, name
EM-ENRGY).
In our example, we are requesting two track-length detectors, to get the
average fluence in the upstream half and in the downstream half of the target,
respectively.
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
* Tracklength fluence inside the target, Upstream part and Downstream part
* Logarithmic energy intervals
USRTRACK -1.0 209.0 -48.0 3.0 1000.0 20. piFluenU
USRTRACK 50.0 0.001 &
USRTRACK -1.0 209.0 -49.0 4.0 1000.0 20. piFluenD
USRTRACK 50.0 0.001 &
The volume input is 20 x 20 x 2.5 = 1000 cm3. We are requesting an energy
spectrum in 20 logarithmic intervals between 0.001 and 50 GeV. In this case, we
ask that the corresponding output be printed, unformatted, on two different
files.
In a name-based input, the above example could be:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
USRTRACK -1.0 PIONS+- -48.0 UpstrBe 1000.0 20. piFluenU
USRTRACK 50.0 0.001 &
USRTRACK -1.0 PIONS+- -49.0 DwnstrBe 1000.0 20. piFluenD
USRTRACK 50.0 0.001 &
Option USRBIN provides detailed space distributions of energy deposition, star
density or integrated fluence (not energy fluence, unless by writing a special
user routine). Using some suitable graphics package, USRBIN output can be
presented in the form of colour maps. Programs for this purpose are available
in the $FLUPRO/flutil directory (pawlevbin.f and various kumac files), and
on the FLUKA website www.fluka.org.
USRBIN results are normalised to bin volumes calculated automatically by the
program (except in the case of region binning and special 3-variable binning
which are only seldom used).
The binning structure does not need to coincide with any geometry region. In
our example we propose to ask for two Cartesian space distributions, one of
charged pion fluence and one of total energy deposited. The first will extend
over a volume larger than the target, because fluence can be calculated even in
vacuum. Energy deposition, on the other hand, will be limited to the target
volume.
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
* Cartesian binning of the pion fluence inside and around the target
USRBIN 10.0 209.0 -50.0 50.0 50.0 50. piFluBin
USRBIN -50.0 -50.0 -10.0 100.0 100.0 60.0 &
* Cartesian binning of the deposited energy inside the target
USRBIN 10.0 208.0 -51.0 10.0 10.0 5. Edeposit
USRBIN -10.0 -10.0 0.0 20.0 20.0 5.0 &
Also in this case, the request is for output on two separate files.
Or, using names:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
USRBIN 10.0 PIONS+- -50.0 50.0 50.0 50. piFluBin
USRBIN -50.0 -50.0 -10.0 100.0 100.0 60.0 &
USRBIN 10.0 ENERGY -51.0 10.0 10.0 5. Edeposit
USRBIN -10.0 -10.0 0.0 20.0 20.0 5.0 &
Angular yields around a fixed direction of particles exiting a given surface
can be calculated using option USRYIELD. The results are double-differential
distributions with respect to a pair of variables, one of which is generally
energy-like (kinetic energy, momentum, etc.) and the other one angle-like (polar
angle, rapidity, Feynman-x, etc.) Distributions in LET (Linear Energy Transfer)
can also be requested by this option. An arbitrary normalisation factor can be
input.
Another commonly used scoring option is RESNUCLEi, which calculates residual
nuclei production in a given region. A normalisation factor (usually the region
volume) can be input.
A detailed summary of the requested estimators is printed on standard output.
The same information is printed in the same format in estimator ASCII output
files, and is available in coded form in unformatted estimator files.
2.2.11} Initialisation of the random number sequence
-----------------------------------------------------
The random number sequence used in a run is initialised by default by the seeds
contained in file random.dat provided with the code. To calculate the statistical
error of the results, it is necessary to perform other independent runs (at
least 4 or 5), each with a different independent initialisation, using the seeds
written by the program at the end of each run. The rfluka script provided with
the code on UNIX and LINUX platforms takes care of this task, provided the
following card is issued in the input file:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
RANDOMIZE 1.0 0.0
The seeds of the random number generator are printed on a special file in
hexadecimal form at the end of each group of histories (the size of
a group depends on the number of histories requested in the START card).
Instead of getting the seeds from the last run, it is also possible to
initialise directly another independent random number sequence by setting the
second RANDOMIZe parameter equal to a different number, for instance:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
RANDOMIZE 1.0 1198.
2.2.12} Starting signal and number of requested histories
----------------------------------------------------------
At the end of the input file, a START card is mandatory in order to actually
start the calculation. That card must indicate also the number of particle
histories requested. The run, however, may be completed before all the histories
have been handled in two cases: if a time limit has been met (on some systems)
or if a "stop file" is created by the user (see instructions in a Note to option
START). The START card is optionally followed by a STOP card. For example, if
the user wants to generate 100000 histories, the input file can be closed with
the following two cards:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
START 100000.0
STOP
2.2.13} The sample input file
-----------------------------
In summary, the input file for our basic example (example.inp), name-based and
written in fixed format, could be the following:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
TITLE
Charged pion fluence inside and around a proton-irradiated Be target
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
BEAM 50.E+00 PROTON
BEAMPOS 0.0 0.0 -50.0
*
GEOBEGIN COMBNAME
A simple Be target inside vacuum
RPP blakhole -5000000.0 +5000000.0 -5000000.0 +5000000.0 -5000000.0 +5000000.0
RPP vacumbox -1000000.0 +1000000.0 -1000000.0 +1000000.0 -100.0 +1000000.0
RPP betarget -10.0 +10.0 -10.0 +10.0 0.0 +5.0
* plane to separate the upstream and downstream part of the target
XYP cutplane 2.5
END
* black hole
Blckhole 5 +blakhole -vacumbox
* vacuum around
Vacarund 5 +vacumbox -betarget
* Be target 1st half
UpstrBe 5 +betarget +cutplane
* Be target 2nd half
DwnstrBe 5 +betarget -cutplane
END
GEOEND
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
MATERIAL 4.0 9.0122 1.848 5.0 BERYLLIU
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
* Be target, 1st and 2nd half
ASSIGNMAT BERYLLIU UpstrBe DwnstrBe
* External Black Hole
ASSIGNMAT BLCKHOLE Blckhole
* Vacuum
ASSIGNMAT VACUUM Vacarund
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
* e+e- and gamma production threshold set at 10 MeV
EMFCUT -0.010 0.010 1.0 BERYLLIU PROD-CUT
* score in each region energy deposition and stars produced by primaries
SCORE ENERGY BEAMPART
* Boundary crossing fluence in the middle of the target (log intervals, one-way)
USRBDX 99.0 PIONS+- -47.0 UpstrBe DwnstrBe 400. piFluenUD
USRBDX +50.0 +50.0 0.0 10.0 &
* Boundary crossing current in the middle of the target (log intervals, one-way)
USRBDX -1.0 PIONS+- -47.0 UpstrBe DwnstrBe 400. piCurrUD
USRBDX +50.00 +50.0 0.0 10.0 &
* Tracklength fluence inside the target, Upstream part and Downstream part
* Logarithmic energy intervals
USRTRACK -1.0 PIONS+- -48.0 UpstrBe 1000.0 20. piFluenU
USRTRACK 50.0 0.001 &
USRTRACK -1.0 PIONS+- -49.0 DwnstrBe 1000.0 20. piFluenD
USRTRACK 50.0 0.001 &
* Cartesian binning of the pion fluence inside and around the target
USRBIN 10.0 PIONS+- -50.0 50.0 50.0 50. piFluBin
USRBIN -50.0 -50.0 -10.0 100.0 100.0 60.0 &
* Cartesian binning of the deposited energy inside the target
USRBIN 10.0 ENERGY -51.0 10.0 10.0 5. Edeposit
USRBIN -10.0 -10.0 0.0 20.0 20.0 5.0 &
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
RANDOMIZE 1.0
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
START 100000.0
STOP
The same input file, number-based and using the free format option for the FLUKA
commands, but not for the geometry, can instead be written as follows:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
TITLE
Charged pion fluence inside and around a proton-irradiated Be target
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
GLOBAL 2.0
BEAM 50.E+00 0. 0. 0. 0. 0. PROTON
BEAMPOS 0. 0. -50.0 0. 0. 0. ' '
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
GEOBEGIN COMBINAT
A simple Be target inside vacuum
RPP 1-5000000.0+5000000.0-5000000.0+5000000.0-5000000.0+5000000.0
RPP 2-1000000.0+1000000.0-1000000.0+1000000.0 -100.0+1000000.0
RPP 3 -10.0 +10.0 -10.0 +10.0 0.0 +5.0
XYP 4 2.5
END
* black hole
BH1 5 +1 -2
* vacuum around
VA2 5 +2 -3
* Be target 1st half
BE3 5 +3 +4
* Be target 2nd half
BE4 5 +3 -4
END
GEOEND
MATERIAL 4.0 9.0122 1.848 5.0 0. 0. BERYLLIU
* Be target, 1st and 2nd half
ASSIGNMAT 5.0 3.0 4.0 0. 0. 0.
* External Black Hole
ASSIGNMAT 1.0 1.0 0. 0. 0. 0.
* Vacuum
ASSIGNMAT 2.0 2.0 0. 0. 0. 0.
* e+e- and gamma production threshold set at 10 MeV
EMFCUT -0.010 0.010 1.0 5.0, , , PROD-CUT
* score in each region energy deposition and stars produced by primaries
SCORE 208.0 210. 0. 0. 0. 0.
* Boundary crossing fluence in the middle of the target (log intervals, one-way)
USRBDX 99.0 +209.0 -47.0 3.0 4.0 +400.0 piFluenUD
USRBDX +50.00 0. +50.0 0. 0. 10.0 &
* Boundary crossing current in the middle of the target (log intervals, one-way)
USRBDX -1.0 +209.0 -47.0 3.0 4.0 +400.0 piCurrUD
USRBDX +50.00 0. +50.0 0. 0. 10.0 &
* Tracklength fluence inside the target, Upstream part and Downstream part
* Logarithmic energy intervals
USRTRACK -1.0 209.0 -48.0 3.0 1000.0 20. piFluenU
USRTRACK 50.0 0.001 0. 0. 0. 0. &
USRTRACK -1.0 209.0 -49.0 4.0 1000.0 20. piFluenD
USRTRACK 50.0 0.001 0. 0. 0. 0. &
* Cartesian binning of the pion fluence inside and around the target
USRBIN 10.0 209.0 -50.0 50.0 50.0 50. piFluBin
USRBIN -50.0 -50.0 -10.0 100.0 100.0 60.0 &
* Cartesian binning of the deposited energy inside the target
USRBIN 10.0 208.0 -51.0 10.0 10.0 5. Edeposit
USRBIN -10.0 -10.0 0.0 20.0 20.0 5.0 &
RANDOMIZE 1.0 0. 0. 0. 0. 0.
START 100000.0 0. 0. 0. 0. 0.
STOP
Other possible combinations are name-based free format and number-based fixed
format.
2.2.14} Running FLUKA
---------------------
It is advisable, but not mandatory, to keep separate the $FLUPRO directory
from that or those where calculations are run and input files are kept.
For instance, flukawork:
cd /home/user/flukawork
As mentioned above, the rfluka script in $FLUPRO/flutil should be used to drive
the FLUKA run. In the following it is supposed that the user is going to ask
for five statistically independent runs, each one made of 100000 histories, of
the proposed basic example. The command is:
$FLUPRO/flutil/rfluka -N0 -M5 example &
(on LINUX/UNIX, the & character allows to run the program in the background
without "freezing" the terminal window).
The script creates a temporary subdirectory called fluka_nnnn where
nnnn is tbe number of the subprocess. For instance, when the first
run (or "cycle") starts, the user will see on the terminal lines similar
to the following ones:
$TARGET_MACHINE = Linux
$FLUPRO = /home/user/flupro
2789: old priority 0, new priority 10
Initial seed already existing
Running fluka in /home/user/flukawork/fluka_2789
================================ Running FLUKA for cycle # 1 ===================
At the end of each cycle the output files will be copied onto the running
directory, the temporary directory will be erased and a new one will be created
where the next run will take place. The names of the output files from each run
are built by appending to the input file name the run number and an extension
depending on their content: .out for the standard output, .err for the error
file, .log for the log file and _fort.nn for the estimator files (with
nn = absolute value of the selected output unit). The file containing the
random number seeds will be called "ran".
The error file may contain error messages related to the event generators (for
instance when the program does not manage to conserve exactly energy or another
quantity) or to the geometry tracking. Most of those are generally only warning
messages which can be ignored unless there is a large number of them.
The log file generally contains messages related to fatal errors (input errors,
overflow, etc.)
During a multiple run, lines like the following will appear on the user's
screen:
================================ Running FLUKA for cycle # 1 ====================
Removing links
Removing temporary files
Saving output and random number seed
Saving additional files generated
Moving fort.47 to /home/fasso/Fluka/test/example01_fort.47
Moving fort.48 to /home/fasso/Fluka/test/example01_fort.48
Moving fort.49 to /home/fasso/Fluka/test/example01_fort.49
Moving fort.50 to /home/fasso/Fluka/test/example01_fort.50
Moving fort.51 to /home/fasso/Fluka/test/example01_fort.51
================================ Running FLUKA for cyle # 2 ====================
Removing links
Removing temporary files
Saving output and random number seed
Saving additional files generated
Moving fort.47 to /home/fasso/Fluka/test/example002_fort.47
Moving fort.48 to /home/fasso/Fluka/test/example002_fort.48
Moving fort.49 to /home/fasso/Fluka/test/example002_fort.49
Moving fort.50 to /home/fasso/Fluka/test/example002_fort.50
Moving fort.51 to /home/fasso/Fluka/test/example002_fort.51
================================ Running FLUKA for cycle # 3 ===================
.....
================================ Running FLUKA for cycle # 4 ===================
.....
================================ Running FLUKA for cycle # 5 ===================
Removing links
Removing temporary files
Saving output and random number seed
Saving additional files generated
Moving fort.47 to /home/fasso/Fluka/test/example005_fort.47
Moving fort.48 to /home/fasso/Fluka/test/example005_fort.48
Moving fort.49 to /home/fasso/Fluka/test/example005_fort.49
Moving fort.50 to /home/fasso/Fluka/test/example005_fort.50
Moving fort.51 to /home/fasso/Fluka/test/example005_fort.51
End of FLUKA run
At this time, in the working directory, the following new files exist:
example001_fort.47 example002_fort.47 .... example005_fort.47
example001_fort.48 example002_fort.48 .... example005_fort.48
example001_fort.49 example002_fort.49 .... example005_fort.49
example001_fort.50 example002_fort.50 .... example005_fort.50
example001_fort.51 example002_fort.51 .... example005_fort.51
example001.out example002.out .... example005.out
example001.err example002.err .... example005.err
In Chapter 9} the user can find a comprehensive description of the content of
the FLUKA standard output. For the purpose of this beginner's guide, it can
just be pointed out that, according to the content of the USRBDX command, the
files with extension fort.47 contain, in binary form, the boundary crossing
estimator output for the required pion fluence and current detectors (for more
details see Chap. 9}). These files must be combined together to produce a
table of values with their statistical errors which can be easily interfaced by
the user to some analysis codes and/or graphic visualisation tools. Similarly,
the files with extension fort.48 and fort.49 will contain the tracklength
estimator output, and those with extension fort.50 and fort.51 the output from
USRBIN.
2.2.15} Accessing results
-------------------------
Boundary crossing estimator
---------------------------
Binary files from the USRBDX estimator can be accessed by means of the usxsuw.f
readout code, which is located in the $FLUPRO/flutil directory.
That readout code can be easily compiled. For example, the same compiling and
linking FLUKA tools can be used for this purpose:
cd $FLUPRO/flutil
./lfluka usxsuw.f -o usxsuw
The simplest way, however, is to use the makefile which is available in the
$FLUPRO/flutil directory. In that directory, just type:
make
and all the postprocessing utilities will be compiled and linked.
In order to process the 5 output files produced by the proposed example, the
following interactive procedure can be used:
cd /home/user/flukawork
$FLUPRO/flutil/usxsuw
The readout code will ask for the first FLUKA estimator file name:
Type the input file:
For each estimator file the program will show the content of the TITLE card of
the FLUKA input file, the date and time of the FLUKA run and the number of
histories for the given run.
The request will be iterated until a blank line is given. This will be
interpreted as the end of the list of files, and then a name for the
output file prefix will be requested. Let's use, for example, the
name "pionbdx":
Type the input file: example001_fort.47
Charged pion fluence inside and around a proton-irradiated Be target
DATE: 7/15/ 5, TIME: 16:22:11
100000.
100000
Type the input file: example002_fort.47
Charged pion fluence inside and around a proton-irradiated Be target
DATE: 7/15/ 5, TIME: 16:23: 3
100000.
100000
Type the input file: example003_fort.47
Charged pion fluence inside and around a proton-irradiated Be target
DATE: 7/15/ 5, TIME: 16:23:54
100000.
100000
Type the input file: example004_fort.47
Charged pion fluence inside and around a proton-irradiated Be target
DATE: 7/15/ 5, TIME: 16:24:51
100000.
100000
Type the input file: example005_fort.47
Charged pion fluence inside and around a proton-irradiated Be target
DATE: 7/15/ 5, TIME: 16:25:45
100000.
100000
Type the input file:
Type the output file name: pionbdx
At this point the following 3 new files are produced:
pionbdx
pionbdx_sum.lis
pionbdx_tab.lis
The first one (pionbdx) is again a binary file that can be read out at any time
by usxsuw. The content of this file is statistically equivalent to that of the
sum of the files used to obtain it, and it can replace them to be combined with
further output files if desired (the usxsuw program takes care of giving it the
appropriate weight).
The other two files are ASCII text files.
Let us first examine pionbdx_sum.lis. This contains many comments which can
help the user to understand the results. Since by means of the USRBDX command
separate detectors for pion fluence and current have been requested, with their
output on the same logical unit, there will be two different sections in the
file, identified by the word "Detector": Detector no. 1 is for fluence and
Detector no. 2 is for current, because this is the order in which the
USRBDX commands have been given.
Let us inspect the output from Detector no. 1:
Charged pion fluence inside and around a proton-irradiated Be target
Total primaries run: 500000
Total weight of the primaries run: 500000.
Detector n: 1( 1) piFluenUD
(Area: 400. cmq,
distr. scored: 209 ,
from reg. 3 to 4,
one way scoring,
fluence scoring)
Tot. resp. (Part/cmq/pr) 8.6904905E-04 +/- 0.6976866 %
( --> (Part/pr) 0.3476196 +/- 0.6976866 % )
The total (summed) number of primaries (histories) is reported at first, then
the main features of USRBDX request are summarised. The following numbers
represent the energy and angle integrated fluence ("total response").
Here and later, the statistical error is always expressed in percentage.
After this heading, the differential fluence tabulation as a function of (pion)
energy, and integrated over solid angle, is reported, starting with the
boundaries of the energy bins. As a general convention, these values are given
from the highest to the lowest value:
**** Different. Fluxes as a function of energy ****
**** (integrated over solid angle) ****
Energy boundaries (GeV):
49.99992 40.27077 32.43475 26.12349 21.04029
16.94620 13.64875 10.99293 8.853892 7.131072
5.743484 4.625898 3.725775 3.000802 2.416896
1.946608 1.567831 1.262757 1.017045 0.8191454
0.6597533 0.5313764 0.4279793 0.3447017 0.2776285
0.2236066 0.1800965 0.1450527 0.1168279 9.4095118E-02
7.5785778E-02 6.1039131E-02 4.9161937E-02 3.9595842E-02 3.1891152E-02
2.5685664E-02 2.0687662E-02 1.6662188E-02 1.3420003E-02 1.0808695E-02
8.7055033E-03 7.0115575E-03 5.6472253E-03 4.5483690E-03 3.6633324E-03
2.9505091E-03 2.3763892E-03 1.9139835E-03 1.5415541E-03 1.2415934E-03
Lowest boundary (GeV): 1.0000000E-03
Flux (Part/GeV/cmq/pr):
1.5418744E-09 +/- 99.00000 % 4.8503271E-08 +/- 6.709127 %
2.3456116E-07 +/- 6.506497 % 5.9040013E-07 +/- 3.466331 %
1.2585346E-06 +/- 4.051404 % 2.5295039E-06 +/- 2.039807 %
4.6113087E-06 +/- 2.195296 % 7.6260553E-06 +/- 1.939942 %
1.2214471E-05 +/- 0.8310503 % 1.8394410E-05 +/- 0.6178440 %
2.6636921E-05 +/- 1.128397 % 3.6855919E-05 +/- 1.204921 %
5.1703457E-05 +/- 1.100655 % 6.9101960E-05 +/- 0.7564522 %
9.0419722E-05 +/- 1.799108 % 1.1945122E-04 +/- 1.256268 %
1.5757892E-04 +/- 0.8898824 % 1.9452766E-04 +/- 1.332425 %
2.4165030E-04 +/- 1.521364 % 3.0573772E-04 +/- 2.473622 %
3.6900895E-04 +/- 1.399170 % 4.4734811E-04 +/- 0.9543594 %
5.2953843E-04 +/- 1.964312 % 6.1596523E-04 +/- 1.349476 %
6.4003764E-04 +/- 3.323846 % 6.8828161E-04 +/- 0.9288639 %
6.8151421E-04 +/- 2.018673 % 7.0822553E-04 +/- 4.401796 %
7.4972271E-04 +/- 2.600316 % 6.9859857E-04 +/- 3.693749 %
6.8915845E-04 +/- 4.332464 % 6.6514849E-04 +/- 8.753220 %
6.4636284E-04 +/- 11.30834 % 5.5008888E-04 +/- 7.691558 %
4.3721433E-04 +/- 11.36630 % 3.2056248E-04 +/- 8.380781 %
4.2511927E-04 +/- 12.24571 % 2.2697043E-04 +/- 12.99932 %
2.0069227E-04 +/- 13.10813 % 1.7180138E-04 +/- 16.90801 %
9.9383309E-05 +/- 21.15753 % 2.9268101E-04 +/- 39.29378 %
1.5672133E-04 +/- 44.01294 % 2.1093644E-04 +/- 34.72458 %
7.4201569E-05 +/- 33.68359 % 7.2452240E-05 +/- 33.54827 %
8.6934262E-05 +/- 62.03180 % 1.0245090E-04 +/- 99.00000 %
1.6312006E-04 +/- 82.06016 % 1.3002084E-04 +/- 52.15991 %
Soon after, the cumulative fluence distribution as a function of energy is also
given:
**** Cumulative Fluxes as a function of energy ****
**** (integrated over solid angle) ****
Energy boundaries (GeV):
49.99992 40.27077 32.43475 26.12349 21.04029
16.94620 13.64875 10.99293 8.853892 7.131072
5.743484 4.625898 3.725775 3.000802 2.416896
1.946608 1.567831 1.262757 1.017045 0.8191454
0.6597533 0.5313764 0.4279793 0.3447017 0.2776285
0.2236066 0.1800965 0.1450527 0.1168279 9.4095118E-02
7.5785778E-02 6.1039131E-02 4.9161937E-02 3.9595842E-02 3.1891152E-02
2.5685664E-02 2.0687662E-02 1.6662188E-02 1.3420003E-02 1.0808695E-02
8.7055033E-03 7.0115575E-03 5.6472253E-03 4.5483690E-03 3.6633324E-03
2.9505091E-03 2.3763892E-03 1.9139835E-03 1.5415541E-03 1.2415934E-03
Lowest boundary (GeV): 1.0000000E-03
Cumul. Flux (Part/cmq/pr):
1.5001119E-08 +/- 99.00000 % 3.9507350E-07 +/- 7.326498 %
1.8754495E-06 +/- 5.464718 % 4.8765669E-06 +/- 1.819896 %
1.0029117E-05 +/- 1.898280 % 1.8370021E-05 +/- 1.277005 %
3.0616819E-05 +/- 0.6900454 % 4.6929261E-05 +/- 0.9553517 %
6.7972585E-05 +/- 0.7029299 % 9.3496434E-05 +/- 0.6531623 %
1.2326548E-04 +/- 0.5382378 % 1.5644032E-04 +/- 0.6154544 %
1.9392396E-04 +/- 0.6043725 % 2.3427299E-04 +/- 0.5368618 %
2.7679623E-04 +/- 0.5548110 % 3.2204165E-04 +/- 0.6000980 %
3.7011484E-04 +/- 0.6263003 % 4.1791250E-04 +/- 0.6480659 %
4.6573509E-04 +/- 0.7125404 % 5.1446725E-04 +/- 0.7778813 %
5.6183949E-04 +/- 0.8066853 % 6.0809392E-04 +/- 0.7142704 %
6.5219263E-04 +/- 0.7654761 % 6.9350738E-04 +/- 0.7260005 %
7.2808337E-04 +/- 0.8159186 % 7.5803063E-04 +/- 0.7573094 %
7.8191340E-04 +/- 0.7549785 % 8.0190296E-04 +/- 0.7531289 %
8.1894622E-04 +/- 0.7366922 % 8.3173712E-04 +/- 0.6872664 %
8.4189989E-04 +/- 0.6799491 % 8.4980001E-04 +/- 0.6579692 %
8.5598318E-04 +/- 0.6862395 % 8.6022145E-04 +/- 0.6667165 %
8.6293457E-04 +/- 0.6859071 % 8.6453673E-04 +/- 0.6995495 %
8.6624804E-04 +/- 0.6864265 % 8.6698390E-04 +/- 0.6886846 %
8.6750800E-04 +/- 0.6864119 % 8.6786930E-04 +/- 0.6882262 %
8.6803763E-04 +/- 0.6885374 % 8.6843700E-04 +/- 0.6933275 %
8.6860918E-04 +/- 0.6915213 % 8.6879585E-04 +/- 0.6911866 %
8.6884876E-04 +/- 0.6931223 % 8.6889038E-04 +/- 0.6942393 %
8.6893054E-04 +/- 0.6953420 % 8.6896872E-04 +/- 0.6967193 %
8.6901762E-04 +/- 0.6981055 % 8.6904905E-04 +/- 0.6976866 %
The numbers for the cumulative distribution have been obtained by multiplying
each value of the differential distribution by the corresponding energy bin
width (variable if the distribution is logarithmic as in our example). The
integral fluence in any given energy interval can be obtained as the difference
between the values of the cumulative distribution at the two bounds of that
interval.
Since more than one angular interval was requested, at this point the angular
distribution WITH RESPECT TO THE NORMAL AT THE BOUNDARY CROSSING POINT is
reported, both in steradians and in degrees:
**** Double diff. Fluxes as a function of energy ****
Solid angle minimum value (sr): 0.000000
Solid angle upper boundaries (sr):
0.6283185 1.256637 1.884956 2.513274 3.141593
3.769911 4.398230 5.026548 5.654867 6.283185
Angular minimum value (deg.): 0.000000
Angular upper boundaries (deg.):
25.84193 36.86990 45.57299 53.13010 60.00000
66.42182 72.54239 78.46304 84.26083 90.00000
Let us take for instance the energy bin between 0.345 GeV and 0.278 GeV:
Energy interval (GeV): 0.3447016 0.2776284
Flux (Part/sr/GeV/cmq/pr):
2.2090337E-04 +/- 2.271138 % 1.6099877E-04 +/- 2.023665 %
1.2373505E-04 +/- 3.802638 % 9.4749055E-05 +/- 2.419357 %
7.0389280E-05 +/- 5.640523 % 6.6853667E-05 +/- 9.292711 %
6.8042267E-05 +/- 5.421218 % 6.8482914E-05 +/- 11.91976 %
5.8157104E-05 +/- 2.943847 % 4.8027632E-05 +/- 39.71496 %
Flux (Part/deg/GeV/cmq/pr):
5.3710260E-06 +/- 2.271138 % 9.1729089E-06 +/- 2.023665 %
8.9330297E-06 +/- 3.802638 % 7.8776966E-06 +/- 2.419357 %
6.4377805E-06 +/- 5.640523 % 6.5410413E-06 +/- 9.292711 %
6.9850003E-06 +/- 5.421218 % 7.2676362E-06 +/- 11.91976 %
6.3026077E-06 +/- 2.943847 % 5.2580162E-06 +/- 39.71496 %
The same structure is then replicated for Detector no. 2:
Detector n: 2( 2) piCurrUD
(Area: 400. cmq,
distr. scored: 209 ,
from reg. 3 to 4,
one way scoring,
current scoring)
Tot. resp. (Part/cmq/pr) 7.1694393E-04 +/- 0.7243900 %
( --> (Part/pr) 0.2867776 +/- 0.7243900 % )
and so on.
Note that in this case the ratio between the calculated fluence (8.690E-04) and
the corresponding current (7.169E-04) is about 1.2. The ratio between the
numerical values of the two quantities would be 1 if the pions were all
crossing the boundary at a right angle, 2 in the case of an isotropic
distribution, and could even tend to infinity if the particle direction were
mainly parallel to the boundary:
FLUENCE AND CURRENT ARE VERY DIFFERENT QUANTITIES AND SHOULD NOT BE CONFUSED!
Note also that the above output reports also the current value not normalised
per unit area. This is equivalent to a simple count of crossing particles, so
we see that in our example about 0.287 charged pions per primary proton cross
the middle plane of the target.
The previous file has a structure which is not easily interfaceable to other
readout codes. This can be easily achieved by means of the other output file,
pionbdx_tab.lis: there the user can find, for each Detector, a simple 4-column
structure for the differential fluence integrated over solid angle. The table
starts from the lowest energy and the four columns represent respectively
E_min, E_max, the differential fluence and the statistical error in percentage:
# Detector n: 1 piFluenUD (integrated over solid angle)
# N. of energy intervals 50
1.000E-03 1.242E-03 1.300E-04 5.216E+01
1.242E-03 1.542E-03 1.631E-04 8.206E+01
1.542E-03 1.914E-03 1.025E-04 9.900E+01
1.914E-03 2.376E-03 8.693E-05 6.203E+01
2.376E-03 2.951E-03 7.245E-05 3.355E+01
2.951E-03 3.663E-03 7.420E-05 3.368E+01
3.663E-03 4.548E-03 2.109E-04 3.472E+01
4.548E-03 5.647E-03 1.567E-04 4.401E+01
5.647E-03 7.012E-03 2.927E-04 3.929E+01
.....
By convention, when in a given bin the statistics is not sufficient to
calculate a standard deviation, the statistical error is printed as 99%. For a
null fluence the statistical error is also null.
After this table, the double differential fluence is reported.
First, one or more lines marked by a # sign in column 1 give, from minimum to
maximum, the extremes of the solid angle intervals. Then, for each energy
interval, the minimum and maximum of the interval followed by as many pairs of
values as the number of angular bins: the first value is the calculated
double-differential quantity (fluence or current) in cm-2 sr-1 and the second
is the corresponding statistical error in percent.
For instance, for our example we obtain the following printout (for the sake of
space only 3 bins in energy are shown):
# double differential distributions
# number of solid angle intervals 10
# 0.000E+00 6.283E-01 6.283E-01 1.257E+00 1.257E+00 1.885E+00 ...
#
....
2.069E-02 2.569E-02 4.013E-05 2.472E+01 4.509E-05 2.068E+01 ...
2.569E-02 3.189E-02 5.408E-05 1.907E+01 4.657E-05 2.200E+01 ...
3.189E-02 3.960E-02 5.150E-05 7.137E+00 5.355E-05 1.587E+01 ...
....
Track length estimator
----------------------
The program to analyse USRTRACK binary output is called ustsuw.f and can also
be found in $FLUPRO/flutil. Its use is very similar to that of usxsuw.f
described above. Applying it to the example00*_fort.48 files (output of the
first USRTRACK detector in our example), we obtain for the average fluence of
charged pions in the upstream half of the beryllium target:
Tot. response (p/cmq/pr) 5.4765277E-04 +/- 0.6965669 %
and from the example00*_fort.49 files (pion fluence in the downstream half):
Tot. response (p/cmq/pr) 1.3474772E-03 +/- 0.5352812 %
As it was to be expected, the average fluence obtained above by the boundary
crossing estimator on the middle surface (8.69E-04 cm-2) has a value which is
intermediate between these two.
Binning estimator
-----------------
To analyse the binary output from USRBIN, two programs are needed, both
available in $FLUPRO/flutil. The first, usbsuw.f, performs a statistical
analysis of the results and produces a new unformatted file, with a name chosen
by the user. The second program, usbrea.f, reads the latter file and writes on
a formatted file two arrays, namely the content of each bin, averaged over the
given number of runs, followed by the corresponding errors in percent. The
second USRBIN detector defined in example.inp gives the following values
of energy deposition (in GeV/cm3):
1
Cartesian binning n. 1 "Edeposit " , generalized particle n. 208
X coordinate: from -1.0000E+01 to 1.0000E+01 cm, 20 bins ( 1.0000E+00 cm wide)
Y coordinate: from -1.0000E+01 to 1.0000E+01 cm, 20 bins ( 1.0000E+00 cm wide)
Z coordinate: from 0.0000E+00 to 5.0000E+00 cm, 5 bins ( 1.0000E+00 cm wide)
Data follow in a matrix A(ix,iy,iz), format (1(5x,1p,10(1x,e11.4)))
accurate deposition along the tracks requested
1.7164E-07 3.4587E-07 2.1976E-07 3.0997E-07 1.4963E-07 3.5431E-07 .....
5.6597E-07 7.5792E-07 3.6563E-07 2.7822E-07 2.6084E-07 2.8645E-07 .....
2.6191E-07 1.6716E-07 3.8680E-07 2.4925E-07 4.2334E-07 3.5025E-07 .....
.............................................................................
and the following corresponding percentage errors:
Percentage errors follow in a matrix A(ix,iy,iz), format (1(5x,1p,10(1x,e11.4)))
1.3936E+01 4.3211E+01 3.0601E+01 2.2874E+01 1.7783E+01 2.7942E+01 .....
1.6548E+01 1.2291E+01 1.4539E+01 2.4576E+01 2.7828E+01 1.7247E+01 .....
2.2423E+01 1.7258E+01 2.0349E+01 3.7997E+01 2.6855E+01 2.9230E+01 .....
.............................................................................
2.2.16} Readout of other FLUKA estimators
-----------------------------------------
The $FLUPRO/flutil directory contains other similar programs to average the
outputs from other FLUKA estimators (not used in the present example):
* usrsuw.f: to read out the RESNUCLEi output
* usysuw.f: to read out the USRYIELD output
2.2.17} Various settings
------------------------
Accuracy and computer speed depend on several parameters that can be freely
tuned by the user: but in general an increase of either one results in a
decrease of the other. The proper balance must be based both on physical and on
practical considerations. The present defaults have been designed to give
satisfactory results in the most common cases: but other sets of defaults can
be implemented using option DEFAULTS (to be placed at the beginning of the
input file, just after the title).
Even when one set of defaults is enforced, the user can still override some of
them by modifying single parameters. The most used ones concern energy cut-offs
(option EMFCUT for electrons and photons, LOW-BIAS for low-energy neutrons,
PART-THR for all other particles), thresholds for delta-ray production (option
DELTARAY), particles to be ignored (option DISCARD), switching on or off some
physical effect (EMFCUT, IONFLUCT, MUPHOTON, PAIRBREM, PHOTONUC, PHYSICS,
POLARIZAti), and (more rarely) the size of the step for transporting charged
particles (FLUKAFIX, MCSTHRES, MULSOPT, STEPSIZE).
Energy cut-offs for each particle are listed in a table on standard output
("Particle transport thresholds").
2.2.18} Biasing
---------------
Although FLUKA is able to perform fully analogue particle transport
calculations (i.e. to reproduce faithfully actual particle histories), in many
cases of very non-uniform radiation fields, such as those encountered in
shielding design, only a very small fraction of all the histories contributes
to the desired response (dose, fluence) in the regions of interest, for
instance behind thick shielding. In these cases, the user's concern is not to
simulate exactly what occurs in reality, but to estimate in the most efficient
way the desired response. This can be obtained by replacing the actual physical
problem with a mathematically equivalent one, i.e. having the same solution but
faster statistical convergence.
A rigorous mathematical treatment of such variance-reduction techniques can be
found in several textbooks (see for instance those of Lux and Koblinger [Lux91]
or Carter and Cashwell [Car75]).
In the present practical introduction we will only issue a few important
warnings:
1. In the limit of the number of histories tending to infinity, the value of
all calculated quantities tend EXACTLY to the same average in the analogue
and in the corresponding biased calculation. In other words, biasing is
mathematically correct and implies no approximation. However, an
acceleration of convergence in certain regions of phase space
(space/energy/angle) will generally be paid for by a slower convergence in
other regions.
Because an actual calculation does not use an infinite number of particles,
but is necessarily truncated after a finite number of histories, results
must be considered with some judgment. For instance, if the number of
histories is too small, it can happen that total energy is not conserved
(check the energy budget summary at the very end of main output!)
2. A bad choice of biasing parameters may have consequences opposite to what is
desired, namely a slower convergence. A long experience, and often some
preliminary trial-and-error investigation, are needed in order to fully
master these techniques (but some biasing algorithms are "safer" than others).
3. Because biasing implies replacing some distributions by others having the
same expectation values but different variance (and different higher
moments), biasing techniques in general do not conserve correlations and
cannot describe correctly fluctuations.
The simplest (and safest) biasing option offered by FLUKA is importance
biasing, which can be requested by option BIASING. Each geometry region is
assigned an "importance", namely a number between 1.0E-4 and 1.0E+4,
proportional to the contribution that particles in that region are expected to
give to the desired result. The ratio of importances in any two adjacent
regions is used to drive a classical biasing algorithm ("Splitting" and
"Russian Roulette"). In a simple, monodimensional attenuation problem, the
importance is often set equal to the inverse of the expected fluence
attenuation factor for each region.
In electron accelerator shielding, two other biasing options are commonly
employed: EMF-BIAS and LAM-BIAS. The first one is used to request leading
particle biasing, a technique which reduces considerably the computer time
required to handle high-energy electromagnetic showers. With this option, CPU
time becomes proportional to primary energy rather than increasing
exponentially with it. Option LAM-BIAS is necessary in order to sample with
acceptable statistics photonuclear reactions which have a much lower
probability than competing electromagnetic photon reactions, but are often
more important from the radiological point of view.
Other important options are those which set weight window biasing (WW-FACTOr
WW-THRESh and WW-PROFIle) but their use requires more experience than assumed
here for a beginner.
Particle importances, weight windows and low-energy neutron biasing parameters
are reported for each region in standard output. On user's request (expressed
as SDUM = PRINT in a BIASING card), Russian Roulette and Splitting counters are
printed for each region on standard output before the final summary. Such
counters can be used for a better tuning of the biasing options.
1********************************************************************************
3} Installation
********************************************************************************
The FLUKA package for LINUX and UNIX platforms is distributed as a tar file
which can be downloaded from the FLUKA Website www.fluka.org.
The release of the FLUKA source code will be available under the licence
reported at the beginning of this volume. For most applications we distribute a
package containing a compiled library, user routines in source form, INCLUDE
files, various unformatted and formatted data files and a number of scripts for
compiling, linking and running the program on a given platform.
A list of the contents is provided in a README file, and information on the
current version, possibly overriding parts of the present manual, may be
contained in a file RELEASE-NOTES.
No external library routines are required. The timing and other necessary
service routines are already included.
In principle, FLUKA can be installed on any computer platform where a Fortran
compiler is available. However, at present only the following are supported
(see the FLUKA website http://www.fluka.org for more information).
* DEC computers running Digital UNIX > 4.0
* Intel PCs running LINUX:
- RedHat 7.3 (compiler gcc-2.96)
- RedHat 9.0 (compiler gcc-3.2.2)
- Fedora
It is suggested that the user define an environmental variable FLUPRO pointing
to the directory where the distribution tar file has been opened. The FLUKA
libraries and most data files will be located in $FLUPRO, the INCLUDE files in
$FLUPRO/flukapro/, the default user routines in $FLUPRO/usermvax/, compilation
and linking scripts (as well as several postprocessing programs to analyse user
scores) in $FLUPRO/flutil/.
If the source code is included in the distribution, it will be contained in
$FLUPRO files with names of the form ...mvax.for.
The basic FLUKA program on UNIX machines consists of 29 files (*):
bamjmvax.for blockmvax.for comlatmvax.for decaymvax.for dedxmvax.for
dumvax.for elsmvax.for emfmvax.for eventqmvax.for eventvmvax.for
evffrmvax.for fluoxmvax.for geolatmvax.for kaskadmvax.for lowneumvax.for
mainmvax.for mathmvax.for neutrimvax.for noptmvax.for opphmvax.for
outputmvax.for pemfmvax.for pgmvax.for preclmvax.for preeqmvax.for
pripromvax.for rndmvax.for usermvax.for XXXmvax.for (**)
Two more files contain source code related to the DPMJET and RQMD packages,
which can be linked with FLUKA to run problems involving heavy ion nuclear
interactions:
dpmmvax rqmdmvax
(*) The form ...vax.for has historical reasons. Actually, as seen later, the
files are automatically split by a Makefile into single routines (with
extension .f) before compilation.
(**) XXX stands for hp, ibm, linux, osf etc. depending on the platform.
Most UNIX Fortran compilers require that the extension .for be replaced by
.f (but the Makefile provided with FLUKA takes care of this, see below).
See 4} for a short description of the content of these files.
If the source code is present, the INCLUDE files needed to compile the program
may be grouped into three files emfadd.add, flukaadd.add and lowneuadd.add.
A Makefile and a number of auxiliary programs split these files into individual
routines and INCLUDE files, which are placed in 29+1 separate directories and
compiled. The object files are inserted in a FLUKA library libflukahp.a.
A shell script lfluka links all routines into an executable flukahp (the name
is the same for all UNIX platforms, the "hp" being due to historical reasons).
The DPMJET and RQMD object files are collected in two separate libraries.
The FLUKA distribution tar file normally does not contain an executable file.
To create the default FLUKA executable, type:
$FLUPRO/flutil/lfluka -m fluka
(the name of the resulting executable will be flukahp)
or, if heavy ion nuclear interactions are needed:
$FLUPRO/flutil/ldpmqmd
(the name of the resulting executable will be flukadpm)
User-written routines (in particular a SOURCE subroutine, see list of user
interface routines in 13}) can be compiled separately and linked overriding
the default routines of the library. The $FLUPRO/flutil/lfluka script can
take care of them in three different ways:
* appending the Fortran files (xxx.f) as last arguments to the
lfluka procedure (Linux only);
* appending the object files (precompiled using the $FLUPRO/flutil/fff
procedure supplied with the code) as last arguments to the lfluka
procedure;
* inserting the object files into a library and giving the library
name to the script with the -O or -l options.
An on-line help is available issuing lfluka -h.
The program may need up to 12 auxiliary data files, containing cross sections,
nuclear and atomic data and so on. Nine of these files are unformatted
and have an extension .bin (or .dat).
The nine unformatted files and three of the remaining auxiliary files require
no modification by the user.
They are generally kept in the main FLUKA directory.
Here is the list:
cohff.bin
Coherent atomic form factors
fluodt.dat
Fluorescence emission data, needed for problems involving
low-energy electron-photon transport
gxsect.bin
Photon cross sections
neuxsc_72.bin
Low-energy neutron cross sections: needed for all problems with
neutron transport below 20 MeV.
nuclear.bin
Nuclide masses, abundances and other data: needed for all
hadronic problems
elasct.bin
Elastic cross sections for hadronic problems
sigmapi.bin
Pion cross sections
brems_fin.bin
Bremsstrahlung cross sections
e6r1nds3.fyi, jef2.fyi, jendl3.fyi, xnloan.dat
Fission nuclide yields and neutron multiplicities
Pre-connected I/O files
-----------------------
FLUKA reads its main input from standard logical unit 5 and writes its main
output to logical unit 11. Both are parameterised in the INCLUDE file
IOUNIT as LUNIN and LUNOUT, and can therefore be redefined if necessary.
