hijing/src/hirobo.f

0001
0002 C*********************************************************************
0003 C THIS SUBROUTINE IS ONLY FOR THE USE OF HIJING TO ROTATE OR BOOST
0004 C       THE FOUR MOMENTUM ONLY
0005 C*********************************************************************
0006
0007       SUBROUTINE HIROBO(THE,PHI,BEX,BEY,BEZ)
0008
0009 C...Purpose: to perform rotations and boosts.
0010       IMPLICIT DOUBLE PRECISION(D)
0011       COMMON/LUJETS/N,K(9000,5),P(9000,5),V(9000,5)
0012       SAVE /LUJETS/
0013       COMMON/LUDAT1/MSTU(200),PARU(200),MSTJ(200),PARJ(200)
0014       SAVE /LUDAT1/
0015       DIMENSION ROT(3,3),PR(3),VR(3),DP(4),DV(4)
0016
0017 C...Find range of rotation/boost. Convert boost to double precision.
0018       IMIN=1
0019       IF(MSTU(1).GT.0) IMIN=MSTU(1)
0020       IMAX=N
0021       IF(MSTU(2).GT.0) IMAX=MSTU(2)
0022       DBX=BEX
0023       DBY=BEY
0024       DBZ=BEZ
0025
0026 C...Check range of rotation/boost.
0027       IF(IMIN.GT.MSTU(4).OR.IMAX.GT.MSTU(4)) THEN
0028         CALL LUERRM(11,'(LUROBO:) range outside LUJETS memory')
0029         RETURN
0030       ENDIF
0031
0032 C...Rotate, typically from z axis to direction (theta,phi).
0033       IF(THE**2+PHI**2.GT.1E-20) THEN
0034         ROT(1,1)=COS(THE)*COS(PHI)
0035         ROT(1,2)=-SIN(PHI)
0036         ROT(1,3)=SIN(THE)*COS(PHI)
0037         ROT(2,1)=COS(THE)*SIN(PHI)
0038         ROT(2,2)=COS(PHI)
0039         ROT(2,3)=SIN(THE)*SIN(PHI)
0040         ROT(3,1)=-SIN(THE)
0041         ROT(3,2)=0.
0042         ROT(3,3)=COS(THE)
0043         DO 130 I=IMIN,IMAX
0044         IF(K(I,1).LE.0) GOTO 130
0045         DO 110 J=1,3
0046   110   PR(J)=P(I,J)
0047         DO 120 J=1,3
0048   120   P(I,J)=ROT(J,1)*PR(1)+ROT(J,2)*PR(2)+ROT(J,3)*PR(3)
0049   130   CONTINUE
0050       ENDIF
0051
0052 C...Boost, typically from rest to momentum/energy=beta.
0053       IF(DBX**2+DBY**2+DBZ**2.GT.1E-20) THEN
0054         DB=SQRT(DBX**2+DBY**2+DBZ**2)
0055         IF(DB.GT.0.99999999D0) THEN
0056 C...Rescale boost vector if too close to unity.
0057           CALL LUERRM(3,'(LUROBO:) boost vector too large')
0058           DBX=DBX*(0.99999999D0/DB)
0059           DBY=DBY*(0.99999999D0/DB)
0060           DBZ=DBZ*(0.99999999D0/DB)
0061           DB=0.99999999D0
0062         ENDIF
0063         DGA=1D0/SQRT(1D0-DB**2)
0064         DO 150 I=IMIN,IMAX
0065         IF(K(I,1).LE.0) GOTO 150
0066         DO 140 J=1,4
0067   140   DP(J)=P(I,J)
0068         DBP=DBX*DP(1)+DBY*DP(2)+DBZ*DP(3)
0069         DGABP=DGA*(DGA*DBP/(1D0+DGA)+DP(4))
0070         P(I,1)=DP(1)+DGABP*DBX
0071         P(I,2)=DP(2)+DGABP*DBY
0072         P(I,3)=DP(3)+DGABP*DBZ
0073         P(I,4)=DGA*(DP(4)+DBP)
0074   150   CONTINUE
0075       ENDIF
0076
0077       RETURN
0078       END