| 1 | SUBROUTINE MUDECY
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| 2 |
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| 3 | C-----------------------------------------------------------------------
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| 4 | C MU(ON) DEC(A)Y
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| 5 | C
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| 6 | C TREATES DECAY OF MUON INTO ELECTRON (INCLUDING POLARISATION EFFECTS)
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| 7 | C INCLUDING NEUTRINOS, IF SELECTED
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| 8 | C THIS SUBROUTINE IS CALLED FROM MUTRAC
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| 9 | C
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| 10 | C DESIGN : D. HECK IK3 FZK KARLSRUHE
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| 11 | C-----------------------------------------------------------------------
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| 12 |
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| 13 | IMPLICIT NONE
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| 14 | *KEEP,CONST.
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| 15 | COMMON /CONST/ PI,PI2,OB3,TB3,ENEPER
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| 16 | DOUBLE PRECISION PI,PI2,OB3,TB3,ENEPER
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| 17 | *KEEP,GENER.
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| 18 | COMMON /GENER/ GEN,ALEVEL
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| 19 | DOUBLE PRECISION GEN,ALEVEL
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| 20 | *KEEP,PAM.
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| 21 | COMMON /PAM/ PAMA,SIGNUM
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| 22 | DOUBLE PRECISION PAMA(6000),SIGNUM(6000)
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| 23 | *KEEP,PARPAR.
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| 24 | COMMON /PARPAR/ CURPAR,SECPAR,PRMPAR,OUTPAR,C,
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| 25 | * E00,E00PN,PTOT0,PTOT0N,THICKH,ITYPE,LEVL
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| 26 | DOUBLE PRECISION CURPAR(14),SECPAR(14),PRMPAR(14),OUTPAR(14),
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| 27 | * C(50),E00,E00PN,PTOT0,PTOT0N,THICKH
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| 28 | INTEGER ITYPE,LEVL
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| 29 | *KEEP,PARPAE.
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| 30 | DOUBLE PRECISION GAMMA,COSTHE,PHI,H,T,X,Y,CHI,BETA,GCM,ECM
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| 31 | EQUIVALENCE (CURPAR(2),GAMMA), (CURPAR(3),COSTHE),
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| 32 | * (CURPAR(4), PHI ), (CURPAR(5), H ),
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| 33 | * (CURPAR(6), T ), (CURPAR(7), X ),
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| 34 | * (CURPAR(8), Y ), (CURPAR(9), CHI ),
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| 35 | * (CURPAR(10),BETA), (CURPAR(11),GCM ),
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| 36 | * (CURPAR(12),ECM )
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| 37 | *KEEP,POLAR.
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| 38 | COMMON /POLAR/ POLART,POLARF
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| 39 | DOUBLE PRECISION POLART,POLARF
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| 40 | *KEEP,RANDPA.
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| 41 | COMMON /RANDPA/ FAC,U1,U2,RD,NSEQ,ISEED,KNOR
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| 42 | DOUBLE PRECISION FAC,U1,U2
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| 43 | REAL RD(3000)
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| 44 | INTEGER ISEED(103,10),NSEQ
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| 45 | LOGICAL KNOR
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| 46 | *KEEP,RUNPAR.
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| 47 | COMMON /RUNPAR/ FIXHEI,THICK0,HILOECM,HILOELB,
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| 48 | * STEPFC,NRRUN,NSHOW,PATAPE,MONIIN,
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| 49 | * MONIOU,MDEBUG,NUCNUC,
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| 50 | * CETAPE,
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| 51 | * SHOWNO,ISHW,NOPART,NRECS,NBLKS,MAXPRT,NDEBDL,
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| 52 | * N1STTR,MDBASE,
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| 53 | * DEBDEL,DEBUG,FDECAY,FEGS,FIRSTI,FIXINC,FIXTAR,
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| 54 | * FIX1I,FMUADD,FNKG,FPRINT,FDBASE
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| 55 | * ,GHEISH,GHESIG
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| 56 | COMMON /RUNPAC/ DSN,HOST,USER
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| 57 | DOUBLE PRECISION FIXHEI,THICK0,HILOECM,HILOELB
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| 58 | REAL STEPFC
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| 59 | INTEGER NRRUN,NSHOW,PATAPE,MONIIN,MONIOU,MDEBUG,NUCNUC,
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| 60 | * SHOWNO,ISHW,NOPART,NRECS,NBLKS,MAXPRT,NDEBDL,
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| 61 | * N1STTR,MDBASE
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| 62 | INTEGER CETAPE
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| 63 | CHARACTER*79 DSN
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| 64 | CHARACTER*20 HOST,USER
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| 65 |
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| 66 | LOGICAL DEBDEL,DEBUG,FDECAY,FEGS,FIRSTI,FIXINC,FIXTAR,
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| 67 | * FIX1I,FMUADD,FNKG,FPRINT,FDBASE
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| 68 | * ,GHEISH,GHESIG
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| 69 | *KEND.