Assignment of unit number 5 and log messages to the corresponding files is
achieved (on Linux/UNIX) via the redirection symbols < and >.
Other input and output files on UNIX can be assigned a I/O unit number by
means of symbolic links (but the syntax for Fortran implicit connection is
not standard and forms like fort.xx or ftnxx can both be found on
different platforms). An alternative way is offered by the OPEN command of
FLUKA, which allows to perform explicit connections.
The $FLUPRO/rfluka script supplied with the code contains all relevant I/O
file definitions, and can be used to run the code interactively or through
a batch queue. It allows to submit multiple runs with a single command. Both
rfluka and lfluka (the script used for linking, see above) contain usage
instructions.
The rfluka script creates a temporary directory where it copies the
necessary files and deletes it after the results have been copied back to
the parent directory, thus allowing to run more than one job at the same
time in the same directory. Appropriate names for the output files are
generated by rfluka, including a sequential number for each run.
If user routines are linked and a new executable executable is created, the
name of the new executable can be input using the -e option. Some on-line
help is available issuing rfluka -h.
1********************************************************************************
4} FLUKA modules (Fortran files)
********************************************************************************
Since several years, the FLUKA source code has been organised in "modules".
This word must not be intended to have the technical meaning which it has
been assigned later in Fortran 90. A FLUKA module is simply a collection of
routines covering the same physics field or belonging to the same class
of functionality.
In the FLUKA2008 version, there are 31 modules:
BAMJM : new hadronisation package (strongly improved version of the
original BAMJET [Rit84])
BLOCKM : block data routines
COMLATM : all geometry routines specific for combinatorial geometry
(CG) and repetition (lattice capability) in the geometry
description
DECAYM : all routines connected with particle decays during transport,
including those managing polarisation or non phase-space-like
decays for pions, kaons, muons and taus
DEDXM : all routines connected with dE/dx and radiative losses of
hadrons and muons, including delta-ray production and cross-
sections for muon photonuclear interactions
DPMM : interface routines for the DPMJET generator
DUM : dummy routines
ELSM : all hadron and photon (photonuclear) cross section routines
EMFM : all routines dealing with electron, positron and photon transport
and interactions (except for photon photonuclear interactions,
fluorescent X-ray and Auger production)
EVENTQM : auxiliary routines for the high energy hadronic interaction
generators
EVENTVM : all routines (besides those in EVENTQM) connected with the high
energy hadronic inelastic interaction package
EVFFRM : separate module with all evaporation, fission and Fermi break-up
routines
FLUOXM : all routines dealing with fluorescence X-ray and Auger production
GEOLATM : geometry navigation and debugging routines
KASKADM : general event steering, most of the relevant transport routines
for hadron and muon transport, including magnetic field tracking,
most of material and region dependent initialisation and source
routines
LOWNEUM : all routines concerning the multigroup treatment of "low" energy
(E < 20 MeV) neutrons
MAINM : main, input parsing and auxiliary routines
MATHM : mathematical auxiliary routines (interpolation, integration, etc.)
Many of them adapted from SLATEC (http://www.netlib.org/slatec).
NEUTRIM : nuclear interactions of neutrinos
NOPTM : all routines connected with new scoring options implemented after
FLUKA86, and blank COMMON setting for scoring options.
OPPHM : optical photon production and transport
OUTPUTM : printing routines (apart from output of new options which is
performed in NOPTM)
PEMFM : electromagnetic initialisation
PGM : PLOTGEOM geometry drawing package
PRECLM : full PEANUT second part
PREEQM : full PEANUT first part
PRIPROM : initialisation and drivers for PEANUT
RNDM : random number generation, including gaussian-distributed random
numbers
RQMDM : interface routines for the RQMD generator
USERM : user oriented routines (see list below)
IBMM/HPM/LINUXM/OSFM/VAXM : timing and "environment" routines. These are
machine specific.
User oriented routines (see description in 13}):
The "FLUKA User Routines" mentioned at point 3) in the FLUKA User License are
those (and only those) contained in the directory usermvax, both in the source
and binary versions of the code.
ABSCFF : absorption coefficient (for optical photons)
COMSCW : response functions, user dependent selection for density-like
quantities
DFFCFF : diffusion coefficient (for optical photons)
ENDSCP : energy density distributed - change of positions
FLDSCP : fluence distributed - change of positions
FLUSCW : response functions, user dependent selection for flux-like
quantities
FORMFU : nuclear charge form factors
FRGHNS : material roughness (for optical photons)
FUSRBV : defines a continuous variable for 3-D binnings
LATTIC : symmetry transformation for lattice geometry
LUSRBL : defines a discrete variable for 3-D binnings
MAGFLD : to use a magnetic field map
MDSTCK : management of secondary stack
MGDRAW : to dump trajectories, etc.
MUSRBR : defines a discrete variable for 3-D binnings
OPHBDX : boundary crossing properties (for optical photons)
QUEFFC : quantum efficiency (for optical photons)
RFLCTV : reflectivity (for optical photons)
RFRNDX : refraction index (for optical photons)
SOEVSV : saving source events
SOURCE : to generate any distribution for source particles
STUPRE : set user variables (electrons and photons)
STUPRF : set user variables (hadrons, muons and neutrinos)
UBSSET : to override input biasing parameters
UDCDRL : decay direction biasing
USIMBS : user-defined importance biasing
USREIN : event initialisation
USREOU : post-event output
USRGLO : user global settings
USRINI : user initialisation
USRMED : to perform user driven biasing and/or particle selections
on a material basis
USROUT : user output
USRRNC : user customisation of residual nuclei scoring
1********************************************************************************
5} Particle and material codes
********************************************************************************
5.1} Particles codes
--------------------
Each particle which can be transported by FLUKA is identified by an
alphanumeric name and by an integer number. Negative values of such numerical
identifiers are reserved to light and heavy ions, and to optical photons. The
value 0 indicates a pseudoparticle RAY, which can be used to scan the geometry.
Numbers > 200 designate "families" of particles, grouped according to some
common characteristics (all hadrons, or all charged particles, etc.). In FLUKA,
they are called Generalised Particles and can be used only for scoring. Various
forms of scored energy, transferred momentum, induced activity etc. are also
treated as Generalised Particles.
The identifier values are reported in the following Table, together with the
corresponding particle numbering scheme of the Particle Data Group [PDG].
Fluka name Fluka number Common name Standard PDG number
(Particle Data Group)
4-HELIUM (*) -6 Alpha ---
3-HELIUM (*) -5 Helium-3
TRITON (*) -4 Triton ---
DEUTERON (*) -3 Deuteron ---
HEAVYION (*) -2 Generic heavy ion (see command HI-PROPE)
OPTIPHOT -1 Optical Photon ---
RAY (**) 0 Pseudoparticle ---
PROTON 1 Proton 2212
APROTON 2 Antiproton -2212
ELECTRON 3 Electron 11
POSITRON 4 Positron -11
NEUTRIE 5 Electron Neutrino 12
ANEUTRIE 6 Electron Antineutrino -12
PHOTON 7 Photon 22
NEUTRON 8 Neutron 2112
ANEUTRON 9 Antineutron -2112
MUON+ 10 Positive Muon -13
MUON- 11 Negative Muon 13
KAONLONG 12 Kaon-zero long 130
PION+ 13 Positive Pion 211
PION- 14 Negative Pion -211
KAON+ 15 Positive Kaon 321
KAON- 16 Negative Kaon -321
LAMBDA 17 Lambda 3122
ALAMBDA 18 Antilambda -3122
KAONSHRT 19 Kaon zero short 310
SIGMA- 20 Negative Sigma 3112
SIGMA+ 21 Positive Sigma 3222
SIGMAZER 22 Sigma-zero 3212
PIZERO 23 Pion-zero 111
KAONZERO 24 Kaon-zero 311
AKAONZER 25 Antikaon-zero -311
Reserved 26 --- ---
NEUTRIM 27 Muon neutrino 14
ANEUTRIM 28 Muon antineutrino -14
Blank 29 --- ---
Reserved 30 --- ---
ASIGMA- 31 Antisigma-minus -3222
ASIGMAZE 32 Antisigma-zero -3212
ASIGMA+ 33 Antisigma-plus -3112
XSIZERO 34 Xi-zero 3322
AXSIZERO 35 Antixi-zero -3322
XSI- 36 Negative Xi 3312
AXSI+ 37 Positive Xi -3312
OMEGA- 38 Omega-minus 3334
AOMEGA+ 39 Antiomega -3334
Reserved 40 --- ---
TAU+ 41 Positive Tau (***) -15
TAU- 42 Negative Tau (***) 15
NEUTRIT 43 Tau neutrino 16
ANEUTRIT 44 Tau antineutrino -16
D+ 45 D-plus 411
D- 46 D-minus -411
D0 47 D-zero 421
D0BAR 48 AntiD-zero -421
DS+ 49 D_s-plus 431
DS- 50 D_s-minus -431
LAMBDAC+ 51 Lambda_c-plus 4122
XSIC+ 52 Xi_c-plus 4232
XSIC0 53 Xi_c-zero 4112
XSIPC+ 54 Xi'_c-plus 4322
XSIPC0 55 Xi'_c-zero 4312
OMEGAC0 56 Omega_c-zero 4332
ALAMBDC- 57 Antilambda_c-minus -4122
AXSIC- 58 AntiXi_c-minus -4232
AXSIC0 59 AntiXi_c-zero -4132
AXSIPC- 60 AntiXi'_c-minus -4322
AXSIPC0 61 AntiXi'_c-zero -4312
AOMEGAC0 62 AntiOmega_c-zero -4332
Reserved 63 --- ---
Reserved 64 --- ---
(*) Heavy fragments produced in evaporation are loaded in a special stack
(COMMON FHEAVY, contained in the INCLUDE file with the same name).
The internal code for heavy evaporation fragments is the following:
3 = deuteron, 4 = 3-H, 5 = 3-He, 6 = 4-He, 7-12 = fission fragments.
Transport capabilities (dE/dx, with account of effective charge and
effective charge straggling, multiple Coulomb scattering, no interaction
yet) are now available for d, t, 3-He and 4-He. Heavier ions can be
transported on demand (see option EVENTYPE), with or without nuclear
interactions. Fission fragments and fragments from Fermi break-up, when
produced, are also put in COMMON FHEAVY with id's ranging from 7 to 12
(usually 7 and 8 for two fragments).
(**) A "RAY" is not a real particle, but a straight line trajectory through the
FLUKA geometry. When a primary particle (defined by options BEAM and
BEAMPOS, or by a SOURCE subroutine) is found to be a RAY, the program
tracks through the geometry in the given direction calculating a number of
quantities (distance traversed in each material, number of radiation
lengths, number of interaction lengths etc.). See 14} for instructions
about its use.
(***) Only leptonic decays of tau's are implemented for the time being.
Generalised particles (to be used only for scoring):
--- 40 Low-energy neutrons (used only in some input
options)
ALL-PART 201 All transportable particles
ALL-CHAR 202 All charged particles
ALL-NEUT 203 All neutral particles
ALL-NEGA 204 All negative particles
ALL-POSI 205 All positive particles
NUCLEONS 206 Protons and neutrons
NUC&PI+- 207 Protons, neutrons and charged pions
ENERGY 208 For dose scoring: Deposited energy
For energy fluence scoring: Kinetic energy
PIONS+- 209 Charged pions
BEAMPART 210 Primary (source or beam) particles
EM-ENRGY 211 Electromagnetic energy (of electrons, positrons
or photons)
MUONS 212 Muons
E+&E- 213 Electrons and positrons
AP&AN 214 Antiprotons and antineutrons
KAONS 215 All kaons
STRANGE 216 All kaons and all hyperons and anti-hyperons
(i.e., all strange particles)
KAONS+- 217 Charged kaons
HAD-CHAR 218 Charged hadrons
FISSIONS 219 Fissions
HE-FISS 220 High energy fissions
LE-FISS 221 Low energy fissions
NEU-BALA 222 Neutron balance (algebraic sum of outgoing
neutrons minus incoming neutrons for all
interactions)
HAD-NEUT 223 Neutral hadrons
KAONS0 224 Neutral kaons
C-MESONS 225 Charmed mesons
C-(A)BAR 226 Charmed (anti)baryons
CHARMED 227 Charmed hadrons
DOSE 228 Dose (energy deposited per unit mass, GeV/g)
UNB-ENER 229 Unbiased deposited energy (****)
UNB-EMEN 230 Unbiased electromagnetic energy (of electrons,
positrons or photons) (****)
X-MOMENT 231 X component of momentum transfer
Y-MOMENT 232 Y component of momentum transfer
Z-MOMENT 233 Z component of momentum transfer
ACTIVITY 234 Activity per unit volume
ACTOMASS 235 Activity per unit mass
SI1MEVNE 236 Silicon 1 MeV-equivalent flux
HADGT20M 237 Hadrons with energy > 20 MeV
DOSE-EQ 240 Dose Equivalent (pSv/primary)
(****) "Unbiased energy" means that the energy deposited (or the energy fluence)
is scored with weight 1, independent of the actual weight of the particle.
Of course, the result will have no physical meaning, but in some
circumstances it will provide useful information about the run itself (for
instance in order to optimise biasing).
(*****) "Activity per unit volume" and "Activity per unit mass"
are meaningful only when used within a 2D or 3D USRBIN estimator
associated (by means of the DCYSCORE option) with a decay time defined
with the DCYTIMES option. The resulting output units are Bq/cm**3 and
Bq/g respectively, unless a binning by region or a special binning is
requested, in which case the output is Bq or Bq cm**3/g.
5.2} Pre-defined materials
--------------------------
Materials can be easily defined by option MATERIAL by assigning a density, a
name, a code number, and, in the case of single elements, an atomic and a mass
number. For compounds, the MATERIAL option card must be accompanied by a
COMPOUND definition referred to the same material name. If low-energy neutrons
(E < 20 MeV) need to be transported, the chosen name of a single element
material must coincide with that of one for which cross sections are available
(see Table in 10}).
However, for user's convenience, 25 common materials are already pre-defined
(see Table below): they are assigned a default density, name and code number
even if no MATERIAL definition has been given. The user can override any of
these if desired (for instance re-assigning code numbers), and can add more
material definitions, by means of one or more MATERIAL cards. The only
constraints are:
* the number sequence of the defined materials must be UNINTERRUPTED, i.e.,
there may not be any gap in the numbering sequence from 25 onwards.
* if one of the pre-defined materials is re-defined using the same name, its
number must be equal to that of the pre-defined material (unless the
input is explicitly number-based).
List of pre-defined FLUKA materials
-----------------------------------
Fluka name Fluka number Common name A Z Density
BLCKHOLE 1 Blackhole or External Vacuum 0 0 0
VACUUM 2 Vacuum or Internal Vacuum 0 0 0
HYDROGEN 3 Hydrogen 1.00794 1. 0.0000837
HELIUM 4 Helium 4.002602 2. 0.000166
BERYLLIU 5 Beryllium 9.012182 4. 1.848
CARBON 6 Carbon 12.0107 6. 2.000
NITROGEN 7 Nitrogen 14.0067 7. 0.00117
OXYGEN 8 Oxygen 15.9994 8. 0.00133
MAGNESIU 9 Magnesium 24.3050 12. 1.740
ALUMINUM 10 Aluminium 26.981538 13. 2.699
IRON 11 Iron 55.845 26. 7.874
COPPER 12 Copper 63.546 29. 8.960
SILVER 13 Silver 107.8682 47. 10.500
SILICON 14 Silicon 28.0855 14. 2.329
GOLD 15 Gold 196.96655 79. 19.320
MERCURY 16 Mercury 200.59 80. 13.546
LEAD 17 Lead 207.2 82. 11.350
TANTALUM 18 Tantalum 180.9479 73. 16.654
SODIUM 19 Sodium 22.989770 11. 0.971
ARGON 20 Argon 39.948 18. 0.00166
CALCIUM 21 Calcium 40.078 20. 1.550
TIN 22 Tin 118.710 50. 7.310
TUNGSTEN 23 Tungsten 183.84 74. 19.300
TITANIUM 24 Titanium 47.867 22. 4.540
NICKEL 25 Nickel 58.6934 28. 8.902
1********************************************************************************
6} General features of FLUKA input
********************************************************************************
The input of FLUKA consists of a text file containing a sequence of option
lines (often called "cards") which are followed sometimes by data cards
specific of the option (or command) requested. Option cards have all the same
structure, and can be read in fixed format or in free format. A description
of free format is given in 7}, options GLOBAL and FREE.
Syntax:
CODEWD, (WHAT(I), I = 1, 6), SDUM
(the fixed format is A8, 2X, 6E10.0, A8)
where:
* CODEWD is the option keyword
* The WHAT-parameters are numerical data (or logical data in numerical form)
* SDUM, if present, contains character data (only in two exceptional cases,
the STERNHEIme and WW-FACTOr options, SDUM contains numerical information)
Since 2006, a very practical and appealing feature has been introduced: INPUT
BY NAMES. This means that the numeric WHAT fields can be filled with
pre-defined or user-defined names, such as:
- material names
- particle or generalised particle names
- region names, if the geometry too is written in free format "name" based
- estimator names
Names must be at most 8 character long, with the exception of detector names
(estimator options (USRBDX, USRTRACK, USRCOLL, USRBIN, USRYIELD, RESNUCLEi)
which can be 10 character long. Leading and trailing blanks are automatically
stripped, and the input parser is case sensitive.
A special name (@LASTMAT, @LASTPAR, @LASTREG) can be used corresponding to the
largest material number, particle id, and region number respectively.
Name values and numeric values can both be used in the same input file, since
the program is able to distinguish a numeric field from a character field. For
this reason, names that can be interpreted as numbers must be avoided. This
means that old numeric inputs need no modification. Fully-numeric
interpretation, however, can be forced by means of the GLOBAL card.
Due to the introduction of input by names, input data cards are no longer
interpreted in the same order as in the input file, therefore the echo on
standard output will look different from the original input.
When using numeric fields, note that even if the values to be assigned
to WHAT-parameters were logically integers, because of the format used
they must be given with a decimal point.
The order of the input cards is almost free, with the following exceptions:
* GLOBAL declarations, if present, must precede any executable option.
* Option DEFAULTS must be issued at the very beginning of input.
It can be preceded only by a GLOBAL card and by command TITLE.
* The START command initiates execution. While old versions of FLUKA were
allowing multiple re-starts, only the first START command is executed now.
Thus any input given after START is ignored, with the exception of
USROCALL and STOP.
* The STOP command stops the execution of the program. Thus any input present
after STOP is ignored.
* Some option cards must or can be immediately followed by a variable amount
of information, not always in the standard format indicated above. These
are:
- OPEN is generally followed by the name of the file to be opened (scratch
files are an exception)
- DETECT, USRBIN, USRBDX, USRCOLL, USRTRACK, USRYIELD, EVENTBIN, EVENTDAT:
data concerning user-defined estimators and binnings extend in general
over two cards. The second card ("continuation card") must come after the
first, but doesn't need to follow it immediately. A continuation card
may be needed also for option GEOEND, when used to invoke the geometry
debugger.
- Input included between GEOBEGIN and GEOEND:
geometry data must be given in a well-defined order and in a special
format between a GEOBEGIN and a GEOEND definition (but the LATTICE and
VOXELS geometry options, and the GEOBEGIN and GEOEND cards themselves
follow the normal FLUKA format convention).
- PLOTGEOM:
Unless a different logical input unit is specified, the call to the
PLOTGEOM program must be followed immediately by the PLOTGEOM input,
in special format.
- TITLE:
the card following the TITLE command is considered as the title of the
run and is reproduced in the output.
* For old, fully numeric input format ONLY:
- In some cases, the MAT-PROP option must be requested after the
corresponding MATERIAL card.
- The PLOTGEOM command must be issued after the geometry input, and,
in case the user chooses to plot only boundaries between different
materials, it must come also after all the ASSIGNMAt cards.
It is also recommended that PLOTGEOM be issued before any biasing
and any other option which makes use of permanent and/or temporary
storage.
Most definitions have some default values. If these are acceptable, it is not
compulsory that the corresponding option card appear explicitly in the input
sequence. Furthermore for most WHAT and/or SDUM parameters a default value
(that may be different from the default value when the definition has not been
input) is applied if the corresponding field is left blank (or set = 0.0) in
the input card.
Several option cards may appear more than once in the input sequence. In most
cases, each of such additional cards obviously adds more definitions to those
already given, provided they are different and not contradictory. In case of
conflict, the last given generally overrides the previous one(s). This feature
may be successfully exploited in the numerous cases where whole arrays are
assigned according to the scheme:
"From .... to .... in step of ...." (corresponding to a Fortran DO-loop)
making the input more compact. An example can be found below in the description
of option ASSIGNMAt, which is used to set a one-to-many correspondence between
material numbers and region numbers.
In most cases of such "DO-loop" assignments, especially when the same option
card can be used to assign a value to more than one quantity, a blank or zero
field does not assign the default value but leaves the previously given value
unchanged. To remove any possible ambiguity, resetting the default value needs
then to be done explicitly (generally -1. has to be input in such cases).
"DO-loop" assignments can be used also when the input is name-based, since the
program replaces each name by the corresponding numerical index. The
correspondence can be found by examining the output from a short test run:
however, it must be remembered that adding a new material, or a new region,
will change the numerical sequence unless the new item is issued as the last
of material or region definitions. In this case, if the "DO-loop" indicates all
materials, or all regions, using the generic names @LASTMAT and @LASTREG makes
a modification of the assignment definition unnecessary.
All defaults and exceptions are listed under the description of each FLUKA
input option. Different defaults, tuned to the type of application of interest,
can be specified using the option DEFAULTS.
Physical units
--------------
Physical units consistently used in FLUKA input and output are:
distance cm (and derived units cm2, cm3 for areas and volumes)
energy GeV
Exceptions:
eV is used for average ionisation potential input by option
MAT-PROP
g/(MeV cm2) are used for Birks coefficients input by option
TCQUENCH.
momentum GeV/c
temperature degree Kelvin
solid angle sr (exception: degrees may be used, on user's request, with
option USRYIELD)
magnetic field T
electric field kV/cm
time s (option TCQUENCH) or ns (option TIME-CUT)
activity Bq
LET keV/(micrometer g/cm3)
6.1} The input preprocessor
---------------------------
FLUKA, since 2005, comes bundled with an internal preprocessor, a simplified
version of a C-like preprocessor. The preprocessor can modify the input file
before it is executed with the use of conditions. Presently the functionality
is limited to 2 types of directives, DEFINITION and CONDITIONAL, and probably
will be expanded in the future. The preprocessor is a particularly useful way
to include or remove blocks of input cards, allowing a more flexible and easy
organization of an input file. One can write the input file around a few
directives to allow easier debugging, changing thresholds, biasing and scoring
cards for the final production.
Syntax
------
All preprocessor directives are single lines starting with the # character in
the first column and can appear anywhere in the input file, either between
normal input cards or inside the geometry definition (inline or externally
defined). Each identifier can be up to 10 characters in length.
Definition of Constants
-----------------------
With the DEFINITION DIRECTIVES one can define identifiers to be used later for
inclusion or removal parts of the input file:
#define [identifier_name]
defines [identifier_name] without giving it a value. This can be used in
conjunction with another set of directives that allow conditional execution.
#undef [identifier_name]
deletes any previously defined [identifier_name].
Conditional directives
----------------------
With the CONDITIONAL DIRECTIVES one can include or remove parts of the input
file before execution. The #if, #elif, #else blocks must be terminated with a
closing #endif. There is a maximum of 10 nesting levels that can be used.
#if [identifier_name]
...
#elif [identifier_name]
...
#else
...
#endif
The #if and #elif (else-if) directive is followed by an identifier. If the
identifier is defined then the statement evaluates to true, otherwise to false.
Example:
#define DEBUG
#define PLOT1
...
#if DEBUG
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
GEOEND 100.0 100.0 100.0 -100.0 -100.0 -100.0 DEBUG
GEOEND 50.0 50.0 50.0 &
#else
GEOEND
#endif
...
#if PLOT1
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
PLOTGEOM 1.0 -2000.0
MBWD6L1
-100.0 0.0 -21620.0 100.0 0.0 -21250.0
1.0 0.0 0.0 0.0 0.0 1.0
-100.0 0.0 -21200.0 100.0 0.0 -20800.0
STOP
#endif
1********************************************************************************
7} Description of FLUKA input options
*********************************************************************************
There are more than 70 option keywords available for input in FLUKA. A summary
is given in the next section, where the commands will be shortly introduced and
grouped by type of functionality. Some of the commands, which can provide
several different services, will be mentioned in the context of more than one
group.
A complete description of each command will follow, in alphabetical order.
Introduction to the FLUKA input options
Summary of the available options.
Here is a list of the options (commands) that are at the disposal of the FLUKA
user to prepare an input file. In the rest of this section, the same commands
will be presented by grouping them according to the different services they can
provide:
ASSIGNMAt defines the correspondence between region and material indices and
defines regions where a magnetic field exists
AUXSCORE allows to associate scoring estimators with auxiliary (generalized)
particle distributions and dose equivalent conversion factors
* Start_Devel_seq
BAMJET defines the parameters of the chain hadronization algorithm
(for developers only)
* End_Devel_seq
BEAM defines most of the beam characteristics (energy, profile,
divergence, particle type)
BEAMAXES defines the axes used for a beam reference frame different from the
geometry frame
BEAMPOS defines the starting point of beam particles and the beam direction
BIASING sets importance sampling (Russian Roulette/splitting) at boundary
crossings and at high-energy hadronic collisions on a region by
region basis
BME defines some I/O parameters relevant to the heavy ion event
generator BME (Boltzmann Master Equation)
COMPOUND defines a compound or a mixture or a mixture of isotopes
CORRFACT allows to alter material density for dE/dx and nuclear processes on
a region-by-region basis
DCYSCORE associates selected scoring detectors of given estimator type with
user-defined decay times
DCYTIMES defines decay times for radioactive product scoring
DEFAULTS sets FLUKA defaults for specified kinds of problems
DELTARAY activates delta-ray production by heavy charged particles and
controls energy loss and deposition
DETECT scores energy deposition in coincidence or anti-coincidence with a
trigger, on an event by event basis
DISCARD defines the particles which must not be transported
* Start_Devel_seq
DPM-PARA defines the parameters of the Dual Parton Model as implemented
in FLUKA (for developers only)
* End_Devel_seq
DPMJET defines some I/O parameters relevant to the heavy ion event
generator DPMJET
ELCFIELD sets the tracking conditions for transport in electric fields and
possibly defines an homogeneous electric field (not yet implemented)
EMF requests detailed transport of electrons, positrons and photons
EMF-BIAS defines electron/photon leading particle biasing or biases
electron/photon interaction length
EMFCUT sets energy cut-offs for electrons, positrons and photons, for
transport and production, or for switching off some physical
interactions
EMFFIX sets the size of electron steps corresponding to a fixed fraction
loss of the total energy
EMFFLUO activates production of fluorescence X rays in selected materials
EMFRAY activates Rayleigh (coherent) scattering in selected regions
EVENTBIN scores energy or star densities in a binning structure independent
from the geometry, and prints the binning output after each "event"
(primary history)
EVENTDAT prints event by event the scored star production and/or energy
deposition in each region, and the total energy balance
EVENTYPE defines the hadron particle production model to be used
* Start_Devel_seq
EVXTEST calculates hadron production histograms without transport
(for developers only)
* End_Devel_seq
EXPTRANS requests exponential transformation ("path stretching") (not yet
implemented)
FLUKAFIX sets the size of the step of muons and charged hadrons to a fixed
fraction loss of the kinetic energy
FREE switches to free-format input (geometry excluded)
GEOBEGIN starts the geometry description
GEOEND ends the geometry description; can also be used to activate the
geometry debugger
GLOBAL issues global declarations about the class of the problem (analogue
or weighted) and about the complexity of the geometry. It also
allows to use free format input (geometry included)
HI-PROPE defines the properties of a heavy ion primary
IONFLUCT calculates ionisation energy losses with fluctuations
IRRPROFI defines an irradiation profile for radioactive decay calculations
LAM-BIAS biases decay length and interaction length
LOW-BIAS requests non-analogue absorption and defines the energy cut-off for
low-energy neutron transport on a region by region basis
LOW-DOWN biases the downscattering probability in low energy neutron
transport on a region by region basis
LOW-MAT sets the correspondence between FLUKA materials and low-energy
neutron cross section data
LOW-NEUT requests low-energy neutron transport
MATERIAL defines a material and its properties
MAT-PROP supplies extra information about gaseous materials and materials
with fictitious or inhomogeneous density and defines other material
properties
MCSTHRES defines energy thresholds for applying the multiple Coulomb
scattering algorithm to the transport of muons and charged hadrons
MGNFIELD sets the tracking conditions for transport in magnetic fields
and possibly defines a homogeneous magnetic field
MULSOPT controls optimisation of multiple Coulomb scattering treatment. It
can also request transport with single scattering
MUPHOTON controls photonuclear interactions of high-energy heavy charged
particles (mediated by virtual photons)
MYRQMD defines some I/O parameters relevant to the new heavy ion event
generator RQMD
OPEN defines input/output files without pre-connecting
OPT-PROP defines optical properties of materials
OPT-PROD controls Cherenkov and Transition Radiation photon production
PAIRBREM controls simulation of pair production and bremsstrahlung by
high-energy heavy charged particles
PART-THR sets different energy cut-offs for selected particles
PHOTONUC activates photon interactions with nuclei
PHYSICS controls some physical processes for selected particles
PLOTGEOM calls the PLOTGEOM package to draw a slice of the geometry
POLARIZA defines polarised beams (only for photons at present)
RADDECAY requests simulation of radioactive decays and sets the corresponding
biasing and transport conditions
RANDOMIZe sets the seeds and selects a sequence for the random number
generator
RESNUCLEi scores residual nuclei after inelastic hadronic interactions
ROT-DEFIni defines rotations/translations to be applied to user-defined
binnings
ROTPRBIN sets the storage precision (single or double) and assigns possible
rotations/translations for a given user-defined binning (USRBIN or
EVENTBIN)
RQMD defines some I/O parameters relevant to the heavy ion event
generator RQMD
SCORE defines the energy deposited or the stars to be scored by region
SOURCE tells FLUKA to call a user-defined source routine
START defines the number of primary particles to follow, gets a primary
particle from a beam or from a source, starts the transport and
repeats until the predetermined number of primaries is reached
STEPSIZE sets the maximum step size in cm (by region) for transport of
charged particles
STERNHEIme allows users to input their own values of the density effect
parameters
STOP stops input reading
TCQUENCH sets scoring time cutoffs and/or Birks quenching parameters
THRESHOLd defines the energy threshold for star density scoring, and sets
thresholds for elastic and inelastic hadron reactions
TIME-CUT sets transport time cutoffs
TITLE gives the title of the run
USERDUMP requests a collision file and defines the events to be written
USERWEIG defines extra weighting to be applied to scored yields, fluences,
doses, residual nuclei or star densities (at scoring time)
USRBDX defines a detector for a boundary crossing fluence or current
estimator
USRBIN scores energy, star density or particle fluence in a binning
structure independent from the geometry
USRCOLL defines a detector for a collision fluence estimator
USRGCALL calls user-dependent global initialisation
USRICALL calls user-dependent initialisation
USROCALL calls user-dependent output
USRTRACK defines a detector for a track-length fluence estimator
USRYIELD defines a detector for scoring particle yield around a given
direction
WW-FACTOr defines weight windows in selected regions
WW-PROFIle defines energy group-dependent extra factors ("profiles") to modify
the basic setting of the low-energy neutron weight windows in
selected sets of regions, or the low-energy neutron importances in
each region
WW-THRESh defines the energy limits for a RR/splitting weight window
7.1} Basic commands
-------------------
Most FLUKA commands are optional, and if anyone of them is not used an
appropriate set of defaults is provided. A few commands, however, are nearly
always needed in order to provide a meaningful definition of the problem to be
studied.
In general, for a problem to be fully determined, the following elements need
to be defined:
1) the radiation source
2) the geometrical layout
3) the materials
4) the requested results
5) setting of parameters, accuracy, conditions, and in general technical
directives to the program on how the calculation shall be performed
Defaults are provided in FLUKA for all the above features, but those for
items 1), 2) and 3) are unlikely to be useful: therefore the few commands used
to define source, geometry and materials are practically always present in the
input file.
For what concerns item 4), the user has a choice of several options to request
the estimation of various radiometric quantities. Of course, there is no much
point in running the program without requesting any result, but in a phase of
input preparation it is quite common to have a few runs without any scoring
commands. A typical minimum input containing only specifications for the above
items 1), 2) and 3) will still produce some useful information. Looking at the
standard FLUKA output, the user can do several consistency checks, and can get
some better insight into the problem from the final statistics and energy
balance.
The last part of problem definition, element 5) (setting) is important but is
supported by very robust defaults. In many cases, the only user concern should
consist in choosing the right set of defaults. However, there are some
applications which require explicit setting commands, for instance to request
photonuclear reactions for electron accelerator shielding.
7.2} Definition of the radiation source
---------------------------------------
The simplest particle source is pointlike, monoenergetic and monodirectional,
that is, a "particle beam". Option BEAM, fully described later, is used to
define the particle type and momentum (or energy). If desired, this option can
also define an energy spread, a beam profile shape and an angular divergence.
However, the two latter distributions are restricted to a beam is directed in
the positive z direction: to describe divergence and beam profile for an
arbitrary beam direction it is necessary to define a beam reference frame by
means of option BEAMAXES.
The energy declared with BEAM is used by the program to initialise
cross section tables and other energy-dependent arrays: therefore that command
must always be present, even when a more complex source is described by means
of a user routine.
The particle starting point and direction are declared by means of option
BEAMPOS. If BEAMPOS is not present, the beam particles are assumed to start
from the origin of the coordinates 0., 0., 0. and to be directed along the z
axis. It is important that the starting point be not on a boundary and not
inside a blackhole region. In many cases, starting in vacuum upstream of the
actual target can be convenient.
Both BEAM and BEAMPOS commands can be placed anywhere in the input file, before
the START command.
Particle sources with more complicated features (with arbitrary distribution in
energy, space, angle, time, and even with more than one type of particle) can
be described by a user-written subroutine SOURCE. To call it, a command SOURCE
must be present in input.
7.3} Description of the geometry
--------------------------------
The Combinatorial Geometry used by FLUKA is based on two important concepts:
bodies and regions. The first ones are closed solid bodies (spheres,
parallelepipeds, etc.) or semi-infinite portions of space (half-spaces,
infinite cylinders) delimited by surfaces of first or second degree. The user
must combine bodies by boolean operations (addition, intersection and
subtraction) to perform a complete partition of the space of interest into
regions, namely cells of uniform material composition. One important rule to
remember is that inside the space of interest, defined by means of an external
closed body, every point must belong to one and only one region.
Input for the geometry description, which has its own format and rules,
explained in Chap. 9, must be contained between a GEOBEGIN and a GEOEND card.
These two cards follow the normal FLUKA input syntax. An option offered by the
GEOBEGIN command is to read the geometry input from a separate file. Command
GEOEND can be used also to invoke the geometry debugger, a check which is
always strongly recommended.
Geometry input, sandwiched between a GEOBEGIN and a GEOEND card can be placed
anywhere in the input file (before the START command). It is mandatory in all
cases.
An optional command related to geometry is PLOTGEOM. It is used to display
sections of the geometry and needs to read its own input, as explained later.
7.4} Materials
--------------
Materials in FLUKA are identified by a name (an 8-character string) and by a
number, or material index. Both are used to create correspondences, for
instance between region number and material number, or between material name
and neutron cross section name.
Some materials are already pre-defined. A Table in 5} lists the 25 available
pre-defined materials with their default name, index number, density and atomic
and mass number. The user can either refer to any one of them as it is, or
override it with a new number, name and other properties, or define a new
material. In the latter two cases, the new material definition is done by
option MATERIAL. If the material is not a single element or isotope, but a
compound, mixture or alloy, a command COMPOUND, extended on as many cards as
necessary, is needed to specify its atomic composition. The correspondence
between the material and the composition is set using the same name in the
MATERIAL and in the COMPOUND cards. Note that material names, if low-energy
neutron transport is desired, cannot be assigned arbitrarily but must match one
of the names available in the FLUKA cross section library (see Table in
Chap. 10}.
Once all the materials to be assigned to the various geometry regions have been
defined (either explicitly with MATERIAL or implicitly in the pre-defined
list), it is necessary to specify of which material each region is made, by
setting a correspondence material index --> region number. This is done by
command ASSIGNMAt.
Command ASSIGNMAt is used also to indicate that a magnetic field exists inside
one or more given regions: in this case a command MGNFIELD is needed to specify
intensity and direction of a constant magnetic field, or a complex one defined
by a user routine as explained below. Note that in practice at least one
ASSIGNMAt command must always be present.
A less common kind of correspondence is set by option LOW-MAT. By default, the
correspondence between a material and a low-energy neutron cross section set
established by name, but in some circumstances this cannot be done, for
instance when two different materials share the same cross section set, or when
two cross section sets have the same name. Option LOW-MAT can be used to set a
different correspondence.
Another FLUKA option concerning the definition of materials is MAT-PROP. It is
used for a variety of purposes: to describe porous, inhomogeneous or gas
materials, to override the default average ionisation potential, to do a rough
temperature re-scaling of thermal neutron cross sections when no cross section
set is available at a desired temperature, and to request a call to a special
user routine when particles are transported in a given material.
7.5} Setting options
--------------------
Many FLUKA input options are not used to describe the radiation transport
problem but to issue directives to the program about how to do the
calculations. Other options are used just to select a preferred input format.
We refer to these options as "setting options".
Thanks to a complete and well-tuned set of defaults, setting options are not
always necessary, especially for a beginner or in a preliminary phase of input
preparation. However, an experienced user can often improve considerably the
code performance by a judicious selection of parameters.
7.6} Format setting
-------------------
The default, fixed input format can be replaced by a free format using option
FREE or better GLOBAL. The latter allows to choose free format for both the
normal input and the geometry input separately, and serves also a few other
purposes: it can be used to increase the maximum allowed number of geometry
regions, and to force a calculation to be fully analogue (i.e., simulating
physical reality as directly as possible, without any biasing to accelerate
statistical convergence. A more esoteric capability of GLOBAL, used mainly for
debugging, is to ensure that the random number sequence be exactly reproduced
even in cases where the geometry tracking algorithm has the possibility to
follow different logical paths to achieve the same result.
7.7} General setting options
----------------------------
The difficult task of choosing the best settings for a calculation problem is
made much easier by the existence of several "pre-packaged" sets of defaults,
each of which is optimised for a particular type of application. Each set is
chosen by option DEFAULTS, which has to be placed at the beginning of the input
file, possibly preceded only by TITLE or GLOBAL. Several possibilities include
hadrotherapy, calorimetry, pure electromagnetic runs without photonuclear
reactions, low-energy neutron runs without gamma production, and others. One
set of defaults is tuned for maximum precision (but not necessarily great time
efficiency). Reasonable defaults, acceptable for most generic routine
calculations, are provided in case DEFAULTS is missing. In most cases, the user
has the possibility to use some of the other setting options described below,
to override one or more of the defaults provided by the chosen set.
In any case, it is important to check the list of defaults to make sure that
nothing important is missing or has been overlooked. For instance, photonuclear
reactions, which are critical for electron accelerator shielding, are not
provided by any of the available default sets and must be added by the user by
means of the PHOTONUC command.
Another setting option, DISCARD, is used to indicate particles which shall not
be transported. The energy of those particles is not deposited anywhere but is
added up in an accumulator which is printed at the end of the FLUKA standard
output. Of course it is the user's responsibility to see that the discarded
particles and their progeny would not give a significant contribution to the
requested results.
7.8} Multiple Coulomb scattering
--------------------------------
The concept of multiple scattering is an approximation to physical reality
(condensed history approximation [Ber63], where charged particles undergo a
very large number of single collisions with the atomic electrons, too many to
be simulated in detail except in very special cases. All the theoretical
treatments which have been developed are valid only within certain limits, and
none of them gives rules on how to handle material boundaries and magnetic
fields. FLUKA uses an original approach [Fer91a, based on Moli\`ere's theory
[Mol47,Mol48,Bet53,Mol55], which gives very good results for all charged
particles in all circumstances (even in backscattering problems), preserving
various angular and space correlations and freeing the user from the need to
control the particle step length.
Although the default treatment is always more than satisfactory, the user has
the possibility to request various kinds of optimisation, for both
electrons/positrons and heavy charged particles. This can be done by means of
option MULSOPT, which offers also the possibility to switch off completely
multiple scattering in selected materials. The latter is a technique used when
simulating particle interactions in gases of very low density such as are
contained in accelerator vacuum chambers: the simulation is done for a gas of
much larger density and the results are scaled to the actual low density: but
scaling is meaningful only if no scattering takes place.
Another very important feature of option MULSOPT is single scattering, which
can be requested in various degrees at boundary crossing, when the limits of
Moli\`ere's theory are not satisfied, and even all the time (but the latter
possibility is to be used only for problems of very low energy, because it is
very demanding in CPU time).
There is also another option connected with multiple scattering, which however
concerns only heavy charged particles such as hadrons and muons: MCSTHRES
allows to set a threshold below which multiple Coulomb scattering is not
performed. However, the CPU time saved is minimal and the option is not
frequently used.
7.9} Step length
----------------
Another aspect of the condensed history approximation is that charged particle
transport is performed in steps. The finite fraction of the particle energy
which is lost and deposited in matter in each step is an approximation for the
sum of innumerable tiny amounts of energy lost by the particle in elastic and
inelastic collisions.
In early Monte Carlo programs results could depend critically on the size of
the step, mainly due to the inaccurate determination of the path length
correction (ratio between the length of the actual wiggling path of the
particle and that of the straight step connecting the two endpoints). For a
more complete discussion, see [Aar93a,Fas01]. The multiple scattering algorithm
used by FLUKA [Fer91a] provides a robust independence of the results from the
step size, but for problems where a special accuracy is requested, or when
magnetic fields are present, it is possible for the user to override the
default step length. Two options control the maximum fractional energy loss per
step: EMFFIX for electrons and positrons, and FLUKAFIX for muons and charged
hadrons. The second one is seldom used, however, except in problems of very
large dimensions typical of cosmic ray research. Option STEPSIZE is used
instead to limit the absolute length of the step, independent of the energy
lost. Contrary to EMFFIX and FLUKAFIX, it works also in vacuum. While its use
is highly recommended in problems with magnetic fields, to ensure that steps be
smaller than the dimensions of the current regions and of those that border it,
when no magnetic fields are present this option should better be avoided, as it
would imply no obvious advantage and could even downgrade performance.
7.10} Energy cut-offs
---------------------
Setting energy cut-offs, for both transport and production, is an important
responsibility of the user, who is interested in choosing the best compromise
between accuracy and time efficiency. Each of the parameter sets available via
option DEFAULTS, including the basic defaults set which exists when that option
has not been explicitly requested, offers a well-optimised choice for the
corresponding class of applications, with only one exception. But even so, it
is often convenient to override some of the default cut-offs in order to
improve performance. The exception concerns the default particle production
cut-offs for electrons, positrons and photons, which are dependent on other
settings (see EMFCUT below).
Transport cut-offs, or thresholds, are set with command PART-THRes for hadrons
and muons, with EMFCUT for electrons, positrons and photons, and with LOW-BIAS
for low-energy neutrons. Despite the similar functionality of the three
commands, there are important differences in their syntax and in the way the
threshold is implemented for the three families of particles. PART-THRes can
assign different transport thresholds to different particles, but the
thresholds are the same in all materials and regions. When the hadron or muon
energy becomes lower than the relevant threshold, the particle is not stopped
but ranged out in a simplified way. Because the electron and photon cut-offs
are more critical with respect to calculation accuracy, EMFCUT can assign
transport thresholds on a region basis: on the other hand no ranging out is
performed, due to the difficulty to clearly define electron ranges. For
low-energy neutrons, the transport threshold is set by LOW-BIAS also on a
region basis, but as a group number rather than an energy.
