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[ <--- prev -- ] [ HOME ] [ -- next ---> ] 13 User routinesUnlike some other Monte Carlo particle transport codes, FLUKA gets its input
mainly from a simple file. It offers a rich choice of options for scoring most
quantities of possible interest and for applying different variance reduction
techniques, without requiring the user to write a single line of code.
However, although normally there is no need for any "user code", there are
special cases where this is unavoidable, either because of the complexity of
the problem, or because the desired information is too unusual or too
problem-specific to be offered as a standard option.
And on the other hand, even when this is not strictly necessary, experienced
programmers may like to create customised input/output interfaces.
A number of user routines (available on LINUX and UNIX platforms in directory
usermvax) allow to define non-standard input and output, and in some cases
even to modify to a limited extent the normal particle transport. Most of them
are already present in the FLUKA library as dummy or template routines, and
require a special command in the standard input file to be activated. Users
can modify any one of these routines, and even insert into them further calls
to their own private ones, or to external packages (at their own risk!). This
increased flexibility must be balanced against the advantage of using as far as
possible the FLUKA standard facilities, which are known to be reliable and well
tested.
A typical way to do this is: ..............
LOGICAL LFIRST
SAVE LFIRST
DATA LFIRST /.TRUE./
* return message from first call
IF (LFIRST) THEN
WRITE(LUNOUT,*) 'Version xxx of Routine yyy called'
LFIRST = .FALSE.
ENDIF
..............
IMPORTANT: The user should not modify the value of any argument in a routine calling list, except when marked as "returned" in the description of the routine here below. Similarly, no variable contained in COMMON blocks should be overwritten unless explicitly indicated.
fff yyy.f (produces a new file yyy.o)
lfluka -o myfluka -m fluka yyy.o This will produce a new executable (indicated here as myfluka). To run the new executable, launch the usual rfluka script with the option -e myfluka. 13.1 INCLUDE files
It is recommended that at least the following lines be present at the beginning of each routine: INCLUDE '(DBLPRC)'
INCLUDE '(DIMPAR)'
INCLUDE '(IOUNIT)'
Each INCLUDE contains a COMMON block, plus related constants.
Additional INCLUDEs may be useful, in particular BEAMCM, CASLIM, EMFSTK, SOURCM,
EVTFLG, FHEAVY, GENSTK, LTCLCM, FLKMAT, RESNUC, SCOHLP, SOUEVT, FLKSTK, SUMCOU,
TRACKR, USRBIN, USRBDX, USRTRC, USRYLD.
DBLPRC: included in ALL routines of FLUKA, contains the declaration
IMPLICIT DOUBLE PRECISION (A-H,O-Z)
and sets many mathematical and physical constants. Users are strongly
encouraged to adhere to "FLUKA style" by using systematically double
precision (except for very good reasons such as calling external single
precision scoring packages), and to use constants defined in this file
for maximum accuracy.
DIMPAR: dimensions of the most important arrays
IOUNIT: logical input and output unit numbers
BEAMCM: properties of primary particles as defined by options BEAM and BEAMPOS CASLIM: number of primary particles followed (needed for normalisation) EMFSTK: particle stack for electrons and photons SOURCM: user variables and information for a user-written source EVTFLG: event flags (still undocumented) FHEAVY: stack of heavy secondaries created in nuclear evaporation GENSTK: properties of each secondary created in a hadronic event LTCLCM: LaTtice CeLl CoMmon (needed when writing symmetry transformations for Lattice Geometry) FLKMAT: material properties RESNUC: properties of the current residual nucleus SCOHLP: SCOring HeLP (information on current detector and estimator type). It contains a flag ISCRNG, indicating the quantity being scored by the current binning or the estimator corresponding to the current detector, and one JSCRNG corresponding to the binning/detector number. Binnings and detectors are sequentially numbered according to their order of appearance in standard input. Note that detectors corresponding to different estimators can have the same JSCRNG number (for instance Binning N. 3 and Tracklength detector N. 3). They can be distinguished based on the value of ISCRNG. However, note that the same value of ISCRNG may have different meanings in functions FLUSCW and COMSCW. SOUEVT: SOUrce EVenT (useful when source particles are obtained from an external event generator) FLKSTK: main FLUKA particle stack SUMCOU: total numbers and total weights relative to many physical and Monte Carlo events (needed for normalisation, energy balance etc.) TRACKR: TRACKs Recording (properties of the currently transported particle and its path) USRBIN, USRBDX, USRSNC, USRTRC, USRYLD: parameters of the requested estimator detectors and binnings 13.2 User routines
13.2.1 abscff.f: user defined ABSorption CoeFFicientArgument list (all variables are input only): WVLNGT : photon wavelength (in cm)
OMGPHO : angular frequency (omega = 2pi nu) of the photon (in s-1)
MMAT : material index
Function ABSCFF returns a user-defined absorption coefficient for optical photons. It is activated by setting WHAT(2) < -99 in command OPT-PROP, with SDUM = blank. See option OPT-PROP and Chap. (12) for more information. 13.2.2 comscw.f: weighting deposited energy, stars or residual nucleiArgument list: IJ : particle type (1 = proton, 8 = neutron, etc.: see code in (5)) Input only, cannot be modified. XA,YA,ZA : current particle position MREG : current geometry region RULL : amount to be deposited (unweighted) LLO : particle generation. Input only, cannot be modified. ICALL : internal code calling flag (not for general use) This routine is activated by option USERWEIG, with WHAT(6) > 0.0. Energy and star densities obtained via SCORE and USRBIN, and energy and stars obtained via EVENTBIN and production of residual nuclei obtained via RESNUCLEi are multiplied by the value returned by this function. The user can implement any desired logic to differentiate the returned value according to any information contained in the argument list (particle type, position, region, amount deposited, particle generation), or information available in the SCOHLP COMMON block (binning number, type of scored quantity). The scored quantity is given by the flag ISCRNG (in SCOHLP): ISCRNG = 1 --> Energy density binning
ISCRNG = 2 --> Star density binning
ISCRNG = 3 --> Residual nuclei scoring
The binning/detector number is given by JSCRNG (in SCOHLP) and is printed in output: Res. nuclei n. 3 äny-name" , "high" energy products, region n. 4
R-Phi-Z binning n. 5 öther-name" , generalised particle n. 1
Note that a detector of residual nuclei can have the same JSCRNG number as a binning (use the value of ISCRNG to discriminate). Further information can be obtained including COMMON TRACKR (for instance particle's total energy, direction cosines, age). TRACKR contains also special user variables (both integer and in double precision) which can be used to save information about particles which have undergone some particular event. If data concerning the current material are needed, it can be accessed as MEDIUM(MREG) if file (FLKMAT) is included. Indeed, a common simple application of COMSCW is to score dose according to the local density (especially useful to get the correct average dose in bins straddling a boundary between two different media): ..................