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| 70 |
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| 71 | DOUBLE PRECISION AUX2,COSDE,COSTH3,COS3CM,COS3C1,COS3C2,
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| 72 | * E3CM,GAMMA3,PHI3CM,PHI3C2,PHI31,
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| 73 | * P3CM,XI
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| 74 | INTEGER I
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| 75 | C-----------------------------------------------------------------------
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| 76 |
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| 77 | IF ( DEBUG ) WRITE(MDEBUG,444) (CURPAR(I),I=1,9)
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| 78 | 444 FORMAT(' MUDECY: CURPAR=',1P,9E10.3)
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| 79 |
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| 80 | C MUON DECAYS INTO ELECTRON AND NEUTRINOS
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| 81 | XI = 2*ITYPE - 11
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| 82 | C ELECTRON ENERGY SPECTRUM N(E) * DE = CONST * E**2 * (3/2*E0-E) * DE
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| 83 | C IS GAINED BY THE REJECTION/REFLECTION METHOD
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| 84 | 6 CALL RMMAR( RD,4,1 )
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| 85 | IF ( RD(1)**2*(3.-RD(1)*2.) .LT. RD(2) ) RD(1) = 1.-RD(1)
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| 86 | E3CM = PAMA(2) + RD(1) * ( C(8) - PAMA(2) )
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| 87 | IF ( E3CM .GT. 0.5D0*PAMA(5) ) GOTO 6
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| 88 | P3CM = SQRT( E3CM**2 - PAMA(2)**2 )
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| 89 | C NOW DETERMINE COS3C1 AND PHI31 BY RANDOM SELECTION
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| 90 | C WITH RESPECT TO THE POLARIZATION DIRECTION OF THE MUON IN THE MU CM
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| 91 | C GIVEN BY POLART, POLARF
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| 92 | COSDE = 2.D0 * RD(4) - 1.D0
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| 93 | AUX2 = ( 1. - 2.*RD(1) ) / ( 3. - 2.*RD(1) )
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| 94 | IF ( ABS(AUX2) .GT. 1.D-2 ) THEN
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| 95 | COS3C1 = XI*(SQRT(1.D0-(2.D0*COSDE-AUX2)*AUX2) - 1.D0) / AUX2
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| 96 | ELSE
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| 97 | COS3C1 = -XI * COSDE
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| 98 | ENDIF
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| 99 | PHI31 = RD(3)*PI2
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| 100 |
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| 101 | C NOW ADD ELECTRON EMISSION ANGLE COS3C1 TO THE POLARISATION DIRECTION
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| 102 | C TO GET THE DIRECTION (RELATIVE TO THE CORSIKA COORDINATE SYSTEM)
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| 103 | CALL ADDANG( POLART,POLARF, COS3C1,PHI31, COS3C2,PHI3C2 )
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| 104 | C GET THE ELECTRON DIRECTION RELATIVE TO THE MUON LAB DIRECTION
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| 105 | CALL ADDANI( CURPAR(3),CURPAR(4), COS3C2,PHI3C2, COS3CM,PHI3CM )
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| 106 | C LORENTZ TRANSFORMATION TO THE LAB SYSTEM
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| 107 | GAMMA3 = GAMMA * ( E3CM + BETA * P3CM * COS3CM ) / PAMA(2)
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| 108 | COSTH3 = MIN( 1.D0, GAMMA * (P3CM * COS3CM + BETA * E3CM) /
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| 109 | * (PAMA(2) * SQRT(GAMMA3**2 - 1.D0)) )
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| 110 | CALL ADDANG( CURPAR(3),CURPAR(4), COSTH3,PHI3CM,
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| 111 | * SECPAR(3),SECPAR(4) )
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| 112 | IF ( SECPAR(3) .GE. C(29) ) THEN
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| 113 | SECPAR(1) = ITYPE - 3
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| 114 | SECPAR(2) = GAMMA3
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| 115 | DO 10 I = 5,8
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| 116 | SECPAR(I) = CURPAR(I)
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| 117 | 10 CONTINUE
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| 118 | SECPAR( 9) = GEN
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| 119 | SECPAR(10) = ALEVEL
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| 120 | CALL TSTACK
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| 121 | ENDIF
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| 122 | POLART = 0.D0
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| 123 | POLARF = 0.D0
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| 124 |
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| 125 | RETURN
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| 126 | END
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