Two input commands can set particle production cut-offs, respectively for heavy
particles and for electrons, positrons and photons.
Thresholds for delta ray production by charged hadrons and muons are assigned,
on a material basis, by means of option DELTARAY. Energy transfers to electrons
lower than the threshold are handled in the continuous slowing down
approximation. Production of bremsstrahlung by electrons and of M\oller/Bhabha
secondary electrons is simulated explicitly above thresholds set on a material
basis with option EMFCUT. Defaults for electron and photon production cut-offs
are dependent on other settings in a complex way. Therefore it is recommended
to check the values printed on standard output, or to set EMFCUT production
cut-offs explicitly for each material. Note also that the same EMFCUT command
is used to set both transport and production cut-offs: but the setting is done
by region in the first case and by material in the second.
To complete the list of commands used for cut-off setting, we will mention
THRESHOLd, which is used to set an energy threshold for star scoring. In
principle, a "star" is any high energy inelastic hadron interaction
(spallation) and star density has always been one the quantities which can be
scored by FLUKA. Since a popular technique to estimate induced radioactivity
was based originally on the density of stars produced by hadrons with energies
higher than 50 MeV, the possibility to set a scoring energy limit is provided.
7.11} Time cut-offs
-------------------
For time-dependent calculations, two time cut-off options are available: one
for particle transport, TIME-CUT, and one for scoring, TCQUENCH. While option
TIME--CUT sets a particle-dependent time limit after which the corresponding
particle history is terminated, the limits set by TCQUENCH are assigned to
selected binnings. Scoring contributions to a binning by particles having
exceeded the corresponding time limit are ignored, but particle transport
continues, possibly contributing to other detector scores.
7.12} Ionisation energy loss
----------------------------
Transport of charged particles can be done in many ways: without delta ray
production and ionisation fluctuations (continuous slowing down approximation),
with ionisation fluctuations and no delta rays, with delta ray production above
a chosen energy threshold and no ionisation fluctuations below the threshold,
and with both: delta rays above the threshold and ionisation fluctuations below
it. Depending on the application type chosen with option DEFAULTS, different
defaults and thresholds apply, which can be modified by the user by means of
options IONFLUCT, DELTARAY and EMFCUT. Option IONFLUCT is used to request
(restricted) ionisation fluctuations on a material basis. In FLUKA, these
fluctuations are not simulated according to Landau or Vavilov theory but
according to an original statistical approach [Fas97a]. They can be requested
separately for electrons and positrons and for muons and charged hadrons. Delta
ray production thresholds are instead set for the two particle families by two
separate options, which have already been mentioned above in the context of
production cut-offs: EMFCUT and DELTARAY. DELTARAY can be used also to define
(and print) the mesh width of the stopping power tabulations used by the program.
The user has also the possibility to change the default parameters used in the
calculation of stopping power. Command STERNHEIme allows to change the density
effect parameters,and MAT-PROP can set, in addition to several other material
properties, a user-defined average ionisation potential.
7.13} Special radiation components or effects
---------------------------------------------
In FLUKA, an effort has been made to implement a full cross-talk between
different radiation components (hadronic, muonic, electromagnetic, low-energy
neutrons, heavy ions, optical photons). However, some components are not
activated by default, and others are only activated in some of the available
default settings. Input options are provided to switch them on and off.
In a similar way, some physical effects may need to be activated, overriding
the chosen defaults. On the other hand, in some cases it can be of interest
(but possibly dangerous!) to ignore some effects. A number of commands are
available for these purposes.
7.13.1} Radiation components
High-energy hadrons and muons are always generated and transported, except with
defaults settings EM-CASCA and NEUTRONS (however, they cannot be requested
overriding these two defaults). To suppress them, one can use command DISCARD.
Option EMF (E_lectroM_agnetic F_luka) can be used to request electron, positron
and photon transport, and also to ask for its suppression (the latter could be
obtained also by discarding electrons, positrons and photons by means of DISCARD).
Low-energy neutron transport (if not already on by default) can be activated
with option LOW-NEUT. Explicit suppression is not possible: but the same effect
can be obtained using option LOW-BIAS to set a cut-off at energy group 1.
Heavy ion transport (only ionisation energy loss, without nuclear interactions)
is implicit with some default settings, while with others it is not available.
Details can be found in the description of command EVENTYPE. The same command
can be used also to request heavy ion interactions using different event
generators: in this case the corresponding libraries must be linked.
A special option, HI-PROPErt, is necessary to define the properties of a heavy
ion primary, since the particle type input via the BEAM command can only be a
generic heavy ion.
Generation and transport of optical photons is available only on explicit user
request. Activation (and deactivation) are requested via OPT-PROD (for
Cherenkov, transition radiation or scintillation photon production) and
OPT-PROP (transport).
7.13.2} Physics effects
Some physical effects are automatically activated, but only when certain
default sets are in force (see option DEFAULTS), and can be switched on or off
with appropriate commands. The command to simulate fluorescence is EMFFLUO,
that for Rayleigh scattering and Compton binding corrections is EMFRAY, while
for multiple scattering there are MULSOPT and MCSTHRESh which we have already
introduced above. High-energy effects such as production of bremsstrahlung and
electron pairs by heavy charged particles (in particular muons) are regulated
by option PAIRBREM.
A few physical effects need to be requested explicitly, whatever the defaults.
These are photon polarisation (command POLARIZA), polarisation of pion, kaon
and muon decays (command PHYSICS), photonuclear reactions (PHOTONUC), and muon
hadronic interactions via virtual photons (MUPHOTON).
In some cases, it is also possible to switch off some important effects to
study the relative importance of different processes. Command THRESHOLd allows
to set a lower energy limit for hadron elastic scattering and inelastic
reactions, and EMFCUT does the same with various kinds of electron and photon
interactions. The user must bear in mind, however, that results obtained
suppressing effects which are critical for the development of the
electromagnetic or hadronic cascade are unlikely to be physically correct.
7.14} Scoring options
---------------------
Any result in a Monte Carlo calculation is obtained by adding up the
contributions to the "score", or "tally" of a detector defined by the user.
A detector is the Monte Carlo equivalent of a measurement instrument. Each
"estimator" (detector type) is designed to estimate one or more radiometric
quantities, and the final score is a statistical estimation of the average
value of the corresponding population. As in experimental measurements, it is
possible to calculate a standard deviation by running several independent
calculations.
No default detector is available: each scoring option must be explicitly
requested. There are different input options corresponding to different types
of detector. The simplest is SCORE which provides energy deposition
(proportional to dose) or star density in every region of the geometry. "Stars"
is an old name for inelastic hadron reactions which derives from early
experiments with nuclear emulsions.
The same quantities can be scored in a uniform spatial mesh independent of
geometry, called a "binning", by means of option USRBIN. There are several
types of binnings: Cartesian, 2D-cylindrical, 3D-cylindrical and even more
complex phase space structures. In addition to dose and star density, it is
possible to use USRBIN to score particle fluence distributions in space. USRBIN
results are often displayed as colour plots where each colour corresponds to a
pre-defined range of values. A post-processing program for this purposes
(PAWLEVBIN) is available in the directory $FLUPRO/flutil, and a GUI interface
can be downloaded from the FLUKA website www.fluka.org.
Fluence, averaged over the volume of a given geometry region, can be calculated
with options USRTRACK and - less often - USRCOLL. The first is a "track-length
estimator" (it estimates fluence as volume density of particle trajectory
lengths), and the second is a "collision estimator" (fluence is estimated as
volume density of collisions weighted with the particle mean free path). Of
course, USRCOLL can be used only in a region of matter, while USRTRACK works
also in vacuum. Both options provide fluence differential energy spectra.
Another common scoring option is USRBDX, which also calculates fluence, but
averaged over the boundary between two geometry regions. It is a "boundary
crossing estimator", which estimates fluence as the surface density of crossing
particles weighted with the secant of the angle between trajectory and normal
to the boundary at the crossing point. Option USRBDX can also calculate
current, i.e. a simple counter of crossings, not weighted by inverse cosine:
but despite a widespread credence, current is only seldom a quantity worth
calculating. The results of USRBDX can account on request for particles
crossing the boundary from either side or from one side only, and are in the
form of double-differential energy and angular spectra. The angle considered
is again that with the normal at the crossing point.
USRYIELD is a multi-purpose estimator option, which can estimate several
different double-differential quantities. The main one is an energy-angle
double-differential yield of particles escaping from a target, the angle in
this case being with respect to a fixed direction. Energy and angle can be
replaced by many other variables which are mostly of the same kind, such as
momentum and rapidity. But it is possible also to score yields as a function of
charge and LET (linear energy transfer).
Production of residual nuclei can be obtained with command RESNUCLEi.
The results, which are closely related to induced activity and dose rate from
activated components, may include nuclei produced in low-energy neutron
interactions, provided the corresponding information is available in
the neutron cross section library for the materials of interest.
7.15} Event by event scoring options
------------------------------------
Typical particle physics applications, in particular calorimetry, require
separate scoring event by event (that is, results are printed after each
primary particle history). Two commands, EVENTBIN and EVENTDAT, are
respectively the event-equivalent of USRBIN and SCORE which have been
introduced before. A third command, DETECT, allows to score event by event
energy deposition simulating a detector trigger, defining coincidences and
anticoincidences. All these options are incompatible with any biasing. It is
suggested to use command GLOBAL to make sure that the run will be completely
analogue.
7.16} Scoring modifying options
-------------------------------
There are a few commands which are used to modify some of the scoring options
already described. TCQUENCH, which has already been shown to define a time
cut-off, can be used also to apply a quenching factor (Birks factor) to energy
deposition scored with USRBIN or EVENTBIN. ROT-DEFI and ROTPRBIN allow to
define roto-translation transformations for binnings not aligned with the
coordinate axes. ROTPRBIN can be used also to set the binning storage
precision: a space saving feature, which is useful mainly when scoring event by
event with EVENTBIN.
7.17} Options to handle radioactive decay
-----------------------------------------
It is possible to transport and score in the same run also the beta and gamma
radiation emitted in the decay of radioactive nuclei produced in the hadronic
or electromagnetic cascade. Several options are available for this purpose:
RADDECAY is used to request the simulation of radioactive decays, IRRPROFIle
defines a time profile for the intensity of the primary particles, DCYTIMES
requests one or more decay times at which the desired scoring shall occur, and
DCYSCORE associates selected scoring detectors to the decay times so requested.
7.18} Biasing options
---------------------
When run in fully analogue mode, FLUKA allows the user to study fluctuations
and correlations, and to set up a direct simulation of physical reality where
all moments of phase space distributions are faithfully reproduced. On the
other hand, in the many applications where only quantities averaged over many
events are of interest, it is convenient to use calculation techniques
converging to the correct expectation values but reducing the variance (or the
CPU time, or both) by sampling from biased distributions. This is especially
useful in deep penetration calculations, or when the results of interest are
driven by rare physical interactions or cover a small domain of phase space.
FLUKA makes available several biasing options. Some are easy to use, but others
require experience and judgment, and often a few preliminary preparation runs
are needed to optimise the biasing parameters.
7.18.1} Simple biasing options
The easiest biasing command is fittingly called BIASING. It provides two
different kinds of variance reduction: Multiplicity Reduction and Importance
Biasing, which is based on the two complementary techniques Geometry Splitting
and Russian Roulette (RR).
Splitting and Russian Roulette are two classical variance reduction techniques,
which are described in most textbooks on Monte Carlo [Car75, Lux91].
A detailed description of how they are implemented in FLUKA is available in a
Note to option BIASING. Importance biasing consists in assigning an importance
value to each geometry region. The number of particles moving from a region to
another will increase (by splitting) or decrease (via RR) according to the
ratio of importances, and the particle statistical weight will be modified
inversely so that the total weight will remain unchanged. In this way, the user
can strive to keep the particle population constant, making up for attenuation,
or to make it decrease in regions far from the detectors where there is a lower
probability to contribute to the score. In FLUKA, importance biasing can be
done separately for hadrons/muons, electrons/positrons/photons and low-energy
neutrons.
Multiplicity Reduction is a simple technique which was introduced for the first
time in FLUKA (now it has been adopted also by other programs), in order to
decrease the computer time needed to simulate a very high energy hadron
cascade. At energies of several hundred GeV and more, the number of
secondaries produced in a hadron-nucleus interaction is very large and the
total number can increase geometrically in the following interactions,
requiring an unacceptably long computer time. Since many secondaries are
particles of the same kind and with a similar angular and energy distribution,
the user can decide to follow only a region-dependent fraction of them.
A biasing option performing a similar multiplicity reduction on electromagnetic
showers is EMF-BIAS. In this case the technique is known as Leading Particle
Biasing and consists in sampling only one of the two secondary particles which
are present in the final state of most electromagnetic interactions. The
secondary of higher energy is sampled with higher probability. The EMF-BIAS
option can be tuned per region below user-defined energy thresholds and is used
very often in shielding calculations for high-energy electron accelerators. The
same command can be used also to bias the electron and photon mean free path
for various types of interaction, for instance to enhance the probability of
interaction in a thin or low-density target.
In a similar way, option LAM-BIAS can be used to increase the probability of
hadronic interactions, and in particular photohadron reactions. These are the
dominant reactions for high-energy electron accelerator induced activity and
shielding design, but because their cross section is small compared to that of
electromagnetic effects, analogue sampling would be very inefficient. The same
command can help to get a higher probability of hadron interaction in a thin
target. It can also be used to bias a particle decay length (for instance, to
enhance muon or neutrino production) and the emission angle of the decay
secondaries in a direction indicated by the user.
7.18.2} Weight window options
The weight window is a very powerful biasing technique, not based on relative
importances, but on the absolute value of particle weight. The user sets an
upper and a lower limit for the particle weight in each geometry region,
possibly tuned per type of particle and energy. Splitting and RR will be
applied so that the weight of all relevant particles will have a value between
the two limits. In addition to controlling the particle population, this
technique helps also to "damp" excessive weight fluctuations due to other
biasing options.
Its use is not as easy as that of importance biasing, because it is necessary
to have at least a rough idea of what are the average weights in different
regions. Special splitting and RR counters can be printed on request to help
setting the window parameters setting SDUM = PRINT in command BIASING. An
explanation about the meaning of the counters can be found in Chap. 9}. Weight
window setting is done in FLUKA by three input commands: WW-FACTOr, WW-THRESh
and WW-PROFIle. The first two commands must be used together: WW-FACTOr sets
the upper and lower weight limits per region, while WW-THRESh defines energy
limits within which the weight window must be applied, and the particles to
which it is to be applied. The third option is reserved to low-energy neutrons,
whose transport characteristics often require a more detailed biasing pattern:
WW-PROFIle allows indeed to tune the weight window by neutron energy group.
7.18.3} Biasing options for low-energy neutrons
The special multigroup transport structure used by FLUKA for low-energy
neutrons calls for some biasing options specific to these particles. We have
just introduced the weight window command WW-PROFIle. Two more options are
LOW-BIAS, which has already been mentioned before in the context of energy
cut-offs, but which is used also to set a user-defined non-analogue absorption
probability, and LOW-DOWN, by which it is possible to bias neutron
thermalisation (downscattering). The latter, however, is an option recommended
only to users with a good knowledge and experience of neutronics.
7.19} Calls to user routines
----------------------------
The purpose of several FLUKA input options is to trigger calls to user routines
(user routines are described in Chap. 13}). One of the most important ones is
SOURCE, which makes FLUKA get the characteristics of its primary particles from
subroutine SOURCE instead of from options BEAM and BEAMPOS. This option allows
to pass to the subroutine several parameters, thus allowing to drive it from
input without the need to re-compile it. Note that even when using a
user-written source, it is still necessary to have in input a BEAM card
indicating the maximum expected energy of a primary particle, so that the
program can prepare appropriate cross section tables. If command SOURCE is
present, but no SOURCE routine has been linked, the default one in the FLUKA
library will be called, which leaves unchanged the particle type, energy,
position etc. as defined by BEAM and BEAMPOS.
Command USERWEIG can call 5 different user routines used to modify a scored
quantity (at the time of scoring). The routines are:
* FLUSCW is a function returning a multiplication factor for fluences.
A typical application is to convert a fluence to dose equivalent.
* COMSCW is a function returning a multiplication factor for star densities
and doses. Common application: converting energy deposition to dose.
* USRRNC is a subroutine providing a convenient user hook for scoring
residual nuclei.
* ENDSCP is a subroutine performing a displacement of the energy deposited
in a particle step, for instance to account for an instrument drift.
* FLDSCP is a subroutine performing a displacement (drift) of the track
corresponding to a particle step.
Complex magnetic fields can be defined or read from a map by a user routine
MAGFLD. Calls to the routine are activated by command MGNFIELD.
A collision file (also called a collision tape, or a phase space file) is a
file on which FLUKA writes on request details of user-selected events:
particle trajectories, energy deposition events, source particles, boundary
crossings, physical interactions, etc. This task is performed by subroutine
MGDRAW, which is called if option USERDUMP is requested in input. The default
routine present in the FLUKA library can be driven as it is, without
re-compilation, by setting some of the USERDUMP parameters, but can also be
modified and re-compiled to adjust to specific needs of the user. A typical
simple task is to draw particles trajectories. Another frequent application of
USERDUMP is to perform a calculation in two steps, where the second step uses
the collision file as a source. In principle it is also possible to use
subroutine MGDRAW for scoring, for instance by interfacing it to some
histogramming package, as it is customary in some other Monte Carlo programs.
However, in general this is discouraged in FLUKA, unless the desired quantity
cannot be scored via the standard FLUKA input commands, which is very rare. The
FLUKA scoring options are indeed highly optimised and well checked against
possible errors and artefacts. It is very unlikely that a user might be able to
achieve in a short time the same level of reliability. In any case,
user-written scoring via MGDRAW MUST be avoided in all runs where biasing is
present, because to handle correctly the particle weights requires other FLUKA
tools which are not available to the normal user.
Three more input options activating calls to user routines are USRICALL,
USROCALL and USRGCALL. The first two allow the user to issue a call respectively
to an initialisation routine USRINI and to an output routine USROUT. The third
one activates a call to a routine USRGLO, which performs a global initialisation
before any other made by FLUKA.
7.20} Miscellaneous
-------------------
Command RANDOMIZe starts a new independent random number sequence. It can be
omitted only in a first run, but it is compulsory if a sequence of independent
runs is desired in order to calculate statistical errors.
Command STOP, inserted at any point in the input file, interrupts the reading.
Any further input card is ignored. It may be made to follow a PLOTGEOM command
and the corresponding input, so that the Plotgeom program is executed, but no
FLUKA simulation is started.
Finally, command START is always needed to give the program the signal to begin
the calculation. The command includes the number of primary histories to be
simulated. A STOP command may follow, but it is not necessary since it is
assumed to be present by default.
1********************************************************************************
Description of available input options
*********************************************************************************
1********************************************************************************
{ASSIGNMA}t
defines the correspondence between region indices (or names) and material
indices (or names). It defines also regions with magnetic field.
See also MATERIAL, MGNFIELD
WHAT(1) = material index, or material name
Default = 1.0 (blackhole or external vacuum)
WHAT(2) = lower bound (or name corresponding to it) of the region indices
with material index equal or corresponding to WHAT(1).
("From region WHAT(2)...")
Default = 2.0
WHAT(3) = upper bound (or name corresponding to it) of the region indices
with material index equal or corresponding to WHAT(1).
("...to region WHAT(3)...")
Default = WHAT(2)
WHAT(4) = step length in assigning indices
("...in steps of WHAT(4)")
Default = 1.0
WHAT(5) = 1.0 : a magnetic field is present in the region(s) defined
by WHAT(2), (3), and (4)
= 0.0 : ignored
< 0.0 : resets the default (no field) in the region(s) defined
by WHAT(2), (3), and (4)
Default = 0.0 (ignored)
WHAT(6), SDUM : not used
Default (option ASSIGNMAt not requested): all regions are assigned material
1.0 (BLCKHOLE) except region 2.0 which is assumed to be COPPER
(FLUKA material 12.0). No magnetic field is the default for all
regions.
Notes:
1) Several ASSIGNMAt definitions are generally necessary to assign a
material to all regions. Standard material names and their numbers
are listed in 5}. They may be redefined and others may be added
(see Note to command MATERIAL)
2) Overlapping region indices can be given in several ASSIGNMAt
definitions, each definition overriding the earlier ones. This makes
the assigning of materials very convenient (see Example below).
The same can be done even if region names are used instead of indices,
The name-index correspondence can be found on standard output after a
short test run.
3) In practice, option ASSIGNMAt must always be present. (If it is not
chosen, all regions are considered to be black holes except region 2
which is assumed to be COPPER).
4) Magnetic field tracking is performed only in regions defined as
magnetic field regions by WHAT(5) = 1.0. It is strongly recommended
to define as such only regions where a magnetic field actually
exists, due to the less efficient and less accurate tracking
algorithm used in magnetic fields. To define a region as one with
magnetic field and to return systematically B = 0.0 in that region
via the user subroutine MAGFLD must be absolutely avoided (see
MGNFIELD)
Example (for an input number-based):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....
MATERIAL 13.0 27.0 2.7 10.0 0.0 0.0 ALUMINUM
ASSIGNMA 10.0 1.0 15.0 0.0 1.0 0.0
ASSIGNMA 2.0 5.0 17.0 6.0 -1.0 0.0
ASSIGNMA 2.0 16.0 18.0 2.0 0.0 0.0
* The above definitions mean that all regions from 1 to 15 are
* aluminium with a magnetic field, except regions 5 and 11 which are
* vacuum without any magnetic field. Regions 16, 17 and 18 are also
* vacuum without field.
* Note that in the above example material 10 has been defined
* overriding the pre-defined FLUKA aluminium material, but keeping
* the same material number.
The corresponding name-based input cards could be (using arbitrary names):
ASSIGNMA ALUMINUM FirstReg Reg15 0.0 1.0 0.0
ASSIGNMA VACUUM FifthReg Reg17 6.0 -1.0 0.0
ASSIGNMA VACUUM Reg16 Reg18 2.0 0.0 0.0
1********************************************************************************
{AUXSCORE}
allows to associate scoring estimators with dose equivalent conversion
factors and to filter scoring estimators according to auxiliary (generalized)
particle distributions.
See also EVENTBIN, USRBDX, USRBIN, USRTRACK, USRCOLL, USRYIELD
WHAT(1) : binning / estimator type to associate the card with
1.0 : USRBDX
2.0 : USRBIN / EVENTBIN
3.0 : USRTRACK
4.0 : USRCOLL
5.0 : USRYIELD
Default = 2.0 USRBIN/EVENTBIN
WHAT(2) : particle (or particle family) to be considered as a filter
for the associated scoring card
> -100.0 : particle or particle family code
<= -100.0 Isotope coding. To select atomic number Z, mass
number A and isomeric state M
what(2)= -(Z*100+A*100000+m*100000000).
Z=0 means all atomic numbers for the given A,
A=0 includes all mass numbers for a given Z,
M=0 includes all ground and isomeric states.
To select only the ground state set M=9
Default = 201.0: all particles (ALL-PART)
WHAT(3) : not used
WHAT(4) : lower bound index (or corresponding name) of the indices
of the estimator in which the associated scoring is
activated (See Note 1)
Default = 1.0
WHAT(5) : upper bound index (or corresponding name) of the indices
of the estimator in which the associated scoring is
activated (See Note 1)
Default = WHAT(4)
WHAT(6) = step length in assigning indices
Default: 1.0
SDUM : For dose equivalent (DOSE-EQ) scoring, the user can provide
the energy dependent factors for the conversion of fluence
to effective dose and ambient dose equivalent for neutrons,
protons, charged pions, muons, photons and electrons.
[Roe06] [Pel00]
The following dose conversion coefficients sets are available:
a) Effective dose sets from ICRP74 and Pelliccioni data
calculated with ICRP radiation weighting factors Wr
EAP74 : Anterior-Posterior irradiation
ERT74 : Rotational irradiation geometry
EWT74 : WORST possible geometry for the irradiation
b) Effective dose sets from ICRP74 and Pelliccioni data
calculated with the Pelliccioni radiation weighting
factors Wr
EAPMP : Anterior-Posterior irradiation
ERTMP : Rotational irradiation geometry
EWTMP : WORST possible geometry for the irradiation
c) Ambient dose equivalent from ICRP74 and Pelliccioni data
AMB74
d) Ambient dose equivalent with old "GRS"-conversion factors
AMBGS
Notes:
1) USRBIN/EVENTBIN estimators are counted together
2) Only the sets EAP74, ERT74, EWT74 and AMB74 are implemented for
photons and electrons.
If sets from the second group (EAPMP, ERTMP, EWTMP) are requested,
the respective set from the first group will be used instead.
For set AMBGS zero values are returned.
3) Dose conversion coefficients exists only for some particle types
hadrons, muons, photons, electrons/positrons. For all other
particle types, zero factor will be returned. This is particularly
important for heavy ions where zero factor will be scored.
Examples:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....
USRBIN 10.0 208.0 -50.0 10.0 10.0 10.0Ene.p
USRBIN -10.0 -10.0 -10.0 100.0 100.0 100.0
AUXSCORE 2.0 1.0 1.0
* The above AUXSCORE card will filter the energy scoring of the
* USRBIN card to only the energy that is deposited by protons
USRBIN 10.0 ENERGY -50.0 10.0 10.0 10.0Ene.pi
USRBIN -10.0 -10.0 -10.0 100.0 100.0 100.0
AUXSCORE USRBIN MUONS Ene.pi
* Similar to the previous example but in a name based input
USRBIN 10.0 DOSE-EQ -50.0 10.0 10.0 10.0DoseEq
USRBIN -10.0 -10.0 -10.0 100.0 100.0 100.0
AUXSCORE USRBIN DoseEq AMB74
* Score ambient dose equivalent in a Cartesian mesh from all particles
USRYIELD 124.0 ALL-PART -87. TARGS3 INAIR 1.0 Fe56
USRYIELD 180.0 0.0 18. 10.0 0.0 3.0 &
AUXSCORE 5.0 -5602600. Fe56 Fe56
* Score yield of 56 Fe ions
1********************************************************************************
{BEAM}
defines several beam characteristics: type of particle, energy, divergence,
profile and statistical weight
See also BEAMAXES, BEAMPOS, SOURCE
WHAT(1) > 0.0 : average beam momentum in GeV/c
< 0.0 : average beam kinetic energy in GeV
This value is available in COMMON BEAMCM as variable PBEAM.
It can be used or modified in subroutine SOURCE if command
SOURCE is present in input.
Default = 200.0 GeV/c momentum
WHAT(2) > 0.0 : beam momentum spread in GeV/c. The momentum distribution is
assumed to be rectangular
< 0.0 : |WHAT(2)| is the full width at half maximum (FWHM) of a
Gaussian momentum distribution (FWHM = 2.355 sigma)
This value is available in COMMON BEAMCM as variable DPBEAM.
It can be used or modified in subroutine SOURCE if command
SOURCE is present in input. However, in that case the
momentum/energy sampling must be programmed by the user.
Default = 0.0
WHAT(3) specifies the beam divergence (in mrad):
> 0.0 : |WHAT(3)| is the width of a rectangular angular
distribution
< 0.0 : |WHAT(3)| is the FWHM of a Gaussian angular distribution
> 2000 x PI mrad (i.e. 2 pi rad) : an isotropic distribution is
assumed (see Note 8 below)
This value is available in COMMON BEAMCM as variable DIVBM.
It can be used or modified in subroutine SOURCE if command
SOURCE is present in input. However, in that case the
divergence sampling must be programmed by the user.
Default = 0.0
WHAT(4) > 0.0 : If WHAT(6) > 0.0, beam width in x-direction in cm. The beam
profile is assumed to be rectangular.
If WHAT(6) < 0.0, WHAT(4) is the maximum radius of an
annular beam spot.
< 0.0 : |WHAT(4)| is the FWHM of a Gaussian profile in x-direction
(whatever the value of WHAT(6))
This value is available in COMMON BEAMCM as variable XSPOT.
It can be used or modified in subroutine SOURCE if command
SOURCE is present in input. However, in that case the
x-profile sampling must be programmed by the user.
Default = 0.0
WHAT(5) > 0.0 : If WHAT(6) > 0.0, beam width in y-direction in cm. The beam
profile is assumed to be rectangular.
If WHAT(6) < 0.0, WHAT(5) is the minimum radius of an
annular beam spot.
< 0.0 : |WHAT(5)| is the FWHM of a Gaussian profile in y-direction
(whatever the value of WHAT(6))
This value is available in COMMON BEAMCM as variable YSPOT.
It can be used or modified in subroutine SOURCE if command
SOURCE is present in input. However, in that case the
y-profile sampling must be programmed by the user.
Default = WHAT(4)
WHAT(6) : |WHAT(6)| = weight of the beam particles.
If WHAT(6) < 0.0, WHAT(4) and WHAT(5), if positive, are
interpreted as the maximum and minimum radii of an annular beam
spot. If negative, they are interpreted as FWHMs of Gaussian
profiles as explained above, independent of the value of WHAT(6)
This value is available in COMMON BEAMCM as variable BEAWEI.
It can be used or modified in subroutine SOURCE if command
SOURCE is present in input.
Default = 1.0
SDUM = beam particle name. Particle names and numerical codes are listed
in the table of FLUKA particle types (see 5}).
For heavy ions, use the name HEAVYION and specify further the ion
properties by means of option HI-PROPErt. In this case WHAT(1)
will mean the energy (or momentum) PER UNIT ATOMIC MASS, and not
the total energy or momentum.
The light nuclei 4He, 3He, triton and deuteron are defined with
their own names (4-HELIUM, 3-HELIUM, TRITON and DEUTERON) and
WHAT(1) will be the total energy or momentum.
For (radioactive) isotopes, use the name ISOTOPE and specify
further the isotope properties by means of option HI-PROPErt.
In this case WHAT(1) and WHAT(2) are meaningless. If no
radioactive isotope evolution or decay is requested, or if a
stable isotope is input, nothing will occur, and no particle will
be transported.
Neutrino interactions are activated by a (A)NEUTRIxx SDUM.
Neutrino interactions are forced to occur in the point (or area)
defined in the BEAMPOS card.
[Not yet implemented: For optical photons, use the name OPTIPHOT
and specify further the transport properties by material by means
of option OPT-PROP.]
This value can be overridden in user routine SOURCE (if command
SOURCE is present in input) by assigning a value to variable
IJBEAM equal to the numerical code of the beam particle.
Default = PROTON
Default (option BEAM not requested): all the above defaults apply, unless
other values are provided by the user by means of a SOURCE
subroutine (see 13} and command SOURCE).
Notes:
1) Cases of distributed, non monoenergetic or other more complex
sources should be treated by means of a user-written subroutine
SOURCE as explained in the description of the SOURCE option (see
13}). In particular, the BEAM definition cannot handle beams of
elliptical cross section and rectangular profile. However, even when
using a SOURCE subroutine, the momentum or kinetic energy defined by
WHAT(1) of BEAM is meaningful, since it is taken as maximum energy
for several scoring facilities.
Advice: when a user-written SOURCE is used, set WHAT(1) in BEAM
equal to the maximum expected source particle momentum (or energy).
2) A two-dimensional distribution, Gaussian with equal variances in x
and y, results in a RADIAL Gaussian distribution with variance
sigma_r = sigma_x = sigma_y
3) The distribution has a form P(r) =
= 1/(2pi sigma_x sigma_y) exp{-1/2[(x/sigma_x)^2 + (y/sigma_y)^2]} =
= 1/(2pi sigma_r^2) exp[-1/2(r/sigma_r)^2]
4) All FLUKA results are normalised per unit incident particle weight.
Thus, setting the starting weight to a fixed value different from 1
has no practical effect. A distribution of initial weights may be
needed, however, when sampling from a non-monoenergetic spectrum: in
this case, a SOURCE subroutine must be written (see 13})).
5) All options governed by WHAT(3,4,5) are meaningful only if the beam
direction is along the positive z axis, unless a command BEAMAXES is
issued to establish a beam reference frame different from the
geometry frame (see command BEAMAXES). If the beam is not in the
positive z direction and no BEAMAXES command has been given,
WHAT(3)-WHAT(5) must be set = 0.0 (unpredictable effects would arise
otherwise).
6) The beam momentum value as defined with the BEAM card is available
to user routines as a variable PBEAM and so is the beam particle
type IJBEAM. These variables, as well as those defining other beam
properties, are in COMMON BEAMCM which can be accessed with the
INCLUDE file (BEAMCM).
7) It is possible to track pseudoparticles by setting SDUM = RAY. See
14} for details.
8) When an isotropic source is defined (by setting WHAT(3) > 2000 pi),
any cosines defined by option BEAMPOS become meaningless, although
their values are still reported on standard output.
Examples:
* The following BEAM card refers to a 100 keV pencil-like
* electron beam:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
BEAM -1.E-4 0.0 0.0 0.0 0.0 1.0 ELECTRON
* The next option card describes a parallel proton beam with a
* momentum of 10.0 +/- 0.2 GeV/c, with a Gaussian profile in
* the x-direction and in the y-direction described by standard
* deviations sigma_x = 1. cm (FWHM = 2.36 cm) and sigma_y = 0.5
* cm (FWHM = 1.18 cm).
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
BEAM 10.0 0.2 0.0 -2.36 -1.18 1.0 PROTON
* The next example concerns a negative muon beam of 2 GeV
* kinetic energy, with a divergence of 3 mrad.
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
BEAM -2.0 0.0 3.0 0.0 0.0 1.0 MUON-
* The next BEAM card describes a 137-Cs isotropic source
BEAM -661.7E-6 0.0 1.E4 0.0 0.0 1.0 PHOTON
* The last example illustrates how to define a hollow 14 MeV
* neutron beam, with an inner radius of 7 mm and an outer radius
* of 1.2 cm.
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
BEAM -14.E-3 0.0 0.0 1.2 0.7 -1.0 NEUTRON
1********************************************************************************
{BEAMAXES}
defines the axes used for a beam reference frame different from the
geometry frame
See also BEAM, BEAMPOS, POLARIZAti, SOURCE
WHAT(1) = cosine of the angle between the x-axis of the beam reference
frame and the x-axis of the geometry frame
Default: no default
WHAT(2) = cosine of the angle between the x-axis of the beam reference
frame and the y-axis of the geometry frame
Default: no default
WHAT(3) = cosine of the angle between the x-axis of the beam reference
frame and the z-axis of the geometry frame
Default: no default
WHAT(4) = cosine of the angle between the z-axis of the beam reference
frame and the x-axis of the geometry frame
Default: no default
WHAT(5) = cosine of the angle between the z-axis of the beam reference
frame and the y-axis of the geometry frame
Default: no default
WHAT(6) = cosine of the angle between the z-axis of the beam reference
frame and the z-axis of the geometry frame
Default: no default
SDUM : not used
Default (option BEAMAXES not requested): the beam frame coincides with the
geometry frame
Notes:
1) Option BEAM describes a simple pencil beam, or also a beam simply
distributed in space (angular divergence and transversal profile),
provided the beam axis coincides with the z-axis of the input
geometry. Also a possible beam polarisation described by option
POLARIZAti refers to a beam with its axis coinciding with the
geometry z-axis.
The purpose of option BEAMAXES is to allow the user to define
angular divergence, transversal profile and polarisation for a beam
of arbitrary direction, either constant as defined by option
BEAMPOS, or not necessarily known in advance as provided by a user
SOURCE routine. For this purpose, the user can define divergence,
profile and polarisation in a beam reference frame. Option BEAMAXES
establishes the correspondence between beam and geometry reference
frame.
2) The origin of the beam reference frame coincides always with that of
the geometry frame.
3) The user needs to input only the direction cosines of the x- and of
the z-axis of the beam frame. The direction of the y-axis is
determined by the program as the vector product z X x.
4) If the the x- and z-axes defined with BEAMAXES are not exactly
perpendicular (in double precision!) the program forces
perpendicularity by adjusting the cosines of the x-axis.
5) The direction cosines of the x- and z-axes do not need to be exactly
normalised to 1. The code takes care of properly normalising all
cosines.
Example:
* The next option cards describe a 10 GeV proton beam with a divergence of
* 50 mrad and a gaussian profile in the "beam x"-direction and in the
* "beam y"-direction described by standard deviations sigma_x = 1. cm
* (FWHM = 2.36 cm) and sigma_y = 0.5 cm (FWHM = 1.18 cm). The beam starts
* from point (0,0,0) and is directed in a direction perpendicular to the
* "geometry x" axis, at 45 degrees with respect to both "geometry y" and
* "geometry z". The "beam x" axis has cosines 1,0,0 and the "beam z"
* axis has cosines 0, cos(pi/4), cos(pi/4)
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
BEAM -10.0 0.0 50.0 -2.36 -1.18 1.0 PROTON
BEAMPOS 0.0 0.0 0.0 0.0 0.7071068 0.0
BEAMAXES 1.0 0.0 0.0 0.0 0.7071068 0.7071068
1********************************************************************************
{BEAMPOS}
defines the coordinates of the centre of the beam spot (i.e. the point from
which transport starts) and the beam direction
See also BEAM, BEAMAXES, SOURCE
WHAT(1) = x-coordinate of the spot centre.
This value is available in COMMON BEAMCM as variable XBEAM.
It can be used or modified in subroutine SOURCE if command SOURCE
is present in input.
Default: 0.0
WHAT(2) = y-coordinate of the spot centre.
This value is available in COMMON BEAMCM as variable YBEAM.
It can be used or modified in subroutine SOURCE if command SOURCE
is present in input.
Default: 0.0
WHAT(3) = z-coordinate of the spot centre.
This value is available in COMMON BEAMCM as variable ZBEAM.
It can be used or modified in subroutine SOURCE if command SOURCE
is present in input.
Default: 0.0
WHAT(4) = direction cosine of the beam with respect to the x-axis.
This value is available in COMMON BEAMCM as variable UBEAM.
It can be used or modified in subroutine SOURCE if command SOURCE
is present in input.
Default: 0.0
WHAT(5) = direction cosine of the beam with respect to the y-axis.
This value is available in COMMON BEAMCM as variable VBEAM.
It can be used or modified in subroutine SOURCE if command SOURCE
is present in input.
Default: 0.0
WHAT(6) : not used
SDUM = NEGATIVE means that the direction cosine with respect to z-axis
is negative.
The value of the direction cosine with respect to the z-axis can
be overridden in user routine SOURCE by assigning a value to
variable WBEAM in COMMON BEAMCM (make sure that the three cosines
are properly normalised so that the sum of their squares is 1.0
in double precision!!)
Default: beam directed in the positive z-direction
Default (option BEAMPOS not requested): all the above defaults apply (the
beam starts at point 0., 0., 0. in the z direction)
Notes:
1) To take full advantage of some tracking optimisation features, it is
often a good idea to create a buffer vacuum region containing the
whole geometry, which must itself be contained within the external
(mandatory) blackhole region. It is then suggested that the beam
impact point be chosen in vacuum, slightly upstream of the actual
one on a material boundary. As a general rule, anyway, it is
recommended to never select the impact point EXACTLY on a boundary.
2) The beam spot coordinates and the beam director cosines as defined
with the BEAMPOS card are available to user routines with names
XBEAM, YBEAM, ZBEAM and UBEAM, VBEAM, WBEAM respectively. These
variables, as well as those defining other beam properties, are in
COMMON BEAMCM which can be accessed with the INCLUDE file (BEAMCM).
3) Beam divergence and transversal profile defined by option BEAM, as
well as polarisation defined by option POLARIZAti, are meaningful
only if the beam direction is along the positive z-axis, unless a
command BEAMAXES is issued to establish a beam reference frame
different from the geometry frame
4) When an isotropic source is defined (by setting command BEAM with
WHAT(3) > 2000 pi), any cosines defined by option BEAMPOS become
meaningless, although their values are still reported on standard
output.
Examples:
* A beam parallel to the x-axis starting at a point of
* coordinates -0.1, 5.0, 5.0 :
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7...
BEAMPOS -0.1 5.0 5.0 1.0 0.0 0.0
* A beam perpendicular to the x-axis, with director cosines
* 0., 1/sqrt(2), -1/sqrt(2) with respect to x, y and z,
* starting at point 0.0, 0.0, 0.0 :
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
BEAMPOS 0.0 0.0 0.0 0.0 0.7071068 0.0 NEGATIVE
1********************************************************************************
{BIASING}
biases the multiplicity of secondaries (only for hadron or muon/photon
photonuclear interactions) on a region by region basis.
Sets importance sampling (Russian Roulette/splitting) at boundary crossing
by region and by particle.
See also EMF-BIAS, LOW-BIAS, LAM-BIAS, WW-FACTOr, WW-PROFIle, WW-THRESh
The meaning of WHAT(1)...WHAT(6) and SDUM is different depending on the
sign of WHAT(1):
If WHAT(1) >= 0.0 :
WHAT(1) specifies the particles to be biased:
= 0.0 : all particles
= 1.0 : hadrons and muons
= 2.0 : electrons, positrons and photons
= 3.0 : low energy neutrons
WHAT(2) = RR (or splitting) factor by which the average number of
secondaries produced in a collision should be reduced (or
increased). Meaningful only for hadron or muon/photon
photonuclear interactions.
This value can be overridden in the user routine UBSSET by
assigning a value to variable RRHADR, see 13})
Default = 1.0
WHAT(3) = region importance (allowed values range from 0.0001 to 10000.)
This value can be overridden in the user routine UBSSET by
assigning a value to one or more of the variables IMPHAD, IMPLOW
and IMPEMF (depending on the value of WHAT(1))
Default = 1.0
WHAT(4) = lower bound (or corresponding name) of the region indices with
importance equal to WHAT(3) and/or with multiplicity biasing
factor equal to WHAT(2).
("From region WHAT(4)...")
Default = 2.0
WHAT(5) = upper bound (or corresponding name) of the region indices with
importance equal to WHAT(3) and/or with multiplicity biasing
factor equal to WHAT(2).
("...to region WHAT(5)...")
Default = WHAT(4)
WHAT(6) = step length in assigning indices.
("...in steps of WHAT(6)").
Default = 1.0
SDUM = PRINT : importance biasing counters are printed (useful to tune
importances and weight windows)
= NOPRINT: counters are not printed (cancels any previous PRINT
request)
= USER: importance biasing according to the user defined
routine USIMBS
= NOUSER: reset to default (cancels any previous USER request)
= RRPRONLY: multiplicity biasing for primary particles only
= blank: ignored
Default: NOPRINT, NOUSER, multiplicity biasing for all
generations (if requested)
If WHAT(1) < 0.0 :
WHAT(1) : flag indicating that all region importances shall be modified by
a particle-dependent factor, based on a modifying parameter as
explained in the Note 3 below
WHAT(2) >= 0.0 : modifying parameter M (see Note 3). See also WARNING
below.
< 0.0 : M is reset to the default value 1.0 (i.e. no
modification)
WHAT(3) = lower bound (or corresponding name) of the particle numbers to
which the indicated modifying parameter applies
("From particle WHAT(3)...")
Default: = 1.0
WHAT(4) = upper bound (or corresponding name) of the particle numbers to
which the indicated modifying parameter applies
("...to particle WHAT(4)...")
Default: = WHAT(3) if WHAT(3) > 0, all particles otherwise
WHAT(5) = step length in assigning particle numbers
("...in steps of WHAT(5)").
Default: 1.0.
WHAT(6) = not used
SDUM = PRIMARY : importance biasing is applied also to primary
particles (cancels any previous NOPRIMARy request)
NOPRIMARy : importance biasing is applied only to secondaries
Default = PRIMARY
WARNING:
Even if a BIASING card is issued only to set PRIMARY/NOPRIMARy, remember
that a value of 0. is meaningful for WHAT(2). Leaving blank WHAT(2) to
WHAT(5)has the effect of turning off all importance biasing for all
particles!