INCLUDE '(FLKMAT)'
INCLUDE '(SCOHLP)'
..................
* ========== In order to compute doses ========= *
* Medium(n) is the material number of region n
* Rho(m) is the density of material m (in g/cm3)
* Iscrng = 1 means we are depositing energy (not stars)
IF ( ISCRNG .EQ. 1 ) THEN
* to get dose in Gy (elcmks is the electron charge in C)
COMSCW = ELCMKS * 1.D12 / RHO (MEDIUM(MREG))
ELSE
* oneone is defined as 1.D0 in include DBLPRC
COMSCW = ONEONE
ENDIF
..................
Note that the variables in the argument list, with the exception of IJ, LLO and ICALL, are local copies of those used for particle transport, and therefore can be modified to have an effect on scoring, without affecting transport. Note: setting the variable LSCZER = .TRUE. before RETURN (LSCZER is in COMMON SCOHLP), will cause zero scoring whatever the value returned by COMSCW. This is more efficient than returning a zero value. 13.2.3 dffcff.f: user defined DiFFusion CoeFFicientArgument list (all variables are input only): WVLNGT : photon wavelength (in cm)
OMGPHO : angular frequency (omega = 2pi nu) of the photon (in s-1)
MMAT : material index
Function DFFCFF returns a user-defined diffusion coefficient for optical photons. It is activated by setting WHAT(3) < -99 in command OPT-PROP, with SDUM = blank. See option OPT-PROP and Chap. (12) for more information. 13.2.4 endscp.f: ENergy density DiStributed - Change of PositionsArgument list (all variables are input only): IJ : particle type (input only)
NTRUCK : number of step points (input only)
XTRUCK,YTRUCK,ZTRUCK : particle step points, can be modified by user
MREG : region number (input only)
LLO : particle generation (input only)
ICALL : internal code calling flag (not for general use)
Subroutine ENDSCP allows to shift by a user-defined distance the energy which is being deposited along a step or several step binning portions, by providing new segment endpoints. A typical application is to simulate an instrument drift. 13.2.5 fldscp.f: FLuence DiStributed - Change of PositionsArgument list (all variables are input only): IJ : particle type
PLA : particle momentum (if > 0), or kinetic energy (if < 0)
(input only)
TXX,TYY,TZZ : particle direction cosines, can be modified by user
NTRUCK : number of step points
XTRUCK,YTRUCK,ZTRUCK : particle step points, can be modified by user
NREG : new region number (input only)
IOLREG : old region number (input only)
LLO : particle generation (input only)
ICALL : internal code calling flag (not for general use)
Subroutine FLDSCP allows to shift by a user-defined distance the track whose length is being scored as fluence along a step or several step binning portions, by providing new segment endpoints. A typical application is to simulate an instrument drift. 13.2.6 fluscw.f: weighting fluence, current and yieldArgument list: IJ : particle type (input only, cannot be modified)
PLA : particle momentum (if > 0), or -PLA = kinetic energy
(if < 0)
TXX,TYY,TZZ: particle current direction cosines
WEE : particle weight
XX,YY,ZZ: particle position
NREG : current region (after boundary crossing)
IOLREG : previous region (before boundary crossing). Useful only
whith boundary crossing estimators; for other estimators it
has no meaming.
LLO : particle generation (input only, cannot be modified)
ICALL : internal code calling flag (not for general use)
Function FLUSCW is activated by option USERWEIG, with WHAT(3) > 0.0. Yields obtained via USRYIELD, fluences calculated with USRBDX, USRTRACK, USRCOLL, USRBIN, and currents calculated with USRBDX are multiplied by the value returned by this function. The user can implement any desired logic to differentiate the returned value according to any information contained in the argument list (particle type, energy, direction, weight, position, region, boundary, particle generation), or information available in the SCOHLP COMMON block (binning or detector number, estimator type). The scored quantity is given by the flag ISCRNG (in SCOHLP): ISCRNG = 1 --> Boundary crossing estimator
ISCRNG = 2 --> Track length binning
ISCRNG = 3 --> Track length estimator
ISCRNG = 4 --> Collision density estimator
ISCRNG = 5 --> Yield estimator
The binning/detector number is given by JSCRNG (in SCOHLP) and is printed in output: Bdrx n. 2 "bdxname" , generalised particle n. 8,
from region n. 22 to region n. 78
Track n. 6 "trkname" , generalised particle n. 14, region n. 9.
Note that a track-length detector can have the same JSCRNG number as
a boundary crossing one or a binning etc. (use the value of ISCRNG to
discriminate).
Further information can be obtained including COMMON TRACKR (for
instance particle age). TRACKR contains also special user variables
(both integer and in double precision) which can be used to save
information about particles which have undergone some particular event.
Function FLUSCW has many applications. A common one in shielding
calculations is to multiply selected scored fluences by
particle/energy-dependent fluence-to-dose equivalent conversion
coefficients, or by some instrument response, radiation damage curve,
etc. A version of FLUSCW converting particle fluences to various
forms of dose equivalent and effective dose is available in file
deq99.f, in the $FLUPRO/flutil directory. Instructions for its use
are contained in the comment lines at the beginning of the file.
CALL USRDCI(IJ,IONA,IONZ,IONM)
The three integer values returned are the following ion properties:
IONA = mass number of the ion
IONZ = atomic number
IONM = flag for isomeric state
Based on their values, the user can decide or not to accept the
scoring.
