HIJING/hijing1_36/hijels.F

   1 * $Id$
   2 C
   3 C
   4 C*******************************************************************
   5 CThis subroutine performs elastic scattering between two nucleons
   6 C
   7 C*******************************************************************
   8         SUBROUTINE HIJELS(PSC1,PSC2)
   9         IMPLICIT DOUBLE PRECISION(D)
  10         DIMENSION PSC1(5),PSC2(5)
  11 #include "hiparnt.inc"
  12         SAVE
  13 C
  14         CC=1.0-HINT1(12)/HINT1(13)
  15         RR=(1.0-CC)*HINT1(13)/HINT1(12)/(1.0-HIPR1(33))-1.0
  16         BB=0.5*(3.0+RR+SQRT(9.0+10.0*RR+RR**2))
  17         EP=SQRT((PSC1(1)-PSC2(1))**2+(PSC1(2)-PSC2(2))**2
  18      &          +(PSC1(3)-PSC2(3))**2)
  19         IF(EP.LE.0.1) RETURN
  20         ELS0=98.0/EP+52.0*(1.0+RR)**2
  21         PCM1=PSC1(1)+PSC2(1)
  22         PCM2=PSC1(2)+PSC2(2)
  23         PCM3=PSC1(3)+PSC2(3)
  24         ECM=PSC1(4)+PSC2(4)
  25         AM1=PSC1(5)**2
  26         AM2=PSC2(5)**2
  27         AMM=ECM**2-PCM1**2-PCM2**2-PCM3**2
  28         IF(AMM.LE.PSC1(5)+PSC2(5)) RETURN
  29 C               ********elastic scattering only when approaching
  30 C                               to each other
  31         PMAX=(AMM**2+AM1**2+AM2**2-2.0*AMM*AM1-2.0*AMM*AM2
  32      &                  -2.0*AM1*AM2)/4.0/AMM
  33         PMAX=ABS(PMAX)
  34 20      TT=RLU_HIJING(0)*MIN(PMAX,1.5)
  35         ELS=98.0*EXP(-2.8*TT)/EP
  36      &          +52.0*EXP(-9.2*TT)*(1.0+RR*EXP(-4.6*(BB-1.0)*TT))**2
  37         IF(RLU_HIJING(0).GT.ELS/ELS0) GO TO 20
  38         PHI=2.0*HIPR1(40)*RLU_HIJING(0)
  39 C
  40         DBX=PCM1/ECM
  41         DBY=PCM2/ECM
  42         DBZ=PCM3/ECM
  43         DB=SQRT(DBX**2+DBY**2+DBZ**2)
  44         IF(DB.GT.0.99999999D0) THEN
  45           DBX=DBX*(0.99999999D0/DB)
  46           DBY=DBY*(0.99999999D0/DB)
  47           DBZ=DBZ*(0.99999999D0/DB)
  48           DB=0.99999999D0
  49           WRITE(6,*) ' (HIJELS) boost vector too large'
  50 C               ********Rescale boost vector if too close to unity.
  51         ENDIF
  52         DGA=1D0/SQRT(1D0-DB**2)
  53 C
  54         DP1=SQRT(TT)*SIN(PHI)
  55         DP2=SQRT(TT)*COS(PHI)
  56         DP3=SQRT(PMAX-TT)
  57         DP4=SQRT(PMAX+AM1)
  58         DBP=DBX*DP1+DBY*DP2+DBZ*DP3
  59         DGABP=DGA*(DGA*DBP/(1D0+DGA)+DP4)
  60         PSC1(1)=DP1+DGABP*DBX
  61         PSC1(2)=DP2+DGABP*DBY
  62         PSC1(3)=DP3+DGABP*DBZ
  63         PSC1(4)=DGA*(DP4+DBP)
  64 C
  65         DP1=-SQRT(TT)*SIN(PHI)
  66         DP2=-SQRT(TT)*COS(PHI)
  67         DP3=-SQRT(PMAX-TT)
  68         DP4=SQRT(PMAX+AM2)
  69         DBP=DBX*DP1+DBY*DP2+DBZ*DP3
  70         DGABP=DGA*(DGA*DBP/(1D0+DGA)+DP4)
  71         PSC2(1)=DP1+DGABP*DBX
  72         PSC2(2)=DP2+DGABP*DBY
  73         PSC2(3)=DP3+DGABP*DBZ
  74         PSC2(4)=DGA*(DP4+DBP)
  75         RETURN
  76         END