Default (option BIASING not given): no multiplicity or RR/splitting biasing
Notes:
1) WHAT(2), with WHAT(1) >= 0, governs the application of Russian
Roulette (or splitting) at hadronic collisions, in order to achieve
a reduction (resp. an increase) of the multiplicity of secondaries.
The same secondary is loaded onto the particle stack for further
transport 0, 1 or any number of times depending on a random choice,
such that ON AVERAGE the requested multiplicity reduction (or
increase) is achieved. The weight of the stacked particles is
automatically adjusted in order to account for the bias thus
introduced.
If Russian Roulette has been requested, the reduction will not
affect the leading particle, which will always be retained, with
unmodified weight. Also, no RR is performed when the number of
secondaries is less than 3. On the contrary, there are no such
limitations for splitting (multiplicity increase).
There is some analogy with leading particle biasing as performed for
electrons and photons with option EMF-BIAS, and for hadrons in codes
like CASIM [Van75].
WHAT(3), with WHAT(1) >= 0, governs RR/splitting at boundary
crossing. The number of particles of the selected type crossing a
given boundary is reduced/increased on average by a factor equal to
the ratio of the importances on either side of the boundary. What is
relevant are the relative importances of adjacent regions, not their
absolute values. As a guideline, in shielding and, in general,
strong attenuation problems, the importance of a region should be
about inversely proportional to the corresponding attenuation factor
(absorption plus distance attenuation). This would exactly
compensate the dilution of particle density leading to a particle
population approximately uniform in space. In some cases, however,
when the user is interested in improving statistics only in a
limited portion of space, a uniform population density is not
desirable, but it is convenient to set importances so as to increase
particle densities in a particular direction.
2) Different importances can be given to the same region for different
particles, using the particle-dependent modifying factor M which can
be defined setting WHAT(1) < 0.
The modifying parameter M (WHAT(2), with WHAT(1) > 0) works as
follows:
At a boundary crossing, let us call I1 the importance of the
upstream region, and I2 that of the downstream region.
- If I2 < I1, Russian Roulette will be played.
Without any modifying factor, the chance of particle survival
is I2/I1.
For 0. <= M <= 1., the survival chance is modified to:
1. - M * (1. - I2/I1)
It can be seen that a value M = 0. resets the chance of survival
to 1., namely inhibits Russian Roulette biasing.
A value M = 1. leaves the survival chance unmodified, while any
value between 0. and 1. INCREASES the probability of survival
with respect to the basic setting.
For M >= 1., the survival chance is modified to:
I2/(M * I1)
So, a value larger than 1. DECREASES the probability of survival
with respect to the basic setting.
- If I2 > I1, there will be splitting. Without any modifying
factor, the number of particles is increased on average by a
factor I2/I1.
With the modifying factor, the number of particles is increased
instead by:
1. + M * (I2/I1 - 1.)
It can be seen that a value M = 0. resets the splitting factor
to 1., namely inhibits splitting.
A value M = 1. leaves the number of particles unmodified; a
value between 0.0 and 1.0 DECREASES the amount of splitting with
respect to the basic setting; a value > 1 INCREASES the amount
of splitting.
Hint: One of the most common uses of the modifying factor is to play
Russian Roulette/splitting only for some selected particles: one
does that by inhibiting biasing for all other particles, i.e.
setting = 0. the modifying factor M (WHAT(2), with WHAT(1) < 0).
3) In the most general case, increasing a region's importance leads
to an increased particle "traffic" through that region and
consequently to a better scoring statistics in regions "beyond".
However, it should be avoided to have relatively large
importances in scoring regions compared with those in adjacent
ones to avoid correlated tallies. If that happens, the scoring
statistics might look only apparently good. It must be avoided
also to have too different importances in adjacent zones: the
best biasing has to be done gently, without forcing and in a way
as continuous as possible.
4) All these biasing techniques are intended to improve statistics
in some parts of phase space AT THE EXPENSES OF THE OTHER PARTS.
Biased runs in particular can neither accelerate convergence in
all regions, nor reproduce natural fluctuations and
correlations. Do not bias unless you know what you are doing!
5) Advice: When choosing the multiplicity reduction option of
BIASING, or any other biasing option which can introduce weight
fluctuations in a given region, it is suggested to set also a
weight window (cards WW-FACTOR and WW-THRESh) in order to avoid
too large fluctuations in weight. The window must be consistent
with the other weight-modifying options, i.e. it must be
approximately centred on the average value of the weight
expected in the region in question. If necessary, set SDUM =
PRINT to get such information.
In case no window has been set, the code still keeps weights
under control (but only those of low-energy neutrons) by
imposing a maximum deviation from a central value. This
reference level is usually equal to the inverse of the neutron
importance in the region in question. However, since for
technical reasons in FLUKA allowed importance values range only
from 0.0001 to 10000., the user can multiply all the importances
by a factor, ONLY FOR THE PURPOSE OF CALCULATING THE REFERENCE
WEIGHT LEVEL, by means of option WW-PROFIle.
If the only biasing is via region importances set by WHAT(3),
only limited fluctuations arise (all particles of a given kind
have about the same weight in the same region), and no window is
needed.
Example, for a number-based input:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
BIASING 2.0 0.0 10.0 7.0 11.0 2.0
BIASING 2.0 0.0 15.0 8.0 9.0 0.0
BIASING -1.0 0.0 3.0 4.0 0.0 0.0
BIASING 1.0 0.7 0.4 3.0 8.0 0.0 PRINT
* In this example, the first two BIASING cards set an importance = 10
* for electrons, positrons and photons in regions 7, 9 and 11; and
* an importance = 15 in regions 8 and 9 for the same particles.
* However, the following card requires a modifying factor = 0.0
* (no splitting or Russian Roulette) for electrons and positrons.
* The net result is that biasing at boundary crossing with the above
* region importances is played only for photons.
* The fourth card sets a reduction factor = 0.7 for the multiplicity
* of hadronic events in regions 3, 4, 5, 6, 7 and 8; the importance
* of these same regions is set = 0.4; and it is required that biasing
* counters be printed.
The following is the same example, in a name-based input:
BIASING 2.0 0.0 10.0 Seventh Eleventh 2.0
BIASING 2.0 0.0 15.0 Eighth Ninth 0.0
BIASING -1.0 0.0 ELECTRON POSITRON 0.0 0.0
BIASING 1.0 0.7 0.4 Third Eighth 0.0 PRINT
1********************************************************************************
{BME}
Not yet implemented. Prepared for the BME event generator.
1********************************************************************************
{COMPOUND}
defines a compound, alloy or mixture, made of several materials, or even a
mixture of different isotopes
See also ASSIGNMAt, CORRFACT, LOW-MAT, MATERIAL, MAT-PROP
If WHAT(1) > 0.0 and WHAT(2) > 0.0 :
WHAT(1) = atom relative content of first material in the compound
WHAT(2) = index (or name) of first material
If WHAT(1) < 0.0 and WHAT(2) > 0.0 :
|WHAT(1)| = mass fraction of first material in the compound
WHAT(2) = index (or name) of first material
If WHAT(1) < 0.0 and WHAT(2) < 0.0 :
|WHAT(1)| = volume fraction of first material in the compound
|WHAT(2)| = index (or name) of first material
No default
In a similar way, WHAT(3) and WHAT(4) refer to the second material in the
compound, WHAT(5) and WHAT(6) to the third one.
SDUM = name of the compound
Default (option COMPOUND not requested): no compound is defined
For more than three materials in the same compound, add as many COMPOUND
cards with the same SDUM name as needed (but the maximum number of
components per compound is 80, and the maximum total number of components
is 1000).
Notes:
1) Option COMPOUND must always be used in conjunction with a MATERIAL
card having the same SDUM name (see MATERIAL). MATERIAL cards used
for this purpose provide the density of the compound, its material
number and name (WHAT(1) and WHAT(2) of the MATERIAL option, namely
atomic and mass number, are ignored).
2) The order of MATERIAL and COMPOUND cards is irrelevant.
3) The atom (or molecule) content, mass fraction or volume fraction
need only to be given on a relative basis (normalisation is done
automatically by the program).
4) Partial pressures of an (ideal) gas are equivalent to molecule
fractions and also to volume fractions.
5) If a compound is defined by volume fractions of the components
(either elements or compounds themselves - see Note 8 below for
recursive definitions), FLUKA internally calculates the atomic
densities of each component using the densities indicated in the
respective MATERIAL cards: in this case, therefore, (and only in
this case), it is important that these correspond to the actual
densities.
6) Isotopic compositions other than natural can be defined by the
COMPOUND option too.
7) When using the LOW-NEUT option (explicitly or by default set by the
DEFAULTS option), a special data set containing low-energy neutron
cross sections for each material used must be available. The data
sets are combined in a single file, delivered with the FLUKA program
(logical input unit 9, see 3}). Each low-energy neutron data set is
identified either by name (if equal to a FLUKA name and unique or
first with that name), or/and by one or more identifiers given with
a card LOW-MAT when necessary to remove ambiguity.
In the case of a composite material defined by a COMPOUND option,
two possibilities are allowed (see LOW-MAT):
- to associate the FLUKA material with a pre-mixed neutron data
set. In this case interactions take place with individual nuclei
at high energy, while average cross sections are used for
low-energy neutrons. Note that no pre-mixed neutron data set is
yet available (at the moment the standard sets contain pure
elements only).
- to associate the FLUKA material with several elemental neutron
data sets (one per component element). In this case both
high-energy and low-energy neutron interactions take place with
individual nuclei. This is the only possibility at present but
it may change in the future.
8) Recursion is allowed, i.e. the components of a composite material
can be composite materials. The depth of recursion is only limited
by the size of the internal arrays (in case of overflow a message
is issued and the job is terminated). Different levels of recursion
can use different units in the definition of the component fractions
(atoms, mass or volume fractions). Note, however, that if a compound
is put together from different composite molecules, the atomic and
molecular fractions have to be given without normalisation (use the
chemical formulae directly).
What follows is an example (for a number-based input) of a simple
compound BOOZE containing 50 weight percent of water and 50 of ethanol.
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
MATERIAL 1.0 1.0 .0000899 3.0 0.0 0.0 HYDROGEN
MATERIAL 6.0 12.0 2.0 4.0 0.0 0.0 CARBON
MATERIAL 8.0 16.0 0.00143 5.0 0.0 0.0 OXYGEN
MATERIAL 0.0 0.0 1.0 20.0 0.0 0.0 WATER
MATERIAL 0.0 0.0 0.7907 7.0 0.0 0.0 ETHANOL
MATERIAL 0.0 0.0 0.9155 8.0 0.0 0.0 BOOZE
COMPOUND 2.0 3.0 1.0 5.0 0.0 0.0 WATER
COMPOUND 2.0 4.0 6.0 3.0 1.0 5.0 ETHANOL
COMPOUND -50.0 20.0 -50.0 7.0 0.0 0.0 BOOZE
* Note that in the above example materials 4, 5, 7 and 8 have been defined
* overriding the default FLUKA material numbers.This is only allowed in
* an explicitly number-based input, declared as such with WHAT(4) = 4.0 in
* command GLOBAL,
The same example, in a name-based input, could be:
MATERIAL 1.0 1.0 .0000899 3.0 0.0 0.0 HYDROGEN
MATERIAL 6.0 12.0 2.0 6.0 0.0 0.0 CARBON
MATERIAL 8.0 16.0 0.00143 8.0 0.0 0.0 OXYGEN
MATERIAL 0.0 0.0 1.0 20.0 0.0 0.0 WATER
MATERIAL 0.0 0.0 0.7907 7.0 0.0 0.0 ETHANOL
MATERIAL 0.0 0.0 0.9155 8.0 0.0 0.0 BOOZE
COMPOUND 2.0 HYDROGEN 1.0 OXYGEN 0.0 0.0 WATER
COMPOUND 2.0 CARBON 6.0 HYDROGEN 1.0 5.0 ETHANOL
COMPOUND -50.0 WATER -50.0 ETHANOL 0.0 0.0 BOOZE
Example of how COMPOUND is commonly used to define a mixture (concrete).
In a number-based input:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
* definition of material 27 (concrete) as compound: H (1%), C(0.1%),
* O(52.9107%), Na(1.6%), Mg(0.2%), Al(3.3872%), Si(33.7021%), K(1.3%),
* Ca(4.4%), Fe(1.4%)
MATERIAL 19.0 39.0983 0.862 26.0 0.0 0.0 POTASSIU
MATERIAL 0.0 0.0 2.35 27.0 0.0 0. CONCRETE
COMPOUND -0.01 3.0 -0.001 6.0 -0.529107 8. CONCRETE
COMPOUND -0.016 19.0 -0.002 9.0 -0.033872 10. CONCRETE
COMPOUND -0.337021 14.0 -0.013 26.0 -0.044 21. CONCRETE
COMPOUND -0.014 11.0
* In the above example, elements 3 (hydrogen), 6 (carbon), 8 (oxygen),
* 9 (magnesium), 10 (aluminium), 11 (iron), 14 (silicon), 19 (sodium) and
* 21 (calcium) are not defined because the corresponding pre-defined FLUKA
* materials are used (see 5}). Potassium is not pre-defined, therefore it is
* assigned a new numbers 26 (that keeps the numbering sequence continuous,
* since the last FLUKA pre-defined material has number 25). The name is
* chosen to correspond with the potassium neutron cross section data set.
* (Chap. 10})
The same example, in a name-based input:
MATERIAL 19.0 39.0983 0.862 26.0 0.0 0.0 POTASSIU
MATERIAL 0.0 0.0 2.35 27.0 0.0 0. CONCRETE
COMPOUND -0.01 HYDROGEN -0.001 CARBON -0.529107 OXYGEN CONCRETE
COMPOUND -0.016 SODIUM -0.002 MAGNESIU -0.033872 ALUMINUM CONCRETE
COMPOUND -0.337021 SILICON -0.013 POTASSIU -0.044 CALCIUM CONCRETE
COMPOUND -0.014 IRON
More complex uses of COMPOUND in connection with MATERIAL and LOW-MAT are
illustrated by examples in 15}.
1********************************************************************************
{CORRFACT}
allows to alter material density for dE/dx and nuclear processes on a
region-by-region basis
See also ASSIGNMAt, COMPOUND, LOW--MAT, MATERIAL, MAT-PROP
WHAT(1) >= 0.0 : density scaling factor for charged particle ionisation
processes (dE/dx, delta ray production, M\oller and Bhabha
scattering)
= 0.0 : ignored
< 0.0 : reset to default
Default: 1.0
WHAT(2) >= 0.0 : density scaling factor for all other processes
= 0.0 : ignored
< 0.0 : reset to default
Default: 1.0
WHAT(3): not used
WHAT(4): lower index bound (or corresponding name) of regions where the
scaling factors shall apply
"From region WHAT(4)..."
Default: 2.0
WHAT(5): upper index bound (or corresponding name) of regions where the
scaling factors shall apply
"...to region WHAT(5)..."
Default: WHAT(4)
WHAT(6): step length in assigning region numbers
"...in steps of WHAT(6)"
Default: 1.0
SDUM : not used
Default (option CORRFACT not requested): no density scaling factors are
applied
Note:
1) Option CORRFACT is mainly used in connection with voxel geometries
derived from a CT scan, where particle transport is done often in an
equivalent material (e.g., water), but accounting for the density
variations provided by scan at the voxel level. While this approach
is reliable for what concerns ionisation, other reactions, which do
not scale with density, must be simulated for the actual material
composition.
Example, in a number-based input:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7...
* Multiply density by a 0.85 factor for what concerns atomic processes
* in regions 7, 8, 9, 10, 11, 12
CORRFACT 0.85 0.0 0.0 7.0 12.
The same example, in a name-based input, supposing that the geometry is
made of 12 regions:
CORRFACT 0.85 0.0 0.0 The7thRg @LASTREG
* Note the use of the name @LASTREG to indicate the maximum number of regions
* in the problem
1********************************************************************************
{DCYSCORE}
associates selected scoring detectors of given estimator type with
user-defined decay times. See WARNING in Note 1 below
See also DCYTIMES, IRRPROFI, RADDECAY, RESNUCLEi
WHAT(1) = cooling time index to be associated with the detector(s) of
estimator type defined by SDUM and with number corresponding to
WHAT(4)-WHAT(6) (see Note 2 below)
Default = 0.0 (no scoring!)
WHAT(2)-WHAT(3) = not used
WHAT(4) = lower index bound (or corresponding name) of detectors of type
SDUM associated with the specified cooling time
("From detector WHAT(4) of estimator type SDUM....")
Default = 1.0
WHAT(5) = upper index bound (or corresponding name) of detectors associated
with the specified cooling time
("...to detector WHAT(5) of estimator type SDUM....")
Default = WHAT(4)
WHAT(6) = step length in assigning indices
("...in step of WHAT(6)")
Default = 1.0
SDUM : identifies the kind of estimator under consideration: EVENTBIN,
RESNUCLEi, USRBDX, USRBIN, USRCOLL, USRTRACK, USRYIELD
Default: no default!
Default (option DCYSCORE not requested): no detector is associated with any
cooling time index
Notes:
1) WARNING: when the DCYSCORE option is applied to a detector, all
quantities are expressed PER UNIT TIME (in seconds). For instance, the
RESNUCLEi estimator will output Bq, dose estimators will provide dose
rate, etc.
2) The cooling time index indicated by WHAT(1) must be one of those
defined by means of option DCYTIMES.
3) USRBIN and EVENTBIN estimators are counted together (they belong to
the same index sequence), and so are USRTRACK and USRCOLL
Example, for a number-based input:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
DCYTIMES 86400. 172800.
DCYSCORE 1. 0. 0. 4. 8. 2.USRBIN
DCYSCORE 2. 0. 0. 1. 5. USRTRACK
* Two cooling times have been defined. Binnings no. 4, 6 and 8 will be
* associated to the first cooling time (one day), and track-length detectors
* no. 1, 2, 3, 4 and 5 will be associated to the second cooling time (2 days)
The same example, in a name-based input:
DCYTIMES 86400. 172800.
DCYSCORE 1. 0. 0. binning4 binning8 2.USRBIN
DCYSCORE 2. 0. 0. trakDet1 trakDet5 USRTRACK
1********************************************************************************
{DCYTIMES}
defines decay times for radioactive product scoring
See also DCYSCORE, IRRPROFI, RADDECAY, RESNUCLEi
Option DCYTIMES defines decay times after irradiations at which selected
quantities (for instance residual dose) are scored.
WHAT(1) = cooling time (in s) after the irradiation end, to be associated
to a scoring detector (see Note 1 below)
>=< 0.0 : a new decay time is added with delay WHAT(1)
Default = scoring at end of irradiation is associated with index 1
WHAT(2) = the same as WHAT(1) (one more cooling time)
WHAT(3) = the same as WHAT(1) (one more cooling time)
WHAT(4) = the same as WHAT(1) (one more cooling time)
WHAT(5) = the same as WHAT(1) (one more cooling time)
WHAT(6) = the same as WHAT(1) (one more cooling time)
SDUM = not used
Default (option DCYTIMES not requested): no decay times are defined
Notes:
1) Each cooling time is assigned an index, following the order in which
it has been input. This index can be used in option DCYSCORE to
assign that particular cooling time to one or more scoring
detectors.
2) Multiple cards can be given, up to a maximum of 20 decay times. All
decay times are counted from the end of the last irradiation period
as defined by the IRRPROFI command. A null decay time activates
scoring exactly at the end of irradiation. A negative decay time is
admitted: scoring is performed at the chosen time "during
irradiation"
Example:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
DCYTIMES 10. 30. 3600. 43200. 86400. 172800.
DCYTIMES 2592000. 31557600.
* Eight different cooling times have been defined, each with an index
* corresponding to its input order: cooling time no. 1 is 10 s, no. 2 is 30 s,
* and those from no. 3 to 8 are respectively 1 h, 1/2 d, 1 d, 2 d, 30 d, 1 y
1********************************************************************************
{DEFAULTS}
sets FLUKA defaults suitable for a specified kind of problems. Starting
from FLUKA99.5 (June 2000) the standard defaults are those described under
NEW-DEFAults below. That is, if no DEFAULTS card is issued the code
behaves as if a card with NEW-DEFAUlts was given.
See also GLOBAL
WHAT(1),....,WHAT(6): not used
SDUM = CALORIME : defaults for calorimeter simulations
EET/TRAN : defaults for Energy Transformer or transmutation
calculations
EM-CASCA : defaults for pure EM cascades
ICARUS : defaults for studies related to the ICARUS experiment
HADROTHE : defaults for hadrotherapy calculations
NEUTRONS : defaults for pure low-energy neutron runs
[NEW-DEFA : reasonable minimal set of new defaults - not needed]
PRECISIO : defaults for precision simulations
SHIELDIN : defaults for shielding calculations
Default: it is not allowed to leave SDUM blank. If the DEFAULT card is
missing, the standard defaults are unchanged (equivalent to setting
SDUM = NEW-DEFAults)
Defaults changed by the various options:
CALORIMEtry
- EMF on (no need for an EMF card)
- Rayleigh scattering and inelastic form factor corrections to Compton
scattering activated (no EMFRAY needed)
- Detailed photoelectric edge treatment and fluorescence photons
activated (no EMFFLUO needed)
- Low-energy neutron transport on (no LOW-NEUT needed) down to
thermal energies included. High energy neutron threshold at 20 MeV.
- Fully analogue absorption for low energy neutrons
- Particle transport threshold set at 1 x m_part / m_prot MeV, except
for neutrons (thermal), and (anti)neutrinos (0, but they are
discarded by default anyway)
- Multiple scattering threshold at minimum allowed energy, for both
primary and secondary charged particles
- Delta ray production on with threshold 100 keV (see option DELTARAY)
- Restricted ionisation fluctuations on, for both hadrons/muons and EM
particles (see option IONFLUCT)
- Fraction of the kinetic energy to be lost in a step set at 0.08,
number of dp/dx tabulation points set at 80 (see options DELTARAY,
EMFFIX, FLUKAFIX)
- Heavy particle e+/e- pair production activated with full explicit
production (with the minimum threshold = 2 m_electron)
- Heavy particle bremsstrahlung activated with explicit photon
production above 300 keV
- Muon photonuclear interactions activated with explicit generation of
secondaries
- Heavy fragment transport activated
EET/TRANsmutation
- Low energy neutron transport on down to thermal energies included
(high energy neutron threshold at 20 MeV)
- Non-analogue absorption for low energy neutrons with probability 0.95
for the last (thermal) groups
- Particle transport threshold set at 1 MeV, except neutrons
(1E-05 eV), and (anti)neutrinos (0, but they are discarded by default
anyway)
- Multiple scattering threshold for primary and secondary charged
particles lowered to 10 and 20 MeV respectively
- Unrestricted ionisation fluctuations on, for both hadrons/muons and EM
particles (if requested) (see option IONFLUCT)
- Both explicit and continuous heavy particle bremsstrahlung and pair
production inhibited
EM-CASCAde
- Electromagnetic interactions on (no need for explicit option EMF)
- Rayleigh scattering and inelastic form factor corrections to Compton
scattering activated (no EMFRAY needed)
- Detailed photoelectric edge treatment and fluorescence photons
activated (no EMFFLUO needed)
- Restricted ionisation fluctuations for EM particles (see option
IONFLUCT)
- Both explicit and continuous heavy particle bremsstrahlung and pair
production inhibited
HADROTHErapy
- EMF on
- Inelastic form factor corrections to Compton scattering activated
- Low-energy neutron transport on down to themral energies included,
no need for option LOW-NEUT (high energy neutron threshold at
20 MeV)
- Fully analogue absorption for low-energy neutrons
- Particle transport threshold set at 100 keV, except for neutrons
(1E-5 eV), and (anti)neutrinos (0, but they are discarded by
default anyway)
- Multiple scattering threshold at minimum allowed energy, for both
primary and secondary charged particles
- Delta ray production on with threshold 100 keV (see option DELTARAY)
- Restricted ionisation fluctuations on, for both hadrons/muons and EM
particles (see option IONFLUCT)
- Tabulation ratio for hadron/muon dp/dx set at 1.03, fraction of the
kinetic energy to be lost in a step set at 0.02 (see options
DELTARAY, EMFFIX, FLUKAFIX)
ICARUS
- EMF on
- Rayleigh scattering and inelastic form factor corrections to Compton
scattering activated (no EMFRAY needed)
- Detailed photoelectric edge treatment and fluorescence photons
activated (no EMFFLUO needed)
- Low energy neutron transport on down to thermal energies included,
(high energy neutron threshold at 20 MeV)
- Fully analogue absorption for low energy neutrons
- Particle transport threshold set at 100 keV, except neutrons
(1E-5 eV), and (anti)neutrinos (0, but they are discarded by default
anyway)
- Multiple scattering threshold at minimum allowed energy, for both
primary and secondary charged particles
- Delta ray production on with threshold 100 keV (see option DELTARAY)
- Restricted ionisation fluctuations on, for both hadrons/muons and EM
particles (see option IONFLUCT)
- Tabulation ratio for hadron/muon dp/dx set at 1.04, fraction of the
kinetic energy to be lost in a step set at 0.05, number of dp/dx
tabulation points set at 80 (see options DELTARAY, EMFFIX, FLUKAFIX)
- Heavy particle e+/e- pair production activated with full explicit
production (with the minimum threshold = 2m_e)
- Heavy particle bremsstrahlung activated with explicit photon
production above 300 keV
- Muon photonuclear interactions activated with explicit generation of
secondaries
- Heavy fragment transport activated
NEUTRONS
- Low energy neutron transport on down to thermal energies included,
no need for LOW-NEUT (high energy neutron threshold at 20 MeV)
- Non-analogue absorption for low-energy neutrons with probability 0.95
for the last (thermal) groups
- Both explicit and continuous heavy particle bremsstrahlung and pair
production inhibited
NEW-DEFAults (standard defaults active even if the DEFAULT card is not
present)
- EMF on, with electron and photon transport thresholds to be set using
the EMFCUT command
- Inelastic form factor corrections to Compton scattering activated (no
need for EMFRAY)
- Low energy neutron transport on down to thermal energies included,
(no need for LOW-NEUT). The neutron high energy threshold is set
at 20 MeV.
- Non analogue absorption for low energy neutrons with probability 0.95
for the last (thermal) groups
- Particle transport threshold set at 10 MeV, except for neutrons
(1E-5 eV), and (anti)neutrinos (0, but they are discarded by default
anyway)
- Multiple scattering threshold for secondary charged particles lowered
to 20 MeV (equal to that of the primary ones)
- Delta ray production on with threshold 1 MeV (see option DELTARAY)
- Restricted ionisation fluctuations on, for both hadrons/muons and EM
particles (see option IONFLUCT)
- Heavy particle e+/e- pair production activated with full explicit
production (with the minimum threshold = 2m_e)
- Heavy particle bremsstrahlung activated with explicit photon
production above 1 MeV
- Muon photonuclear interactions activated with explicit generation of
secondaries
PRECISIOn
- EMF on
- Rayleigh scattering and inelastic form factor corrections to Compton
scattering activated
- Detailed photoelectric edge treatment and fluorescence photons
activated
- Low energy neutron transport on down to thermal energies included,
(high energy neutron threshold at 20 MeV)
- Fully analogue absorption for low-energy neutrons
- Particle transport threshold set at 100 keV, except neutrons
(1E-5 eV), and (anti)neutrinos (0, but they are discarded by default
anyway)
- Multiple scattering threshold at minimum allowed energy, for both
primary and secondary charged particles
- Delta ray production on with threshold 100 keV (see option DELTARAY)
- Restricted ionisation fluctuations on, for both hadrons/muons and EM
particles (see option IONFLUCT)
- Tabulation ratio for hadron/muon dp/dx set at 1.04, fraction of the
kinetic energy to be lost in a step set at 0.05, number of dp/dx
tabulation points set at 80 (see options DELTARAY, EMFFIX, FLUKAFIX)
- Heavy particle e+/e- pair production activated with full explicit
production (with the minimum threshold = 2m_e)
- Heavy particle bremsstrahlung activated with explicit photon
production above 300 keV
- Muon photonuclear interactions activated with explicit generation of
secondaries
- Heavy fragment transport activated
SHIELDINg
- Low energy neutron transport on down the thermal energies included,
(the neutron high energy threshold is set at 20 MeV)
- Non-analogue absorption for low energy neutrons with probability 0.95
for the last (thermal) groups
- Particle transport threshold set at 10 MeV, except neutrons
(1E-5 eV), and (anti)neutrinos (0, but they are discarded by default
anyway)
- Multiple scattering threshold for secondary charged particles lowered
to 20 MeV (= primary ones)
- Both explicit and continuous heavy particle bremsstrahlung and pair
production inhibited
- EMF off!!! This default is meant for simple hadron shielding only!
Notes:
1) If an option does not appear in input, FLUKA provides default
parameter values in most cases. Standard defaults are also applied
when the option is present but not all its WHAT and SDUM parameters
have been defined explicitly by the user. However, some types of
problems are better handled using different defaults. Option
DEFAULTS allows to override the standard ones with others, tuned to
a specific class of transport problems.
The present set of defaults (valid if no DEFAULTS card is issued) is
equivalent to that set by SDUM = NEW-DEFAults.
2) IMPORTANT! Option DEFAULTS must be issued at the very beginning of
input. It can be preceded only by a GLOBAL card and by command
TITLE. This is one of the rare cases, like GLOBAL, MAT-PROP and
PLOTGEOM, where sequential order of input cards is of importance in
FLUKA (see 7}).
3) The name of the SHIELDINg default refers to simple calculations for
proton accelerators, where the electromagnetic component can be
neglected. It is not applicable to electron accelerator shielding or
any other shielding problem where the gamma component is important.
4) The responsibility of choosing reasonable defaults, compatible with
the rest of input, is left to the user. In particular, choosing the
defaults corresponding to pure EM cascade or to pure low-energy
neutron problems has the effect of turning off all initialisations
related to the hadronic generators. This will save a considerable
time at the beginning of the run, but will lead to a crash if a
hadron generator is called because of some other input option. In
particular, SDUM = EM-CASCA is incompatible with option PHOTONUC and
with beam particles different from PHOTON, ELECTRON and POSITRON;
and SDUM = NEUTRONS is incompatible with option EMF, with any beam
particle different from NEUTRON and with energies higher than 20
MeV.
On the other hand, it is possible to override some of the defaults,
in particular the various thresholds, by issuing the corresponding
command after DEFAULTS (PART-THR, EMFCUT. DELTARAY, etc.)
Example:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....
DEFAULTS 0.0 0.0 0.0 0.0 0.0 0.0 EM-CASCA
* The above declaration refers to a problem where only electrons, positrons
* and photons are transported.
1********************************************************************************
{DELTARAY}
activates delta ray production by muons and charged hadrons and controls the
accuracy of the dp/dx tabulations
See also IONFLUCT
WHAT(1) > 0.0 : kinetic energy threshold (GeV) for delta ray production
(discrete energy transfer). Energy transfers lower than
this energy are assumed to take place as continuous energy
losses
= 0.0 : ignored
< 0.0 : resets the default to infinite threshold, i.e. no delta ray
production
Default = 0.001 if option DEFAULTS is not used, or if it is used
with SDUM = NEW-DEFAults.
If DEFAULTS is used with SDUM = CALORIMEtry,
HADROTHErapy, ICARUS or PRECISIOn, the default
is 0.0001.
If it is used with any other SDUM value, the default
is -1.0 (continuous slowing down approximation without
production of delta rays)
WHAT(2) > 0.0 : number of logarithmic intervals for dp/dx momentum loss
tabulation
= 0.0 : ignored
< 0.0 : resets the default to 50.0
Default = 50.0 (this is the default if option DEFAULTS is not
used, or is used with anything but SDUM = CALORIMEtry,
ICARUS or PRECISIOn).
With the latter, the default is 80.
See Note 1 below for more details
WHAT(3) > 1.0 : logarithmic width of dp/dx momentum loss tabulation
intervals (ratio between upper and lower interval limits).
0.0 =< WHAT(3) =< 1.0: ignored
< 0.0 : resets the default to 1.15
Default = 1.15 (this is the default if option DEFAULTS is not
used, or is used with any SDUM value but HADROTHErapy,
ICARUS or PRECISIOn).
If DEFAULTS is used with SDUM = ICARUS or PRECISIOn, the
default is 1.04.
With SDUM = HADROTHErapy the default is 1.03.
See Note 1 below for more details
WHAT(4) = lower index bound (or corresponding name) of materials where
delta ray production or specified tabulation accuracy are
requested
("From material WHAT(4)...")
Default = 3.0
WHAT(5) = upper index bound (or corresponding name) of materials where
delta ray production or specified tabulation accuracy are
requested
("...to material WHAT(5)...")
Default = WHAT(4)
WHAT(6) = step length in assigning indices
("...in steps of WHAT(6)")
Default = 1.0
SDUM: = PRINT: prints the dp/dx tabulations for the given materials on
standard output
= NOPRINT: resets to no printing a possible previous request for
these materials
= blank: ignored
Default: NOPRINT
Default (option DELTARAY not requested): the defaults depend on option
DEFAULTS as explained above. See also Note 8.
Notes:
1) The upper and lower limit of the dp/dx tabulations are determined by
the options BEAM and PART-THR, or by the corresponding defaults.
Therefore, either the number OR the width of the intervals are
sufficient to define the tabulations completely. If both WHAT(2) and
WHAT(3) are specified, or if the value of both is defined implicitly
by the chosen default, the most accurate of the two resulting
tabulations is chosen.
2) The lower tabulation limit is the momentum of the charged particle
which has the lowest transport threshold. The upper limit
corresponds to the maximum primary energy (as set by BEAM) plus an
additional amount which is supposed to account for possible
exoenergetic reactions, Fermi momentum and so on.
3) This option concerns only charged hadrons and muons. Delta rays
produced by electrons and positrons are always generated, provided
their energy is larger than the production threshold defined by
option EMFCUT.
4) Request of delta ray production is not alternative to that
of ionisation fluctuations (see IONFLUCT). The two options, if not
used at the same time, give similar results as far as transport and
energy loss are concerned, but their effect is very different
concerning energy deposition: with the IONFLUCT option the energy
lost is sampled from a distribution but is deposited along the
particle track, while DELTARAY, although leading to similar
fluctuations in energy loss, will deposit the energy along the delta
electron tracks, sometimes rather far from the primary trajectory.
IONFLUCT can be used even without requesting the EMF option, while
when requesting DELTARAY the EMF card must also be present (or
implicitly activated by default) - see option DEFAULTS - if
transport of the generated electrons is desired.
5) Normally, the energy threshold for delta ray production should be
higher than the electron energy transport cut-off specified by
EMFCUT. If it is not, the energy of the delta electron produced is
deposited on the spot. As explained above, this will result in
correct energy loss fluctuations but with the energy deposited along
the particle track, a situation similar to that obtained with
IONFLUCT alone.
6) Note that FLUKA makes sure that the threshold for delta ray
production is not set much smaller than the average ionisation
potential.
7) Presently, DELTARAY can be used together with the IONFLUCT option
with a threshold for delta rays chosen by the user. As a result,
energy losses larger than the threshold result in the production and
transport of delta electrons, while those smaller than the threshold
will be sampled according to the correct fluctuation distribution.
8) Here are the settings for delta ray production and dp/dx tabulations
corresponding to available DEFAULTS options:
- ICARUS, PRECISIOn: threshold for delta ray production 100 keV;
momentum loss tabulation with 80 logarithmic intervals or 1.04
logarithmic width (whichever is more accurate)
- CALORIMEtry: threshold for delta ray production 100 keV; momentum
loss tabulation with 80 logarithmic intervals or 1.15 logarithmic
width
- HADROTHErapy: threshold for delta ray production 100 keV; momentum
loss tabulation with 50 logarithmic intervals or 1.03 logarithmic
width
- NEW-DEFAults, or DEFAULTS missing: threshold for delta ray
production 1 MeV; momentum loss tabulation with 50 logarithmic
intervals or 1.15 logarithmic width
- Any other SDUM value: no delta ray production; momentum loss
tabulation with 50 logarithmic intervals or 1.15 logarithmic
width
Example, for a number-based input:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
DELTARAY 0.01 30. 0.0 3.0 18.0 PRINT
DELTARAY 0.02 0.0 1.05 4.0 12.0 8.0 NOPRINT
* In this example, delta rays with energies higher than 20 MeV (0.02 GeV)
* will be produced in materials 4 and 12; for the same materials,
* logarithmic intervals with a ratio of 1.05 between the the upper and the
* lower limit of each interval are requested for the dp/dx tabulation. For
* all other materials with number between 3 and 18, delta rays are
* produced above 10 MeV and 30 intervals are used in the dp/dx tabulation.
* Tabulations are printed for all materials except 4 and 12.
An equivalent example, for a name-based input, is:
DELTARAY 0.01 30. 0.0 HYDROGEN TANTALUM PRINT
DELTARAY 0.02 0.0 1.05 HELIUM COPPER 8.0 NOPRINT
The following is an example where a threshold of 500 keV is set for delta
ray production in ALL materials:
DELTARAY 5.E-4 0.0 0.0 HYDROGEN @LASTMAT PRINT
1********************************************************************************
{DETECT}
Scores energy deposition on an event by event basis (detector), providing
coincidence and anti-coincidence capabilities such as those of a trigger.
In the following, an "event" means energy deposited in one or more DETECTOR
REGIONS by one primary particle and its descendants, i.e. between two
successive calls to the FEEDER subroutine (case of an incident beam) or to a
user-written SOURCE subroutine (case of an extended source, or of a source
read from a collision file or sampled from a distribution).
A "signal" means energy deposited in one or more TRIGGER REGIONS by the same
primary particle and descendants (i.e., between the same calls).
The output of DETECT is a distribution of energy deposited per event in the
region(s) making up the detector in (anti)coincidence with a signal larger
than a given cut-off or threshold in the trigger region(s).
It is also possible to define DETECTOR COMBINATIONS. [NOT YET IMPLEMENTED!!]
This option can extend over several sequential cards. The meaning of the
parameters on the first card are:
WHAT(1) = 0.0 for a detector, > 0.0 for a combination of detectors
If WHAT(1) = 0.0:
WHAT(2) = minimum total energy to be scored in the detector regions in one
event, i.e. lower limit of the event distribution.
Default: 0.0
WHAT(3) = maximum total energy to be scored in the detector regions in one
event, i.e. upper limit of the event distribution
No default
WHAT(4) = cut-off energy for the signal (coincidence/anticoincidence
threshold). The energy deposition event is scored only if a total
of more than WHAT(4) GeV are/aren't correspondingly deposited in
the trigger regions.
Default: 1.E-9 (= 1 eV)
WHAT(5) = > 0.0 : the detector regions, taken together, must be considered
in COINCIDENCE with the trigger regions (also taken together)
< 0.0 : the detector regions must be considered in
ANTI-COINCIDENCE with the trigger regions
Default: anti-coincidence
WHAT(6) = region number or name not preceded by a minus sign: first region
of the DETECTOR
region number or name preceded by a minus sign: first region of
the TRIGGER
(the other regions will be given with continuation cards, see
below).
No default
SDUM = detector name (max. 10 characters) unless the character "&"
is present
Continuation card (if present):
WHAT(1) = same as WHAT(1) for the first card
WHAT(2-6) = following regions (with sign). If not preceded by a minus sign,
they are considered detector regions, otherwise trigger regions
SDUM = "&" in any position in column 71 to 78 (or in the last field
if free format is used)
Note: if no trigger region is given (i.e. no region with negative sign)
a simple event-by-event scoring takes place.
If WHAT(1) > 0: [NOT YET IMPLEMENTED!!!]
WHAT(2): first detector to be considered for this combination, in
coincidence if WHAT(2) is not preceded by a minus sign, in
anticoincidence otherwise
Default: ignored
WHAT(3): second detector to be considered for this combination, in
coincidence if WHAT(3) is not preceded by a minus sign, in
anticoincidence otherwise
Default: ignored
WHAT(4): third detector to be considered for this combination, in
coincidence if WHAT(4) is not preceded by a minus sign, in
anticoincidence otherwise
Default: ignored
WHAT(5): fourth detector to be considered for this combination, in
coincidence if WHAT(5) is not preceded by a minus sign, in
anticoincidence otherwise
Default: ignored
WHAT(6): fifth detector to be considered for this combination, in
coincidence if WHAT(6) is not preceded by a minus sign, in
anticoincidence otherwise
Default: ignored
SDUM = combination name (max. 10 characters) unless the character "&" is
present
Continuation card (if present):
WHAT(1) = same as WHAT(1) for the first card
WHAT(2-6) = following detectors (with sign). If not preceded by a minus sign,
they are considered in coincidence, otherwise in anti-coincidence
SDUM = "&" in any position (or in the last field if free format is used)
Default (option DETECT not requested): no (anti)coincidence scoring
Notes:
1) Output from DETECT is written unformatted on logical unit 17. To
recover the output, it is necessary to run a Fortran program
containing the following lines:
.........................................
CHARACTER*80 RUNTIT, RUNTIM*32, CHNAME*10
INTEGER*4 NCASE, NDET, NBIN, IV(1024)
REAL EMIN, EBIN, ECUT
.........................................
.........................................
READ(17) RUNTIT, RUNTIM, WEIPRI, NCASE
READ(17) NDET, CHNAME, NBIN, EMIN, EBIN, ECUT
READ(17) (IV(I), I = 1, NBIN)
.........................................
This is the meaning of variables read:
RUNTIT: title of the job (as given by input option TITLE)
RUNTIM: time of the job (printed also at the beginning of the main
output)
WEIPRI: total weight of the primary particles
NCASE: number of primary particles
NDET: detector number
CHNAME: detector name (= SDUM of the first DETECT card)
NBIN: number of energy bins (presently fixed = 1024)
EMIN: minimum total energy (= WHAT(2) of the first DETECT card)
EBIN: width of each energy bin
ECUT: cutoff energy for the signal (= WHAT(4) of the first DETECT
card)
The NBIN values IV(I) are the spectrum channels, or energy bins.
2) Important: option DETECT will give meaningful results ONLY when
FLUKA is used in a completely analogue mode, since correlations are
destroyed by biasing. Thus, DETECT cannot be used together with any
biasing option or weight-changing facility. It is recommended for
this purpose to issue a GLOBAL command with WHAT(2) < 0.0 at the
beginning of input (see GLOBAL).
A list of incompatible options is: BIASING, EMF-BIAS, LOW-BIAS,
LAM-BIAS, WW-FACTOr, EMFCUT with WHAT(3) > 0, EMF with WHAT(6) <> 1,
EXPTRANS, LOW-DOWN.
Example (number-based):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
DETECT 0.0 1.E-4 1.E-2 5.E-5 1.0 7.0 Coincid_1
DETECT 0.0 -9.0 -12.0 10.0 11.0 &
* The meaning of the above lines is the following:
* a "signal" equal to energy deposition in regions 7 + 10 + 11 will be
* scored if:
* 1) that signal is larger than 1.E-4 GeV and smaller than 0.01 GeV
* 2) at the same time (in coincidence) an energy deposition of at least
* 5.0E-5 GeV occurs in regions 9 + 12
* The output will give a signal (event) spectrum between the energy
* limits 1.0E-4 and 0.010 GeV, distributed over a fixed number of channels
* (1024 in the standard version).
The same example, name-based:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
DETECT 0.0 1.E-4 1.E-2 5.E-5 1.0 The7thRg Coincid_1
DETECT 0.0 -The9thRg -Region12 Region10 Region11 &
1********************************************************************************
{DISCARD}
defines the particle types to be discarded (i.e. not to be transported)
WHAT(1...6) = id-number or name of particles to be discarded (see particle
numbers and names in 5}).