Other interesting applications are based on the fact that FLUSCW is called at every boundary crossing, provided that at least one USRBDX detector has been requested. Although the function has been designed mainly to weight scored quantities, it can be "cheated" to do all sorts of side things, even not directly connected with scoring. Note that the variables in the argument list, with the exception of IJ, LLO and ICALL, are local copies of those used for particle transport, and therefore can be modified to have an effect on scoring, without affecting transport. Note: setting the variable LSCZER (in SCOHLP) = .TRUE. before
RETURN, will cause zero scoring whatever the value returned
by FLUSCW. This is more efficient than returning a zero value.
13.2.7 formfu.f nuclear form factorArgument list (all variables are input only): IJ : particle code, except that it is set to 3 for both e+ and e-
QU2 : squared momentum transfer (GeV/c)^2
ZMEDIU : atomic number of target nucleus
AMEDIU : atomic mass of target nucleus
Function FORMFU can be used to override the standard value of the nuclear charge form factor. It must return the squared value of the nuclear charge form factor for particle IJ. The default version computes the form factor in Born approximation for a medium of given composition, using the simple expression given by Tsai [Tsa74], and accounts also for the contribution of incoherent scattering. The function is called by the multiple and single scattering routines if option MULSOPT has been issued with WHAT(3) <t 0.0 for electrons and positrons, and WHAT(2) < 0.0 for hadrons and muons. See Note 2) to option MULSOPT. 13.2.8 frghns.f material roughness (for optical photons)Argument list (all variables are input only): TXX, TYY, TZZ : particle direction cosines
UXSRFC, UYSRFC, UZSRFC: direction of the normal to the surface
MREG : region the particle is coming from
NEWREG : region the particle is going to
MMAT : material the particle is coming from
MMATNW : material the particle is going to
Function FRGHNS can be used to return a non-zero value for the roughness of a boundary between two materials, relevant for optical photon transport (default roughness is zero for all boundaries). Meaningful only if options OPT-PROP or OPT-PROD have been requested. 13.2.9 musrbr.f 1st user defined quantity for special binning lusrbl.f 2nd user defined quantity for special binning fusrbv.f 3rd user defined quantity for special binningThese three functions are used to define 3-dimensional fluence distributions to be calculated by special user-defined binnings (see USRBIN with WHAT(1) = 8.0 in the first card).
Argument list (all variables are input only): IJ : particle type
PCONTR : particle momentum
XA,YA,ZA : particle position
MREG : current region
LATCLL : current lattice cell
ICALL : internal code calling flag (not for general use)
Argument list: same as for MUSRBR above
Argument list: same as for MUSRBR above (except LATCLL)
13.2.10 lattic.f (symmetry transformation for lattice geometry)Subroutine LATTIC is activated by one or more LATTICE cards in the
geometry input (see (8)). It is expected to transform coordinates and
direction cosines from any lattice cell (defined by card LATTICE) to
the reference system in which the basic structure has been described.
The user is expected to provide a transformation of coordinates and
vector direction cosines from each lattice cell to the corresponding
basic structure (in ENTRY LATTIC) and of direction cosines from the
basic structure to each corresponding lattice cell (in ENTRY LATNOR).
Argument list: XB(1), XB(2), XB(3) : actual physical position coordinates in IRLTGG
lattice cell
WB(1), WB(2), WB(3) : actual physical direction cosines in IRLTGG
lattice cell
DIST : current step length
SB(1), SB(2), SB(3) : transformed coordinates in prototype cell
UB(1), UB(2), UB(3) : transformed cosines in prototype cell
IR : region number in prototype cell
IRLTGG : lattice cell number
IRLT : array containing region indices corresponding to
lattice cells
IFLAG : reserved variable
LATTIC returns the tracking point coordinates (SB) and direction cosines(UB) in the reference prototype geometrical structure, corresponding to real position/direction XB, WB in the actual cell IRLTGG (defined as input region IR by a LATTICE card). When the lattice option is activated, the tracking proceeds in two different systems: the "real" one, and that of the basic symmetry unit. Particle positions and directions are swapped from their real values to their symmetric ones in the basic cell, to perform the physical transport in the regions and materials that form the prototype geometrical structure and back again to the real world. The correspondence between "real" and "basic" position/direction depends on the symmetry transformation and on the lattice cell number.
Argument list: UN(1), UN(2), UN(3) : direction cosines of the vector normal to the
surface, in the prototype cell (entry values)
and in the lattice cell (returned values)
IRLTNO : present lattice cell number
Entry LATNOR transforms the direction cosines stored in the vector
UN(3) from the system of the basic prototype unit to that of the real
world in lattice cell number IRLTNO. Therefore, this cosine
transformation must be the inverse of that performed on the cosines by
the LATTIC entry: but while LATTIC maps vector UB to a different
vector WB, LATNOR maps the UN vector to itself.
Note that if the transformation implies a rotation, it is necessary to
save first the incoming UN cosines to local variables, to avoid
overwriting the vector before all transformation statements are executed.
Different symmetry transformations can of course be implemented
in the same LATTIC routine (each being activated by a different cell
number or range of cell numbers).
The advantage of the lattice geometry is to avoid describing in detail
the geometry of repetitive multi-modular structures. It must be
realised, however, that a penalty is generally paid in computer efficiency.
Also, a region contained in the prototype cell and all those "mapped"
to it inside lattice cells are treated by the program as if they
were connected with "non-overlapping ORs" into a single region.
Therefore, any region-based scoring (options SCORE, USRTRACK, etc.)
can only provide quantities averaged over the whole structure. More
detailed information must be obtained by region-independent options
such as USRBIN or by user-written routines (MGDRAW).
The USRBIN and EVENTBIN options, with WHAT(1) = 8, can also be used
to request a special binning type which activates the MUSRBR,
LUSRBL, FUSRBV user routines to recover lattice information (see
routine musrbr.f below)
A transformation between a lattice cell and a prototype region can
alternatively be defined without resorting to the LATTIC user routine.
In this case, the transformation is defined via a ROT-DEFIni card and
the correspondence is established by giving the transformation index
in the SDUM of the LATTICE card (see Chap. (8)).
13.2.11 magfld.f definition of a magnetic fieldArgument list: X,Y,Z : current position (input only)
BTX,BTY,BTZ : direction cosines of the magnetic field vector
(returned).
