| 1 | SUBROUTINE ANNIH
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| 2 | C VERSION 4.00 -- 26 JAN 1986/1900
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| 3 | C******************************************************************
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| 4 | C GAMMA SPECTRUM FOR TWO GAMMA IN-FLIGHT POSITRON ANNIHILATION.
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| 5 | C USING SCHEME BASED ON HEITLER'S P269-270 FORMULAE
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| 6 | C THIS ROUTINE SHOULD GIVE THE CORRECT DISTRIBUTION, BUT MORE
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| 7 | C THOUGHT COULD BE PUT INTO DEVISING A FASTER SCHEME. HOWEVER,
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| 8 | C SINCE POSITRON ANNIHILATION IN FLIGHT IS RELATIVELY INFREQUENT
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| 9 | C THIS MAY NOT BE WORTHWHILE.
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| 10 | C******************************************************************
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| 11 | DOUBLE PRECISION PAVIP
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| 12 | *KEEP,RANDPA.
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| 13 | COMMON /RANDPA/ FAC,U1,U2,RD,NSEQ,ISEED,KNOR
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| 14 | DOUBLE PRECISION FAC,U1,U2
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| 15 | REAL RD(3000)
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| 16 | INTEGER ISEED(103,10),NSEQ
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| 17 | LOGICAL KNOR
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| 18 | *KEEP,RUNPAR.
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| 19 | COMMON /RUNPAR/ FIXHEI,THICK0,HILOECM,HILOELB,
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| 20 | * STEPFC,NRRUN,NSHOW,PATAPE,MONIIN,
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| 21 | * MONIOU,MDEBUG,NUCNUC,
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| 22 | * CETAPE,
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| 23 | * SHOWNO,ISHW,NOPART,NRECS,NBLKS,MAXPRT,NDEBDL,
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| 24 | * N1STTR,MDBASE,
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| 25 | * DEBDEL,DEBUG,FDECAY,FEGS,FIRSTI,FIXINC,FIXTAR,
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| 26 | * FIX1I,FMUADD,FNKG,FPRINT,FDBASE
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| 27 | * ,GHEISH,GHESIG
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| 28 | COMMON /RUNPAC/ DSN,HOST,USER
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| 29 | DOUBLE PRECISION FIXHEI,THICK0,HILOECM,HILOELB
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| 30 | REAL STEPFC
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| 31 | INTEGER NRRUN,NSHOW,PATAPE,MONIIN,MONIOU,MDEBUG,NUCNUC,
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| 32 | * SHOWNO,ISHW,NOPART,NRECS,NBLKS,MAXPRT,NDEBDL,
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| 33 | * N1STTR,MDBASE
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| 34 | INTEGER CETAPE
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| 35 | CHARACTER*79 DSN
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| 36 | CHARACTER*20 HOST,USER
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| 37 |
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| 38 | LOGICAL DEBDEL,DEBUG,FDECAY,FEGS,FIRSTI,FIXINC,FIXTAR,
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| 39 | * FIX1I,FMUADD,FNKG,FPRINT,FDBASE
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| 40 | * ,GHEISH,GHESIG
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| 41 | *KEEP,STACKE.
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| 42 | COMMON/STACKE/ E,TIME,X,Y,Z,U,V,W,DNEAR,IQ,IGEN,IR,IOBS,LPCTE,NP
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| 43 | DOUBLE PRECISION E(60),TIME(60)
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| 44 | REAL X(60),Y(60),Z(60),U(60),V(60),W(60),DNEAR(60)
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| 45 | INTEGER IQ(60),IGEN(60),IR(60),IOBS(60),LPCTE(60),NP
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| 46 | *KEND.
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| 47 | COMMON/UPHIOT/THETA,SINTHE,COSTHE,SINPHI, COSPHI,PI,TWOPI,PI5D2
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| 48 | DOUBLE PRECISION PZERO,PRM,PRMT2,RMI,VC
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| 49 | COMMON/USEFUL/PZERO,PRM,PRMT2,RMI,VC,RM,MEDIUM,MEDOLD,IBLOBE,ICALL
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| 50 | COMMON/ACLOCK/NCLOCK,JCLOCK
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| 51 | C_____IF (NCLOCK.GT.JCLOCK) THEN
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| 52 | C______WRITE(MDEBUG,* )' ANNIH: NP=',NP,' IR=',IR(NP),' IOBS=',IOBS(NP)
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| 53 | C______CALL AUSGB2
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| 54 | C_____END IF
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| 55 | PAVIP=E(NP)+PRM
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| 56 | AVIP=PAVIP
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| 57 | A=AVIP*RMI
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| 58 | AI=1.0/A
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| 59 | G=A-1.0
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| 60 | T=G-1.0
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| 61 | P=SQRT(A*T)
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| 62 | POT=P/T
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| 63 | EP0I=(A+P)
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| 64 | 331 CONTINUE
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| 65 | CALL RMMAR(RD,2,2)
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| 66 | RNNO01=RD(1)
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| 67 | RNNO02=RD(2)
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| 68 | EP=EXP(RNNO01*LOG(EP0I-1.0))/EP0I
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| 69 | REJF=1.0-EP+AI*AI*(2.0*G-1.0/EP)
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| 70 | IF((RNNO02.LE.REJF))GO TO332
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| 71 | GO TO 331
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| 72 | 332 CONTINUE
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| 73 | ESG1=AVIP*MAX(EP,1.-EP)
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| 74 | E(NP)=ESG1
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| 75 | E(NP+1)=PAVIP-E(NP)
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| 76 | ESG2=E(NP+1)
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| 77 | IQ(NP)=1
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| 78 | COSTHE=(ESG1-RM)*POT/ESG1
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| 79 | SINTHE=SQRT(MAX(1.0-COSTHE*COSTHE,0.))
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| 80 | CALL UPHI(2,1)
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| 81 | NP=NP+1
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| 82 | IQ(NP)=1
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| 83 | COSTHE=(ESG2-RM)*POT/ESG2
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| 84 | SINTHE=SQRT(MAX(1.0-COSTHE*COSTHE,0.))
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| 85 | CALL UPHI(3,2)
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| 86 | RETURN
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| 87 | END
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