If one of the WHATs is preceded by a minus sign a previous corresponding
DISCARD command (explicit or by default) will be canceled.
When full heavy particle transport is activated (see EVENTYPE), discarding
of heavies can be performed setting the WHATs = (1000 + Kheavy),
with Kheavy = 3....6 (heavy ion particle code):
3 = 2-H, 4 = 3-H, 5 = 3-He, 6 = 4-He, 7-12 = fission fragments.
Except for fission fragments, the corresponding names can also be used.
Undiscarding heavies is obtained by setting WHATs equal to (1000 - Kheavy),
or by making the corresponding names to be preceded by a minus sign.
The whole scheme is shown in the following table:
Discard Undiscard
2-H 1003 or DEUTERON 997 or -DEUTERON
3-H 1004 or TRITON 996 or -TRITON
3-He 1005 or 3-HELIUM 995 or -3-HELIUM
4-He 1006 or 4-HELIUM 994 or -4-HELIUM
fission fragments 1007-1012 993-988
No default
SDUM: not used
Default (option DISCARD not given): only neutrinos and antineutrinos are
discarded by default. Set the WHATs = -5., -6., -27., -28., -43.,
-44. or NEUTRIE, ANEUTRIE, NEUTRIM, ANEUTRIM, NEUTRIT, ANEUTRIT
in order to have them transported.
Notes:
1) There is no limit to the number of DISCARD definitions given.
Discarding a particle means that that type of particle will possibly
be produced but not transported.
2) The user may want to process some particle types with other programs
providing only the production by the FLUKA code. These particles can
be discarded. The results will then not contain the contribution of
the discarded particle types and of their descendants.
3) Neutrinos are always discarded by default, to avoid useless
tracking. To force neutrinos (or other particles) to be NOT
discarded, make their particle number or name to be preceded by a
minus sign. In that case, however, remember that:
- no neutrino cross sections are available for transport in FLUKA:
these particles are just tracked through the geometry until they
escape. Boundary crossing and tracklength density can however be
scored if requested
- if neutrinos are not discarded, their transport threshold is set
= 0. by default. This value can be changed (by option PART-THR),
but it must be kept in mind that the energy of any neutrino
produced below the threshold WILL BE DEPOSITED LOCALLY, generating
a likely bias in dose calculations.
4) WARNING: discarding the particles which propagate the hadronic
cascade (neutrons, protons, pions) will lead in general to
unpredictable results.
Example (number-based):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
DISCARD 3.0 4.0 7.0 10.0 11.0 23.0
* This example illustrates a typical situation where the use of DISCARD
* can considerably reduce the computing time: for instance in pure
* hadronic or neutron problems (fluence calculations without interest in
* energy deposition). In this case electrons, positrons, photons, muons
* and pi0 do not contribute to the result and can be discarded
The same example, name-based:
DISCARD ELECTRON POSITRON PHOTON MUON+ MUON- PIZERO
1********************************************************************************
{DPMJET}
Defines some I/O parameters relevant to the heavy ion event generator DPMJET
Option DPMJET is useful only for development work: generally the user does
not need this option - to request activation of DPMJET use the command
EVENTYPE
See also BME, EVENTYPE, MYRQMD, PHYSICS, RQMD
WHAT(1) : format of the required pre-processed Glauber parameters.
A complete set of projectile-target combinations for the entire
FLUKA energy range is utilised. To revert to the original DPMJET
format set this value to 1. See also Note 2 below.
Default = 0.0
WHAT(2) : allows to change the logical unit number which is assigned to the
DPMJET output.
Default = 19.0
WHAT(3) : selects the level of output verbosity for DPMJET. The default
corresponds to minimal output. If this value is set to 1.0,
initialisation and minor error messages are printed. In addition,
one can request information about the DPMJET common block (the
internal list of objects considered by DPMJET). If set equal to
2.0 all the available information is output, if set equal to 3.0
only information about final residual nuclei is output, and if
set to 4.0 information about all final state objects is written.
Default = 0.0
WHAT(4)-WHAT(6) : not used
SDUM : not used
Default (option DPMJET not given): all the above defaults apply
Notes:
1) FLUKA utilises DPMJET and a heavily modified version of a
RQMD-2.4 implementation (H. Sorge [Sor89, Sor89a, Sor95]) in order
to simulate heavy ion interactions.
2) Glauber parameter sets in the original ASCII format can be generated
by running the stand-alone DPMJET program. Only up to 10 different
projectile/target combinations can be initialised per run. Parameter
sets in excess of the first 10 combinations will be provided by the
default mechanism.
Examples:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7...
DPMJET 0.0 71. 4.
* running with the pre-processed, full matrix of Glauber parameter sets
* but requesting more verbose output for DPMJET: initialisation related
* messages, all error messages and information about final state objects
* in the DPMJET common block.
* DPMJET is told not to read any specific input options.
* All output will be found in file connected to logical unit 71 instead
* of 19 (under Linux this file would be named fort.71)
1********************************************************************************
{ELCFIELD}
defines an homogenous electric field (not yet fully implemented)
See also MGNFIELD
WHAT(1) = largest angle (in degrees) that a particle is allowed to travel
in a single step
Default: 20 degrees
WHAT(2) = error of the boundary iteration (minimum accuracy accepted in
determining a boundary intersection)
Default: 0.01 cm
WHAT(3) = minimum step if the step is forced to be smaller due to a too
large angle
Default: 0.1 cm
WHAT(4) = Ex (x-component of the electric field, in kV/cm)
WHAT(5) = Ey (y-component of the electric field, in kV/cm)
WHAT(6) = Ez (z-component of the electric field, in kV/cm)
Note:
1) This option is being implemented, but it is not yet operational.
1********************************************************************************
{EMF}
activates ElectroMagnetic FLUKA: transport of electrons, positrons and
photons
See also DEFAULTS, DELTARAY, EMF-BIAS, EMFCUT, EMFFIX, EMFFLUO, EMFRAY,
MULSOPT, PHOTONUC
WHAT(1-6): not used
SDUM : EMF-OFF to switch off electron and photon transport.
Useful with the new defaults where EMF is on by default.
Default: EMF on
Default (option EMF not requested): if option DEFAULTS is not used, or if
it is used with SDUM = NEW-DEFAults, CALORIMEtry, EM-CASCAde,
HADROTHErapy, ICARUS or PRECISIOn, electrons, positrons and
photons are transported.
If DEFAULTS is used with SDUM = EET/TRANsmut, NEUTRONS, SHIELDINg
or anything else, electrons, positrons and photons are not
transported (see Note 2). To avoid their energy to be deposited
at the point of production, it is generally recommended to
discard those particles (see Note 5).
Notes:
1) Option EMF is used to request a detailed transport of electrons,
positrons and photons. Even if the primary particles are not photons
or electrons, photons are created in high-energy hadron cascades,
mainly as a product of pi0 decay, but also during evaporation and
fission of excited nuclei; and capture gamma-rays are generated
during low-energy neutrons transport. Electrons can arise from muon
decay or can be set in motion in knock-on collisions by charged
particles (delta-rays).
2) If EMF has been turned off by overriding the default (by setting
SDUM = EMF-OFF or by a DEFAULT option which switches off
electron-photon transport, such as OLD-DEFAults, EET/TRANsmut,
NEUTRONS, SHIELDINg, not accompanied by an explicit EMF request),
such electrons, positrons and photons are not transported and their
energy is deposited on the spot at the point of creation unless
those particles are DISCARDed (see Note 5 below).
3) Of course, it is also mandatory to request option EMF (either
explicitly or implicitly via option DEFAULTS) in any pure electron,
positron or photon problem (i.e. with electrons, positrons or
photons as primary particles).
4) Using EMF without any biasing can lead to very large computing
times, especially in problems of high primary energy or with low
energy cut-offs. See in particular leading-particle biasing with
EMF-BIAS.
5) In case of a pure hadron or neutron problem (e.g. neutron activation
calculation) it is recommended to DISCARD electrons, positrons and
photons (id-number 3, 4 and 7). In this case it is irrelevant
whether the EMF card is present or not. Discarding only electrons
and positrons, but not photons, may also be useful in some cases
(for instance when calculating photon streaming in a duct).
6) An alternative is to set very large energy cut-offs for electrons
and positrons (see EMFCUT). That will result in the electron energy
being deposited at the point of photon interaction (kerma
approximation, often sufficient for transport of photons having an
energy lower than a few MeV).
7) Hadron photoproduction is dealt with by option PHOTONUC.
Example:
*....+....1....+....2....+....3....+....4....+....5....+....6....+....7...+...8
EMF EMF-OFF
* This command must be issued without any WHAT parameter.
1********************************************************************************
{EMF-BIAS}
Sets electron and photon special biasing parameters, including leading
particle biasing region by region, and mean free path biasing material by
material
See also EMF, EMFCUT, LAM-BIAS
For SDUM = LPBEMF (default):
WHAT(1) > 0.0: leading particle biasing (LPB) is activated. Which
combination of leading particle biasing is actually set up
depends on the bit pattern of WHAT(1)
Let WHAT(1) be represented as:
2^0xb0 + 2^1xb1 + 2^2xb2 + 2^3xb3 + 2^4xb4 +
2^5xb5 + 2^6xb6 + 2^7xb7 + 2^8xb8 + 2^9xb9
then the meaning of the ten bits is the following:
b0 = 1 --> LPB activated for bremsstrahlung and pair production
(old default)
b1 = 1 --> LPB activated for bremsstrahlung
b2 = 1 --> LPB activated for pair production
b3 = 1 --> LPB activated for positron annihilation at rest
b4 = 1 --> LPB activated for Compton scattering
b5 = 1 --> LPB activated for Bhabha & Moller scattering
b6 = 1 --> LPB activated for photoelectric effect
b7 = 1 --> LPB activated for positron annihilation in flight
b8 = 1 --> not used
b9 = 1 --> not used
Note that WHAT(1) = 1022 activates LPB for all physical effects
(values larger than 1022 are converted to 1022)
< 0.0: leading particle biasing is switched off
= 0.0: ignored
WHAT(2) > 0.0: energy threshold below which leading particle biasing is
played for electrons and positrons (for electrons, such
threshold refers to kinetic energy; for positrons, to total
energy plus rest mass energy)
< 0.0: resets any previously defined threshold to infinity (i.e.,
leading particle biasing is played at all energies)
= 0.0: ignored
This value can be overridden in the user routine UBSSET (see 13})
by assigning a value to variable ELPEMF
Default: leading particle biasing is played at all energies for
electrons and positrons
WHAT(3) > 0.0: energy threshold below which leading particle biasing is
played for photons
< 0.0: resets any previously defined threshold to infinity (i.e.,
leading particle biasing is played at all energies)
= 0.0: ignored
This value can be overridden in the user routine UBSSET by
assigning a value to variable PLPEMF.
Default: leading particle biasing is played at all energies for
photons
WHAT(4) = lower bound (or corresponding name) of the region indices where
the selected leading particle biasing has to be played
("From region WHAT(4)...")
Default = 2.0
WHAT(5) = upper bound (or corresponding name) of the region indices where
the selected leading particle biasing has to be played
("...to region WHAT(5)...")
Default = WHAT(4)
WHAT(6) = step length in assigning indices
("...in steps of WHAT(6)")
Default = 1.0
SDUM = LPBEMF (Leading Particle Biasing for EMF). This is the
default, for other values of SDUM see below.
This value can be overridden in the user routine UBSSET by
assigning a value to variable LPEMF
For SDUM = LAMBEMF, LAMBCOMP, LAMBBREM, LBRREMF, LBRRCOMP, LBRRBREM:
(not yet implemented for photons)!
WHAT(1) > 0.0 and < 1.0: the interaction mean free paths for all electron
and positron electromagnetic interactions (SDUM = LAMBEMF), or
for electron/positron bremsstrahlung only (SDUM = LAMBBREM) are
reduced by a multiplying factor = WHAT(1)
= 0.0: ignored
< 0.0 or >= 1: resets to default (no mean free path biasing for
electrons and positrons)
WHAT(2) > 0.0 and < 1.0: the interaction mean free paths for all photon
electromagnetic interactions (SDUM = LAMBEMF), or for Compton
scattering only (SDUM = LAMBCOMP) are reduced by a multiplying
factor = WHAT(2)
= 0.0: ignored
< 0.0 or >= 1: resets to default (no mean free path biasing for
photons)
WHAT(3) = generation up to which the biasing has to be applied
Default: biasing is applied only the first generation (i.e., the
primary BEAM or SOURCE particles)
WHAT(4) = lower bound (or corresponding name) of the indices of materials
in which the indicated mean free path biasing has to be applied
("From material WHAT(4)...")
Default = 3.0
WHAT(5) = upper bound (or corresponding name) of the indices of materials
in which the indicated mean free path biasing has to be applied
("... to material WHAT(5)...")
Default = WHAT(4)
WHAT(6) = step length in assigning indices
("...in steps of WHAT(6)")
Default = 1.0
SDUM = LAMBEMF (LAMbda Biasing for ElectroMagnetic FLUKA): mean
free path biasing is applied to all electron, positron
and photon interactions, and both the incident and the
secondary particle are assigned a reduced weight
LAMBCOMP (LAMbda Biasing for Compton interactions): mean free
path biasing is applied only to photon Compton effect,
and both the incident photon and the secondary electron
are assigned a reduced weight
LAMBBREM (LAMbda Biasing for BREMsstrahlung interactions): mean
free path biasing is applied only to electron and
positron bremsstrahlung, and both the incident
electron/positron and the secondary photon are assigned
a reduced weight
LBRREMF (Lambda Biasing with Russian Roulette for
ElectroMagnetic FLUKA): mean free path biasing is applied
to all electron, positron and photon interactions, and the
incident particle either is suppressed or survives with
the same weight it had before collision, depending on a
random choice
LBRRCOMP (Lambda Biasing with Russian Roulette for Compton
interactions): mean free path biasing is applied only to
photon Compton effect, and the incident photon either is
suppressed or survives with the same weight it had before
collision, depending on a random choice
LBRRBREM (Lambda Biasing with Russian Roulette for
BREMsstrahlung interactions): mean free path biasing is
applied only to electron and positron bremsstrahlung, and
the incident electron/positron either is suppressed or
survives with the same weight it had before collision,
depending on a random choice
Default: LPBEMF (see above)
Default (option not requested): none of the above biasings apply. Note,
however, that leading particle biasing can also be requested by
option EMFCUT (not recommended).
Notes:
1) Depending on the SDUM value, different kinds of biasing are applied
to the secondary particles issued from the reaction.
2) If SDUM = LPBEMF, the interaction point of electrons, positrons and
photons is sampled analogically and Leading Particle Biasing is
applied to the secondary particles, in a manner similar to
that provided by option EMFCUT.
However, Leading Particle Biasing with EMFCUT applies to all
electromagnetic effects, while EMF-BIAS can be tuned in detail for
each type of electron and photon interactions.
3) With all other values of SDUM, the interaction point is sampled from
an imposed (biased) exponential distribution, in a manner similar to
that provided by option LAM-BIAS for hadrons and muons. Further
differences in SDUM values allow to restrict biasing to one specific
type of interaction and/or to select different treatments of the
incident particle.
4) If SDUM = LAMBEMF, LAMBCOM, LAMBBREM, the weights of both the
incident and the secondary particle are adjusted according to the
ratio between the biased and the physical interaction probability
at the sampled distance.
5) If SDUM = LBRREMF, LBRRCOM, LBRRBREM, the suppression or survival
of the incident particle (with unchanged weight) is decided by
Russian Roulette with a probability equal to the ratio between the
biased and the physical interaction probability at the sampled
distance. The weight of the secondary particle is adjusted by the
same ratio.
6) When using option EMF-BIAS, and in particular when choosing the
Russian Roulette alternative, it is suggested to set also a weight
window (cards WW-FACTOR and WW-THRESh) in order to avoid too large
weight fluctuations.
7) LAMBCOMP (LBRRCOMP) and LAMBBREM (LBRRBREM) are synonyms: i.e.,
input concerning photon interaction biasing given with SDUM =
LAMBBREM (LBRRBREM) is accepted and treated in the same
way as with SDUM = LAMBCOMP (LBRRCOMP); and input concerning
electron/positron interaction biasing with SDUM = LAMBCOMP
(LBRRCOMP) is the same as with LAMBBREM (LBRRBREM).
This allows to issue just a single EMF-BIAS card requesting both
electron and photon interaction biasing at the same time.
8) Option EMF-BIAS option concerns only electromagnetic interactions;
photonuclear interaction biasing is provided by option LAM-BIAS.
9) Leading particle biasing (LPB):
Leading particle biasing (available only for electrons, positrons
and photons) is generally used to avoid the geometrical increase
with energy of the number of particles in an electromagnetic shower.
It is characteristic of all electromagnetic interactions that two
particles are present in the final state: when this option is
selected, only one of them (with a probability proportional to its
energy) is randomly retained and its weight is adjusted accordingly.
Derived from the EGS4 implementation [Nel85], it has been modified
to account for the indirectly enhanced penetration potential of
positrons due to the emission of annihilation photons. The
probability of each of the two particles to be selected is therefore
not proportional to their kinetic energy but rather to their
"useful" energy (kinetic plus - in the case of positrons only -
twice the mass energy).
The weight of the particle selected is adjusted multiplying it by
the inverse of the selection probability. This kind of biasing is
aimed at reducing the mean computing time per history rather than
the variance of the scored quantities (computer cost is defined as
the product of variance times the computing time per primary
particle). It is mainly used to estimate shower punchthrough (but
comparable and even better efficiency can be obtained with
importance splitting, see BIASING), or to reduce the time spent in
simulating secondary electromagnetic showers produced by pi0 in
hadronic cascades. As any other kind of biasing, leading particle
biasing must be used with judgement, since it may lead to a slower
convergence of dose estimation in some regions of phase
space (see Note 5 to option BIASING). In particular, the fact that
the particle of highest energy is selected preferentially can have
the following effects:
- the radial profile of the electromagnetic shower might be
reproduced less efficiently. This is in general not very
important for showers generated inside hadronic cascades, since
the overall lateral spread is governed essentially by hadrons.
- a few low-energy particles might result with a very large weight
giving rise to strong energy deposition fluctuations (this
inconvenience can be limited to some extent by the use of a
weight window). Therefore, biasing should be avoided in scoring
regions and in adjacent ones, especially when using energy
deposition bins of very small volume.
When applied in energy deposition calculations, the use of weight
windows is recommended in order to avoid large local dose
fluctuations (see WW-FACTOR and WW-THRESh).
3) Option EMFCUT provides an alternative way to request LPB, but
without the possibility to set an energy threshold or to limit
biasing to a specified number of generations.
Example 1 (number-based):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7...+...8
EMF-BIAS 152. 0. 5.E-4 16. 20. 2.LPBEMF
* LPB is applied in regions 16, 18 and 20 as regards Compton scattering
* below 0.5 MeV and positron annihilation in flight and at rest.
* Code 152 = 2^3 (annihilation at rest) + 2^4 (Compton) + 2^7
* (annihilation in flight).
The same example, name-based:
EMF-BIAS 152. 0. 5.E-4 Rsixteen Rtwenty 2.LPBEMF
Example 2 (number-based):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7...+...8
EMF-BIAS 1022. 0.0 0.0 3.0 8.0
* LPB is applied in regions 3, 4, 5, 6, 7 and 8 for all electron and photon
* interactions at all energies
The same example, name-based:
EMF-BIAS 1022. 0.0 0.0 thirdReg eighthRg
Example 3 (number-based):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7...+...8
EMF-BIAS 1022. 0.0 0.0 1.0 15.0
EMF-BIAS -1. 0.0 0.0 7.0 11.0 2.0
WW-FACTOR 0.5 5.0 1.0 1.0 15.0
WW-FACTOR 0.5 5.0 0.2 7.0 11.0 2.0
WW-THRESH 1.0 0.001 20.0 3.0 4.0
WW-THRESH 1.0 1.E-4 20.0 7.0
* The above example illustrates the combined use of leading particle biasing
* and a region-dependent weight-window. Leading particle biasing is requested
* in all regions from 1 to 15, except 7, 9 and 11. To avoid too large weight
* fluctuations, a weight window is defined such that at the lowest energies
* (=< 20 keV for photons and =< 200 keV for electrons in regions 7, 9, 11;
* =< 100 keV for photons and <= 1 MeV for electrons in the other regions),
* Russian Roulette will be played for particles with a weight =< 0.5 and
* those with weight larger than 5.0 will be splitted. The size of this window
* (a factor 10) is progressively increased up to 20 at the higher threshold
* (200 MeV for both electrons and photons in regions 7, 9 and 11, 1 GeV in
* the other regions).
The same example, name-based, assuming that the 15 regions are all the
regions of the problem:
EMF-BIAS 1022. 0.0 0.0 first @LASTREG
EMF-BIAS -1. 0.0 0.0 seventh eleventh 2.0
WW-FACTOR 0.5 5.0 1.0 1.0 15.0
WW-FACTOR 0.5 5.0 0.2 seventh eleventh 2.0
WW-THRESH 1.0 0.001 20.0 ELECTRON POSITRON
WW-THRESH 1.0 1.E-4 20.0 PHOTON
1********************************************************************************
{EMFCUT}
Sets the energy thresholds for electron and photon production in different
materials, and electron and photon transport cut-offs in selected regions.
This command can also request leading particle biasing, but EMF-BIAS must
be preferred.
It also allows to set an arbitrary energy threshold for all electron and
photon interactions managed by EMF on a material basis. This is of course
non-physical and it is provided primarily for particular studies where the
user wants to switch off selectively a physical process.
Only meaningful when the EMF option is chosen (explicitly or implicitly
via option DEFAULTS)
See also EMF, EMF-BIAS, BIASING, PART-THR, MATERIAL
For SDUM = PROD-CUT:
|WHAT(1)| = energy threshold for electron and positron production in GeV:
> 0.0 : energy threshold for electron and positron production is
expressed as total energy (kinetic plus rest mass)
< 0.0 : energy threshold for electron and positron production is
expressed as kinetic energy
= 0.0 : ignored
Default: equal to the lowest electron transport cut-off in all
regions made of this material (see Note 1 below)
WHAT(2) > 0.0 : energy threshold for photon production in GeV
= 0.0 : ignored
Default: equal to the lowest photon transport cut-off in all
regions made of this material (see Note 1 below)
WHAT(3) = FUDGEM parameter. This parameter takes into account the
contribution of atomic electrons to multiple scattering. For
production and transport cut-offs larger than 100 keV it must be
set = 1.0, while in the keV region it must be set = 0.0
Default: 0.0
WHAT(4) = lower bound (or corresponding name) of the FLUKA material number
where electron/positron and photon production thresholds
respectively equal to |WHAT(1)| and WHAT(2) apply. The material
numbers or names are those pre-defined or assigned using a
MATERIAL card.
("From material WHAT(4)...")
Default: 3.0
WHAT(5) = upper bound (or corresponding name) of the FLUKA material number
where electron/positron and photon production thresholds
respectively equal to |WHAT(1)| and WHAT(2) apply. The material
numbers or names are those pre-defined or assigned using a
MATERIAL card.
("...to material WHAT(5)...")
Default: = WHAT(4)
WHAT(6) = step length in assigning the material number.
("...in steps of WHAT(6)")
Default: 1.0.
Default (option EMFCUT with SDUM = PROD-CUT not requested): production
cut-offs in a material are set equal to the lowest transport
cut-offs in the regions with that material.
For SDUM = blank:
|WHAT(1)| = electron and positron transport energy cut-off in GeV.
WHAT(1) > 0.0 : electron and positron cut-off is expressed as total
energy (kinetic plus rest mass)
< 0.0 : electron and positron transport cut-off is expressed as
kinetic energy
= 0.0 : ignored
This value can be overridden in user routine UBSSET by assigning
a value to variable ELECUT.
Default: the e+e- transport cut-off is set equal to the production
threshold for discrete electron interactions
WHAT(2) > 0.0 : photon transport energy cut-off (GeV)
= 0.0 : ignored
This value can be overridden in the user routine UBSSET by
assigning a value to variable GAMCUT.
Default: the photon transport cut-off is set equal to threshold for
photon production by electron bremsstrahlung
WHAT(3) > 0.0 : leading particle biasing is activated for electrons,
positrons and photons. Which combination of leading
particle biasing is actually set up depends on the bit
pattern of WHAT(3)
Let WHAT(3) be represented as:
2^0xb0 + 2^1xb1 + 2^2xb2 + 2^3xb3 + 2^4xb4 +
2^5Xb5 + 2^6xb6 + 2^7xb7 + 2^8xb8 + 2^9xb9
where the meaning of the ten bits is the following:
b0 = 1 --> LPB activated for bremsstrahlung and pair
production (old default)
b1 = 1 --> LPB activated for bremsstrahlung
b2 = 1 --> LPB activated for pair production
b3 = 1 --> LPB activated for positron annihilation at rest
b4 = 1 --> LPB activated for Compton scattering
b5 = 1 --> LPB activated for Bhabha & Moller scattering
b6 = 1 --> LPB activated for photoelectric effect
b7 = 1 --> LPB activated for positron annihilation in flight
b8 = 1 --> not used
b9 = 1 --> not used
Note that WHAT(1) = 1022 activates LPB for all physical
effects (values larger than 1022 are converted to 1022)
< 0.0 : no leading particle biasing for electrons, positrons and
photons
= 0.0 : ignored (previous definitions hold, if any; otherwise
default, i.e. no leading particle biasing)
This value can be overridden in the user UBSSET routine by
assigning a value to variable LPEMF.
WHAT(4) = lower bound (or corresponding name) of the region indices with
electron cut-off equal to |WHAT(1)| and/or photon cut-off equal
to WHAT(2) and/or leading particle biasing
("From region WHAT(4)...")
Default: = 2.0.
WHAT(5) = upper bound (or corresponding name) of the region indices with
electron cut-off equal to |WHAT(1)| and/or photon cut-off equal
to WHAT(2) and/or leading particle biasing
("...to region WHAT(5)...")
Default: = WHAT(4)
WHAT(6) = step length in assigning indices
("...in steps of WHAT(6)")
Default: 1.0.
Default (option EMFCUT with SDUM = blank not requested): transport
cut-offs in a region are set equal to the production cut-offs
in the material of that region.
For SDUM = ELPO-THR:
WHAT(1) > 0.0 : kinetic energy threshold (GeV) for e+/e- bremsstrahlung
= 0.0 : ignored
< 0.0 : resets to default
Default: 0.
WHAT(2) > 0.0 : kinetic energy threshold (GeV) for Bhabha/Moller scattering
= 0.0 : ignored
< 0.0 : resets to default
Default: 0.
WHAT(3) > 0.0 : kinetic energy threshold (GeV) for e+/e- photonuclear
interactions
= 0.0 : ignored
< 0.0 : resets to default
Default: 0.
WHAT(4) - WHAT(6): see below
For SDUM = ANNH-THR:
WHAT(1) > 0.0 : kinetic energy threshold (GeV) for e+ annihilation
= 0.0 : ignored
< 0.0 : resets to default
Default: 0.
WHAT(2) - WHAT(3) : not used
WHAT(4) - WHAT(6): see below
For SDUM = PHOT-THR:
WHAT(1) > 0.0 : energy threshold (GeV) for Compton scattering
= 0.0 : ignored
< 0.0 : resets to default
Default: 0.
WHAT(2) > 0.0 : energy threshold (GeV) for photoelectric
= 0.0 : ignored
< 0.0 : resets to default
Default: 0.
WHAT(3) > 0.0 : energy threshold (GeV) for gamma pair production
= 0.0 : ignored
< 0.0 : resets to default
Default: 0.
WHAT(4) - WHAT(6): see below
For SDUM = PHO2-THR:
WHAT(1) > 0.0 : energy threshold (GeV) for Rayleigh scattering
= 0.0 : ignored
< 0.0 : resets to default
Default: 0.
WHAT(2) > 0.0 : energy threshold (GeV) for photonuclear interactions
= 0.0 : ignored
< 0.0 : resets to default
Default: 0.
WHAT(3) : not used
WHAT(4) - WHAT(6): see below
For SDUM equal to ELPO-THR, ANNH-THR, PHOT-THR, PHO2-THR:
WHAT(4) = lower bound (or corresponding name) of the material indices in
which the respective thresholds apply
("From material WHAT(4)...")
Default = 3.
WHAT(5) = upper bound (or corresponding name) of the material indices in
which the respective thresholds apply
("... to material WHAT(5)...")
Default = WHAT(4)
WHAT(6) = step length in assigning indices
("...in steps of WHAT(6)")
Default = 1.
Default (option EMFCUT not requested): no leading particle biasing, unless
requested by the alternative option EMF-BIAS.
Transport cut-offs are set equal to production thresholds for discrete
electron interactions and for discrete photon production.
Notes:
1) Default values are available for the electron and photon production
thresholds in electromagnetic interactions, but they are generated
by a complex logic based on possible other settings (transport
cut-offs, delta-ray production thresholds, DEFAULTS card, other
defaults). It is not always guaranteed that the resulting values be
appropriate to the problem of interest. Therefore, in order to have
good control of the physics, the user is recommended to provide
explicit threshold values, or at least to check them on the main
output.
2) Transport cut-offs set by EMFCUT override the production thresholds
(set with SDUM = PROD-CUT) for discrete interactions, but only if
higher than them. If lower, the production thresholds apply, of
course. The production thresholds are overridden only for transport
purposes, that is, particles with energy higher than production
thresholds and lower than transport cut-offs are not transported but
are still generated (their energy is deposited at the point of
production). It is suggested to avoid such a situation unless it is
really necessary, as particle generation demands a considerable
computer time and partially offsets the gain due to a higher
transport cut-off.
3) If WHAT(3) is set > 0, Leading Particle Biasing (LPB) is applied at
photon and/or electron interactions, in a manner similar to that
provided by option EMF-BIAS (see the Note 9 to that option for a
description of the technique and guidance to its use). However,
EMF-BIAS offers more flexibility, since it allows to set also an
energy threshold for LPB, and to select a number of generations
to which it can be applied.
Example 1 (number-based):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7...
EMFCUT -1.0E-5 1.0E-5 0.0 4.0 8.0 PROD-CUT
* A production threshold of 10 keV is set for electrons, positrons and
* photons in all materials from 4 to 8.
The same example, name-based:
EMFCUT -1.0E-5 1.0E-5 0.0 HELIUM OXYGEN PROD-CUT
Example 2 (number-based):
EMFCUT -0.002 2.E-4 1.0 1.0 15.0
EMFCUT -1.0E-4 1.E-5 -1.0 7.0 11.0 2.0
* A kinetic energy transport cut-off for electrons and positrons is set
* at 100 keV in regions 7, 9 and 11 and at 2 MeV in all other regions from 1
* to 15. Photon transport cut-off is set equal to 10 keV in regions 7, 9, 11
* and to 200 keV in the other regions.
The same example, name-based, assuming that the 15 regions are all the
regions of the problem:
EMFCUT -0.002 2.E-4 1.0 FirstReg @LASTREG
EMFCUT -1.0E-4 1.E-5 -1.0 Seventh Eleventh 2.0
1********************************************************************************
{EMFFIX}
Sets the size of electron steps corresponding to a fixed fraction of the
total energy. The setting is done by material, giving as many EMFFIX
definitions as needed. Only meaningful when the EMF option has been
requested (explicitly or implicitly via option DEFAULTS).
See also EMF, FLUKAFIX, MULSOPT, STEPSIZE
WHAT(1) = index or name of the material concerned
WHAT(2) = maximum fraction of the total energy to be lost in a step
Default: 20% (it is strongly recommended not to set higher
than this value!)
WHAT(3) = same as WHAT(1); WHAT(4) = same as WHAT(2)
WHAT(5) = same as WHAT(1); WHAT(6) = same as WHAT(2)
SDUM = PRINT : electron and positron dE/dx and maximum allowed step
tabulations for this material are printed
= NOPRINT: tabulations are not printed (cancels any previous PRINT
request for the given materials)
= blank: ignored
Default: NOPRINT
Default (option EMFFIX not requested): the energy lost per step is 20% for
all materials
Notes:
1) The default provided (step length such that 20% of the energy is
lost) is acceptable for most routine problems.
In dosimetry problems and in thin-slab geometries it is recommended
not to exceed 5-10%.
For a detailed discussion of the step length problem, see [Fer91a].
2) Related options are STEPSIZE, MCSTHRES, FLUKAFIX and MULSOPT (see).
MCSTHRES and FLUKAFIX concern only heavy charged particles (hadrons
and muons), while STEPSIZE applies to ALL charged particles
(hadrons, muons and electrons). However, STEPSIZE defines the
steplength in cm and by region, while EMFFIX relates the step
length to the maximum allowed energy loss and is based on
materials. STEPSIZE works also in vacuum and is adapted to problems
with magnetic fields; if both options are used, the smallest of the
two steps is always chosen. Note however that if a step required by
STEPSIZE is too small for the Moli\`ere algorithm, multiple
scattering IS turned off (contrary to what happens with EMFFIX).
MULSOPT is very CPU-time consuming; however, it gives the highest
accuracy compatible with the Moli\`ere theory. It is used rarely,
mostly in low-energy and in backscattering problems.
Example (number based):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7...
MATERIAL 13. 26.98 2.6989 3. 0. 0. ALUMINUM
MATERIAL 82. 207.20 11.35 4. 0. 0. LEAD
MATERIAL 29. 63.546 8.96 12. 0. 0. COPPER
MATERIAL 6. 12.000 2.00 26. 0. 0. CARBON
MATERIAL 7. 14.000 0.0012 27. 0. 0. NITROGEN
MATERIAL 8. 16.000 0.0014 28. 0. 0. OXYGEN
MATERIAL 1. 1.000 0.0001 29. 0. 1. HYDROGEN
MATERIAL 0. 0.0 1.0000 30. 0. 0. TISSUE
COMPOUND 5.57E-3 26.0 1.118E-3 27. 2.868E-2 28. TISSUE
COMPOUND 6.082E-2 29.0 0. 0. 0. 0. TISSUE
EMFFIX 3. 0.15 4. 0.15 12. 0.15
EMFFIX 30. 0.05 0. 0. 0. 0. PRINT
* In this example, a maximum energy loss per step of 15% is requested
* for aluminium, copper and lead, while a more accurate 5% is requested
* for tissue
The same example, name based:
MATERIAL 13. 26.98 2.6989 10. 0. 0. ALUMINUM
MATERIAL 82. 207.20 11.35 17. 0. 0. LEAD
MATERIAL 29. 63.546 8.96 12. 0. 0. COPPER
MATERIAL 6. 12.000 2.00 6. 0. 0. CARBON
MATERIAL 7. 14.000 0.0012 7. 0. 0. NITROGEN
MATERIAL 8. 16.000 0.0014 8. 0. 0. OXYGEN
MATERIAL 1. 1.000 0.0001 3. 0. 1. HYDROGEN
MATERIAL 0. 0.0 1.0000 0. 0. 0. TISSUE
COMPOUND 5.57E-3 CARBON 1.118E-3 NITROGEN 2.868E-2 OXYGEN TISSUE
COMPOUND 6.082E-2 HYDROGEN 0. 0. 0. 0. TISSUE
EMFFIX ALUMINUM 0.15 LEAD 0.15 COPPER 0.15
1********************************************************************************
{EMFFLUO}
Activates a detailed treatment of photoelectric interactions and of
the following atomic deexcitation, with production of fluorescence
X-rays (and a rough treatment of Auger electrons)
See also EMF
This option, meaningful only if the EMF option has been requested
(explicitly or implicitly via option DEFAULTS), requires a special
unformatted file, pre-connected as logical input unit 13 (see Chap. 3}).
This file is delivered with the FLUKA code.
WHAT(1) >= 0: set fluorescence on
< 0 : set fluorescence off
= 0 : ignored
Default = -1.0 (no fluorescence) if option DEFAULTS is not used, or
if it is used with anything but CALORIMEtry, EM-CASCAde,
ICARUS or PRECISIOn.
If DEFAULTS is used with a SDUM value equal to one of the
latter, the default is 1.0 (fluorescence on).
WHAT(2) = lower bound (or corresponding name) of the material indices in
which fluorescence is activated
("From material WHAT(2)...")
Default = 3.
WHAT(3) = upper bound (or corresponding name) of the material indices in
which fluorescence is activated
("... to material WHAT(3)...")
Default = WHAT(2)
WHAT(4) = step length in assigning indices
("...in steps of WHAT(4)")
Default = 1.
WHAT(5), WHAT(6), SDUM : not used
Default (option EMFFLUO not requested): fluorescence is not simulated
unless option DEFAULTS is chosen with SDUM = CALORIMEtry,
EM-CASCAde, ICARUS or PRECISIOn.
Notes:
1) Selection of EMFFLUO option is only meaningful for a material
defined with electron and photon cut-offs lower than the highest
K-edge in the elements constituents of that material.
2) When EMFFLUO is activated for a compound material, if the incident
photon energy is lower than the highest K-edge for any constituent
element, FLUKA uses separate parameterised representations of the
photoelectric cross section between different edges of each
constituent element (all levels having a binding energy > 1 keV are
tabulated).
If the photon energy is higher than the highest K-edge, average
cross sections for the compound are used, but FLUKA still samples a
single element on which to interact, in order to generate the
correct fluorescence photon or Auger electron.
Example (number-based):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7...
EMF
EMFCUT 1.E-5 1.E-5 0.0 17. 18.
EMFFLUO 1.0 17. 18.
* In the above example, the user activates fluorescence production in
* Lead and Tantalum (standard FLUKA material numbers 17 and 18). The
* photon and electron cut-off has been set at 10 keV (the K-edge for
* Pb and Ta is of the order of 100 keV).
The same example, name-based:
EMF
EMFCUT 1.E-5 1.E-5 0.0 LEAD TANTALUM
EMFFLUO 1.0 LEAD TANTALUM
1********************************************************************************
{EMFRAY}
Activates Rayleigh (coherent) scattering and Compton binding corrections in
selected regions. Only meaningful when the EMF option has been requested,
explicitly or implicitly via option DEFAULTS.
See also EMF
WHAT(1) = 1.0 : both Rayleigh scattering and Compton binding corrections
are activated
2.0 : only Rayleigh scattering activated
3.0 : only Compton binding corrections are activated
0.0 : ignored
< 0.0 : no Rayleigh scattering and no binding corrections for
Compton
Default: if option DEFAULTS is used with SDUM = NEW-DEFAults or
HADROTHErapy, the default is 3.0.
If it is not used, or is used with SDUM = CALORIMEtry,
EM-CASCAde, ICARUS or PRECISIOn, the default is 1.0.
With any other value of SDUM, the default is 0.0.
WHAT(2) = lower bound (or corresponding name) of the region indices where
Rayleigh scattering and/or Compton binding corrections are
requested.
("From region WHAT(2)...")
Default = 2.0
WHAT(3) = upper bound (or corresponding name) of the region indices where
Rayleigh scattering and/or Compton binding corrections are
requested.
("...to region WHAT(3)...")
Default = WHAT(2)
WHAT(4) = step length in assigning indices.
("...in steps of WHAT(4)").
Default = 1.0
WHAT(5), WHAT(6), SDUM : not used
Default (option EMFRAY not requested): if option DEFAULTS is used with
SDUM = NEW-DEFAults or HADROTHErapy, binding corrections in
Compton scattering are activated, but not Rayleigh scattering.
If DEFAULTS is not used, or is used with SDUM = CALORIMEtry,
EM-CASCAde, ICARUS or PRECISIOn, both are activated.
With any other value of SDUM, binding corrections and Rayleigh
scattering are not activated.
Note:
1) The treatment of Rayleigh scattering is rather poor for non
monoatomic materials (it assumes additivity and does not take into
account important molecular effects). However, Rayleigh scattering,
in general, has little effect on energy deposition and on particle
transport.
Example (number based):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7...
EMF
EMFRAY 1.0 8.0 12.0 4.0
EMFRAY 3.0 9.0 15.0 2.0
EMFRAY 1.0 EightReg TwelvReg 4.0
EMFRAY 3.0 NineReg FifteenR 2.0
* In the above example, Compton binding corrections are requested in
* regions 8 to 15, excluding regions 10 and 14.
* Rayleigh scattering is requested only in regions 8 and 12
The same example, name-based:
EMF
EMFRAY 1.0 EightReg TwelvReg 4.0
EMFRAY 3.0 NineReg FifteenR 2.0
1********************************************************************************
{EVENTBIN}
For calorimetry only.
Superimposes a binning structure to the geometry and prints the
result after each "event"
See also USRBIN, EVENTDAT
For a description of input for this option, refer to USRBIN. Meaning of
WHATs and SDUM is practically identical for the two options. The only
difference here is that if WHAT(1) is given with a negative sign, only
non-zero data ("hit cells") are printed.
For Cartesian binning, WHAT(1) = 0.0 prints all cells, and a negative
number > -0.5 must be used to print only the "hit cells".
See Note 2 below and Note 3 to option ROTPRBIN.
This card is similar to USRBIN, but the binning data are printed at the end
of each event (primary history).
Information about the binning structure is printed at the beginning, then
binning data are printed at the end of each event WITHOUT ANY NORMALISATION
(i.e. energy per bin and not energy density per unit incident particle
weight).
If the sign of WHAT(1) in the first card defining the binning is negative,
only those elements of the binning which are non zero are printed at the
end of each event, together with their index.
Default (option EVENTBIN not requested): no event-by-event binning.
To read EVENTBIN unformatted output, see instruction for USRBIN, with the
following differences:
* first all binning definitions are written
* then, for each event all binnings are dumped, two records for each
binning:
- First record: NB, NCASE, WEIGHT (resp. binning number, number and weight
of the event)
- Second record: binning energy deposition data (see USRBIN)
* if the LNTZER flag (only non-zero cells) is activated, the energy
deposition can be read as:
READ (...) NHITS, (IHELP(J), GMHELP(J), J = 1, NHITS)
where:
IHELP = cell index = IX + (IY-1)*NX + (IZ-1)*NX*NY
GMHELP = cell content
Notes:
1) Normally, this option is meaningful only in fully analogue runs. Any
biasing option should be avoided, and a GLOBAL declaration with
WHAT(2) < 0. is recommended. Also, it is recommended to request an
option DEFAULTS with SDUM = CALORIMEtry, ICARUS or PRECISIOn.
2) In many cases, binnings defined by EVENTBIN result in a number of
sparse "hit" cells, while all other bins are empty (scoring zero).
In such cases, it is convenient to print to file only the content of
non-empty bins. In these circumstances, it may also be convenient to
allocate a reduced amount of storage (see option ROTPRBIN, and in
particular the Note 3 to that option).
Example 1 (number-based):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....
EVENTBIN 10.0 208.0 25.0 150.0 200.0 180. Firstscore
EVENTBIN -150.0 100.0 -20.0 75.0 50.0 20.0 &
* In the above example, the user requests an event-by-event scoring of
* energy deposition (generalised particle 208), in a Cartesian
* three-dimensional array. The bins are 4 cm wide in x (75 bins between
* x = -150 and x = 150), 2 cm wide in y (50 bins between y = 100 and
* y = 200), and 10 cm wide in z (20 bins between z = -20 and z = 180).
* The results are written, formatted, on logical unit 25. The name given
* to the binning is "Firstscore".
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....
The same example, name-based:
EVENTBIN 10.0 ENERGY 25.0 150.0 200.0 180. Firstscore
EVENTBIN -150.0 100.0 -20.0 75.0 50.0 20.0 &
Example 2 (number-based):
* Event-by-event scoring of photon fluence in a cylindrical mesh of
* 1200x3800 bins 1 mm wide in R and Z. Results are written unformatted on
* logical unit 27. The user requests not to print bins with zero content.
* The binning name is "Bigcylindr".
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....