B : magnetic field intensity in Tesla (returned)
NREG : current region (input only)
IDISC : if returned = 1, the particle will be discarded
MAGFLD is activated by option MGNFIELD with WHAT(4-6) = 0.0 and is used to return intensity and direction of a magnetic field based on the current position and region. It is called only if the current region has been flagged as having a non-zero magnetic field by option ASSIGNMAt, with WHAT(5) = 1.0. The magnetic field spatial distribution is often read and interpolated from an external field map. Note that in any case the direction cosines MUST be properly normalised in double precision (e.g. BTX = SQRT(ONEONE - BTY**2 - BTZ**2)), even if B = 0.0. Please read carefully the notes on option MGNFIELD. 13.2.12 mdstck.f management of the stack of secondariesArgument list: IFLAG : type of nuclear interaction which has produced secondaries:
1 : inelastic
2 : elastic
3 : low-energy neutron
NUMSEC : number of secondary particles produced in the interaction
MDSTCK is called after a nuclear interaction in which at least one secondary particle has been produced, before any biasing is applied to decide which secondary will be loaded in the main stack for further transport. The properties of the secondaries are stored in the secondary stack (COMMON GENSTK). With MDSTCK, the user can analyse those secondaries, write them to a file, or even modify the content of GENSTK (for instance applying his own biasing). In the latter case, however, it is his responsibility to make sure that energy is conserved, the various physical quantities are still consistent, etc. 13.2.13 mgdraw.f general event interfaceSubroutine MGDRAW, activated by option USERDUMP with WHAT(1) >= 100.,
usually writes a "collision tape", i.e. a file where all or selected
transport events are recorded. The default version (unmodified by the
user) offers several possibilities, selected by WHAT(3) in USERDUMP.
Details are given in (11).
Additional flexibility is offered by a user entry USDRAW, selected
by WHAT(4) in USERDUMP, interfaced with the most important physical
events happening during particle transport.
The user can modify of course also any other entry of this
subroutine (BXDRAW called at boundary crossings, EEDRAW called at event
end, MGDRAW for trajectory drawing, ENDRAW for recording of
energy depositions and SODRAW for recording of source events:
for instance the format of the output file can be changed, and
different combinations of events can be written to file.
Argument list (all variables are input only): ICODE : FLUKA physical compartment originating the call
= 1: call from Kaskad (hadrons and muons)
= 2: call from Emfsco (electrons, positrons and photons)
= 3: call from Kasneu (low-energy neutrons)
= 4: call from Kashea (heavy ions)
= 5: call from Kasoph (optical photons)
MREG : current region
MGDRAW writes by default, for each trajectory, the following variables (contained in COMMON TRACKR): NTRACK : number of track segments
MTRACK : number of energy deposition events along the track
JTRACK : type of particle
ETRACK : total energy of the particle
WTRACK : weight of the particle
Ntrack values of XTRACK, YTRACK, ZTRACK : end of each track segment
Mtrack values of DTRACK : energy deposited at each deposition event
CTRACK : total length of the curved path
Other variables are available in TRACKR (but not written by MGDRAW unless the latter is modified by the user: particle momentum, direction cosines, cosines of the polarisation vector, age, generation, etc. (see a full list in the comment in the INCLUDE file).
Argument list (all variables are input only): ICODE : FLUKA physical compartment originating the call
= 19: call from Kaskad (hadrons and muons)
= 29: call from Emfsco (electrons, positrons and photons)
= 39: call from Kasneu (low-energy neutrons)
= 49: call from Kashea (heavy ions)
= 59: call from Kasoph (optical photons)
MREG : number of region before boundary crossing
NEWREG : number of region after boundary crossing
XSCO, YSCO, ZSCO : coordinates of crossing point
BXDRAW is called at each boundary crossing (if requested by the user
with USERDUMP, WHAT(3) < 7.0). There is no default output: any
output must be supplied by the user.
CALL GEOR2N (NUMREG, NAMREG, IERR) where NUMREG (input variable) is a region number, and NAMREG (returned variable) is the corresponding region name (to be declared as CHARACTER*8). IERR is a returned error code: if = 0, the conversion is successful. Example: .......................................
CHARACTER*8 MRGNAM, NRGNAM
.......................................
ENTRY BXDRAW ( ICODE, MREG, NEWREG, XSCO, YSCO, ZSCO )
CALL GEOR2N ( MREG, MRGNAM, IERR1 )
CALL GEOR2N ( NEWREG, NRGNAM, IERR2 )
IF(IERR1 .NE. 0 .OR. IERR2 .NE. 0) STOP "Error in name conversion"
.......................................
IF(MRGNAM .EQ. "MyUpsREG" .AND. NRGNAM .EQ. "MyDwnREG") THEN
.......................................
Argument list: ICODE = -1: event not completed
= 0: normal event termination
= 4: stack overflow
EEDRAW is called at the end of each event, or primary history, (if requested by the user with USERDUMP, WHAT(3) =< 0.0). There is no default output: any output must be supplied by the user.
