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FLUKA: 13.2.21} ubsset.f User BiaSing SETting Previous Index Next

13.2.21} ubsset.f User BiaSing SETting

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     Argument 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. The UBSSET subroutine is used especially in cases with a large number of regions, because it allows to derive the biasing parameters from simple algorithms instead of entering each input value by hand. Choosing an appropriate numbering scheme for the geometry regions can often facilitate the task. For instance, assuming a simple slab geometry with an expected exponential hadron attenuation from region 3 to region 20, each region being one half-value-layer thick, one could write the following in order to set importances that would keep the hadron number about constant in all regions: 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. If name-based input is being used, the name corresponding to IR can be obtained via a call to routine GEOR2N: CALL GEOR2N (NUMREG, NAMREG, IERR) where NUMREG (input variable) is the 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. See example in the description of BXDRAW above.

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