EVENTBIN -11.0 7.0 -27.0 600.0 0.0 1900. Bigcylindr
EVENTBIN 0.0 0.0 0.0 1200.0 0.0 3800.0 &
The same example, name-based:
EVENTBIN -11.0 PHOTON -27.0 600.0 0.0 1900. Bigcylindr
EVENTBIN 0.0 0.0 0.0 1200.0 0.0 3800.0 &
1********************************************************************************
{EVENTDAT}
For calorimetry only.
Prints event by event the scored star production and/or energy
deposition in each region, and the total energy balance.
See also EVENTBIN, SCORE
EVENTDAT requests separate scoring by region of energy and/or
star density for each event (primary history).
The quantities to be scored are defined via a SCORE command (see
SCORE for details).
As for SCORE, a maximum per run of 4 different star densities is allowed.
The EVENTDAT output includes also a detailed energy balance event by event.
WHAT(1) = output unit
If < 0, the output is unformatted. Values of |WHAT(1)| < 21
should be avoided (with the exception of +11).
Default = 11 (standard output)
WHAT(2) to WHAT(6) : not used
SDUM = output file name (no default!) Max. 10 characters.
Default (option EVENTDAT not given): no event by event scoring
Note: Unformatted data are written as follows.
Once, at the beginning of the run:
- RUNTIT, RUNTIM, NREGS, NSCO, (ISCORE(IS), IS = 1, NSCO)
Then, for each primary particle:
- NCASE, WEIPRU, ENETOT
- (ENDIST(IE), IE = 1, 12)
Then, NSCO times:
- ISC, ISCORE(ISC)
- (REGSCO(IR,ISC), IR = 1, NREGS)
Then one dummy record (for historical reasons):
- NDUM, DUM1, DUM2
Then:
- ISEED1, ISEED2, SEED1, SEED2, SOPP1, SOPP2
where:
RUNTIT = title of the run (CHARACTER*80 variable), which appears
also at the beginning of the standard output
RUNTIM = time of the run (CHARACTER*32 variable), which appears
also at the beginning of the standard output
NREGS = number of regions
NSCO = number of scoring distributions requested by SCORE
ISCORE(I) = Ith requested (generalised) particle distribution
(see 5})
NCASE = number of primaries handled so far (current one included)
WEIPRU = primary weight
ENETOT = primary particle total energy (GeV)
ENDIST(I) are 12 energy contributions to the total energy balance,
some of which appear at the end of the standard output.
Here they are given separately for each primary history
(in GeV) and NOT normalised to the weight of the
primary. Note that some of the contributions are
meaningful only in specific contexts (e.g. if low-energy
neutron transport has been requested).
ENDIST(1) = energy deposited by ionisation
ENDIST(2) = en. depos. by pi0, electrons, positrons and photons
ENDIST(3) = en. depos. by nuclear recoils and heavy fragments
ENDIST(4) = energy deposited by particles below threshold
ENDIST(5) = energy leaving the system
ENDIST(6) = energy carried by discarded particles
ENDIST(7) = residual excitation energy after evaporation
ENDIST(8) = energy deposited by low-energy neutrons (kerma,
proton recoil energy not included)
ENDIST(9) = energy of particles out of the time limit
ENDIST(10) = energy lost in endothermic nuclear reactions
(gained in exothermic reactions if < 0) above 20 MeV
(not implemented yet)
ENDIST(11) = energy lost in endothermic low-energy neutron
reactions (gained in exothermic reactions if < 0)
(not implemented yet)
ENDIST(12) = missing energy
NDUM, DUM1, DUM2 = three dummy variables, with no meaning
REGSCO(IR,ISC) = energy or stars (corresponding to the ISCth
generalised particle distribution) deposited or
produced in the IRth region during the current
primary history. NOT normalised, neither to the
the primary weight nor to the region volume
ISEED1, ISEED2, SEED1, SEED2, SOPP1, SOPP2 = random number
generator information to be read in order to
reproduce the current sequence (skipping calls, see
RANDOMIZE).
Note: All the above quantities are REAL*4, except RUNTIT and RUNTIM
(which are of type CHARACTER) and those with a name
beginning with I,J,K,L,M,N (which are integer).
The different items appearing in the EVENTDAT energy balance
may sometimes give overlapping information and are not all
meaningful in every circumstance (for instance residual
excitation energy is meaningful only if gamma de-excitation
has not been requested). Unlike the balance which is printed at
the end of standard output, these terms are not additive.
The next is an example of a user program to read a binary file
written by EVENDAT.
PROGRAM RDEVDT
CHARACTER*80 RUNTIT, FILNAM
CHARACTER*32 RUNTIM
DIMENSION ISCORE(4), ENDIST(12), REGSCO(5000,4)
WRITE(*,*) 'Name of the EVENTDAT binary file?'
READ(*,'(A)') FILNAM
IB = INDEX(FILNAM,' ')
OPEN(UNIT = 7, FORM = 'UNFORMATTED', FILE = FILNAM(1:IB-1),
& STATUS = 'OLD')
OPEN(UNIT = 8, FORM = 'FORMATTED', FILE = FILNAM(1:IB-1)//'.txt',
& STATUS = 'NEW')
* Once, at the beginning of the run:
READ(7) RUNTIT, RUNTIM, NREGS, NSCO, (ISCORE(IS), IS = 1, NSCO)
WRITE(8,'(A80)') RUNTIT
WRITE(8,'(A32)') RUNTIM
WRITE(8,'(A,I6,5X,A,I4)') 'Number of regions: ', NREGS,
& ' Number of scored quantities: ', NSCO
WRITE(8,'(A,4I6)') 'The scored quantities are: ',
& (ISCORE(IS), IS = 1, NSCO)
* Loop on each primary particle:
100 CONTINUE
WRITE(8,*)
READ(7,END=300) NCASE, WEIPRU, ENETOT
WRITE(8,'(A,I10,1P,2G12.4)') 'NCASE, WEIPRU, ENETOT: ',
& NCASE, WEIPRU, ENETOT
READ(7) (ENDIST(IE), IE = 1, 12)
WRITE(8,'(A)') 'ENDIST: '
DO 400 IE = 1, 12, 2
WRITE(8,'(2(I5,5X,1P,G12.4))') IE,ENDIST(IE),IE+1,ENDIST(IE+1)
400 CONTINUE
DO 200 ISC = 1, NSCO
READ(7) IISC, ISCORE(ISC)
* IISC is redundant, must be equal to ISC
IF(IISC .NE. ISC) STOP 'Wrong sequence'
WRITE(8,'(A,I2,A,I3,A)')
& 'Quantity n. ',ISC, ' (',ISCORE(ISC),'):'
READ(7) (REGSCO(IR,ISC), IR = 1, NREGS)
WRITE(8,*) 'Scoring per region:'
DO 500 IR = 1, NREGS
WRITE(8,'(I7,3X,1P,G12.4)') IR, REGSCO(IR,ISC)
500 CONTINUE
200 CONTINUE
READ(7) NDUM, DUM1, DUM2
IF (DUM1 .LT. 0.) THEN
* DUM1 < 0 is used to signal that seeds follow
READ(7) ISEED1, ISEED2, SEED1, SEED2, SOPP1, SOPP2
WRITE(8,*) ISEED1, ISEED2, SEED1, SEED2, SOPP1, SOPP2
ELSE
BACKSPACE 7
END IF
* This event is finished, start again with the next one
GO TO 100
300 CONTINUE
WRITE(8,*) "End of a run of ", NCASE, " particles"
CLOSE (UNIT = 7)
CLOSE (UNIT = 8)
END
Example (number-based):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
SCORE 208. 211. 201. 8. 0. 0.
EVENTDAT -23. 0. 0. 0. 0. 0. EVT.SCOR
* In this example, the user requests (with option SCORE) scoring of
* total and electromagnetic energy deposition, total stars and
* neutron-produced stars. The average scores for each region will be
* printed on standard output (as an effect of SCORE command), and
* corresponding scores, as well as the energy balance, will be written
* separately for each primary particle on an unformatted file EVT.SCOR
The same example, name-based:
SCORE ENERGY EM-ENRGY ALL-PART NEUTRON 0. 0.
EVENTDAT -23. 0. 0. 0. 0. 0. EVT.SCOR
1********************************************************************************
{EVENTYPE}
defines the hadronic particle production model to be used
See also EVXTEST
FLUKA is designed to work with different particle production
models. The SDUM parameter of option EVENTYPE is used to indicate
the desired hadronic event generator. However, only one generator
(EVAP) is available at present in the standard FLUKA version.
This option is intended only for code development and should not
be requested by the normal user, except to activate heavy recoil
transport (see WHAT(3)) and/or ion-ion interactions
(see SDUM = DPMJET)).
The meaning of WHAT(1),...,WHAT(6) depends on the model chosen
WHAT(1), WHAT(2) : reserved for program development
WHAT(3) =< -1.0: resets the default (no ion transport at all)
-1.0 < WHAT(3) < 1.0: ignored
= 1.0 : approximated transport of ions and recoils (dE/dx only)
= 2.0 : all heavy recoils and ions are transported with energy
loss and multiple scattering, without nuclear
interactions if SDUM = blank or = EVAP, with nuclear
interactions if SDUM = DPMJET
3.0 =< WHAT(3) =< 6.0: heavy recoils up to |particle id| = WHAT(3)
are transported with energy loss and multiple scattering,
but no nuclear interactions (3=d,4=t,5=3-He,6=4-He)
Default = 1.0 if option DEFAULTS is not used, or is used with
SDUM = CALORIMEtry, EET/TRANsmut, ICARUS,
NEW-DEFAults, PRECISIOn or SHIELDINg.
With any other value of SDUM in option DEFAULTS,
ions are not transported.
WHAT(4)...(6) : reserved for program development
SDUM = EVAP : DPM model + PEANUT + evaporation/fission + gamma
de-excitation
= DPMJET : same as EVAP, plus heavy ion nuclear interactions
(provided the DPMJET library has been linked). The value of
WHAT(3) defaults to 2.0)
Default : EVAP
Default (option EVENTYPE not given): defaults are as explained for
WHAT(3) above.
Note: Option EVENTYPE is mainly for development purposes and should
not be used for routine work except (temporarily) to request
transport of heavy recoils. See option DEFAULTS in order to
set up suitable defaults for different classes of problems.
If heavy ion nuclear interactions are requested, the user must
link FLUKA with the DPMJET library, which is provided together
with the normal FLUKA distribution.
Example 1:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....
EVENTYPE 0. 0. 2. 0. 0. 0.EVAP
* In this example, the user requests transport of heavy ions without
* nuclear interactions
Example 2:
EVENTYPE 0. 0. 2. 0. 0. 0.DPMJET
* The user requests transport of heavy ions with nuclear interactions
Example 3:
EVENTYPE 0. 0. 5. 0. 0. 0.EVAP
* The user requests transport of deuterons, tritons and 3He, but not
* of alphas and heavier ions.
* Start_Devel_seq
1********************************************************************************
{EVXTEST}
!!! IMPLEMENTED ONLY FOR INTERNAL DEVELOPMENT VERSIONS !!!
calculates histograms of particle production in hadron-nucleus
collisions using the particle production model selected by the
EVENTYPE card. (No transport is done).
This option is intended only for code development and should not
be requested by the normal user.
See also EVENTYPE
WHAT(1) = number of events to be simulated
WHAT(2) = projectile particle number (see numbering scheme in 5})
WHAT(3) = projectile momentum in GeV/c
WHAT(4) = index or name of target material (as from list in 5}, or
defined by a MATERIAL card)
WHAT(5)=< 0.0 : cascade nucleons and excitation energy are included
> 0.0 : cascade nucleons and excitation energy are excluded
= -1. : evaporation is performed (included by default)
= -2. : gamma deexcitation is performed (included by default)
[the last 2 options work only if evaporation has not
been deactivated (see option EVENTYPE)]
Default = 0.0 (cascade nucleons and excitation energy are
included)
WHAT(6) <> 0.0: diffractive events are excluded
= 0.0 : diffractive events are included
[this option works only if EVAP (improved quark
model with EVAP5 evaporation model) has not been
deactivated (see option EVENTYPE)]
Default = 0.0 (diffractive events are included)
SDUM : = PRINT : tables of information on particles and resonances,
their reaction and decay channels, etc. are printed
Default: tables are not printed
Default (option EVXTEST not given): no event generator testing
Note: EVXTEST is intended for code development only and should
normally not be requested by the general user. It cannot be
applied to PEANUT (pre-equilibrium), for which a
standalone code is available to test the generator.
Example:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....
EVENTYPE 11. 0. 0. 0. 0. 0. EVAP
MATERIAL 79. 196.967 1. 26. 0. 0. GOLD
EVXTEST 1000. 8. 750. 26. -2. 1.
* In this example, the first card requests standard EVAP level densities
* with Cook pairing energies and high energy fission; the second card
* defines a material Gold with index 26 (note that density has been
* set = 1. because anyway it does not affect EVXTEST, which acts on single
* nuclei); and the last card requests 1000 events produced by 750 GeV
* neutrons on gold nuclei, disregarding diffractive events but performing
* gamma de-excitation after evaporation
* End_Devel_seq
1********************************************************************************
{EXPTRANS}
!!! NOT IMPLEMENTED YET !!!
requests an exponential transformation ("path stretching")
WHAT(1) >= 0.0 : WHAT(2) to WHAT(5) are used to input a parameter
defining the exponential transformation in various
regions
< 0.0 : WHAT(2) to WHAT(5) are used to define the particles
to which the exponential transformation must be
applied
Default = 0.0
For WHAT(1) >= 0.0 :
WHAT(2) = exponential transformation parameter ETA
( 0 =< |ETA| < 1 )
This value can be overridden in the user routine UBSSET
(argument EXPTR in the calling list, see 13})
Default = 0.0
WHAT(3) = lower bound (or corresponding name) of the region indices
with exponential transformation parameter ETA = WHAT(2)
("From region WHAT(3)...")
Default = 2.0.
WHAT(4) = upper bound of (or corresponding name) the region indices
with exponential transformation parameter equal to WHAT(2)
("...to region WHAT(4)...")
Default = WHAT(3)
WHAT(5) = step length in assigning indices. ("...in steps of
WHAT(5)").
Default = 1.0
WHAT(6), SDUM : not used
For WHAT(1) < 0 :
WHAT(2) = lower bound (or corresponding name) of the particle indices
to which exponential transformation is to be applied
("From particle WHAT(2)...")
Default = 1.0.
WHAT(3) = upper bound (or corresponding name) of the particle indices
to which exponential transformation is to be applied
("...to particle WHAT(3)...")
Default : = WHAT(2) if WHAT(2) > 0.0, otherwise = 40.0
(low-energy neutrons)
WHAT(4) = step length in assigning indices. ("...in steps of
WHAT(4)"). Default: 1.0
WHAT(5), WHAT(6), SDUM : not used
Default (option EXPTRANS not given): no exponential transformation
Example (number based):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....
EXPTRANS 1. 0.8 10. 18. 8. 0.
EXPTRANS -1. 7. 8. 0. 0. 0.
* Exponential transformation is requested for photons (particle no. 7)
* and neutrons (particle 8), in regions 10 and 18 with an ETA parameter
* equal to 0.8
The same example, name-based:
EXPTRANS 1. 0.8 tenthReg eighteen 8. 0.
EXPTRANS -1. PHOTON NEUTRON 0. 0. 0.
1********************************************************************************
{FLUKAFIX}
Sets the size of the step of muons and charged hadrons to a fixed
fraction of the kinetic energy in different materials
See also EMFFIX, MULSOPT, STEPSIZE
WHAT(1) = fraction of the kinetic energy to be lost in a step
(cannot be > 0.2)
Default: if option DEFAULTS is used with SDUM = ICARUS, the
default is 0.02.
With SDUM = HADROTHErapy or PRECISIOn, the default
is 0.05.
If SDUM = CALORIMEtry, the default is 0.08.
With any other SDUM value, or if DEFAULTS is missing,
the default is 0.1.
WHAT(2) = "epsilon" parameter used to check the finite size of the
nucleus when the nuclear form factor is not invoked by
the multiple scattering algorithm (see note below)
For code development only, do not change!
Default = 0.15
WHAT(3) = high-energy limit for the fraction of energy to be lost
in a step (the fraction is given by WHAT(3) times WHAT(1))
For code development only, do not change!
Default = 0.012
WHAT(4) = lower index bound (or corresponding name) of materials where
the specified energy loss per step is to be applied
(From material WHAT(4)...)
Default = 3
WHAT(5) = upper index bound (or corresponding name) of materials where
the specified energy loss per step is to be applied
(... to material WHAT(5)...)
Default = WHAT(4)
WHAT(6) = step length in assigning indices
(...in steps of WHAT(6))
Default = 1
SDUM : not used
Default (option FLUKAFIX not given): the defaults listed above apply
Note: Usually there is no need for changing the default value of
10% (0.1) for WHAT(1)
The input value is actually applied as such only at
intermediate energies (between about a few tens of MeV and
1 GeV): at low energies it is slowly increased
to twice the requested value, while at high energies it
decreases to a limit controlled by WHAT(3), usually about one
hundredth of the input value.
The "epsilon" parameter controls the accuracy of the multiple
scattering algorithm by limiting the step. In most cases the
length of the step is practically limited anyway by the hadron
interaction length, so the "epsilon" default value is of little
importance and does not need to be changed.
However, in some problems of large dimensions, especially when
transporting muons, a small value of epsilon can slow down the
calculations without necessity. In such cases, WHAT(2) can be
safely set = 1000.0
Example (number based):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....
FLUKAFIX 0.03 0. 0. 21. 0. 0.
* The maximum fractional energy loss for hadrons and muons is set to
* 3 percent in material 21.
The same example, name-based:
FLUKAFIX 0.03 0. 0. CALCIUM 0. 0.
1********************************************************************************
{FREE}
activates free-format input
See also GLOBAL
WHAT(1-6) and SDUM are not used.
Default (option FREE not given): input must follow the standard
FLUKA format (A8,2X,6E10.0,A8) (see 6}), unless free format has
been chosen via a GLOBAL command.
FREE can be given at any point in input, excluding the geometry.
All successive input (excepted the geometry) will be read in free format,
VOXELS and LATTICE cards included.
In free-format input, keywords, WHATs and SDUM do not need to be aligned in
columns but can be written anywhere on the input line, alternating with
"separators" in a manner similar to that of list-oriented format in
Fortran (but character strings - keywords and SDUMs - must NOT be put
between quotes!). A separator is any one of the following:
* One of the five characters ',' (comma), ';' (semicolon),
'/' (slash), '\' (backslash), ':' (colon), preceded or not
by one or more blanks, and followed or not by one or more blanks
* One or more successive blanks without any non-blank separator
Notes:
Different separators may be used on the same line.
If a non-blank separator is immediately followed by another one
(with or without blanks in between), a value of 0.0 is assumed to
be given between them.
Zero values must be given explicitly or as empty places between
two non-blank separators as explained above.
Geometry input (i.e. input between GEOBEGIN and GEOEND cards not
included) must still respect the column format described in 8},
except if free-format geometry input has been requested by GLOBAL.
PLOTGEOM input, whether in a separate file PLG.GFXINDAT or directly
after a PLOTGEOM card in standard input, must still be formatted as
shown in the description of that option.
If FREE has been issued, from then on constants must be written
without any blank imbedded (e.g. 5.3 E-5 is not allowed, but must
be written 5.3E-5 or 5.30E-5)
Free format, if requested, applies to option cards (of the form
KEYWORD WHAT(1) WHAT(2) ... WHAT(6) SDUM)
but not to any data card specific to certain options (for instance the
card following TITLE)
Free format can be requested also by option GLOBAL, but extended to the
whole input and not only from the point where the command is issued.
GLOBAL can also be used to request free format geometry input.
Example:
* The following fixed-format input line:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
BEAM 20. 0.0 -1.0 E-2 -0.02 1.0 PION+
* can be given in free format in any of the following equivalent ways:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
FREE
BEAM 2. 0.0 0.0 -1.0E-2 -0.02 1.0 PION+
*...equivalent to:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
FREE
BEAM, 2.,0.0 , 0.0, -1.0E-2; -0.02 1.0 /PION+ ! 2 GeV/c momentum?
* (note the possibility to insert comments at the end of the line)
*...and also to:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
FREE
BEAM : 20. ,, , -1.0E-2\ -0.02 1.0 PION+
etc...
1********************************************************************************
{GEOBEGIN}
starts the geometry description
See also GEOEND, PLOTGEOM
WHAT(1) : not used
WHAT(2) : used to set the accuracy parameter - reserved
for program development
WHAT(3) > 0.0 : logical unit for geometry input. The name of the
corresponding file must be input on the next card
if WHAT(3) is different from 5. Note that values of
WHAT(3) /= 5.0 and < 21.0 must be avoided
because of possible conflicts with FLUKA pre-defined
units.
Default = 5.0 (i.e. geometry input follows)
WHAT(4) > 0.0 : logical unit for geometry output. If different from
11, the name of the corresponding file must be input
on the next card if WHAT(3) = 0 or 5, otherwise on
the card following the next one. Values of
WHAT(3) /= 11.0 and < 21.0 must be avoided because
of possible conflicts with FLUKA pre-defined units.
Default = 11.0 (i.e. geometry output is printed on
the standard output)
WHAT(5) : parentheses optimisation level = i0 + i1 x 1000
i0 = 1: logical optimisation only activated
2: logical + "plane" optimisation activated
3: logical + "plane" + "bounding box"
optimisation activated
(Default: 3)
i1 > 0 forces optimisation even if no parentheses
are found in the region under scrutiny
(Default: 0)
* Start_Devel_seq
WHAT(6) : if > 0 it indicates the number of geometry output
lines to be skipped before starting writing
debugging lines. Please note that the output
can rapidly become huge
* End_Devel_seq
* Start_Prod_seq
* WHAT(6) : not used
* End_Prod_seq
SDUM = COMBINAT : Combinatorial geometry is used. See section
on Combinatorial Geometry for input description
Other geometries, available in older versions of
FLUKA, are no longer supported.
Default: COMBINAT
SDUM = COMBNAME : Combinatorial geometry is used in free format, and
names can be used instead of body and region numbers
Default (option GEOBEGIN not given): not allowed! GEOBEGIN and
GEOEND must always be present.
Note: Geometry input and output:
i) If WHAT(3) and WHAT(4) are both =< 0, the geometry input and
output are part of the standard I/O streams: the GEOBEGIN
card must be immediately followed by the Combinatorial
Geometry input, and then by GEOEND. (See Example 1 below).
ii) If WHAT(3) is > 0 (and not = 5) and WHAT(4) is =< 0, GEOBEGIN
must be followed by one card with the name of the CG input
file, and then by GEOEND. (See Example 2 below).
iii) If WHAT(4) is > 0 (and not = 11) and WHAT(3) is =< 0, GEOBEGIN
must be followed by one card with the name of the CG output
file, then by the CG input, and then by GEOEND. (See Example 3 below).
iv) Otherwise, if WHAT(3) is > 0 (and not = 5), and WHAT(4) is > 0
(and not = 11), GEOBEGIN must be followed, in the order, by
a line with the name of the CG input file, another line with
the name of the CG output file and the GEOEND card.
(See Example 4 below).
The CG output is essentially an echo of the input, and gives
in addition some information on storage allocation of body and
region data. It is recommended to check on it that the
geometry description has been correctly reproduced, since
column alignment errors are critical due to the CG strict
input format. In case of severe error (next region not found,
or similar) the CG output will also contain all error and
debugging messages. Minor tracking problems, however, are
reported on the error message file (logical unit 15, see 3}),
unless reporting has been de-activated by setting WHAT(1)<>0.
Special algorithms have been implemented in the Combinatorial
Geometry package of FLUKA in order to minimise tracking errors
due to rounding, to improve tracking speed and to handle
charged particle transport near boundaries and in magnetic
fields. Since these facilities could not be made readily
available in other geometries previously used in FLUKA, the
latter have been removed from the code. Combinatorial Geometry
is thus the only geometrical package available at present.
Information on how to set up Combinatorial Geometry input is
given in 8}
End of geometry information must end with a GEOEND card (see).
The same card can also be used to activate a geometry debugger.
Option PLOTGEOM allows to draw sections of the geometry on
planes specified by the user.
Only one GEOBEGIN card is allowed.
Example 1:
* CG Input follows, output is printed as part om Main Output
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
GEOBEGIN 0. 0. 0. 0. 0. 0.COMBINAT
Example 2:
* CG Input read from file BigHall.geo, output printed as part om Main Output
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
GEOBEGIN 0. 0. 25. 0. 0. 0.COMBINAT
BigHall.geo
Example 3:
* CG Input follows, output is printed on file geo2.out
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
GEOBEGIN 0. 0. 0. 26. 0. 0.COMBINAT
geo2.out
Example 4:
* CG Input read from file BigHall.geo,, output printed on file geo2.out
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
GEOBEGIN 0. 0. 25. 26. 0. 0.COMBINAT
BigHall.geo
geo2.out
1********************************************************************************
{GEOEND}
ends the geometry definitions.
This option can also be used to debug the geometry: in this case
it may extend over two cards
See also GEOBEGIN, PLOTGEOM
Normally, only one GEOEND card is issued, at the end of the geometry
description, with all the WHATs and the SDUM equal to zero or blank.
However, GEOEND can also be used to activate the FLUKA geometry debugger:
in this case one or two GEOEND cards are needed, providing the
information described below.
1st GEOEND card:
WHAT(1) = X_max of the geometry region to be debugged (no default)
WHAT(2) = Y_max of the geometry region to be debugged (no default)
WHAT(3) = Z_max of the geometry region to be debugged (no default)
WHAT(4) = X_min of the geometry region to be debugged (no default)
WHAT(5) = Y_min of the geometry region to be debugged (no default)
WHAT(6) = Z_min of the geometry region to be debugged (no default)
SDUM = DEBUG to activate the debugger, otherwise must be left blank
2nd (optional) GEOEND card:
WHAT(1) = Number of mesh intervals in the x-direction between
X_min and X_max
Default = 20.0
WHAT(2) = Number of mesh intervals in the y-direction between
Y_min and Y_max
Default = 20.0
WHAT(3) = Number of mesh intervals in the z-direction between
Z_min and Z_max
Default = 20.0
WHAT(4,5,6) : not used
SDUM = "&" in any position in column 71 to 78 (or in the last
field if free format is used)
Default (option GEOEND not given): not allowed! GEOBEGIN and
GEOEND must always be present.
Note: the geometry debugger can detect both undefined points (points
which are not included in any defined region) or multiple defined
points (points which are included in more than one region (i.e.
there are overlapping regions) in the selected X,Y,Z mesh. The
first kind of error is likely to cause a run-time error every time
a particle is passing through the undefined zone, the second one
is more subtle and it is not usually detected at run-time, the
actual region used for those multiple defined points being
unpredictable.
The geometry debugger cannot assure that a bug-free geometry
input is what the user would like to describe, however it seldom
occurs that users are able to define a bug-free input different
from what they wanted to describe.
It must be stressed that only the points of the defined X,Y,Z mesh
are checked, therefore mesh dimensions and pitches should be
chosen according to the present geometry, taking into account
region thicknesses etc.
It must be stressed too that the geometry debugger can be very
time consuming, so don't ask for 100 micrometres pitches in X,Y,Z
over 10 metres or the code will run forever! Make use as much
as possible of geometry symmetries (for example for a cylindrical
geometry there is no need for a 3-D scan) and possibly "zoom"
with fine meshes only around points where you suspect possible
errors. Note that you can scan as many areas as you wish with
different meshes of the SAME geometry, simply changing the mesh
parameters each time.
WARNING: the program does not stop if an error is detected but
a message is issued on the output units, and checking goes on.
If the code is "stepping" into an area erroneously defined, it is
likely that plenty of such error messages will be printed. If your
operating system allows inspection of output files before they
are closed, check the size of your output from time to time. If it
is growing too much, stop the code and correct the geometry for the
printed errors before restarting the debugger.
Example of a normal GEOEND card without debugging:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
GEOEND 0. 0. 0. 0. 0. 0.
* The next is an example of geometry debugging:
GEOEND 150. 75. 220. 30. 0. -220.DEBUG
GEOEND 120. 1. 110. 0. 0. 0. &
* The above cards request a scan of the geometry portion delimited
* by planes x = 30, x = 150, y = 0, y = 75, z = -220, z = 220,
* with 120 steps 1-cm wide along x, one single step along y and
* 110 4-cm wide steps along z. A single step in one direction (here y)
* is typical of searches through cylindrically symmetric geometries.
1********************************************************************************
{GLOBAL}
Makes a global declaration about the present run, setting some
important parameters that must be defined before array memory
allocation
Note: GLOBAL declarations, if present, must precede any executable
option
WHAT(1) = maximum number of regions (must be =< 10000)
Default: 1000
WHAT(2) = declaration of "how analogue" this run must be: fully
analogue, as biased as possible, or automatically chosen by
the program?
< 0.0: as analogue as possible (provided the input is
consistent with this choice)
> 1.0: as biased as possible (allowed also for a run in
which no explicit biasing option is requested: in
this case it simply means "do not try to be
analogue")
0.0 <= WHAT(2) <= 1.0: as analogue as decided by the program
according to the selected biasing options
Default: 0.0 (input decides the amount of biasing)
WHAT(3): declaration about the use of the DNEAR variable (see Note
below) when computing physical steps:
< 0 --> always use DNEAR when computing the tentative
length of particle steps (it can cause non
reproducibility of the random number sequence when
starting from different histories, but it does not
affect physics)
> 0 --> do not use DNEAR when computing the tentative
length of particle steps (full reproducibility
of the random number sequence starting from different
histories, some penalty in CPU)
= 0 --> (default) use DNEAR when computing the tentative
length of particle steps only when random
seed reproducibility is assured (full reproducibility
of the random number sequence within the same
geometry package, possible non reproducibilities
among different geometry packages describing
Default: 0.0 (random number sequence reproducible within the
same geometry package)
WHAT(4): flag to request various types of input
< 0.0: resets the default
= 0.0: ignored
= 1.0: requests the use of names (alphanumerical 8-character
strings beginning by alphabetical) instead of numbers
as identifiers of particles, materials and regions in
the relevant "WHAT" fields of input commands. If fixed
format is used, each name must be contained inside
the corresponding 10-character field. If free-format,
name-based geometry input has not been requested (see
WHAT(5)) the region names, generated automatically by
FLUKA, can be found on standard output.
= 2.0: requests free-format input for all input commands (for
geometry body and region input, see WHAT(5)). The six
"WHAT" fields must all be input, or replaced by two
successive separators (together with zero or more blanks)
= 3.0: the two previous options are both requested, i.e.
alphanumerical 8-character names are used to identify
particles, materials and regions in the relevant "WHAT"
fields of input commands, and free format is also used
(for geometry body and region input, see WHAT(5)).
The six "WHAT" fields must all be input, or replaced by two
successive separators (together with zero or more blanks)
= 4.0: requests numerical format input for all input commands
Default: 1.0 (name-based, fixed format input)
WHAT(5): flag to request free format in the geometry input for bodies
and regions. This format is described in 8}, and requires the
use of names (alphanumerical 8-character strings beginning by
alphabetical) as identifiers. Parentheses are allowed.
< 0.0: resets the default
= 0.0: ignored
> 0.0: geometry input for bodies and regions will be in free
format and name-based
Default = -1. (numerical, fixed format geometry input)
WHAT(6): not used
SDUM: not used
Notes: In most cases the user should not worry about the number
of geometry regions. Despite the fact that FLUKA input
does not follow any specific order, the program is able to
manage initialisation of all geometry-dependent arrays
by allocating temporary areas of memory even before the
actual dimensions of the problem are known. The unused parts
of such areas are recovered at a later time when the whole
input has been read. However, if the number of regions is
very large (> 1000), the program needs to be informed in order
to increase the size of such temporary areas. This information
must be given at the very beginning: therefore GLOBAL
(together with DEFAULTS, MAT-PROP and PLOTGEOM) is a rare
exception to the rule that the order of FLUKA input cards is free.
The "hard" limit of 10000 regions represents the maximum that
can be obtained without recompiling the program. It can be
overridden, but only by increasing the value of variable
MXXRGN in the INCLUDE file DIMPAR and recompiling the whole
code. In this case, however, it is likely that the size of
variable NBLNMX in INCLUDE file BLNKCM will have to be
increased too.
In a "fully analogue" run, each interaction is simulated by
sampling each exclusive reaction channel with its actual
physical probability. In general, this is not always the case,
especially concerning low-energy neutron interactions.
Only issuing a GLOBAL declaration with WHAT(2) < 0 can it
be ensured that analogue sampling is systematically carried
out whenever it is possible. The lack of biasing options in
input is not sufficient for this purpose. This facility should
be used in problems where fluctuations or correlations cannot
be ignored, but is likely to lead to longer computing times.
DNEAR designates the distance between the current particle
position and the nearest boundary (or a lower bound to that
distance), and it is used by FLUKA to optimise the step
length of charged particles. The concept and the name have
been borrowed from the EGS4 code, but the FLUKA implementation
is very different because it is fully automatic rather than left
to the user, and it is tailored for Combinatorial Geometry, where
a region can be described by partially overlapping sub-regions
(described in input by means of the OR operator).
The sequential order in which overlapping sub-regions are
considered when evaluating DNEAR is irrelevant from the point
of view of particle tracking, but can affect the random number
sequence. This does not have any effect on the average results
of the calculation, but the individual histories can differ due
the different random number sequence used. Option GLOBAL can be
used in those cases where the user wants to reproduce exactly
each particle history, or on the contrary to forgo it in order to
get a better step optimisation.
Free format can be requested also by option FREE, but only for
the part of input that follows the command. FREE cannot be used
to request free format geometry input. See the Notes to FREE for
the rules governing separators.
Free-format, name-based geometry input can be requested also by
setting SDUM = COMBNAME in command GEOBEGIN.
Example 1:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
TITLE
A fully analogue run (no other commands precede this TITLE card)
GLOBAL 2000. -1. 1. 0. 0. 0.
* This run needs more than the default maximum number of regions. It is
* requested to be as analogue as possible and to avoid using DNEAR if
* it risks to affect the random number sequence.
Example 2:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
TITLE
Full free-format input (no other commands precede this TITLE card)
GLOBAL 0.0 0.0 0.0 2.0 1.0 0.
* The following input will be all in free format (both the FLUKA commands
* and the geometry description)
1********************************************************************************
{HI-PROPE}rt
Specifies the properties of a heavy ion primary, or a radioactive
isotope primary
See also BEAM
WHAT(1) = Atomic number Z of the heavy ion
Default: 6.0 (Carbon)
WHAT(2) = Mass number A of the heavy ion
Default: 12.0
WHAT(3) = Excitation energy of the heavy ion above ground state
if > 0 (NOT YET IMPLEMENTED), isomeric state of the
heavy ion if < 0.
Default: 0.0
WHAT(4)-WHAT(6): not used
SDUM: not used
Default: If no HI-PROPE definition is given, a HEAVYION projectile
is assumed to be 12C in the ground state.
Note:
Option HI-PROPErt is used to specify the properties of a generic heavy
ion primary declared by a BEAM command with SDUM = HEAVYION, or by a
user-written subroutine SOURCE with id number IJ = -2.
Example:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7...
* Primary particles are 10 GeV Au-197 ions in the ground state:
BEAM -10.0 0.0 0.0 0.0 0.0 0. HEAVYION
HI-PROPE 79.0 197.0 0.0 0.0 0.0 0.
1********************************************************************************
{IONFLUCT}
calculates ionisation energy losses of charged hadrons, muons, and
electrons/positrons with ionisation fluctuations
See also DELTARAY
For any SDUM's but PRIM-ION:
WHAT(1) >= 1.0 : restricted energy loss fluctuations (for hadrons
and muons) switched on
=< -1.0 : restricted energy loss fluctuations (for hadrons
and muons) switched off
= 0.0 : ignored
Default: restricted energy loss fluctuations for hadrons
and muons are activated if option DEFAULTS is missing or
if it is used with SDUM = CALORIMEtry, EET/TRANSmut,
HADROTHErapy, ICARUS, NEW-DEFAults or PRECISIOn.
With any other SDUM value, they are not activated.
WHAT(2) >= 1.0 : restricted energy loss fluctuations (for electrons
and positrons) switched on
=< -1.0 : restricted energy loss fluctuations (for electrons
and positrons) switched off
= 0.0 : ignored
Default: restricted energy loss fluctuations for electrons
and positrons are activated if option DEFAULTS is missing
or if it is used with SDUM = CALORIMEtry, EM-CASCAde,
HADROTHErapy, ICARUS, NEW-DEFAults or PRECISIOn.
With any other SDUM value, they are not activated.
WHAT(3) : If WHAT(1) (resp. WHAT(2)) >=1, WHAT(3) represents the accuracy
parameter for the ionisation fluctuation algorithm (see [Fas97a])
for hadrons and muons (resp. electrons and positrons).
The accuracy parameter can take integer values from 1 to 4
(corresponding to increasing levels of accuracy)
< 0.0 : resets to default
Default = 1.0 (minimal accuracy)
WHAT(4) = lower bound (or corresponding name) of the indices of the
materials in which the restricted energy loss fluctuations are
activated
("From material WHAT(4)...")
Default = 3.0
WHAT(5) = upper bound (or corresponding name) of the indices of the
materials in which the restricted energy loss fluctuations are
activated
("... to material WHAT(5)...")
Default = WHAT(4)
WHAT(6) = step length in assigning indices
("...in steps of WHAT(6)")
Default: 1.0
For SDUM = PRIM-ION:
generation of primary ionisation electrons is switched on (or switched
off, if WHAT(3) < 0)
Delta rays below threshold for explicit generation are generated anyway:
for close collisions down to the threshold, and for distant collisions down
to an internally computed value, such as to match the input 1st ionisation
potential and the average number of primary ionisations per unit length.
WHAT(1) = effective 1st ionisation potential (eV)
(meaningless for model 1)
No default
WHAT(2) = number of primary ionisations per cm for a mimimum ionising
particle (assumed to be a muon+ at beta*gamma = 3). For gases it
must be the value at NTP.
If set = 0 (valid value), only primary electrons related to
close collisions will be produced and WHAT(1) and WHAT(3)
will be meanigless.
No default
WHAT(3) = primary ionisation model type (1, 2, 3 or 4)
0 is ignored if a previous call set a value > 0, otherwise it
forces the default
A value < 0 switches off primary ionisation production
Default: 1
WHAT(4) = lower bound (or corresponding name) of the indices of the
materials in which the choices represented by WHAT(1),(2) and (3)
apply
("From material WHAT(4)...")
Default = 3.0
WHAT(5) = upper bound (or corresponding name) of the indices of the
materials in which the choices represented by WHAT(1),(2) and (3)
apply
("... to material WHAT(5)...")
Default = WHAT(4)
WHAT(6) = step length in assigning indices
("...in steps of WHAT(6)")
Default: 1.0
SDUM = PRIM-ION
Default (option IONFLUCT not given): ionisation fluctuations are simulated
or not depending on option DEFAULTS as explained above. Explicit
primary ionisation events are never simulated by default.
Note 1: The energy loss fluctuation algorithm is fully compatible
with the DELTARAY option.
Note 2: Primary ionisation electron energies are stored in COMMON ALLDLT at
each step in the selected materials.
Use with care and possibly for gases only. The number of primary
ionisations electrons can quickly escalate, particularly when
multiply charged ions are involved. No COMMON saturation crash
should occur since the code is piling up all the remaining primary
electrons into the last COMMON location if no further one is
available, however CPU penalties can be severe if used without
wisdom.
Example (number-based):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
IONFLUCT 0.0 1.0 3.0 7.0 16.0 3.0
IONFLUCT 1.0 0.0 2.0 8.0 10.0 2.0
DELTARAY 1.E-3 0.0 0.0 10.0 11.0
* The special FLUKA algorithm for ionisation fluctuations is activated
* with accuracy level 3 for photons and electrons in materials 7, 10, 13 and
* 16 (Nitrogen, Aluminum, Silver and Mercury). The same algorithm is activated,
* at an accuracy level = 2, for materials 8 and 10 (Oxygen and Aluminum), but
* in the latter material only for ionisation losses with energy transfer
* < 1 MeV. Losses with larger energy transfer will result in explicit delta
* electron production. In material 11 (Iron), delta rays will be produced if
* the energy transfer is larger than 1 MeV, but fluctuations for lower energy
* transfers will be ignored.
The same example, name based:
IONFLUCT 0.0 1.0 3.0 NITROGEN MERCURY 3.0
IONFLUCT 1.0 0.0 2.0 OXYGEN ALUMINUM 2.0
DELTARAY 1.E-3 0.0 0.0 ALUMINUM IRON
1********************************************************************************
{IRRPROFI}le
defines an irradiation profile for radioactive decay calculations
See also DCYTIMES, DCYSCORE, RADDECAY
WHAT(1) = length of a newly defined irradiation interval (in s)
> 0.0 : a new interval is added with length WHAT(1)
= 0.0 : ignored
< 0.0 : the last defined interval (if any) is deleted
Default = no new irradiation interval is defined
WHAT(2) = beam intensity of the newly defined (see WHAT(1)) irradiation
interval
>= 0.0 : beam intensity in particles/s (0 is accepted)
< 0.0 : considered as 0.0
Default: 0.0 particles/s
WHAT(3) = the same as WHAT(1)
WHAT(4) = the same as WHAT(2)
WHAT(5) = the same as WHAT(1)
WHAT(6) = the same as WHAT(2)
SDUM = not used
Default (option IRRPROFIle not given): no irradiation interval is defined
Note: Several cards can be combined up to a maximum of 20 irradiation
intervals. Decay times as requested by DCYTIMES commands will be
calculated from the end of the last one. Scoring during irradiation
can be obtained giving negative decay times in DCYTIMES
Example:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
IRRPROFILE 1800. 1.5E12 250. 3.E10 4500. 4.2E12
* The profile defined consists of 1800 s of irradiation at an intensity of
* 1.5E12 particles/s, followed by 250 s at low intensity (3.E10 particles/s),
* and then a third 4500 s interval at 4.2E12 particles/s
1********************************************************************************
{LAM-BIAS}
Used to bias the decay length of unstable particles, the inelastic
nuclear interaction length of hadrons, photons and muons and the
direction of decay secondaries
The meaning of WHAT(1)...WHAT(6) depends on the value of SDUM.
SDUM = DCDRBIAS and SDUM = DCY-DIRE are used to activate and
define decay direction biasing; SDUM = GDECAY selects decay length
biasing and inelastic nuclear interaction biasing; and if
SDUM = blank, decay life biasing and inelastic nuclear interaction
biasing are selected.
Other LAM-BIAS cards with SDUM = DECPRI, DECALL, INEPRI, INEALL
allow to restrict biasing to primary particles or to extend it
also to further generations.
for SDUM = DCY-DIRE:
The decay secondary product direction is biased in a direction
indicated by the user by means of a unit vector of components
U, V, W (see Notes below):
WHAT(1) = U (x-direction cosine) of decay direction biasing
Default: 0.0
WHAT(2) = V (y-direction cosine) of decay direction biasing
Default: 0.0)
WHAT(3) = W (z-direction cosine) of decay direction biasing
Default: 1.0
WHAT(4) > 0.0: lambda for decay direction biasing. The degree of
biasing decreases with increasing lambda (see Note below).
= 0.0: a user provided routine (UDCDRL, see 13}) is called at
each decay event, to provide both direction and lambda for
decay direction biasing
< 0.0 : resets to default (lambda = 0.25)
Default = 0.25
WHAT(5) = not used
WHAT(6) = not used
for SDUM = DCDRBIAS:
WHAT(1) > 0.0: decay direction biasing is activated
= 0.0: ignored
< 0.0: decay direction biasing is switched off
WHAT(2) = not used
WHAT(3) = not used
WHAT(4) = lower bound of the particle id-numbers (or corresponding name) for
which decay direction biasing is to be applied
("From particle WHAT(4)...").