Argument list (all variables are input only): ICODE : type of event originating energy deposition
1x: call from Kaskad (hadrons and muons)
10: elastic interaction recoil
11: inelastic interaction recoil
12: stopping particle
13: pseudo-neutron deposition
14: particle escaping (energy deposited in blackhole)
15: time kill
2x: call from Emfsco (electrons, positrons and photons)
20: local energy deposition (i.e. photoelectric)
21 or 22: particle below threshold
23: particle escaping (energy deposited in blackhole)
24: time kill
3x: call from Kasneu (low-energy neutrons)
30: target recoil
31: neutron below threshold
32: neutron escaping (energy deposited in blackhole)
33: time kill
4x: call from Kashea (heavy ions)
40: ion escaping (energy deposited in blackhole)
41: time kill
42: delta ray stack overflow
5x: call from Kasoph (optical photons)
50: optical photon absorption
51: optical photon escaping (energy deposited in
blackhole)
52: time kill
MREG : current region
RULL : energy amount deposited
XSCO, YSCO, ZSCO : point where energy is deposited
ENDRAW writes by default, for each energy deposition point: 0 : flag identifying ENDRAW output from that of other entries
ICODE : see argument list
JTRACK, ETRACK, WTRACK : see MGDRAW above
XSCO, YSCO, ZSCO, RULL : see argument list
No arguments
-NCASE (in COMMON CASLIM, with a minus sign to identify
Sodraw output): number of primaries followed so far
NPFLKA (in COMMON FLKSTK): stack pointer
NSTMAX (in COMMON FLKSTK): highest value of the stack pointer
encountered so far
TKESUM (in COMMON SOURCM): total kinetic energy of the
primaries of a user written source (see source.f
here below), if applicable. Otherwise = 0.0
WEIPRI (in COMMON SUMCOU): total weight of the primaries
handled so far
Npflka times: ILOFLK : type of source particle
TKEFLK+AM : total particle energy (kinetic+mass)
WTFLK : source particle weight
XFLK, YFLK, ZFLK : source particle position
TXFLK, TYFLK, TZFLK : source particle direction cosines
Argument list (all variables are input only): ICODE : 10x: call from Kaskad (hadron and muon interactions)
100: elastic interaction secondaries
101: inelastic interaction secondaries
102: particle decay secondaries
103: delta ray generation secondaries
104: pair production secondaries
105: bremsstrahlung secondaries
110: radioactive decay products
20x: call from Emfsco (electron, positron and photon
interactions)
208: bremsstrahlung secondaries
210: Moller secondaries
212: Bhabha secondaries
214: in-flight annihilation secondaries
215: annihilation at rest secondaries
217: pair production secondaries
219: Compton scattering secondaries
221: photoelectric secondaries
225: Rayleigh scattering secondaries
30x: call from Kasneu (low-energy neutron interactions)
300: interaction secondaries
40x: call from Kashea (heavy ion interactions)
400: delta ray generation secondaries
MREG : current region
XSCO, YSCO, ZSCO : interaction point
USDRAW is called after each particle interaction (if requested by
the user with USERDUMP, WHAT(4) >= 1.0). There is no default output:
any output must be supplied by the user.
13.2.14 ophbdx.f user defined Optical PHoton BounDary-(X)crossing propertiesArgument list (all variables are input only): OMGPHO : angular frequency (omega = 2 pi nu) of the photon (in s-1)
WVLNGT : photon wavelength (in cm)
MREG : old region number
NEWREG : new region number
SIGANW : absorption coefficient in the new region (cm-1)
SIGDNW : diffusion coefficient in the new region (cm-1)
RFNDPR : refractive index in the new region
VGRPNW : group velocity in the new region (cm s-1)
LPHKLL : if .TRUE., the photon will be absorbed on the boundary
Subroutine OPHBDX sets the optical properties of a boundary surface. The call is activated by command OPT-PROP, with SDUM = SPEC-BDX. See option OPT-PROP and Chap. (12) for more information. 13.2.15 queffc.f: user defined QUantum EFFiCiencyArgument list (all variables are input only): WVLNGT : photon wavelength (in cm)
OMGPHO : angular frequency (omega = 2pi nu) of the photon (in s-1)
Function QUEFFC returns a user-defined quantum efficiency for an optical photon of the given wavelength or frequency. It is activated by OPT-PROP, with SDUM = SENSITIV, by setting the 0th photon sensitivity parameter to a value < -99. See option OPT-PROP and Chap. (12) for more information. 13.2.16 rflctv.f: user defined ReFLeCTiVityArgument list (all variables are input only): WVLNGT : photon wavelength (in cm)
OMGPHO : angular frequency (omega = 2pi nu) of the photon (in s-1)
MMAT : material index
Function RFLCTV returns a user-defined value equal to 1-R, where R is the reflectivity of the current material for an optical photon of the given wavelength or frequency. It is activated by OPT-PROP, with SDUM = METAL, and WHAT(3) < -99. See option OPT-PROP and Chap. (12) for more information. 13.2.17 rfrndx.f: user defined ReFRaction iNDeXArgument list (all variables are input only): WVLNGT : photon wavelength (in cm)
OMGPHO : angular frequency (omega = 2pi nu) of the photon (in s-1)
MMAT : material index
Function RFRNDX returns a user-defined refraction index of the current material for an optical photon of the given wavelength or frequency. It is activated by OPT-PROP, with SDUM = blank, and WHAT(1) < -99. See option OPT-PROP and Chap. (12) for more information. 13.2.18 soevsv.f SOurce EVent SaVingNo arguments
13.2.19 source.f user-written sourceArgument list: NOMORE : if set = 1, no more calls will occur (the run will be
terminated after exhausting the primary particles loaded
into FLKSTK stack in the present call). The history number
limit set with option START will be overridden.
Subroutine SOURCE is probably the most frequently used user routine. It is activated by option SOURCE and is used to sample primary particle properties from distributions (in space, energy, time, direction, polarisation or mixture of particles) too complicated to be described with the BEAM, BEAMPOS and POLARIZAti cards alone. For each phase-space variable, a value must be loaded into COMMON FLKSTK (particle bank) before returning control. These values can be read from a file, generated by some sampling algorithm, or just assigned.
Reading from a file is needed, for instance, when the particle data are taken from a collision file, written by FLUKA or by another program. The user must open the file with a unit number > 20 (unit numbers lower than 20 are reserved), in one of the following ways:
Then, a READ statement in SOURCE can be used to get the data to load in stack, for instance: READ(21,*) IPART, X, Y, Z, COSX, COSY, COSZ, ENERGY, WEIGHT
ILOFLK (NPFLKA) = IPART
XFLK (NPFLKA) = X
YFLK (NPFLKA) = Y
ZFLK (NPFLKA) = Z
TXFLK (NPFLKA) = COSX
...etc...
(NPFLKA is the current stack index).
Direct assignment can be done explicitly, for instance: PMOFLK (NPFLKA) = 305.2D0 or implicitly, leaving unmodified values input with BEAM or BEAMPOS: PMOFLK (NPFLKA) = PBEAM (PBEAM is the momentum value input as WHAT(1) in option BEAM). A set of direct assignments, one for each of several different stack entries, can be useful, for example, to define a series of RAYs through the geometry (see (14)): DO 10 I = 1, 20
NPFLKA = NPFLKA + 1
ILOFLK (NPFLKA) = 0 (0 is the RAY particle id number)
XFLK (NPFLKA) = 500.D0 + DBLE(I) * 40.D0
YFLK (NPFLKA) = 200.D0
...etc...
