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