GEANT321/erdecks/erland.F

   1 *
   2 * $Id$
   3 *
   4 * $Log$
   5 * Revision 1.1.1.1  1996/03/06 15:37:34  mclareni
   6 * Add geane321 source directories
   7 *
   8 *
   9 #include "geant321/pilot.h"
  10 *CMZ :  3.21/02 29/03/94  15.41.49  by  S.Giani
  11 *-- Author :
  12       SUBROUTINE ERLAND (STEP, Z, A, RHO, P, E, XMASS, DEDX2)
  13 C.
  14 C.    ******************************************************************
  15 C.    *                                                                *
  16 C.    *  Calculates energy straggling using Gaussian theory in a step  *
  17 C.    *                                                                *
  18 C.    *  Input  STEP   =  current step-length (cm)                     *
  19 C.    *         Z      =  Z of the material                            *
  20 C.    *         A      =  A of the material                            *
  21 C.    *         RHO    =  density of the material                      *
  22 C.    *         P      =  momentum of the particle                     *
  23 C.    *         E      =  energy   of the particle                     *
  24 C.    *         XMASS  =  mass     of the particle                     *
  25 C.    *                                                                *
  26 C.    *  Output DEDX2  =  mean square of the straggling in G           *
  27 C.    *                                                                *
  28 C.    *    ==>Called by : ERTRCH                                       *
  29 C.    *       Author    E.Nagy  *********                              *
  30 C.    *       Original routine : GLANDO                                *
  31 C.    *                                                                *
  32 C.    ******************************************************************
  33 C.
  34 #include "geant321/gconst.inc"
  35 *
  36       IF (STEP.LT.1.E-7) THEN
  37          DEDX2=0.
  38          RETURN
  39       ENDIF
  40 *
  41 *     Calculate xi factor (KeV).
  42       BETA   = P/E
  43       GAMMA  = E/XMASS
  44       XI     = (153.5*Z*STEP*RHO)/(A*BETA*BETA)
  45 *
  46 *     Maximum energy transfer to atomic electron (KeV).
  47       ETA    = BETA*GAMMA
  48       ETASQ  = ETA*ETA
  49       RATIO  = EMASS/XMASS
  50       F1     = 2.*EMASS*ETASQ
  51       F2     = 1.+2.*RATIO*GAMMA+RATIO*RATIO
  52       EMAX   = 1.E+6*F1/F2
  53 *
  54 *
  55 * *** and now sigma**2  in GeV
  56 *        gaussian
  57       DEDX2  = XI*EMAX*(1.-(BETA*BETA/2.))*1.E-12
  58 *
  59       END