10 CONTINUE
To sample from a uniform distribution, the user must use the function FLRNDM(DUMMY), which returns a double precision pseudo-random number uniformly distributed between 0 (included) and 1 (not included). Actually, DUMMY can be any variable name. A simple example of sampling from a uniform distribution is that of a linear source along the Z axis, between Z = 10 and Z = 80: Z1 = 10.D0
Z2 = 80.D0
ZFLK (NPFLKA) = 10.D0 + (Z2 - Z1) * FLRNDM(XXX)
One way to sample a value XX from a generic distribution f(x) is the following. First integrate the distribution function, analytically or numerically, and normalise to 1 to obtain the normalised cumulative distribution: /x /xmax
F(x) = | f(x)dx / | f(x)dx
/xmin /xmin
Then, sample a uniform pseudo-random number t using FLRNDM and get the desired result by finding the inverse value: -1
XX = F (t)
(analytically or most often by interpolation).
CALL FLNRRN (RGAUSS) or, if two independent Gaussian distributed numbers are needed: CALL FLNRR2 (RGAUS1, RGAUS2) (faster than calling FLNRRN twice).
The technique for sampling from a generic distribution described above can be extended to modify the probability of sampling in different parts of the interval (importance sampling). We replace f(x) by a weighted function g(x) = f(x) * h(x), where h(x) is any appropriate function of x we like to choose. We normalise g(x) in the same way as f(x) before: /x /xmax /x
G(x) = | g(x)dx / | g(x)dx = | f(x)*h(x)dx / B
/xmin /xmin /xmin
and we need also the integral of f(x) over the whole interval: /xmax
A = | f(x)dx
/xmin
All the sampling is done using the biased cumulative normalised function G instead of the original unbiased F: we sample a uniform pseudo-random number t as before, and we get the sampled value XX by inverting G(x): -1
XX = G (t)
The particle is assigned a weight B/(A * h(XX))
h(x) = 1/f(x)
g(x) = f(x) * h(x) = 1
G(x) = (x - xmin) / (xmax - xmin)
In this case we sample a uniform pseudo-random number t using FLRNDM as shown above. The sampled value XX is simply given by: XX = xmin + (xmax - xmin)*t and the particle is assigned a weight: /xmax
B/(A h(X)) = f(XX)*(xmax - xmin) / | f(x)dx
/xmin
But since FLUKA normalizes all results per unit primary weight, any
constant factor is eliminated in the normalization. Therefore it is
sufficient to assign each particle a weight f(x).
INCLUDE '(SOURCM)' These values can be used as parameters or switches for a multi-source
routine capable to handle several cases, or to identify an external
file to be read, etc., without having to compile and link again the
routine.
* +-------------------------------------------------------------------*
* | First call initialisations:
IF ( LFIRST ) THEN
* | *** The following 3 cards are mandatory ***
TKESUM = ZERZER
LFIRST = .FALSE.
LUSSRC = .TRUE.
* | *** User initialisation ***
END IF
* |
* +-------------------------------------------------------------------*
The user can insert into the above IF block any other initialisation
needed, for instance the preparation of a cumulative spectrum
array from which to sample the energy of the source particles.
Note that user initialisation can take place also in routines USRINI
and USRGLO (activated at input time by input options USRICALL and
USRGCALL) and USREIN (called before unloading from stack the first
source particle of an event, i.e., just after the call to SOURCE)
NPFLKA = NPFLKA + 1 increases the pointer The following statements assign a value to each of the FLKSTK variables concerning the particle being loaded: WTFLK (NPFLKA) = ONEONE sets the weight of the particle = 1.
This must be changed if the sampling of one or more of the
particle properties are biased. In that case, generally the weight
must be set after the sampling, and its value depends on the
sampling outcome.
WEIPRI = WEIPRI + WTFLK (NPFLKA) updates the total weight of the
primaries (don't change)
ILOFLK (NPFLKA) = IJBEAM by default sets the type of particle equal to the one defined by the BEAM card. If no BEAM card is given in input, IJBEAM is = 1 (proton), but it is strongly recommended to always provide a BEAM command in input (see Note 1 at the end of Section 13.2.19}). The above statement is followed by several others that must not be changed or removed. In the template routine, they are encompassed by the comment lines: From this point .... / ... to this point: don't change anything These statements are: * From this point ....
LOFLK (NPFLKA) = 1 Generation is 1 for source particles
LOUSE (NPFLKA) = 0 User variables: the user can set
DO 100 ISPR = 1, MKBMX1 different values in the STUPRF or
SPAREK (1,NPFLKA) = ZERZER STUPRE routine, but it is better
100 CONTINUE not to do it here
DO 200 ISPR = 1, MKBMX2
ISPARK (ISPR,NPFLKA) = 0 More user variables (integer)
200 CONTINUE
NPARMA = NPARMA + 1 Updating the maximum particle number
NUMPAR (NPFLKA) = NPARMA Setting the current particle number
NEVENT (NPFLKA) = 0 Resetting the current event number
DFNEAR (NPFLKA) = +ZERZER Resetting the distance to the
nearest boundary
* ... to this point: don't change anything
The following statements can be overridden or rewritten by the user, assigning new values or sampling them from problem-dependent distributions. First three statements which are rarely modified: AGESTK (NPFLKA) = +ZERZER Particle age is zero by default
AKNSHR (NPFLKA) = -TWOTWO Resets the Kshort component of
K0/K0bar. Usually not to be changed.
IGROUP (NPFLKA) = 0 Group number for low energy
neutrons: if set to 0, the program
derives it from the kinetic energy
Then the most frequently changed lines: both energy and momentum of
the particle must be loaded onto FLKSTK, but the two cannot be defined
independently. Appropriate kinematical (relativistic) relations must
be applied to derive one from the other.