Default = 1.0.
WHAT(5) = upper bound of the particle id-numbers (or corresponding name) for
which decay direction biasing is to be applied
("...to particle WHAT(5)...").
Default = WHAT(4) if WHAT(4) > 0, 64 otherwise.
WHAT(6) = step length in assigning numbers. ("...in steps of WHAT(6)").
Default = 1.0.
for all other SDUM's:
WHAT(1): biasing parameter for decay length or life, applying only to
unstable particles (with particle numbers >= 8). Its meaning
differs depending on the value of SDUM, as explained in the
following.
for SDUM = GDECAY:
WHAT(1) < 0.0 : the mean DECAY LENGTH (in cm) of the particle in the
LABORATORY frame is set = |WHAT(1)| if smaller than
the physical decay length (otherwise it is left
unchanged). At the decay point sampled according to
the biased probability, Russian Roulette (i.e.
random choice) decides whether the particle actually
will survive or not after creation of the decay
products. The latter are created in any case and
their weight adjusted taking into account the ratio
between biased and physical survival probability.
> 0.0 : the mean DECAY LENGTH (in cm) of the particle in the
LABORATORY frame is set = WHAT(1) if smaller than
the physical decay length (otherwise it is left
unchanged). Let P_u = unbiased probability and
P_b = biased probability: at the decay point sampled
according to P_b, the particle always survives
with a reduced weight W(1 - P_u/P_b), where W is the
current weight of the particle before the decay. Its
daughters are given a weight W P_u/P_b (as in
case WHAT(1) < 0.0).
= 0.0 : ignored
for SDUM = blank:
-1 < WHAT(1) < 0. : the mean LIFE of the particle in its REST frame
is REDUCED by a factor = |WHAT(1)|. At the decay
point sampled according to the biased
probability, Russian Roulette (i.e. random
choice) decides whether the particle actually
will survive or not after creation of the decay
products. The latter are created in any case and
their weight adjusted taking into account the
ratio between biased and physical survival
probability.
0 < WHAT(1) < +1. : the mean LIFE of the particle in the REST frame
is REDUCED by a factor = |WHAT(1)|. At the decay
point sampled according to the biased
probability, the particle always survives with
a reduced weight. Its daughters are given the
same weight.
|WHAT(1)| > 1 : a possible previously given biasing parameter
is reset to the default value (no biasing)
WHAT(1) = 0 : ignored
WHAT(2) : biasing factor for hadronic inelastic interactions
-1 < WHAT(2) < 0. : the hadronic inelastic interaction length of the
particle is reduced by a factor |WHAT(2)|.
At the interaction point sampled according to
the biased probability, Russian Roulette (i.e.
random choice) decides whether the particle actually
will survive or not after creation of the
secondaries products. The latter are created in
any case and their weight adjusted taking into
account the ratio between biased and physical
survival probability.
0. < WHAT(2) < 1. : the hadronic inelastic interaction length of the
particle is reduced by a factor WHAT(2),
At the interaction point sampled according to
the biased probability, the particle always
survives with a reduced weight. The secondaries
are created in any case and their weight
adjusted taking into account the ratio between
biased and physical survival probability.
= 0.0 : ignored
|WHAT(2)| >= 1.0 : a possible previously set biasing factor is
reset to the default value of 1 (no biasing).
WHAT(3) : If > 2.0 : number or name of the material to
which the inelastic biasing factor has to be applied.
< 0.0 : resets to the default a previously assigned value
= 0.0 : ignored if a value has been previously assigned to
a specific material, otherwise all materials (default)
0.0 < WHAT(3) =< 2.0 : all materials.
WHAT(4) = lower bound of the particle id-numbers (or corresponding name) for
which decay or inelastic interaction biasing is to be applied
("From particle WHAT(4)...").
Default = 1.0.
WHAT(5) = upper bound of the particle id-numbers (or corresponding name) for
which decay or inelastic interaction biasing is to be applied
("...to particle WHAT(5)...").
Default = WHAT(4) if WHAT(4) > 0, 46 otherwise.
WHAT(6) = step length in assigning numbers. ("...in steps of WHAT(6)").
Default = 1.0.
for SDUM = DECPRI, DECALL, INEPRI, INEALL:
SDUM = DECPRI: decay biasing, as requested by another LAM-BIAS card with
SDUM = GDECAY or blank, must be applied only to primary particles.
= DECALL: decay biasing, as requested by another LAM-BIAS card with
SDUM = GDECAY or blank, must be applied to all generations (default).
= INEPRI: inelastic hadronic interaction biasing, as requested by
another LAM-BIAS card with SDUM = blank, must be applied only to
primary particles.
= INEALL: inelastic hadronic interaction biasing, as requested by
another LAM-BIAS card with SDUM = blank, must be applied to all
generations (default)
Default (option LAM-BIAS not given): no decay length or inelastic
interaction or decay direction biasing
Note: Option LAM-BIAS can be used for three different kinds of biasing:
1) biasing of the particle decay length (or life),
2) biasing of the direction of the decay secondaries, and
3) biasing of the inelastic hadronic interaction length.
Depending on the SDUM value, two different kinds of biasing are
applied to the particle decay length (or life).
In both cases, the particle is transported to a distance
sampled from an imposed (biased) exponential distribution:
If WHAT(1) is positive, decay products are created, but the
particle survives with its weight and the weight of its
daughters is adjusted according to the ratio between the biased
and the physical survival probability at the sampled
distance. If WHAT(1) is negative, decay is performed and the
weight of the daughters is set according to the biasing, but the
survival of the primary particle is decided by Russian
Roulette according to the biasing. Again, the weights are adjusted
taking the bias into account.
The laboratory decay length corresponding to the selected
mean decay life is obtained by multiplication by BETA*GAMMA*c.
Decay direction biasing is activated by a LAM-BIAS card
with SDUM = DCDRBIAS. The direction of decay secondaries is
sampled preferentially close to the direction specified by
the user by means of a second LAM-BIAS card with SDUM = DCY-DIRE.
The biasing function for the decay direction is of the form
exp{-[1-cos(theta)]/lambda}
where theta is the polar angle between the sampled direction and the
preferential direction (transformed to the centre of mass reference
system). The degree of biasing is largest for small positive values
of lambda (producing direction biasing strongly peaked along the
direction of interest) and decreases with increasing lambda. Values
of lambda >= 1.0 result essentially in no biasing.
Biasing of hadronic inelastic interaction length can be done either
in one single material (indicated by WHAT(3)) or in all materials
(default). No other possibility is foreseen for the moment.
Note that biasing of the hadronic inelastic interaction length can be
applied also to photons (provided option PHOTONUC is also
requested) and muons (provided option MU-PHOTON is also requested);
actually, it is often a good idea to do this in
order to increase the probability of photon nuclear interaction.
When choosing the Russian Roulette alternative, it is
suggested to set also a weight window (cards WW-FACTOr and
WW-THRESh) in order to avoid too large weight fluctuations.
Reduction factors excessively large can result in an abnormal
increase of the number of secondaries to be loaded on the stack,
especially at high primary energies. In such cases, FLUKA issues
a message that the secondary could not be loaded because of a
lack of space. The weight adjustment is modified accordingly
(therefore the results are not affected) but if the number of
messages exceeds a certain limit, the run is terminated.
For photons, a typical reduction factor of the hadronic inelastic
interaction length is the order of 0.01-0.05 for a shower initiated
by 1 GeV photons or electrons, and of 0.1-0.5 for one at 10 TeV.
Examples (number based):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
LAM-BIAS -3.E+3 1. 1. 13. 16. 0.GDECAY
* The mean decay length of pions and kaons (particles 13, 14, 15 and 16)
* is set equal to 30 m. Survival of the decaying particle is decided by
* Russian Roulette.
LAM-BIAS 0.0 0.02 11. 7. 0. 0.INEPRI
* The interaction length for nuclear inelastic interactions of primary
* photons (particle 7) is reduced by a factor 50 in material 11.
* (Note that such a large reduction factor is often necessary for photons,
* but generally is not recommended for hadrons). The photon survives after
* the nuclear interaction with a reduced weight.
The same examples, name based:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
LAM-BIAS -3.E+3 1. 1. PION+ KAON- 0.GDECAY
*
LAM-BIAS 0.0 0.02 11. PHOTON 0. 0.INEPRI
1********************************************************************************
{LOW-BIAS}
requests non-analogue absorption and/or an energy cut-off during
low-energy neutron transport on a region by region basis
See also PART-THR, LOW-NEUT
WHAT(1) > 0.0 : group cut-off (neutrons in energy groups with number
>= WHAT(1) are not transported).
This value can be overridden in the user routine UBSSET
(argument IGCUTO in the calling list, see 13})
Default = 0.0 (no cut-off)
WHAT(2) > 0.0 : group limit for non-analogue absorption (neutrons in
energy groups >= WHAT(2) undergo non-analogue absorption)
This value can be overridden in the user routine UBSSET
(argument IGNONA in the calling list, see 13})
Non-analogue absorption is applied to the NMGP-WHAT(2)+1
groups with energies equal or lower than those of
group WHAT(2) if WHAT(2) is not > NMGP, otherwise it
isn't applied to any group (NMGP is the number of
neutron groups in the cross section library used:
it is = 260 in the standard FLUKA neutron library)
Default: if option DEFAULTS is used with SDUM = CALORIMEtry,
ICARUS, NEUTRONS or PRECISIOn, the default is = NMGP+1
(usually 261), meaning that non-analogue absorption is
not applied at all.
If DEFAULTS is missing, or is present with any other
SDUM value, the default is the number of the first thermal
group (usually 230).
WHAT(3) > 0.0 : non-analogue SURVIVAL probability. Must be =< 1.
This value can be overridden in the user routine UBSSET
(argument PNONAN in the calling list, see 13})
Default: if option DEFAULTS is used with SDUM = EET/TRANsmut,
HADROTHErapy, NEW-DEFAults or SHIELDINg, the default
is = 0.95.
If DEFAULTS is missing, or is present with any other
SDUM value, the default is 0.85.
WHAT(4) = lower bound of the region indices (or corresponding name) in
which the indicated neutron cut-off and/or survival parameters
apply
("From region WHAT(4)...")
Default = 2.0.
WHAT(5) = upper bound of the region indices (or corresponding name) in
which the indicated neutron cut-off and/or survival parameters
apply
("...to region WHAT(5)...")
Default = WHAT(4)
WHAT(6) = step length in assigning indices. ("...in steps of
WHAT(6)").
Default = 1.
SDUM : not used
Default (option LOW-BIAS not given): the physical survival probability
is used for all groups excepting thermal ones, which are assigned
a probability of 0.85. However, if option DEFAULTS has been
issued with SDUM = EET/TRANsmut, HADROTHErapy, NEW-DEFAults or
SHIELDINg, this default value is changed to 0.95.
If SDUM = CALORIMEtry, ICARUS, NEUTRONS or PRECISIOn, the default
is physical survival probability for all groups, including thermal.
Note: the groups are numbered in DECREASING energy order (see 10}
for a detailed description). Setting a group cut-off larger
than the last group number (e.g. 261 when using a 260-group
cross section set) results in all neutrons been transported,
i.e. no cut-off is applied.
Similarly, if WHAT(2) is set larger than the last group number,
non-analogue neutron absorption isn't applied to any group (this is
recommended for calorimetry studies and all cases where fluctuations
and correlations are important).
The survival probability is defined as 1 - (Sigma_abs/Sigma_T)
where Sigma_abs is the inverse of the absorption mean free
path and Sigma_T the inverse of the mean free path for
absorption plus scattering (total macroscopic cross section).
The LOW-BIAS option allows the user to control neutron
transport by imposing an artificial survival probability
and corrects the particle weight taking into account the
ratio between physical and biased survival probability.
In some programs like MORSE the survival probability is always
forced to be = 1. In FLUKA, if the LOW-BIAS option is not
chosen, the physical survival probability is used for all
non-thermal groups, and the default 0.85 is used for the
thermal groups. (This exception is to avoid endless thermal
neutron scattering in materials with low thermal neutron
absorption cross section). To get the physical survival
probability applied to ALL groups, as needed for fully analogue
calculations, the user must use LOW-BIAS with WHAT(2) larger
than the last group number.
In selecting a forced survival probability for the thermal
neutron groups, the user should have an idea of the order of
magnitude of the actual physical probability. The latter can
take very different values: for instance it can range between
a few per cent for thermal neutrons in Boron-10 to about
80-90% in Lead and 99% in Carbon. The choice will be often for
small values of survival probability in the thermal groups in
order to limit the length of histories, but not if thermal
neutron effects are of particular interest.
Concerning the other energy groups, if there is interest in
low-energy neutron effects, the survival probability for
energy groups above thermals in non-hydrogenated materials
should be set at least = 0.9, otherwise practically no
neutron would survive enough collisions to be slowed down. In
hydrogenated materials, a slightly lower value could be
acceptable. Setting less than 80% is likely to lead to
erroneous results in most cases.
Use of a survival probability equal or smaller than the
physical one is likely to introduce important weight
fluctuations among different individual particles depending
on the number of collisions undergone. To limit the size of
such fluctuations, which could slow down statistical
convergence, it is recommended to define a weight window by
means of options WW-THRESh, WW-FACTOr and WW-PROFIle.
Example (number based):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
LOW-BIAS 60.0 47.0 0.95 5.0 19.0 0.0
LOW-BIAS 261.0 230.0 0.82 7.0 15.0 4.0
* Note that the second LOW-BIAS card overrides the settings of the first one
* concerning regions 7, 11 and 15. Therefore, we will have an energy cutoff
* equal to the upper edge of the 60th group (4.493290 MeV in the standard
* FLUKA neutron library) in regions 5,6,8,9,10,12,13,14,16,17,18 and 19. In
* these same regions, analogue neutron absorption is requested down to an
* energy equal to the upper edge of group 47 (6.592384 MeV in the standard
* library), and biased absorption, with a fixed probability of 95%, at lower
* energies.
* In regions 7, 11 and 15, no cutoff is applied (supposing we are using the
* standard 260-group library), and non-analogue absorption is requested for
* groups 230 to 260 (the thermal groups in our case), with a probability of
* 82%.
The same example, name based:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
LOW-BIAS 60.0 47.0 0.95 FifthReg Nineteen 0.0
LOW-BIAS 261.0 230.0 0.82 RegSeven Fifteen 4.0
1********************************************************************************
{LOW-DOWN}
biases the downscattering probability during low energy neutron
transport on a region by region basis
See also LOW-NEUT, LOW-BIAS
WHAT(1) > 0.0 : group limit for biased downscattering probability.
Neutrons in energy groups IG >= WHAT(1) are given
downscattering importances = WHAT(2)**(IG-WHAT(1)).
This value can be overridden in the user routine UBSSET
(argument IGDWSC in the calling list, see 13})
Default = 0.0 (no biased downscattering)
WHAT(2) = biasing factor for down-scattering from group IG-1 into group IG
This value can be overridden in the user routine UBSSET
(argument FDOWSC in the calling list, see 13})
Default = 1.5
WHAT(3) : not used
WHAT(4) = lower bound of the region indices (or corresponding name) to
which downscattering biasing is to be applied
("From region WHAT(4)...").
Default: = 2.0
WHAT(5) = upper bound of the region indices (or corresponding name) to
which downscattering biasing is to be applied
("...to region WHAT(5)...")
Default: = WHAT(4)
WHAT(6) = step length in assigning indices. ("...in steps of
WHAT(6)").
Default: 1.0
SDUM : not used
Default (option LOW-DOWN not given): no downscatter biasing
Note: this option can be useful only in very particular problems,
for instance to calculate the response of instruments
based on moderation (Bonner spheres, rem-counters).
Very powerful but also very dangerous, can lead to errors
of orders of magnitude if not used by experts.
U S E W I T H T H E M A X I M U M C A R E !!!!
P A R T I C U L A R L Y F O R H Y D R O G E N A -
T E D M A T E R I A L S !!!!
The groups are numbered in DECREASING energy order (see 10}
for a detailed description).
When this option is used, the natural probabilities of scatter
from group I to group J, P(I-->J), are altered by an importance
factor V(J). Selection of the outgoing group L is made from
a biased distribution function P(I-->J)*V(J) with an associated
weight correction.
Example (number based):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
LOW-DOWN 38.0 1.1 0.0 4.0 25.0 0.0
* In all regions from 4 to 25, neutron downscattering is biased from
* group 38 to last. Assuming we are using the standard FLUKA library with
* 260 groups, that means all energies below 7.985162 MeV. In group 38, the
* downscattering relative importance is set equal to 1.1, in group 39 to
* 1.1**2 = 1.21, in group 40 to 1.1**3 = 1.331 etc.
The same example, name based:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
LOW-DOWN 38.0 1.1 0.0 RegFour The25Reg 0.0
1********************************************************************************
{LOW-MAT}
sets the correspondence between FLUKA materials and low-energy
neutron cross sections
See also LOW-NEUT
WHAT(1) = number or name of the FLUKA material, either taken from the list
of standard FLUKA materials (see 5}), or defined via
a MATERIAL option.
No default!
WHAT(2) = first numerical identifier of the corresponding
low-energy neutron material. Not used if = 0.0
WHAT(3) = second numerical identifier of the corresponding low-energy neutron
material. Not used if = 0.0
WHAT(4) = third numerical identifier of the corresponding low-energy neutron
material. Not used if = 0.0
WHAT(5) = compound material if > 0. This applies only to pre-mixed
low-energy neutron compound materials, which could
possibly be available in the future; at the moment
however, none is yet available. (It would be allowed
anyway only if the corresponding FLUKA material is also a
compound).
Default: compound if the FLUKA material is a compound,
otherwise not.
WHAT(6) = atomic or molecular density (in atoms/(10**-24 cm3), or
number of atoms contained in a 1-cm long cylinder with
base 1 barn. To be used ONLY if referring to a pre-mixed
compound data set (see COMPOUND and note to WHAT(5) above)
Note that no such data set has been made available yet.
SDUM = name of the low-energy neutron material.
Default: same name as the FLUKA material.
Default (option LOW-MAT not given): correspondence between FLUKA
and low-energy neutron materials is by name; in case of
ambiguity the first material in the relevant list (see 10})
is chosen.
Notes:
Each material in the FLUKA low-energy neutron library (see 10})
is identified by an alphanumeric name (a string of <= 8 characters,
all in upper case), and by three integer numbers. Correspondence with
FLUKA materials (pre-defined or user-defined) is based on any
combination of name and zero or more identifiers. In case of
ambiguity, the first material in the list fulfilling the
combination is selected.
Option LOW-MAT should be avoided if it is not really necessary
(experience has shown that it is often misinterpreted by beginner
users). The option is NOT REQUIRED if the following 3 conditions
are all true:
1) the low-energy neutron material desired is unique or is
listed before any other material with the same name in
list 10}
and
2) that name is the same as one in the FLUKA list (see 5}) or as
given by a MATERIAL option
and
3) there is only one FLUKA material associated with that
low-energy neutron material
On the other hand, the option IS REQUIRED in any one of the
following cases:
1) there is more than one low-energy neutron material with
that name (this can happen because of data sets coming
from different sources, or corresponding to different
neutron temperatures, or concerning different isotopes, or
weighted on different spectra, etc), and the one desired
is not coming first in the list. In this case it is
sufficient to provide just as many identifiers as required
to remove ambiguity
or
2) The FLUKA name is different from the name of the
low-energy neutron material
or
3) There is more than one FLUKA material associated with the
given low-energy neutron material. This can happen for
instance when the same material is present with different
densities in different regions. In reality this is a
special case of 2) above, since to distinguish between the
different densities, different names must be used and one
at least will not be equal to the name of the
low-energy neutron material.
If WHAT(5) is set > 0.0 because a pre-mixed compound
low-energy neutron material is used, average cross sections
are used (as for instance in the MORSE code). Otherwise, if
each of the FLUKA elemental components has been associated
with one of the elemental low-energy neutron components
and the composition of the compound has been defined by a
COMPOUND option, low-energy neutron interactions will take
place randomly with each individual component, with the
appropriate probability.
It is however possible to have in the same run detailed
individual interactions at high energies and average
compound interactions for low-energy neutrons. But NOT
THE OTHER WAY AROUND!
See 15} for a complex example showing the use of
MATERIAL, COMPOUND and LOW-MAT.
Example (number based):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
MATERIAL 6. 12.011 2.000 6. 0.0 0. CARBON
MATERIAL 6. 12.011 1.700 15. 0.0 0. GRAPHITE
MATERIAL 6. 12.011 3.520 16. 0.0 0. DIAMOND
LOW-MAT 15.0 6. -3. 296. 0.0 0. CARBON
LOW-MAT 16.0 6. -2. 296. 0.0 0. CARBON
* We have three materials with the same atomic composition, but different
* density (amorphous carbon, graphite and diamond). Graphite is declared as
* having the cross section of Graphite bound natural Carbon, while diamond
* is declared as having the same low-energy neutron cross section as Free Gas
* Carbon.
The same example, name based:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
MATERIAL 6. 12.011 2.000 6. 0.0 0. CARBON
MATERIAL 6. 12.011 1.700 15. 0.0 0. GRAPHITE
MATERIAL 6. 12.011 3.520 16. 0.0 0. DIAMOND
LOW-MAT GRAPHITE 6. -3. 296. 0.0 0. CARBON
LOW-MAT DIAMOND 6. -2. 296. 0.0 0. CARBON
1********************************************************************************
{LOW-NEUT}
activates low-energy neutron transport
See also LOW-MAT, LOW-BIAS
WHAT(1) = number of neutron groups in the cross section set used.
The FLUKA standard neutron library has 260 groups (see 10}).
Default = 260
WHAT(2) = number of gamma groups
No default if WHAT(1) is given, 42 otherwise. (The standard
FLUKA neutron library has 42 gamma groups).
WHAT(3) = maximum energy of the low-energy cross section neutron library.
For the standard FLUKA neutron library, the maximum energy is
0.020 GeV.
Default = 0.020 GeV.
WHAT(4) = printing flag: from 0.0 to 3.0 increases the amount of
output about cross sections, kerma factors, etc.
1.0 : Standard output includes integral cross sections,
kerma factors and probabilities
2.0 : In addition, downscattering matrices and group
neutron-to-gamma transfer probabilities are printed
3.0 : In addition, scattering probabilities and angles are
printed
4.0 : In addition, information on residual nuclei is printed
Default: 0.0 (minimum output)
WHAT(5) = number of neutron groups to be considered thermal ones. (The
standard FLUKA neutron library has 31 thermal groups).
= 0, ignored
< 0: resets to the default = 1.0
Default = 31.0
WHAT(6) = i0 + 10 * i1:
i0 = 1: available pointwise cross sections used (see Note
below) and explicit and correlated 6-Li(n,gamma)7-Li,
10-B(n,t gamma)4-He, 40-Ar(n,gamma)41-Ar,
x-Xe(n,gamma)x+1-Xe and 113-Cd(n,gamma)114-Cd
photon cascade requested
= 0: ignored
=<-1: resets to the default (pointwise cross sections
are not used)
i1 = 1, fission neutron multiplicity forced to 1, with
proper weight
= 0, ignored
=<-1: resets to the default (normal fission multiplicity)
Default = -11., unless option DEFAULTS is present with
SDUM = CALORIMEtry, ICARUS, NEUTRONS or PRECISIOn,
in which case the default is 1.0 (pointwise cross sections
are used when available and fission multiplicity is not
forced)
SDUM: Not used
Default (option LOW-NEUT not given): if option DEFAULTS is used with
SDUM = CALORIMEtry, EET/TRANsmut, HADROTHErapy, ICARUS, NEUTRONS,
NEW-DEFAults, PRECISIOn or SHIELDINg, low-energy neutrons are
transported and a suitable cross section library must be
available.
In all other cases, low-energy neutrons are not transported, and
their energy is deposited as explained in the note below.
Notes: Evaporation option is mandatory by default or explicitly
(see EVENTYPE) if LOW-NEUT is requested (by default or
explicitly).
If low-energy neutrons are not transported (because of the chosen
DEFAULTS, or because a DEFAULTS card is absent), the energy
of neutrons below threshold (default or set by PART-THR)
is deposited on the spot.
This is true also for evaporation neutrons.
If there is no interest in low-energy neutron transport, but that
feature is implicit in the DEFAULTS option chosen, it is suggested
to use LOW-BIAS with a group cutoff WHAT(1) = 1.0.
Gamma data are used only for gamma generation and
not for transport (transport is done via the FLUKA
ElectroMagnetic module EMF using continuous cross sections).
The actual precise energy of a photon generated by (n,gamma)
or by inelastic reactions such as (n,n') is sampled randomly within
the gamma energy group concerned, except for a few important
reactions where a single monoenergetic photon is emitted. By
default, for the 1-H(n,gamma)2-H reaction the actual photon energy
of 2.226 MeV is used. It is possible to do the same with the
capture gammas in 6-Li, 10-B, 40-Ar, x-Xe and 113-Cd, by
setting WHAT(6) = 1.0 or 11.0.
Pointwise neutron transport is available, by setting
WHAT(6) = 1.0 or 11.0, for the following nuclides: 1-H (above
10 keV), 6-Li (all reactions), 10-B (only for the reaction
10-B(n,t gamma)4-He). Recoil protons are always transported
explicitly, and so is the proton from the 14-N(n,p) reaction,
for which a pointwise treatment is always applied
The groups are numbered in DECREASING energy order (see 10}
for a detailed description).
The energy limits of the thermal neutron groups in the standard
FLUKA neutron library neutron library are reported in 10.4.1.1}
Here are the settings for transport of low-energy neutrons
corresponding to available DEFAULTS options:
CALORIMEtry, ICARUS, NEUTRONS, PRECISIOn: low-energy neutrons
are transported, using pointwise cross section when available
EET/TRANsmut, HADROTHErapy, NEW-DEFAults, SHIELDINg: low-energy
neutrons are transported using always multigroup cross sections
Any other SDUM value, or DEFAULTS missing: no low-energy neutron
transport
Example:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
LOW-NEUT 260.0 42.0 0.020 2.0 31.0 11.0
* The low-energy neutron library used is the (260n, 42gamma) standard
* multigroup library. The user requests a printout of cross sections, kerma
* factors, probabilities, downscattering matrices and n-->gamma transfer
* probabilities. Pointwise cross sections will be used where available, and
* only one neutron per low-energy fission will be emitted, with an adjusted
* weight.
1********************************************************************************
{MATERIAL}
defines a single-element material or (coupled to a COMPOUND card) a
compound
See also COMPOUND, MAT-PROP, LOW-MAT
WHAT(1) = atomic number (meaningful only when NOT coupled to a
COMPOUND card; otherwise set = 0.)
No default.
WHAT(2) = atomic weight (meaningful only when NOT coupled to a
COMPOUND card; otherwise set = 0.)
Default: computed according to the natural composition
of an element with atomic number WHAT(1) if not coupled to a
COMPOUND card, no default otherwise.
WHAT(3) = density in g/cm**3. Note that if the density is lower than
0.01, the material is considered to be a gas at
atmospheric pressure unless set otherwise by MAT-PROP
No default.
WHAT(4) = number (index) of the material
Default = NMAT + 1 (NMAT is the current number of defined
materials. Its value is = 25 before any MATERIAL card is
given, and doesn't change if WHAT(4) overrides a number
which has already been assigned)
WHAT(5) >= 2.0: alternate material number (or name, in name-based input)
for ionisation processes (this material will be used instead
of WHAT(1) for dE/dx etc.)
0 =< WHAT(5) =< 2: ignored
< 0.0: reset to default
Default: no alternate material
WHAT(6) = mass number of the material: set = 0 unless a specific
individual isotope is desired. If not zero a nucleus of
the given mass number is used by the EVAP generator for
inelastic collisions, else the natural isotopic
composition of the WHAT(1) element is used. For isotopic
composition other than natural or single isotope, see
COMPOUND
SDUM = name of the material
Default: COPPER, FLUKA material 12
Default (option MATERIAL not given): standard pre-defined
material numbers are used (see list in 5}).
Notes: MATERIAL cards can be used in couple with COMPOUND cards
in order to define compounds, mixtures or isotopic
compositions. See COMPOUND for input instructions.
Material number 1 is always Black Hole (called also External Vacuum)
and it can not be redefined. (All particles vanish when
they reach the Black Hole, which has an infinite
absorption cross section)
Material number 2 is always Vacuum (of zero absorption
cross section) and it can not be redefined.
Although the material number can be omitted, it is not recommended
to do so if the input is number-based. On the contrary, it may be
convenient to omit it in name-based inputs, but only if the
material name has not already been used, explicitely (by another
MATERIAL card) or implicitely (predefined material, see list 5}). If
the number of the material has been omitted, it is recommended to use
only its name in COMPOUND and ASSIGNMAt commands.
In an explicitely number-based input (declared as such by
WHAT(4) = 4.0 in command GLOBAL) it is allowed to redefine a
material name overriding a number already assigned (either by
default, see list 5}, or by a previous MATERIAL card), or by using
a new number. But in a name-based input, whether defined as such
by default or explicitely (by WHAT(4) = 1.0 in command GLOBAL), a
material name can be redefined only by explicitly setting the
material number in WHAT(4) of the MATERIAL card, and that number
must be identical to that previously assigned.
If the number has not been assigned before, it must be the next
number available (26, 27... for successive MATERIAL cards).
In a number-based input, it is dangerous to leave empty gaps in the
number sequence, although the program takes care of redefining the
number: in fact, the incorrect number is likely to be still used in
other commands such as ASSIGNMAt and COMPOUND, leading to crashes or
to undetected errors.
If the input is name-based and the number is not given explicitely,
the program automatically assigns the next available number and
the number sequence is automatically respected. The assigned number
can be read from standard output, but the user only needs to refer
to that material by its name in other input cards.
Materials having a different density at the macroscopic and at
the microscopic level (e.g. spongy matter or approximations
for not entirely empty vacuum) need a special treatment
regarding stopping power (density effect). In such cases, see
MAT-PROP.
See 15} for examples of use of MATERIAL, COMPOUND and
LOW-MAT.
If low-energy neutron transport is desired, the material name
must coincide with that of one of the low-energy neutron
cross section materials in the Fluka library (see 10}), or a
correspondence must be set using option LOW-MAT.
Example:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
MATERIAL 1. 1.0079 8.988E-5 3. 0.0 1. HYDROGEN
LOW-MAT HYDROGEN 1. 11. 296. 0.0 0. HYDROGEN
MATERIAL 6. 12.011 2.265 6. 0.0 0. CARBON
MATERIAL 6. 12.011 2.0 26. 0.0 0. GRAPHITE
LOW-MAT CARBON 6. -3. 296. 0.0 0. GRAPHITE
MATERIAL 41. 92.9064 8.57 27. 0.0 0. NIOBIUM
MATERIAL 48. 112.411 8.650 28. 0.0 0. CADMIUM
MATERIAL 24. 51.996 7.19 29. 0.0 0. CHROMIUM
MATERIAL 27. 58.93320 8.90 30. 0.0 0. COBALT
* Several cases are illustrated:
* Hydrogen, pre-defined as material 3, is re-defined with the same number, but
* as monoisotopic 1-H. Command LOW-MAT has been added to force this material to
* be mapped to CH2-bound 1-H for what concerns low energy neutron transport.
* Carbon, pre-defined as material 6.0, is re-defined with a different density,
* and is also redefined with a different name (GRAPHITE), mapped to
* graphite-bound carbon, and is assigned a number corresponding to the first
* free slot (26.0).
* Niobium, Cadmium, Chromium and Cobalt are added to the list, and are assigned
* further consecutive numbers.
1********************************************************************************
{MAT-PROP}
Provides extra information about materials
See also MATERIAL, STERNHEIme
* can supply extra information about gaseous materials and
materials with fictitious or effective density.
* can be used to override the default average ionisation potential.
* allows a rough rescaling of thermal neutron cross sections
if the actual material temperature is different from the one of
the low energy neutron cross section data set.
* allows to set a flag to call the user routine USRMED every
time a particle is going to be transported in the selected
material(s)
For SDUM whatever except LOWNTEMP, USERDIRE:
WHAT(1) = Gas pressure in atmospheres.
0.0 : ignored
< 0.0 : resets to 1 atm a possible previously input
pressure value
WHAT(2) = RHOR factor : this factor multiplies the density of the
material(s) when calculating the density effect parameters
(e.g. if a reduced density is used to simulate voids, but
of course the density effect parameters must be computed
with the actual local physical density at the microscopic
level).
= 0.0 : ignored
< 0.0 : a possible previously input value is restored to
default = 1.0
Default = 1.0
WHAT(3) > 0: average ionisation potential to be used for dE/dx
calculations (eV)
< 0: a default value of the average ionisation potential
is obtained from the systematics of Ziegler [Zie77]
or Sternheimer, Berger and Seltzer [Ste84]
= 0: ignored
Default: ionisation potential calculated from systematics
WHAT(4) = lower bound of the indices of materials, or corresponding
name, in which gas pressure, RHOR factor or ionisation
potential are set
("From material WHAT(4)...")
Default = 3.0
WHAT(5) = upper bound of the indices of materials, or corresponding
name, in which gas pressure, RHOR factor or ionisation
potential are set
("... to material WHAT(5)...")
Default = WHAT(4)
WHAT(6) = step length in assigning indices
("...in steps of WHAT(6)")
Default = 1.
Default (option MAT-PROP not given): if the density of the default
material or that assigned by a MATERIAL card is > 0.01, the
material is not assumed to be a gas. Otherwise it is a gas
at a default pressure of 1 atmosphere. If the material is a
compound, the average ionisation potential is that resulting
from applying Bragg's rule of additivity to stopping power.
For SDUM = LOWNTEMP:
WHAT(1) = Temperature ratio (T_actual/T_xsec) with respect to the
nominal one. The nominal temperature T_xsec (given by
WHAT(3), see below) is the temperature for which the
neutron cross sections of the FLUKA material(s) concerned
have been prepared (see the Table in 10}). See Notes below
for more details and limitations.
= 0.0 : ignored
< 0.0 : a possible previously given value is restored to
default = 1.0
Default = 1.0
WHAT(2) = Number of (thermal) groups to which the temperature
ratio has to be applied. It must be <= N_th, where
N_th is the number of thermal groups in the cross section
library. If WHAT(2) < N_th, the last WHAT(2) groups are
affected (see the LOW-NEUT option for setting the number
of thermal groups).
= 0.0 : ignored
< 0.0 : a possible previously given value is restored to
default = 0.0
Default = 0.0 (i.e., no correction, the whole command is
ignored).
WHAT(3) = Nominal temperature (K) of the indicated FLUKA materials
= 0.0 : ignored
< 0.0 : a possible previously given value is restored to
default (3rd identifier, see below)
Default = the temperature given as 3rd identifier of the
associated low energy neutron data set (see
LOW-MAT and the cross section description in 10})
WHAT(4) = lower bound of the indices of materials, or corresponding
name, in which the temperature rescaling has to be applied
("From material WHAT(4)...")
Default = 3.0
WHAT(5) = upper bound of the indices of materials, or corresponding
name, in which the temperature rescaling has to be applied
("... to material WHAT(5)...")
Default = WHAT(4)
WHAT(6) = step length in assigning indices
("...in steps of WHAT(6)")
Default = 1.
For SDUM = USERDIREctive
WHAT(1) = 0.0 : ignored
> 0.0 : a call to the user routine USRMED will be performed
at run time every time a particle is going to be transported
in the selected materials (spot depositions ARE anyway performed)
< 0.0 : a possible previously given value is restored to
default = no call
Default = no call (-1.0)
WHAT(2) = Not used
WHAT(3) = Not used
WHAT(4) = lower bound of the indices of materials for which the
call to USRMED has to be performed
("From material WHAT(4)...")
Default = 3.0
WHAT(5) = upper bound of the indices of materials for which the
call to USRMED has to be performed
("... to material WHAT(5)...")
Default = WHAT(4)
WHAT(6) = step length in assigning indices
("...in steps of WHAT(6)")
Default = 1.
Default (option MAT-PROP not given): no extra information about the
assigned materials is supplied.
Notes:
SDUM = blank (i.e. /= LOWNTEMP, USERDIREctive):
When issuing a MATERIAL definition the gas pressure is set to
1 if the density RHO is < 0.01. If this value is not
acceptable to the user, a MAT-PROP card must be issued AFTER
the MATERIAL card to force a different value of the gas
pressure. Note that this is one of the rare cases (with GLOBAL,
DEFAULTS and PLOTGEOM) where sequential order of input cards is of
importance in FLUKA.
A non-zero value of WHAT(1) must be given only for gases: it
is important when calculating the density effect parameters
of the stopping power (see Note to option STERNHEIme).
If WHAT(1) is set to a value > 0.0, the transport of hadrons will
be calculated according to a density RHO defined at the actual pressure
by the corresponding MATERIAL card, while the density effect
correction to stopping power will be calculated using a density
RHO(NTP) = RHO/WHAT(1) and then re-scaled to the actual density.
When giving a WHAT(2) non-zero value, remember that if RHO (defined
by a MATERIAL card) indicates the "transport (effective) density",
the "physical density" used to calculate the density effect on
stopping power will be RHOR*RHO.
SDUM = LOWNTEMP:
The temperature ratio is used to rescale the thermal group
velocities, absorption probabilities, gamma generation
probabilities, fission probabilities and kermas. For absorption,
fission and gamma generation a 1/v dependence of the corresponding
cross sections is implicitly assumed: IF THIS IS NOT THE CASE THE
WHOLE PROCEDURE IS MEANINGLESS.
No modification is made to the elastic cross section and hence to the
downscattering matrix: THIS CAN BE A VERY BAD APPROXIMATION,
ESPECIALLY FOR LIGHT MATERIALS. No modification is applied for
possible Doppler broadening effects on resonances for thermal and
epithermal neutrons: again, this can be a bad approximation.
The total cross section is rescaled according to the modified
absorption and fission cross sections.
At present, temperature rescaling can be done only for the 72-group
neutron cross section library.
The temperature ratio is used to rescale the thermal group(s)
velocities, absorption probabilities, gamma generation prob-
abilities, fission probabilities and kermas. For absorption,
fission and gamma generation it is implicitly assumed a 1/v
dependence of the corresponding cross section(s): if this is
not the case all the procedure is crazy. No modification is
made to the elastic cross section and hence to the downscat-
tering matrix: this can be a very bad approximation, mostly
for light materials. No modification is applied for
possible Doppler broadening effects on resonances for thermal
and epithermal neutrons: again this can be a bad approxim-
ation. The total cross section is rescaled according to the
modified absorption and fission ones.
Cross section rescaling is applied to the FLUKA materials at
run time, that is if for example two 10-B materials are def-
ined and both point to the same cross section data set, a
possible temperature rescaling will affect only the FLUKA
material indicated by MAT-PROP, while the other one will be
unaffected, although they share the same low energy neutron
cross section data set.
Velocity setting is applied for compounds INDEPENDENT from
cross section rescaling, that is, a (nominal) temperature
input for a compound is fully meaningful and will be used for
velocity computation. However cross section rescaling is
applied on single constituents (of course!) and therefore...
!!!!! IMPORTANT WARNING !!!!
...it cannot be used for compounds unless the corresponding
neutron cross section data sets is a pre-mixed one. Other-
wise a new compound must be created with new elemental
constituents and the correction must be invoked for each
constituent.
SDUM = USERDIREctive:
User routine USRMED is typically used to implement albedo and
refraction, especially in connection with optical photon
transport as defined by OPT-PROP. See 13} for instructions.
Example 1 (number based):
* Call USRMED every time a particle is going to be transported in Pb Glass or
* in plexiglas (PMMA)
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
MATERIAL 1. 1.00794 8.3748E-5 3. 0.0 1. HYDROGEN
MATERIAL 6. 12.011 2.265 6. 0.0 0. CARBON
MATERIAL 8. 15.9994 0.001429 8. 0.0 0. OXYGEN
MATERIAL 14. 28.0855 2.33 14. 0.0 0. SILICON
MATERIAL 22. 47.88 4.54 11. 0.0 0. TITANIUM
MATERIAL 33. 74.9216 5.73 12. 0.0 0. ARSENIC
MATERIAL 82. 207.2 11.35 17. 0.0 0. LEAD
MATERIAL 0. 0. 6.22 18. 0.0 0. LEADGLAS
COMPOUND -0.156453 8. -0.080866 14. -0.008092 11. LEADGLAS
COMPOUND -0.002651 12. -0.751938 17. 0.0 0. LEADGLAS
MATERIAL 0. 0. 1.19 15. 0.0 0. PMMA
COMPOUND -0.080538 3. -0.599848 6. -0.319614 8. PMMA
MAT-PROP 1.0 0.0 0.0 15. 18. 3. USERDIRE
The same example, name based:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
MATERIAL 1. 1.00794 8.3748E-5 3. 0.0 1. HYDROGEN
MATERIAL 6. 12.011 2.265 6. 0.0 0. CARBON
MATERIAL 8. 15.9994 0.001429 8. 0.0 0. OXYGEN
MATERIAL 14. 28.0855 2.33 14. 0.0 0. SILICON
MATERIAL 22. 47.88 4.54 11. 0.0 0. TITANIUM
MATERIAL 33. 74.9216 5.73 12. 0.0 0. ARSENIC
MATERIAL 82. 207.2 11.35 17. 0.0 0. LEAD
MATERIAL 0. 0. 6.22 18. 0.0 0. LEADGLAS
COMPOUND -0.156453 OXYGEN -0.080866 SILICON -0.008092 TITANIUM LEADGLAS
COMPOUND -0.002651 ARSENIC -0.751938 LEAD 0.0 0. LEADGLAS
MATERIAL 0. 0. 1.19 15. 0.0 0. PMMA
COMPOUND -0.080538 HYDROGEN -0.599848 CARBON -0.319614 OXYGEN PMMA
MAT-PROP 1.0 0.0 0.0 PMMA LEADGLAS 3. USERDIRE
Example 2:
* Lung tissue with ICRP composition and Sternheimer parameters
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
MATERIAL 1. 1.00794 8.3748E-5 3. 0.0 1. HYDROGEN
MATERIAL 6. 12.011 2.265 6. 0.0 0. CARBON
MATERIAL 7. 14.00674 0.0011653 7. 0.0 0. NITROGEN
MATERIAL 8. 15.9994 0.001429 8. 0.0 0. OXYGEN
MATERIAL 12. 24.305 1.74 9. 0.0 0. MAGNESIU
MATERIAL 11. 22.98977 0.971 10. 0.0 0. SODIUM
MATERIAL 26. 55.847 7.874 11. 0.0 0. IRON
MATERIAL 16. 32.066 2.0 12. 0.0 0. SULFUR
MATERIAL 17. 35.4527 2.9947E-3 13 0.0 0. CHLORINE
MATERIAL 19. 39.0983 0.862 14. 0.0 0. POTASSIU
MATERIAL 15. 30.97376 2.2 16. 0.0 0. PHOSPHO
MATERIAL 30. 65.39 7.133 17. 0.0 0. ZINC
MATERIAL 20. 40.078 1.55 21. 0.0 0. CALCIUM
* Local density of lung is 1.05 g/cm3
MATERIAL 0.0 0.0 1.05 18. 0.0 0. LUNG
COMPOUND -0.101278 3. -0.10231 6. -0.02865 7. LUNG
COMPOUND -0.757072 8. -0.00184 10. -0.00073 9. LUNG
COMPOUND -0.0008 16. -0.00225 12. -0.00266 13. LUNG
COMPOUND -0.00194 14. -0.00009 21. -0.00037 11. LUNG
COMPOUND -0.00001 17. 0. 0. 0. 0. LUNG
* Average density of lung is 1.05*0.286 = 0.3 g/cm3. Average ionisation
* potential is 75.3 eV (At. Data Nucl. Data Tab. 30, 261 (1984))
MAT-PROP 0.0 0.286 75.3 18. 0. 0.
