hijing/src/pyhiovly.f

0001
0002 C*********************************************************************
0003
0004       SUBROUTINE PYHIOVLY(MOVLY)
0005
0006 C...Initializes multiplicity distribution and selects mutliplicity
0007 C...of overlayed events, i.e. several events occuring at the same
0008 C...beam crossing.
0009       COMMON/LUDAT1/MSTU(200),PARU(200),MSTJ(200),PARJ(200)
0010       SAVE /LUDAT1/
0011       COMMON/PYHIPARS/MSTP(200),PARP(200),MSTI(200),PARI(200)
0012       SAVE /PYHIPARS/
0013       COMMON/PYHIINT1/MINT(400),VINT(400)
0014       SAVE /PYHIINT1/
0015       DIMENSION WTI(0:100)
0016       SAVE IMAX,WTI,WTS
0017
0018 C...Sum of allowed cross-sections for overlayed events.
0019       IF(MOVLY.EQ.1) THEN
0020         VINT(131)=VINT(106)
0021         IF(MSTP(132).GE.2) VINT(131)=VINT(131)+VINT(104)
0022         IF(MSTP(132).GE.3) VINT(131)=VINT(131)+VINT(103)
0023         IF(MSTP(132).GE.4) VINT(131)=VINT(131)+VINT(102)
0024
0025 C...Initialize multiplicity distribution for unbiased events.
0026         IF(MSTP(133).EQ.1) THEN
0027           XNAVE=VINT(131)*PARP(131)
0028           IF(XNAVE.GT.40.) WRITE(MSTU(11),1000) XNAVE
0029           WTI(0)=EXP(-MIN(50.,XNAVE))
0030           WTS=0.
0031           WTN=0.
0032           DO 100 I=1,100
0033           WTI(I)=WTI(I-1)*XNAVE/I
0034           IF(I-2.5.GT.XNAVE.AND.WTI(I).LT.1E-6) GOTO 110
0035           WTS=WTS+WTI(I)
0036           WTN=WTN+WTI(I)*I
0037   100     IMAX=I
0038   110     VINT(132)=XNAVE
0039           VINT(133)=WTN/WTS
0040           VINT(134)=WTS
0041
0042 C...Initialize mutiplicity distribution for biased events.
0043         ELSEIF(MSTP(133).EQ.2) THEN
0044           XNAVE=VINT(131)*PARP(131)
0045           IF(XNAVE.GT.40.) WRITE(MSTU(11),1000) XNAVE
0046           WTI(1)=EXP(-MIN(50.,XNAVE))*XNAVE
0047           WTS=WTI(1)
0048           WTN=WTI(1)
0049           DO 120 I=2,100
0050           WTI(I)=WTI(I-1)*XNAVE/(I-1)
0051           IF(I-2.5.GT.XNAVE.AND.WTI(I).LT.1E-6) GOTO 130
0052           WTS=WTS+WTI(I)
0053           WTN=WTN+WTI(I)*I
0054   120     IMAX=I
0055   130     VINT(132)=XNAVE
0056           VINT(133)=WTN/WTS
0057           VINT(134)=WTS
0058         ENDIF
0059
0060 C...Pick multiplicity of overlayed events.
0061       ELSE
0062         IF(MSTP(133).EQ.0) THEN
0063           MINT(81)=MAX(1,MSTP(134))
0064         ELSE
0065           WTR=WTS*RLU(0)
0066           DO 140 I=1,IMAX
0067           MINT(81)=I
0068           WTR=WTR-WTI(I)
0069           IF(WTR.LE.0.) GOTO 150
0070   140     CONTINUE
0071   150     CONTINUE
0072         ENDIF
0073       ENDIF
0074
0075 C...Format statement for error message.
0076  1000 FORMAT(1X,'Warning: requested average number of events per bunch',
0077      &'crossing too large, ',1P,E12.4)
0078
0079       RETURN
0080       END