PMOFLK (NPFLKA) = PBEAM Therefore, the kinetic energy (in GeV) must be derived: TKEFLK (NPFLKA) = SQRT ( PBEAM**2 + AM (IJBEAM)**2 ) - AM (IJBEAM) (where AM is the rest mass, in COMMON PAPROP, and IJBEAM is the particle type, in COMMON BEAMCM) If instead the energy had been sampled first from some spectrum, and ENSAMP would be the sampled value, the two statements above would become: TKEFLK (NPFLKA) = ENSAMP
PMOFLK (NPFLKA) = SQRT(ENSAMP * (ENSAMP + TWOTWO * AM(IJBEAM)))
The direction cosines are loaded next: TXFLK (NPFLKA) = UBEAM Assumed here to be the same as TYFLK (NPFLKA) = VBEAM defined by option BEAMPOS. UBEAM, TZFLK (NPFLKA) = WBEAM VBEAM, WBEAM are some among the beam properties in COMMON BEAMCM. (If BEAMPOS is not given, by default UBEAM = VBEAM = 0.0, WBEAM= 1.0) Remember to make sure that the cosines are normalised! One could replace the last statement by: TZFLK (NPFLKA) = SQRT ( ONEONE - TXFLK(NPFLKA)**2 - TYFLK(NPFLKA)**2 ) The polarisation cosines are not set by default: TXPOL (NPFLKA) = -TWOTWO -2 is a flag for "no polarisation"
TYPOL (NPFLKA) = +ZERZER
TZPOL (NPFLKA) = +ZERZER
but appropriate values need to be given in some cases, for instance
in synchrotron radiation shielding problems.
XFLK (NPFLKA) = XBEAM Assumed here to be the same as YFLK (NPFLKA) = YBEAM defined by option BEAMPOS. XBEAM, ZFLK (NPFLKA) = ZBEAM YBEAM, ZBEAM are also in COMMON BEAMCM. (If BEAMPOS is not given, by default XBEAM = YBEAM = ZBEAM = 0.0) If for example our problem required instead a linear source uniformly distributed along Z between Z1 and Z2, we could replace the last statement by: ZFLK (NPFLKA) = Z1 + FLRNDM(UGH) * (Z2 - Z1) The following lines in the template SOURCE routine should never be changed. They calculate the total energy of the primary particles, define the remaining properties of the particles (starting region and lattice cell) and do some geometry initialisation. The last line calls the SOEVSV user routine (see description above) to save the stack for possible further use. IMPORTANT!Note 1: Even though a user-written source is used, it is recommended to issue in input a card BEAM with an energy larger than the maximum energy that can be sampled by the user source. This value is used to set up tables such as stopping powers, cross sections etc., and if not provided, crashes can occur. Note 2: The values of beam characteristics defined by commands BEAM and POLARIZAti are available in COMMON BEAMCM: the angular divergence (variable DIVBM), beam width (XSPOT and YSPOT), and the polarisation vector (UBMPOL, VBMPOL, WBMPOL) can help to set up a scheme to sample the corresponding quantities from user-defined distributions. But sampling from the distributions pre-defined by BEAM and POLARIZAti is not simply inherited by subroutine SOURCE: it is the responsibility of the user to write such a scheme! For this task, it may be useful to define a "beam reference frame" by means of option BEAMAXES (see more details at the BEAMAXES command). 13.2.20 stupre.f SeT User PRoperties for EMF particles stuprf.f SeT User PRoperties for FLUKA particlesMF particles stuprf.f SeT User PRoperties for FLUKA particles|stupre.f SeT User PRoperties for EMF particles stuprf.f SeT User PRoperties for FLUKA particles|99|13| -->These two functions are used to assign a value to one or more stack user variables when the corresponding particle is loaded into one of the stacks (FLKSTK for hadrons/muons, EMFSTK for electrons/photons, OPPHST for optical photons). In each of these stacks the user has access to one integer variable, one integer array and one double precision array. Each of them is copied to a correspondent variable or array in COMMON TRACKR at the beginning of transport: Correspondence: FLKSTK EMFSTK OPPHST TRACKR -------------- ----- ------ ------ ------ integer variable: LOUSE LOUEMF LOUOPP --> LLOUSE integer array: ISPARK IESPAK ISPORK --> ISPUSR double precision array: SPAREK ESPARK SPAROK --> SPAUSR The user can access and modify the TRACKR variables via subroutine MGDRAW and its entries ENDRAW, SODRAW and especially USDRAW (see description above). STUPRF and STUPRE can be used to do the reverse, namely to copy TRACKR user variables to those of the relevant stack (see USDRAW above).
No arguments
Argument list: IJ : type of the parent particle
MREG : current region
XX, YY, ZZ : particle position
NUMSEC : index in the GENSTK COMMON of the secondary being loaded
onto stack
NPPRMR : if > 0, the secondary being loaded is actually still the
interacting particle (it can happen in some biasing
situations)
Note that heavy ions in FLUKA carry all the same id-number IJ = -2. The characteristics of primary ions are characterised by option HI-PROPE. To obtain the those of a secondary ion, call the routine USRDCI as follows: CALL USRDCI(IJ,IONA,IONZ,IONM) The three integer values returned are the following ion properties: IONA = mass number of the ion
IONZ = atomic number
IONM = flag for isomeric state
The default version of STUPRF copies to stack the user flags of the parent. 13.2.21 ubsset.f User BiaSing SETtingArgument list: IR : region number
RRHADR : multiplicity biasing factor to be applied to the
secondaries from hadronic interactions in region IR
(WHAT(2) of card BIASING)
HMPHAD : Importance of region IR for hadrons and muons (WHAT(3) of
card BIASING, with WHAT(1) = 0 or 1).
Actually the routine argument is an integer, IMPHAD, equal
to importance multiplied by 10000, but the user should
consider only the double precision version HMPHAD
(a conversion from and to the integer version is provided
at the beginning and at the end of the routine, and should
not be changed).
HMPLOW : Importance of region IR for low energy neutrons (WHAT(3)
of card BIASING, with WHAT(1) = 0 or 3).
Actually the routine argument is an integer, IMPLOW, equal
to importance multiplied by 10000, but the user should
consider only the double precision version HMPLOW
(a conversion from and to the integer version is provided
at the beginning and at the end of the routine, and should
not be changed).
HMPEMF : Importance of region IR for electrons and photons (WHAT(3)
of card BIASING, with WHAT(1) = 0 or 2).
Actually the routine argument is an integer, IMPEMF, equal
to importance multiplied by 10000, but the user should
consider only the double precision version HMPEMF
(a conversion from and to the integer version is provided
at the beginning and at the end of the routine, and should
not be changed).
