GEANT321/gphys/gphsgp.F

   1 *
   2 * $Id$
   3 *
   4 * $Log$
   5 * Revision 1.1.1.1  1995/10/24 10:21:30  cernlib
   6 * Geant
   7 *
   8 *
   9 #include "geant321/pilot.h"
  10 *CMZ :  3.21/02 29/03/94  15.41.22  by  S.Giani
  11 *-- Author :
  12       FUNCTION GPHSGP(IELEM,E)
  13 C.
  14 C.    ******************************************************************
  15 C.    *                                                                *
  16 C.    *       FUNCTION TO COMPUTE THE PHOTOEFFECT TOTAL CROSS-SECTION  *
  17 C.    *       AS A FUNCTION OF Z AND E                                 *
  18 C.    *                                                                *
  19 C.    *    ==>CALLED BY : special dE/dx                                *
  20 C.    *                                                                *
  21 C.    *    (1) Sandia parametrizsation is used;                        *
  22 C.    *    (2) GPHSGP in cm**/g                                        *
  23 C.    *    (3) E in GeV                                                *
  24 C.    *                                                                *
  25 C.    *     J. Chwastowski 31.03.93                                    *
  26 C.    ******************************************************************
  27 C.
  28 #include "geant321/gcbank.inc"
  29 #include "geant321/gcjloc.inc"
  30 #include "geant321/gconsp.inc"
  31 #include "geant321/gcunit.inc"
  32 #include "geant321/gc10ev.inc"
  33 #if !defined(CERNLIB_SINGLE)
  34       DOUBLE PRECISION EINV,ECUR,ONE
  35 #endif
  36       PARAMETER (ONE=1)
  37 C.
  38 C.    ------------------------------------------------------------------
  39 C.
  40       RES = 0.
  41       IF(E.LT.G10EV) GO TO 20
  42 C Use Sandia data
  43       JPHXS  = LQ(JPHOT-1)
  44       IF(IELEM.GT.IQ(JPHXS-2)) THEN
  45          WRITE(CHMAIL,10010) IELEM, IQ(JPHXS-2)
  46 10010 FORMAT(' *** GPHSGP : element N ',I6,' requested, ',
  47      +'but only ',I6,' elements in present mixture')
  48          CALL GMAIL(0,0)
  49          GOTO 20
  50       ENDIF
  51       JPHXSI = LQ(JPHXS-IELEM)
  52       IPOINT = JPHXSI+1
  53       IMAX = Q(IPOINT)
  54       IPOINT = IPOINT+1
  55       ECUR = E*1.E6
  56       IF(ECUR.LT.Q(IPOINT)) GO TO 20
  57       EINV = ONE/ECUR
  58       DO 10 I = 2,IMAX
  59          IPOINT = IPOINT+5
  60          IF(ECUR.LT.Q(IPOINT)) THEN
  61             J = IPOINT+1
  62             RES = EINV*(Q(J)+EINV*(Q(J+1)+EINV*(Q(J+2)+EINV*Q(J+3))))
  63             GO TO 20
  64          ENDIF
  65    10 CONTINUE
  66 C This value is in cm**2/g
  67    20 GPHSGP = MAX(RES,0.)
  68 C
  69       END