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[u/mrichter/AliRoot.git] / GEANT321 / neutron / barier.F

*
* $Id$
*
* $Log$
* Revision 1.1.1.1  1995/10/24 10:21:54  cernlib
* Geant
*
*
#include "geant321/pilot.h"
*CMZ :  3.21/02 29/03/94  15.41.48  by  S.Giani
*-- Author :
      SUBROUTINE BARIER(KZ1,KZ2,A1,A2,CB)
C       THIS ROUTINE CALCULATES THE COULOMB BARRIER FOR A
C       COLLISION INVOLVING CHARGED PARTICLE EMISSION
      IFLG=0
C       CALCULATE THE RADIUS OF THE NUCLEUS AND CHARGED PARTICLE
      A=A1
   10 IF(A.LT.5.5)R=1.20E-13
      IF((A.GE.5.5).AND.(A.LT.6.5))R=2.02E-13
      IF((A.GE.6.5).AND.(A.LT.7.5))R=2.43E-13
      IF((A.GE.7.5).AND.(A.LT.8.5))R=2.84E-13
      IF((A.GE.8.5).AND.(A.LT.9.5))R=3.25E-13
      IF(A.GE.9.5)R=(A**(1.0/3.0))*1.70E-13
      IF(IFLG.EQ.0)R1=R
      IF(IFLG.EQ.1)GO TO 20
      IFLG=1
      A=A2
      GO TO 10
   20 R2=R
C       CALCULATE THE COULOMB BARRIER (UNITS=MEV)
C       THE FACTOR 0.75 IS ARBITRARYLY SET TO ACCOUNT FOR CHARGED
C       PARTICLE EMISSION BELOW THE COULOMB BARRIER
      CB=((KZ1*KZ2*1.44E-13)/(R1+R2))*0.75
      IF(CB.LT.0.0) CB = 0.0
      RETURN
      END