GEANT321/gphys/gbfsig.F

   1 *
   2 * $Id$
   3 *
   4 * $Log$
   5 * Revision 1.1.1.1  1995/10/24 10:21:21  cernlib
   6 * Geant
   7 *
   8 *
   9 #include "geant321/pilot.h"
  10 *CMZ :  3.21/02 29/03/94  15.41.21  by  S.Giani
  11 *-- Author :
  12       FUNCTION GBFSIG(T,C)
  13 C.    ******************************************************************
  14 C.    *                                                                *
  15 C.    *  It calculates a weight factor for the positron discrete       *
  16 C.    *       (hard) bremsstrahlung cross section                      *
  17 C.    *                                                                *
  18 C.    *  Input:T kinetic energy (GeV)                                  *
  19 C.    *        C cut for bremsstrahlung (BCUTE)                        *
  20 C.    *        ETA ratio of positron to electron brems cross section   *
  21 C.    *  Output: weight factor                                         *
  22 C.    *                                                                *
  23 C.    *  ===>  positron sigma = Fsig * electron sigma  <===            *
  24 C.    *                                                                *
  25 C.    *  Author   L. Urban                                             *
  26 C.    *                                                                *
  27 C.    ******************************************************************
  28 C.
  29       ETA = GCBREM(T)
  30       IF(ETA.LT.0.0001) THEN
  31          F=1.E-10
  32       ELSEIF(ETA.GT.0.9999) THEN
  33          F=1.
  34       ELSE
  35 C
  36          E0=C/T
  37 C
  38          IF(E0.GE.1.) THEN
  39             F=1.E-10
  40          ELSE
  41             ALFA=1./ETA
  42             E1=1.-E0
  43             F=ETA*E1**ALFA/E1
  44          ENDIF
  45       ENDIF
  46 C
  47       GBFSIG=F
  48       END