FLUKA: USRTRACK
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USRTRACK
defines a detector for a track-length fluence estimator
See also USRBDX, USRBIN, USRCOLL
The full definition of the detector may require two successive cards
(the second card, identified by the character '&' in any column > 70,
must be given unless the corresponding defaults are accepted)
For all SDUM
's except EN-NUCL and ENERGY:
First card:
WHAT(1)
= i1 + i4 * 10000, where i1, i4, have the following meaning:
i1 = 1.0 : linear energy binning
= -1.0 : logarithmic energy binning
i4 = 0.0 : group-wise scoring for low energy neutrons
=+/-1.0 : point-wise scoring for low energy neutrons
Default
= 1.0 (linear binning, groupwise scoring)
WHAT(2)
= (generalised) particle type to be scored
Default
= 201.0 (all particles)
WHAT(3)
= logical output unit:
> 0.0 : formatted data are written on WHAT(3)
unit
< 0.0 : unformatted data are written on |WHAT(3)
| unit
Values of |WHAT(3)
| < 21 should be avoided (with the
exception of +11).
Default
= standard output unit
WHAT(4)
> 0: region defining the detector
= -1: all regions (see Note 8)
Default
= 1.0
WHAT(5)
= volume of the detector in cm**3
Default
= 1.0
WHAT(6)
= number of energy bins
Default
= 10.0
SDUM
= any character string (not containing '&') identifying the
track-length detector. Max. 10 characters.
Continuation card:
WHAT(1)
= maximum kinetic energy for scoring (GeV)
Default
: Beam momentum value according to the BEAM option
(if no BEAM card is given, 200 GeV)
WHAT(2)
= minimum kinetic energy for scoring (GeV)
(default: 0 if linear binning, 0.001 GeV otherwise)
Note that the lowest energy limit of the last neutron group
is 1.E-14 GeV (1.E-5 eV) for the 260 data set.
WHAT(3)
..WHAT(6)
: not used
SDUM
= & in any position in column 71 to 78
For SDUM
= EN-NUCL:
The energy scale for all USRTRACK estimators will be changed from energy
to energy per nucleon (for particles with baryon number = 0 or 1, i.e.
all elementary hadrons and leptons, nothing will be changed).
For SDUM
= ENERGY:
the energy scale for all USRTRACK estimators will be changed to the default,
that is total kinetic energy.
Default
(option not given): no tracklength estimator detector
IMPORTANT!
----------
Notes:
1) IMPORTANT! The results of USRTRACK are always given as DIFFERENTIAL
distributions of fluence (or tracklength, if the detector region
volume is not specified) in energy, in units of cm-2 GeV-1 (or
cm GeV-1) per incident primary unit weight. Thus, for example, when
requesting a fluence energy spectrum, to obtain INTEGRAL BINNED
results (fluence in cm-2 or tracklength in cm PER ENERGY BIN per
primary) one must multiply the value of each energy bin by the width
of the bin (even for logarithmic binning). This is done automatically
by the dedicated post-processing utility program USTSUW (see Note 7).
2) If the generalised particle is 208 (ENERGY) or 211 (EM-ENRGY), the
quantity scored is differential energy fluence (or tracklength, if
the detector region volume is not specified), expressed in GeV per
cm2 (or cm GeV) per energy unit per primary. That can sometimes lead
to confusion since GeV cm-2 GeV-1 = cm-2, where energy does not appear.
Note that integrating over energy one gets GeV/cm2.
3) The maximum number of tracklength + collision detectors (see
option USRCOLL) that the user can define is 2500.
4) The logical output unit for the estimator results (WHAT(3)
of
the first USRTRACK card) can be any one of the following:
- the standard output unit 11: estimator results will be
written on the same file as the standard FLUKA output
- a pre-connected unit (via a symbolic link on most UNIX systems,
ASSIGN under VMS, or equivalent commands on other systems)
- a file opened with the FLUKA command OPEN
- a file opened with a Fortran OPEN statement in a user-written
initialisation routine such as USRINI, USRGLO or SOURCE (see 13})
- a dynamically opened file, with a default name assigned by the
Fortran compiler (typically fort.xx or ftn.xx, with xx equal
to the chosen logical output unit number).
The results of several USRTRACK and USRCOLL detectors in a same
FLUKA run can be written on the same file, but of course only if
they are all in the same mode (all formatted, or all unformatted).
It is also possible in principle to write on the same file the
results of different kinds of estimators (USRBDX, USRBIN, etc.)
but this is not recommended, especially in the case of an
unformatted file, because it would make very difficult any reading
and analysis.
5) When scoring neutron fluence, and the requested energy interval
overlaps with the structure of the low energy neutron groups,
one gets two separate tables. In the lower one, interval boundaries
are forced to coincide with group boundaries. For the upper one,
the program uses the input energy limits and number of intervals to
estimate the desired interval width. The number of intervals above
the upper limit of the first low-energy neutron group is recalculated
according to such width, which is readjusted to match the number of
intervals with the least greater integer.
Note that the lowest energy limit of the last neutron group
is 1.E-14 GeV (1.E-5 eV) for the 260-group data set.
All group energy boundaries are listed in Table 10.4.1.1}.
6) If the scored fluence is that of a generalised particle which
includes neutrons (e.g. ALL-PART, ALL-NEUT, NUCLEONS, NUC&PI+-,
HAD-NEUT, and even ENERGY), the spectrum is also presented in two
separate tables. One table refers to all non-neutron particles and
to neutrons with energies above the upper limit of the first low-energy
neutron group (20 MeV). In case an interval crosses 20 MeV, it will
include the contribution of neutrons with energy > 20 MeV and not that
of neutrons with energy < 20 MeV. The second table refers only to
low-energy neutrons and its interval structure is that of the neutron
energy groups.
7) A program USTSUW is available with the normal FLUKA code distribution
in directory $FLUPRO/flutil. USTSUW reads USRTRACK results in binary
form from several runs and allows to compute standard deviations. It
returns differential and cumulative fluence, with the corresponding
percent errors, in a file, and differential fluence in another file
formatted for easy plotting. It also returns a binary file that can
be read out in turn by USTSUW. 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 USTSUW program takes care of giving it
the appropriate weight).
8) Setting WHAT(4)
= -1 will provide the sum of the track-lengths in
all regions, divided by the value set by the user for WHAT(5)
.
Example:
USRTRACK 1.0 PHOTON -24.0 16.0 4500.0 150.PhotFlu
USRTRACK 1.5 0.0 0.0 0.0 0.0 0. &
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