IGCUTO : Cutoff group index for low energy neutrons in region IR
(WHAT(1) in card LOW-BIAS)
IGNONA : Non-analogue absorption group limit for low energy neutrons
in region IR (WHAT(2) in card LOW-BIAS)
PNONAN : Non-analogue survival probability for low energy neutrons in
region IR (WHAT(3) in card LOW-BIAS)
IGDWSC : Group limit for biased downscattering for low energy
neutrons in region IR (WHAT(1) in card LOW-DOWN)
FDOWSC : Biased downscattering factor for low energy neutrons in
region IR (WHAT(2) in card LOW-DOWN)
JWSHPP : Weight-Window/importance profile index for low energy
neutrons in region IR (SDUM in WW-FACTO)
WWLOW : Weight-Window lower level in region IR (WHAT(1) in card
WW-FACTO, possibly modified by WHAT(4) in WW-THRES or
WHAT(2) in WW-PROFI)
WWHIG : Weight-Window upper level in region IR (WHAT(2) in card
WW-FACTO, possibly modified by WHAT(4) in WW-THRES or
WHAT(2) in WW-PROFI)
WWMUL : Weight-Window multiplicative factor applied to the two
energy thresholds defined with WW-THRES, for region IR
(WHAT(3) in card WW-FACTO)
EXPTR : Exponential transform parameter for region IR (WHAT(2) in
card EXPTRANS) (not implemented yet!!!!!!!!)
ELECUT : e+,e- cutoff in region IR (WHAT(1) in card EMFCUT)
GAMCUT : Photon cutoff in region IR (WHAT(2) in card EMFCUT)
LPEMF : Leading Particle Biasing flag in region IR (SDUM = LPBEMF
in card EMF-BIAS, or WHAT(3) in card EMFCUT)
ELPEMF : Maximum e+/e- energy for applying Leading Particle Biasing
(WHAT(2) in card EMF-BIAS with SDUM = LPBEMF)
PLPEMF : Maximum photon energy for applying leading particle
biasing (WHAT(3) in card EMF-BIAS with SDUM = LPBEMF)
Subroutine UBSSET does not require a special command to be activated:
it is always called several times for each region: (once for every
biasing option or suboption) after the end of input reading and
before starting the calculations. The default version is a dummy and
does nothing. The user can replace it to override any biasing
parameters specified in input.
IF(IR .GE. 3 .AND. IR .LE. 20) HMPHAD = ONEONE * TWOTWO**(IR-3) It is important, however, not to do recursive assignments of the type: GAMCUT(5) = GAMCUT(5) * HLFHLF (HLFHLF is a FLUKA constant for 0.5D0) because that would halve the value of the photon cutoff for Region 5 AT EVERY CALL, and the number of calls is not known to the user. 13.2.22 udcdrl.f User defined DeCay DiRection biasing and Lambda(for neutrinos only)Argument list: IJ : type of decaying particle
KPB : outgoing neutrino, the one direction biasing is asked for
NDCY : (???)
UDCDRB, VDCDRB, WDCDRB : cosines of the preferential outgoing
direction for the neutrino
Function UDCDRL is used to bias the direction of a neutrino emitted by a decaying particle of type IJ. The value returned by UDCDRL is the Lambda for direction biasing (1-cos(theta)) (???) 13.2.23 usimbs.f User defined IMportance BiaSingArgument list: input:
MREG : region at the beginning of the step
NEWREG : region at the end of the step
output:
FIMP : returns the user-defined importance ratio between the
position at the end and at the beginning of the step
The routine is called AT EVERY PARTICLE STEP. It can be used to
implement any importance biasing scheme based on region number and
on phase space coordinates and other information provided by COMMON TRACKR.
13.2.24 usrein.f USeR Event INitialisationNo arguments
13.2.25 usreou.f USeR Event OUtput (called at the end of each event)No arguments
13.2.26 usrglo.f USeR GLObal settingsArgument list: WHAT(1), (2), (3), (4), (5), (6) : user-given numerical parameters
SDUM : user-given character string (8 characters)
Subroutine USRGLO is called before any other initialisation is done by the program, provided a command USRGCALL is present anywhere in the input. The calling parameters can carry any kind of useful information or can be used as flags to choose between different possible actions to be performed before any particle transport takes place. 13.2.27 usrini.f USeR INItialisationArgument list: WHAT(1), (2), (3), (4), (5), (6) : user-given numerical parameters
SDUM : user-given character string (8 characters)
Subroutine USRINI is called every time a USRICALL card is read in input. It can be used to do any kind of initialisation: reading and manipulating data from one or more files, calling other private routines, etc. The calling parameters can carry any kind of useful information or can be used as flags to choose between different possible actions to be performed before any particle transport takes place. 13.2.28 usrmed.f USeR MEDium dependent directivesArgument list: IJ : particle type
EKSCO : particle kinetic energy (GeV)
PLA : particle momentum (GeV/c)
WEE : particle weight
MREG : previous region number
NEWREG : current region number
XX, YY, ZZ : particle position
TXX, TYY, TZZ : particle direction
Subroutine USRMED is activated by option MAT-PROP with SDUM = USERDIRE, for one or more materials indicated by the user. It is called every time a particle is going to be transported in one of the user-flagged materials. Two cases are possible:
In both cases the weight can also be reduced to account for surface reflectivity or similar (if the particle is an optical photon, the FRGHNS user function can be called to establish a surface roughness) 13.2.29 usrout.f USeR OUTputArgument list: WHAT(1), (2), (3), (4), (5), (6) : user-given numerical parameters
SDUM : user-given character string (8 characters)
Subroutine USROUT is called every time a USROCALL card is read in input. It is used to print special user-written output in addition to the standard one provided by default. The calling parameters can carry any kind of useful information or can be used as flags to choose between different possible actions to be performed after all particle transport has taken place. 13.2.30 usrrnc.f USeR Residual NuCleiArgument list: IZ : atomic number of the residual nucleus
IA : mass number of the residual nucleus
IS : isomeric state of the residual nucleus
X, Y, Z : particle position
MREG : number of the current region
WEE : particle weight
ICALL : internal code calling flag (not for general use)
Subroutine USRRNC is called every time a residual nucleus is produced, if option USERWEIG has been requested with WHAT(5) > 0. |
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