STERNHEI 3.4708 0.2261 2.8001 0.08588 3.5353 0. 18
The same example, name based:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
MATERIAL 1. 1.00794 8.3748E-5 3. 0.0 1. HYDROGEN
MATERIAL 6. 12.011 2.265 6. 0.0 0. CARBON
MATERIAL 7. 14.00674 0.0011653 7. 0.0 0. NITROGEN
MATERIAL 8. 15.9994 0.001429 8. 0.0 0. OXYGEN
MATERIAL 12. 24.305 1.74 9. 0.0 0. MAGNESIU
MATERIAL 11. 22.98977 0.971 10. 0.0 0. SODIUM
MATERIAL 26. 55.847 7.874 11. 0.0 0. IRON
MATERIAL 16. 32.066 2.0 12. 0.0 0. SULFUR
MATERIAL 17. 35.4527 2.9947E-3 13 0.0 0. CHLORINE
MATERIAL 19. 39.0983 0.862 14. 0.0 0. POTASSIU
MATERIAL 15. 30.97376 2.2 16. 0.0 0. PHOSPHO
MATERIAL 30. 65.39 7.133 17. 0.0 0. ZINC
MATERIAL 20. 40.078 1.55 21. 0.0 0. CALCIUM
MATERIAL 0.0 0.0 1.05 18. 0.0 0. LUNG
COMPOUND -0.101278 HYDROGEN -0.10231 CARBON -0.02865 NITROGEN LUNG
COMPOUND -0.757072 OXYGEN -0.00184 SODIUM -0.00073 MAGNESIU LUNG
COMPOUND -0.0008 PHOSPHO -0.00225 SULFUR -0.00266 CHLORINE LUNG
COMPOUND -0.00194 POTASSIU -0.00009 CALCIUM -0.00037 IRON LUNG
COMPOUND -0.00001 ZINC 0. 0. 0. 0. LUNG
MAT-PROP 0.0 0.286 75.3 LUNG 0. 0.
STERNHEI 3.4708 0.2261 2.8001 0.08588 3.5353 0. LUNG
Example 3 (number based):
* Definition of air at non-standard pressure.
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
MATERIAL 6. 12.011 2.265 6. 0.0 0. CARBON
MATERIAL 7. 14.00674 0.0011653 7. 0.0 0. NITROGEN
MATERIAL 8. 15.9994 0.001429 8. 0.0 0. OXYGEN
MATERIAL 18. 39.948 1.662E-3 20. 0.0 0. ARGON
* AIR defined as air with normal NTP density (0.001205)
MATERIAL 0.0 0.0 0.001205 10. 0.0 0. AIR
COMPOUND -0.000124 6. -0.755267 7. -0.231781 8. AIR
COMPOUND -0.012827 20. AIR
* AIR2 defined as air with a density 0.002410, double of that at NTP
MATERIAL 0.0 0.0 0.002410 11. 0.0 0. AIR2
COMPOUND -0.000124 6. -0.755267 7. -0.231781 8. AIR2
COMPOUND -0.012827 20. AIR2
* The pressure of AIR2 is 2 atm. Set also the ionisation potential = 85.7 eV
MAT-PROP 2.0 0.0 85.7 10.
STERNHEI 10.5961 1.7418 4.2759 0.10914 3.3994 0. 11
The same example, name based:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
MATERIAL 6. 12.011 2.265 6. 0.0 0. CARBON
MATERIAL 7. 14.00674 0.0011653 7. 0.0 0. NITROGEN
MATERIAL 8. 15.9994 0.001429 8. 0.0 0. OXYGEN
MATERIAL 18. 39.948 1.662E-3 20. 0.0 0. ARGON
MATERIAL 0.0 0.0 0.001205 10. 0.0 0. AIR
COMPOUND -0.000124 CARBON -0.755267 NITROGEN -0.231781 OXYGEN AIR
COMPOUND -0.012827 ARGON AIR
MATERIAL 0.0 0.0 0.002410 11. 0.0 0. AIR2
COMPOUND -0.000124 CARBON -0.755267 NITROGEN -0.231781 OXYGEN AIR2
COMPOUND -0.012827 ARGON AIR2
MAT-PROP 2.0 0.0 85.7 AIR
STERNHEI 10.5961 1.7418 4.2759 0.10914 3.3994 0. AIR2
Example 4 (name based):
* The total and capture cross sections of Au have a good 1/v dependence in the
* thermal region. Here we assume Gold to be at a temperature of 300K, while
* the cross sections in the 72-group ENEA library are at 293K.
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
LOW-NEUT 72.0 22.0 0.0196 0. 1.0 0.
MATERIAL 79.0 196.9665 19.32 15. 0.0 0.
* (300/293 = 1.02389). The ENEA library has only 1 thermal group.
MAT-PROP 1.02389 1.0 293. 15. 0.0 0. LOWNTEMP
The same example, name based:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
LOW-NEUT 72.0 22.0 0.0196 0. 1.0 0.
MATERIAL 79.0 196.9665 19.32 15. 0.0 0. GOLD
MAT-PROP 1.02389 1.0 293. GOLD 0.0 0. LOWNTEMP
1********************************************************************************
{MCSTHRES}h
Defines some of the accuracy requirements for Multiple Coulomb
Scattering (MCS) of heavy charged particles (hadrons and muons).
See also MULSOPT
WHAT(1) >= 0.0 : detailed multiple Coulomb scattering for primary
charged hadrons and muons down to the minimum energy
allowed by Moli\`ere's theory
< 0.0 : detailed multiple Coulomb scattering for primary
charged hadrons and muons down to a kinetic energy
equal to |WHAT(1)| (GeV)
Default = 1.0 if DEFAULTS is present with SDUM = CALORIMEtry,
HADROTHErapy, ICARUS or PRECISIOn.
If SDUM = EET/TRANsmut, the default is = -0.01 (transport
of primaries with multiple Coulomb scattering down to
10 MeV).
With any other SDUM value, or if DEFAULTS is missing, the
default is = -0.02 (transport of secondaries with multiple
Coulomb scattering down to 20 MeV).
WHAT(2) >= 0.0 : detailed multiple Coulomb scattering for secondary
charged hadrons and muons down to the minimum energy
allowed by Moli\`ere's theory
< 0.0 : detailed multiple Coulomb scattering for secondary
charged hadrons and muons down to a kinetic energy
equal to |WHAT(2)| (GeV)
Default = 1.0 if DEFAULTS is present with SDUM = CALORIMEtry,
HADROTHErapy, ICARUS or PRECISIOn.
If SDUM = EET/TRANsmut, NEW-DEFAults or SHIELDINg, the
default is = -0.02 (transport of secondaries with multiple
Coulomb scattering down to 20 MeV).
With any other SDUM value, or if DEFAULTS is missing, the
default is = -1.0 (transport of secondaries with multiple
Coulomb scattering down to 1 GeV).
WHAT(3), WHAT(4), WHAT(5), WHAT(6) : not used
SDUM : not used
Default (option MCSTHRES not given): the defaults depend on
option DEFAULTS as explained above.
Notes: The MCSTHRES option is not often used, since option DEFAULTS
ensures the MCS parameter setting most appropriate for a wide range
of problems. In most cases, it is suggested to have multiple
Coulomb scattering fully activated for both primary and secondary
particles over the whole energy range. This corresponds to using
WHAT(1) >= 0.0 and WHAT(2) >= 0.0 (or at least WHAT(2) < 0.0 with
an absolute value much smaller than beam energy).
WHAT(1) < 0.0 with |WHAT(1)| not much smaller than primary energy
should generally be avoided. The reason is twofold:
i) tracking accuracy would be spoiled for no substantial
gain in speed, and
ii) FLUKA tracking without MCS does not take into account
the variation of nuclear interaction cross section
with energy.
However, there are some cases where it can be useful to set
WHAT(1) and/or WHAT(2) to a negative number with absolute value
LARGER than beam energy. In this case no MCS is performed at all,
but tracking and maximum energy loss per step are controlled anyway
by the most sophisticated transport algorithm available (see
FLUKAFIX, STEPSIZE).
Complete suppression of multiple scattering can be useful in
some particular cases, for instance when replacing a gas of
extremely low density by a gas of the same composition but of
much larger density in order to increase the frequency of
inelastic interactions (of course, the results must then be
scaled by the density ratio). In such a case, one should also
select the biased density so that no re-interaction of
secondaries can take place. An alternative way to switch off
completely multiple Coulomb scattering of hadrons and muons
is to use MULSOPT with WHAT(2) >= 3.0 (MULSOPT, however, can
deal also with electrons and positrons, while MCSTHRES can't;
on the other hand, MULSOPT does not allow to distinguish between
primary and secondary particles).
In order to get the most accurate treatment of Multiple
Coulomb Scattering, a step optimisation and higher order
corrections can be requested by option MULSOPT (but with
an important increase in CPU time).
In pure electromagnetic or low-energy neutron problems,
MCSTHRES does not need to be given and has no effect.
Here are the MCS settings corresponding to available DEFAULTS
SDUM options:
CALORIMEtry, HADROTHErapy, ICARUS, PRECISIOn: Multiple scattering
threshold at minimum allowed energy both for primary and
secondary charged particles
EET/TRANsmutation: MCS threshold = 10 MeV for primaries and 20 MeV
for secondaries
NEW-DEFAults, SHIELDINg: 20 MeV threshold for both primaries and
secondaries
Any other SDUM value, or DEFAULTS missing: 20 MeV for primaries
and 1 GeV for secondaries
Example:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
BEAM 120.0 0.0 0.0 0.0 0.0 1.0 PION+
MCSTHRES 1.0 -0.01 0.0 0.0 0.0 0.0
* In this example, the primary beam consists of 120 GeV/c pi+
* mesons which are transported by simulating accurately multiple
* Coulomb scattering at all energies. For the secondary hadrons
* generated, MCS is performed instead only until they reach 10 MeV.
1********************************************************************************
{MGNFIELD}
sets the tracking conditions for transport in magnetic fields and
also may define an homogeneous magnetic field.
See also ASSIGNMA, STEPSIZE
WHAT(1) = largest angle in degrees that a charged particle is
allowed to travel in a single step
Default = 57 (but a maximum of 30 is recommended!)
WHAT(2) = upper limit to the error of the boundary iteration in cm.
(minimum accuracy accepted in determining a boundary
intersection). It also sets the minimum radius of curvature
for stepping according to WHAT(1)
Default = 0.05 cm
WHAT(3) = minimum step length if the step is forced to be smaller
because the angle is larger than WHAT(1).
Default = 0.1 cm
WHAT(4..6) = Bx, By, Bz components of magnetic field on the
coordinate axes (in tesla).
Default (Bx = By = Bz = 0.0): user-supplied subroutine
MAGFLD is assumed to provide the actual values (see note
below)
SDUM : not used
Default (option MGNFIELD not given): the defaults indicated for
WHAT(1-6) apply if a magnetic field exists in the current
region because of an ASSIGNMA command.
Note: If Bx = By = Bz = 0, the user-written subroutine MAGFLD is
called at each step to get the direction cosines and the
module (in tesla) of the magnetic field as a function of
region or of coordinates. A sample subroutine is provided
with the FLUKA code; instructions on how to write
user-supplied routines can be found in 13}.
Note that the argument list of subroutine MAGFLD is
( X, Y, Z, BTX, BTY, BTZ, B, NREG, IDISC )
where BTX, BTY, BTZ are the DIRECTION COSINES of the magnetic
field at point X, Y, Z (NOT the components of the field!
The field magnitude is given by B). For this reason, it
is imperative that MAGFLD returns normalised values of BTX,
BTY and BTZ such that the sum of their squares is = 1.0
IN DOUBLE PRECISION.
Three zero values are not accepted: if the field is zero
at the point in question, you must return for instance 0, 0, 1
and B = 0. On the contrary, note that Bx, By, Bz in the
MGNFIELD option, given by WHAT(4)...WHAT(6) as described
above, are the field components and not the cosines.
Magnetic field tracking is performed only in regions defined
as magnetic field regions by command ASSIGNMAt. It is
strongly recommended to define as such only regions where a
magnetic field effectively exists, due to the less efficient
and accurate tracking algorithm used in magnetic fields.
To define a region as having a magnetic field and to return
systematically B = 0 in that region via subroutine MAGFLD, is
not allowed.
The maximum error on the boundary iteration, WHAT(2), must be
compatible with the minimum linear dimension of any region.
It is recommended to activate also option STEPSIZE inside and
close to regions where a magnetic field is present. That option
can be used to set a minimum and a maximum step size (in cm)
for every region. (The max. step size is not yet implemented).
In case of conflict, WHAT(3) overrides the step size requested
by option STEPSIZE. Therefore, it is suggested to set it not
larger than the latter. The purpose of this constraint is to
avoid tracking in detail low-energy particles along a helix of
very small radius, by forcing several tours into a single step
(all the energy will be deposited at the same point).
Example (number based):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
ASSIGNMAT 2.0 15.0 30.0 5.0 1.0 0.0
* A magnetic field is present in vacuum regions 15, 20, 25 and 30.
MGNFIELD 20.0 0.2 0.10 0.0 0.0 0.0
STEPSIZE -0.05 0.0 20.0 25.0 0.0 0.0
STEPSIZE 0.3 0.0 15.0 0.0 0.0 0.0
* The maximum deviation angle due to magnetic field in any step is set
* = 20 degrees, and boundary crossings must be identified with an error
* not larger than 2 mm. If the max. angle constraint forces the step to
* be shorter than 10 cm, the step will be set = 10 cm in region 20, 25, 30,
* but will be set = 3 mm in region 15 (WHAT(1) of STEPSIZE overrides the
* general setting due to WHAT(3) of MGNFIELD). Whatever the size of the
* step, however, the accuracy of the boundary crossing position must be
* equal or better than 0.5 mm in regions 20 and 25 (probably contiguous,
* since the same accuracy must be set for regions on either side of a
* boundary). The value of the magnetic field will be provided at each
* step by the user routine MAGFLD.
The same example, name based:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
ASSIGNMAT VACUUM Reg15th Reg30th 5.0 1.0 0.0
MGNFIELD 20.0 0.2 0.10 0.0 0.0 0.0
STEPSIZE -0.05 0.0 Reg20th Reg20th 0.0 0.0
STEPSIZE 0.3 0.0 Reg15th 0.0 0.0 0.0
1********************************************************************************
{MULSOPT}
Sets the tracking conditions for multiple Coulomb scattering (MCS), for both
FLUKA and EMF particles. Can also be used to activate single scattering.
See also EMFFIX, FLUKAFIX, MCSTHRES, STEPSIZE
For SDUM = anything except GLOBAL/GLOBEMF/GLOBHAD:
WHAT(1) : controls the step optimisation for multiple Coulomb scattering,
and the number of (possible) single scatterings on a material
by material basis
<= -1.0 : a possible previous request of optimisation is cancelled
and the number of single scatterings in the materials
indicated by WHAT(4)-WHAT(6) is reset to the default value
(i.e. 0, or the global default possibly set previously by
this option with SDUM = GLOBAL/GLOBHAD/GLOBEMF)
= 0.0 : ignored
= I0 + I1*10 + I2*100000
(with 0=< I0 =<1, 0=< I1 <10000, 0 =< I2 < 10000):
I0 >= 1 : the optimisation is activated
I1 - 1 = number of single scattering steps for hadrons and muons
in the materials indicated by WHAT(4)-WHAT(6)
I1 = 0 : ignored
I2 - 1 = number of single scattering steps for electrons and
positrons in the materials indicated by WHAT(4)-WHAT(6)
I2 = 0 : ignored
Default: -1.0 (no multiple scattering optimisation and no single
scattering)
WHAT(2) :
|WHAT(2)| = 1.0: spin-relativistic corrections are activated for
hadrons and muons at the 1st Born approximation
level
|WHAT(2)| = 2.0: spin-relativistic corrections are activated for
hadrons and muons at the 2nd Born approximation
level
WHAT(2) < 0.0: nuclear finite size effects are activated.
= -3.0: nuclear finite size effects (form factors) are
considered but not the spin-relativistic effects
WHAT(2) >= 3.0: multiple scattering for hadrons and muons is
completely suppressed
Default: 0.0 (no corrections)
WHAT(3) :
|WHAT(3)| = 1.0: spin-relativistic corrections are activated for
e+ and e- at the 1st Born approximation level
|WHAT(3)| = 2.0: spin-relativistic corrections are activated for
e+ and e- at the 2nd Born approximation level
WHAT(3) < 0.0: nuclear finite size effects are activated
WHAT(3) >= 3.0: multiple scattering for e+ and e- is completely
suppressed
Default: 0.0 (no corrections)
WHAT(4) = lower bound of the indices of the materials, or corresponding
name, in which the corrections are activated
("From material WHAT(4)...")
Default = 3.0
WHAT(5) = upper bound of the indices of the materials, or corresponding
name, in which the corrections are activated
("... to material WHAT(5)...")
Default = WHAT(4)
WHAT(6) = step length in assigning indices
("...in steps of WHAT(6)")
Default: 1.0
SDUM = FANO-ON : Fano correction for inelastic interactions
on atomic electrons switched on (for the moment
only for charged hadrons and muons)
FANO-OFF: Fano correction for inelastic interactions on
atomic electrons is switched off
MLSH-ON : Moliere screening angle on for hadrons and muons
MLSH-OFF: Moliere screening angle for hadrons and muons as
modified by Berger & Seltzer for electrons
Default: Fano correction on, original Moliere screening
angle for hadrons on
Default (option MULSOPT not given): no MCS optimisation
For SDUM=GLOBAL/GLOBEMF/GLOBHAD: (GLOBEMF restricts
the input value use to the EM part, GLOBHAD to the hadron and muon
part)
WHAT(1) : controls the minimum MCS step size used by the boundary approach
algorithm for electron/positrons and charged heavy
particles (in the multiple scattering routine)
0.2 > WHAT(1) >= 0.0 : ignored
WHAT(1) >= 0.2 : the minimum step size is set equal to the size
corresponding to B=5 in Moliere theory,
multiplied by WHAT(1)
< 0.0 : the minimum step is reset to default
Default: WHAT(1) = 1 (maximum accuracy)
WHAT(2) : index of step stretching factor tabulation to be used
by the electron/positron transport algorithm when
approaching a boundary.
The values of the index implemented for the moment are 1,2,3,4.
Values 11,12,13,14 cause the sensing algorithm to multiply
the range/mcs step rather than the current step.
Values 101,111,102,112,103,113,104,114 have the additional
effect of making the algorithm resample as unphysical any
step cut at a boundary and "reflected" from the boundary.
= 0.0 : ignored
< 0.0 : the tabulation index is reset to default
Default: WHAT(2) = 1 (maximum accuracy)
WHAT(3) : controls the optimal step to be used by the optimisation
option (and to some extent by the hadron/muon boundary approach
algorithm).
0.2 > WHAT(3) >= 0.0 : ignored
WHAT(3) >= 0.2 : the minimum step size is set equal to the size corresponding
to B = 5 in Moli\`ere theory [Mol47,Mol48,Mol55,Bet53],
multiplied by WHAT(3)
< 0.0 : the minimum step is reset to its default value
Default: minimum step equal to that corresponding to B=5,
multiplied by 20
WHAT(4) > 0: single scattering option activated at boundaries or
for too short steps
< 0: resets to default
= 0: ignored
Default: single scattering not activated
WHAT(5): (meaningful only if single scattering is activated at
boundaries and when step is too short: see WHAT(4) above)
> 0: single scattering option activated for energies too small
for Moli\`ere theory to apply
< 0: not activated
= 0: ignored
Default: not activated
WHAT(6): (meaningful only if single scattering is activated at
boundaries and when step is too short: see WHAT(4) above)
> 0: number of single scatterings to be performed when
crossing a boundary
= 0: ignored
< 0: resets the default
Default: 1
Note: When optimisation is requested, the program always makes the
minimum step for which the Moli\`ere theory of multiple
scattering is applicable. Optimisation via MULSOPT is
available only for charged hadrons and muons. For
electrons and positrons, option EMFFIX is recommended.
The correction for the nuclear finite size has been
implemented using simple Thomas-Fermi form factors
according to Tsai [Tsa74]. The user can provide more
sophisticated values by supplying a function FORMFU
which must return the square of the nuclear form factor.
(See details in 13}).
Complete suppression of multiple scattering can be useful in
some particular cases, for instance when replacing a gas of
extremely low density by a gas of the same composition but of
much larger density in order to increase the frequency of
inelastic interactions or bremsstrahlung reactions (of course,
the results must then be scaled by the density ratio). In such
a case, one should also select the biased density so that
no re-interaction of secondaries can take place.
Runs for which the nuclear form factor is taken into account
and/or the 2nd Born approximation is requested are very
CPU-time consuming at low energy (but not at high energy).
Setting WHAT(6) > 1000.0 with SDUM = GLOBAL, GLOBHAD or GLOBEMF,
replaces systematically multiple scattering with single scattering
everywhere. This choice is generally extremely demanding in CPU
time, except for particles of very low energy (a few keV), which
have a very short history anyway. In such cases, the single
scattering option is even recommended ([Fas01]).
Example 1 (number based):
* Activate spin-relativistic corrections and nuclear finite size effects
* for heavy charged particles in the first Born approximation.
* Activate spin-relativistic corrections but not nuclear size effects
* for electrons and positrons in materials 5, 10 and 15
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
MULSOPT 1.0 -1.0 2.0 5.0 15.0 5.0
The same example, name based:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
MULSOPT 1.0 -1.0 2.0 BERYLLIU GOLD 5.0
Example 2:
* Maximum accuracy requested for the electron step size used in the boundary
* approach and in the optimisation algorithm. Single scattering activated for
* electrons at boundary crossing and when the step is too short for Moliere
* (but not when the energy is too low for Moliere). Boundaries will be
* crossed with 2 single scatterings.
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
MULSOPT 1.0 1.0 1.0 1.0 0.0 2. GLOBEMF
Example 3:
* Single scattering activated everywhere for all charged particles
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
MULSOPT 0.0 0.0 0.0 1.0 1.0 99999999.GLOBAL
1********************************************************************************
{MUPHOTON}
controls muon photonuclear interactions
See also PAIRBREM, PHOTONUC
WHAT(1) : flag to switch on muon nuclear interactions:
= -1.0 : resets to default (muon nuclear interactions are not
simulated)
= 0.0 : ignored
= 1.0 : full simulation of muon nuclear interactions and
production of secondary hadrons
= 2.0 : muon nuclear interactions are simulated but no
secondary hadron is produced; the energy lost by the
muon is deposited at the point of interaction
Default = 0.0 (ignored)
WHAT(2) = ratio of longitudinal to transverse virtual photon
cross section
Warning: for code development only, do not change!
If changed the new value is applied to ALL materials.
Default = 0.25.
WHAT(3) = fraction of rho-like interactions ( must be < 1).
Warning: for code development only, do not change!
If changed the new value is applied to ALL materials.
Default = 0.75.
WHAT(4) = lower bound of the indices of the materials, or corresponding
name, in which muon nuclear interactions must be simulated
("From material WHAT(4)...").
Default = 3.0.
WHAT(5) = upper bound of the indices of the materials, or corresponding
name, in which muon nuclear interactions must be simulated
("...to material WHAT(5)...")
Default = WHAT(4)
WHAT(6) = step length in assigning indices. ("...in steps of
WHAT(6)").
Default = 1.0
SDUM : not used
Default (option MUPHOTON not given): muon nuclear interactions
are not simulated
Notes: Other high-energy interactions of muons with nuclei (pair
production, bremsstrahlung) are controlled by option
PAIRBREM, which applies also to charged hadrons.
Use of WHAT(1) = 2.0 (interaction without transport of the
secondaries) gives the correct muon straggling but
simulates only in an approximate way the energy deposition
distribution. A similar approach is found in A. Van
Ginneken's codes CASIM and MUSIM [Van75,Van86].
Example (number based):
* Explicit pair production and bremsstrahlung requested for heavy charged
* particles in materials 12 and 13, provided the energy of the secondary
* electrons and positrons is > 500 keV. No threshold is requested for photon
* production. For muons, explicit nuclear interactions are also requested.
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
PAIRBREM 3.0 0.0 0.0005 12.0 13.0
MUPHOTON 1.0 0.0 0.0 12.0 13.0
The same example, name based:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
PAIRBREM 3.0 0.0 0.0005 COPPER SILVER
MUPHOTON 1.0 0.0 0.0 COPPER SILVER
1********************************************************************************
{MYRQMD}
Not yet implemented. prepared for new QMD generator
1********************************************************************************
{OPEN}
defines input/output files to be connected at run-time
WHAT(1) > 0. : logical unit number of a FORMATTED file to be opened
< 0. : logical unit number of an UNFORMATTED file to be
opened
Default : no default (WHAT(1) must not be = 0.)
WHAT(2-6) : not used
SDUM = NEW : the file is opened with status 'NEW'
= OLD : the file is opened with status 'OLD'
= UNKNOWN : the file is opened with status 'UNKNOWN'
= READONLY : the file is opened with status 'OLD' and (only
on VAX VMS/OpenVMS) in mode 'READONLY'
= SCRATCH : the file is opened with status 'SCRATCH'
Default: SDUM = OLD if |WHAT(1)| = 9, 12, 13, 14
= NEW otherwise
If SDUM is not = SCRATCH, the name of the file to be opened must be
given in the card which immediately follows.
Default (option OPEN not given): no file is opened at run time. In
this case the I/O files must be pre-connected via ASSIGN on
VAX VMS/OpenVMS (see 3}). On UNIX and Linux, the rfluka
script provided with the FLUKA code creates the necessary
symbolic links. On some UNIX systems (e.g. HPUX-9),
OPEN MUST be given in any case for the data files.
Note: The input/output files used by FLUKA are of several kinds.
- Standard input (logical unit 5) and standard output (logical
unit 11) must be redirected via < and > (on UNIX and Linux), or
pre-connected via FILEDEF, ASSIGN, etc. on other systems.
- cross section unformatted data files (logical unit numbers 9, 13
and 14) can be opened with the OPEN option (SDUM = OLD or
READONLY), or can be pre-connected (on most UNIX systems,
preconnection is obtained by means of symbolic links).
If OPEN is used, the full file name must be given in the card
which follows.
- Scratch files (unit 8 for EMF auxiliary output and unit 16
for Combinatorial Geometry working space) can also be OPENed
(with SDUM = SCRATCH) or pre-connected (not on UNIX).
No file name card must be given for scratch files.
- The "next seeds" file from the random number generator (logical unit
number 2) can be opened by any of the three ways described
above (i.e. by OPEN, by pre-connection or automatically) on any of
the supported systems.
- Error message file (logical unit number 15) and estimator output
files (created by scoring options such as USRBIN, USRBDX, DETECT
etc.):
. On UNIX systems, they can either be opened by the user
(with option OPEN, SDUM = NEW or UNKNOWN and file name given
on the next card) or automatically by the program with a
default name of the form fort.xxx or ftn.xxx, where xxx is the
logical unit number.
. On VAX VMS/OpenVMS, all the three possibilities are available:
pre-connection, OPEN option and automatic opening with a
default name of the form FORxxx.DAT.
- Files created by user-written code: all the three possibilities
are available. Of course, a Fortran statement OPEN can also be
used in this case.
It is possible to pre-connect some of the files and to OPEN
others.
Examples:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
* opening the file with the random number seeds for the next run
OPEN 2. NEW
newseed.random
* the neutron cross section file
OPEN -9. READONLY
neuxsc_72.bin
* the working space for Combinatorial Geometry
OPEN 16. SCRATCH
1********************************************************************************
{OPT-PROD}
requests and controls production of Cherenkov, Transition and Scintillation
Radiation in specified materials
See also OPT-PROP, Chap. 12}.
For SDUM = CERE-OFF: switches off Cherenkov production
WHAT(1-3): not used
WHAT(4-6): assignment to materials, see below
SDUM = CERE-OFF
For SDUM = TRD-OFF: switches off Transition Radiation production
WHAT(1-3): not used
WHAT(4-6): assignment to materials, see below
SDUM = TRD-OFF
For SDUM = SCIN-OFF: switches off Scintillation light production
WHAT(1-3): not used
WHAT(4-6): assignment to materials, see below
SDUM = SCIN-OFF
For SDUM = CERENKOV: switches on Cherenkov production and defines photon
energy range
WHAT(1) = minimum Cherenkov photon emission energy in GeV
Default: 2.07E-9 GeV (2.07 eV, corresponding to 600 nm)
WHAT(2) = maximum Cherenkov photon emission energy in GeV
Default: 4.96E-9 GeV (4.96 eV, corresponding to 250 nm)
WHAT(3) : not used
WHAT(4-6): assignment to materials, see below
SDUM = CERENKOV
For SDUM = CEREN-WV: switches on Cherenkov production and defines photon
wavelength range
WHAT(1) = minimum Cherenkov photon emission wavelength in cm
Default: 2.50E-5 cm (250 nm, or 1.2E6 GHz)
WHAT(2) = maximum Cherenkov photon emission wavelength in cm
Default: 6.00E-5 cm (600 nm, or 5.E5 GHz)
WHAT(3) : not used
WHAT(4-6): assignment to materials, see below
SDUM = CEREN-WV
For SDUM = CEREN-OM: switches on Cherenkov production and defines photon
angular frequency range
WHAT(1) = minimum Cherenkov photon angular frequency omega
= 2 x pi x frequency (in rad/s)
Default: 3.14E15 rad/s (corresponding to 600 nm)
WHAT(2) = maximum Cherenkov photon angular frequency omega
= 2 x pi x frequency (in rad/s)
Default: 7.53E15 rad/s (corresponding to 250 nm)
WHAT(3) : not used
WHAT(4-6): assignment to materials, see below
SDUM = CEREN-OM
For SDUM = TR-RADIA: switches on Transition Radiation production and
defines its energy range
WHAT(1) = minimum TRD photon emission energy
WHAT(2) = maximum TRD photon emission energy
WHAT(3) : not used
WHAT(4-6): assignment to materials, see below
SDUM = TR-RADIA
For SDUM = SCINTILL: switches on Scintillation Light production and
defines photon energy
WHAT(1) = i-th scintillation photon emission energy in GeV (i_max =3,
see Note 4)
WHAT(2) > 0: fraction of deposited energy going into i-th scintillation
photon emission
=< -100: forces to use a user routine (NOT YET IMPLEMENTED)
>= -99.0 and =< 0.0: ignored
WHAT(3) : time constant of scintillation light in seconds
WHAT(4-6): assignment to materials, see below
SDUM = SCINTILL
For SDUM = SCINT-WV: switches on Scintillation Light production and
defines photon wavelength
WHAT(1) = i-th scintillation photon emission wavelength in cm (i_max =3,
see Note 4)
Default: 2.50E-5 cm (250 nm, or 1.2E6 GHz)
WHAT(2) > 0: fraction of deposited energy going into i-th scintillation
photon emission
=< -100: forces to use a user routine (NOT YET IMPLEMENTED)
>= -99.0 and =< 0.0: ignored
WHAT(3) : time constant of scintillation light in seconds
WHAT(4-6): assignment to materials, see below
SDUM = SCINT-WV
For SDUM = SCINT-OM: switches on Scintillation Light production and
defines photon angular frequency range
WHAT(1) = i-th scintillation photon emission angular frequency omega =
2 x pi x frequency (in rad/s), (i_max =3, see Note 4)
Default: 3.14E15 rad/s (corresponding to 600 nm)
WHAT(2) > 0: fraction of deposited energy going into i-th scintillation
photon emission
=< -100: forces to use a user routine (NOT YET IMPLEMENTED)
>= -99.0 and =< 0.0: ignored
WHAT(3) : time constant of scintillation light in seconds
WHAT(4-6): assignment to materials, see below
SDUM = SCINT-OM
For all previous SDUM's:
WHAT(4) = lower bound of the indices of materials in which the indicated
Cherenkov, Scintillation or TRD photon emission range is defined
From material WHAT(4)...
Default = 3
WHAT(5) = upper bound of the indices of materials in which the indicated
Cherenkov or TRD photon emission range is defined
...To material WHAT(5)...
Default = WHAT(4)
WHAT(6) = step length in assigning indices
...in step of WHAT(6)
Default = 1
Default: (option OPT-PROD not given): no Cherenkov, scintillation or TRD
photon production
Notes: 1) Optical photons such as those produced by Cherenkov effect
are distinguished by their FLUKA name (OPTIPHOT) and by
their FLUKA id number (-1), as shown in 5}.
2) To transport optical photons, it is necessary to define
the optical properties of the relevant materials by
means of option OPT-PROP. Users can also write their own
routines USRMED (which is called at every step and at
boundary crossings when activated with MAT-PROP) and FRGHNS
(which defines surface roughness).
3) The energy/wavelength/frequency range as defined
by OPT-PROD for Cherenkov photon production is not
necessarily the same as that defined for transport by means
of OPT-PROP. The default values, however, are the same.
4) In case of scintillation light, only monochromatic photons are
considered for the moment, with a maximum of 3 different lines. The
lines can be defined repeating i times the OPT-PROD card with
SDUM = SCINTILL
Example:
* Request production of Cherenkov photons with energies between 2 and 3 eV in
* materials 16, 17, 19 and 20, with wavelengths between 300 and 600 nm in
* materials 18, 20 and 22, and with frequencies between 0.5 and 1 million GHz
* in material 21
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
OPT-PROD 2.E-9 3.E-9 0.0 16.0 17.0 0. CERENKOV
OPT-PROD 2.E-9 3.E-9 0.0 19.0 20.0 0. CERENKOV
OPT-PROD 3.E-5 6.E-5 0.0 18.0 22.0 2. CEREN-WV
OPT-PROD 3.14E15 6.28E15 0.0 21.0 0.0 0. CEREN-OM
* Optical photon transport requested between 300 and 500 nm for all materials
* with number between 16 and 21
OPT-PROP 3.E-5 5.E-5 6.E-5 16.0 22.0 0. WV-LIMIT
* User routine USRMED called when an optical photon is going to be transported
* in materials 17 and 21
MAT-PROP 1.0 0.0 0.0 17. 21. 4. USERDIRE
1********************************************************************************
{OPT-PROP}
defines optical properties of specified materials
See also OPT-PROD, Chap. 12}.
For SDUM = WV-LIMIT: defines wavelength range for optical photon transport
WHAT(1) > 0.0: minimum wavelength (in cm) for optical photon transport
= 0.0: ignored
< 0.0: resets to default
Default: 2.50E-5 (250 nm)
WHAT(2) > 0.0: central wavelength (in cm) for optical photon transport
= 0.0: ignored
< 0.0: resets to default
Default: 5.89E-5 ((589 nm, Na D line)
WHAT(3) > 0.0: maximum wavelength (in cm) for optical photon transport
= 0.0: ignored
< 0.0: resets to default
Default: 6.00E-5 (600 nm)
WHAT(4-6): assignment to materials, see below
SDUM = WV-LIMIT
For SDUM = OM-LIMIT: defines angular frequency range for optical photon transport
WHAT(1) > 0.0: minimum angular frequency for optical photon transport
omega = 2pi x frequency (in rad/s)
= 0.0: ignored
< 0.0: resets to default
Default: 3.14E15 rad/s (corresponding to 600 nm)
WHAT(2) > 0.0: central angular frequency for optical photon transport
omega = 2pi x frequency (in rad/s)
= 0.0: ignored
< 0.0: resets to default
Default: 3.20E15 rad/s (corresponding to 589 nm, Na D line)
WHAT(3) > 0.0: maximum angular frequency for optical photon transport
omega = 2pi x frequency (in rad/s)
= 0.0: ignored
< 0.0: resets to default
Default: 7.53E15 rad/s (corresponding to 250 nm)
WHAT(4-6): assignment to materials, see below
SDUM = OM-LIMIT
For SDUM = RESET: all optical properties are zeroed
WHAT(1-3) = no meaning
WHAT(4-6): assignment to materials, see below
SDUM = RESET
For SDUM = METAL: flag the material as a metal
WHAT(1) = 1st optical property (not used at the moment)
WHAT(2) = 2nd optical property (not used at the moment)
WHAT(3) = 3rd optical property: (1-r), where r is the reflectivity
index at the central wavelength (or at the central angular
frequency, depending on which one of the two quantities has been
defined). See also Note 2
Default = 0.0
WHAT(4-6): assignment to materials, see below
SDUM = METAL
For SDUM = blank:
WHAT(1) = 1st optical property: refraction index at the central
wavelength (or at the central angular frequency, depending
on which one of the two quantities has been defined)
< -99: forces to use user routine RFRNDX (see Note 1)
Default = 1.0
WHAT(2) = 2nd optical property: absorption coefficient (cm^-1) at
the central wavelength (or at the central angular
frequency, depending on which one of the two quantities has
been defined)
< -99: forces to use user routine ABSCFF (see Note 1)
Default = 0.0
WHAT(3) = 3rd optical property: diffusion coefficient (cm^-1) at
the central wavelength (or at the central angular
frequency, depending on which one of the two quantities has
been defined)
< -99: forces to use user routine DFFCFF (see Note 1)
Default = 0.0
WHAT(4-6): assignment to materials, see below
SDUM = blank
For SDUM containing &1 (resp. &2) (resp. &3):
WHAT(1) = 4th (resp. 7th) (resp. 10th) optical property of the material
(derivatives of the refraction index, see Note 2 below)
Default = 0.0
WHAT(2) = 5th (resp. 8th) (resp. 11th) optical property of the material
(derivatives of the absorption coefficient, see Note 2 below)
Default = 0.0
WHAT(3) = 6th (resp. 9th) (resp. 12th) optical property of the material
(derivatives of the diffusion coefficient, see Note 2 below)
Default = 0.0
WHAT(4-6): assignment to materials, see below
SDUM = &1, &2 or &3
For all previous SDUM's:
WHAT(4) = lower bound of the indices of materials to which the indicated
optical properties refer
From material WHAT(4)...
Default = 3
WHAT(5) = upper bound of the indices of materials to which the indicated
optical properties refer
...To material WHAT(5)...
Default = WHAT(4)
WHAT(6) = ... in step of WHAT(6)
Default = 1
For SDUM = SENSITIV: sets up the optical photon detection sensitivity parameters
(See also SDUM = WV-SENSI, SDUM = OM-SENSI, Note 3 below and the examples in
Chap. 12})
WHAT(1) = 0th photon sensitivity parameter
< -99: forces to use user routine QUEFFC (see Note 1)
WHAT(2) = 1st optical property (not used at the moment)
WHAT(3) = 2nd optical property (not used at the moment)
WHAT(4) = 3rd optical property: (1-r), where r is the reflectivity
index at the central wavelength (or at the central angular
frequency, depending on which one of the two quantities has been
defined). See also Note 2
Default = 0.0
WHAT(5) = maximum optical photon sensitivity over the allowed range (must be
consistent with the previous values). It can be overestimated.
Default = 1.0
WHAT(6) : not used
SDUM = SENSITIV
For SDUM = WV-SENSI: setup the wavelength of the optical photon sensitivity
(See also SDUM = SENSITIV, SDUM = OM-SENSI and Note 3 below)
WHAT(1) > 0.0: minimum wavelength (in cm) for optical photon sensitivity
= 0.0: ignored
< 0.0: resets to default
Default = 2.5 x 1.0E-5 (250 nm)
WHAT(2) > 0.0: central wavelength (in cm) for optical photon sensitivity
= 0.0: ignored
< 0.0: resets to default
Default = 5.89 x 1.0E-5 (589 nm, Na D line)
WHAT(3) > 0.0: maximum wavelength (in cm) for optical photon sensitivity
= 0.0: ignored
< 0.0: resets to default
Default = 6.0 x 1.0E-5 (600 nm)
WHAT(4)-WHAT(6): not used
SDUM = WV-SENSI
For SDUM = OM-SENSI: setup the angular frequency of the optical photon sensitivity
(See also SDUM = SENSITIV, SDUM = WV-SENSI and Note 3 below)
WHAT(1) > 0.0: minimum angular frequency for optical photon sensitivity
omega = 2 pi x frequency in rad/s
= 0.0: ignored
< 0.0: resets to default
Default = 3.14E15 rad/s (corresponding to 600 nm)
WHAT(2) > 0.0: central angular frequency for optical photon sensitivity
omega = 2 pi x frequency in rad/s
= 0.0: ignored
< 0.0: resets to default
Default = 3.20E15 rad/s (corresponding to 589 nm, Na D line)
WHAT(3) > 0.0: maximum angular frequency for optical photon sensitivity
omega = 2 pi x frequency in rad/s
Default = 7.53E15 rad/s (corresponding to 250 nm)
WHAT(4)-WHAT(6): not used
SDUM = OM-SENSI
For SDUM = SPEC-BDX: flags special boundary crossings for optical photons
At the selected boundary crossings special user defined properties
are defined by means of the user routine OPHBDX (see Note 1 below).
A maximum of 40 boundaries can be flagged by issuing option OPT-PROP with
SDUM = SPEC-BDX as many times as needed.
WHAT(1) >= 1.0: special boundary treatment activated for the n-th+1 boundary
= 0.0: ignored
=< -1.0: special boundary treatment deactivated for the n-th+1 boundary
WHAT(2) = One of the two regions defining the n-th+1 boundary
WHAT(3) = The other region defining the n-th+1 boundary
WHAT(4) >= 1.0: special boundary treatment activated for the n-th+2 boundary
= 0.0: ignored
=< -1.0: special boundary treatment deactivated for the n-th+2 boundary
WHAT(5) = One of the two regions defining the n-th+2 boundary
WHAT(6) = The other region defining the n-th+2 boundary
SDUM = SPEC-BDX
Default (option OPT-PROP not given): no optical photon transport
Note:
1) The optional user routines concerning optical photons are:
i) RFRNDX: to specify a refraction index as a function of wavelength,
frequency or energy. Activated by setting WHAT(1) < -99 when
SDUM = blank.
ii) ABSCFF: to specify an absorption coefficient as a function of wavelength,
frequency or energy. This is activated by setting WHAT(2) < -99 when
SDUM = blank.
iii) DFFCFF: to specify a diffusion coefficient as a function of wavelength,
frequency or energy. Activated by setting WHAT(3) < -99 when
SDUM = blank.
iv) RFLCTV: to specify the reflectivity of a material.
This can be activated with SDUM = METAL and WHAT(3) < -99
v) OPHBDX: to set optical properties of a boundary surface. The call is
activated with SDUM = SPEC-BDX
vi) FRGHNS: to set a possible degree of surface roughness, in order to have
both diffusive and specular reflectivity from a given material surface
(NOT YET IMPLEMENTED)
vii) QUEFFC: to introduce Quantum efficiency. This is activated by setting
the 0-th photon sensitivity parameter to a value < -99 with
SDUM = SENSITIV .
2) The 9 material properties input by the user with SDUM = &1, &2 and &3
are derivatives of order 1 to 3 of the three basic quantities which are
input with SDUM = blank or SDUM = METAL. The three basic quantities and
their derivatives are used to perform three series expansions centreed
on the selected central wavelength (if SDUM = WV-LIMIT has been used
for the material concerned) or on the selected central angular frequency
(if SDUM = OM-LIMIT has been used). The variable x used in the expansion
is adimensional:
x = ( lambda - lambda_central ) / lambda_central or
x = ( omega - omega_central ) / omega_central
The three basic quantities are:
If SDUM = blank: 1) refraction index n_refr
2) absorption coefficient mu_abs
3) diffusion coefficient mu_diff
If SDUM = METAL: 1) (not implemented yet)
2) (not implemented yet),
3) (1-r) (r = reflectivity index)
The 4th, 5th, 6th material properties are:
d n_refr/ dx, d mu_abs/dx, d mu_diff/dx
the 7th, 8th, 9th material properties are:
d2 n_refr/ dx^2