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fe4da5cc | 1 | * |
2 | * $Id$ | |
3 | * | |
4 | * $Log$ | |
5 | * Revision 1.1.1.1 1995/10/24 10:21:28 cernlib | |
6 | * Geant | |
7 | * | |
8 | * | |
9 | #include "geant321/pilot.h" | |
10 | *CMZ : 3.21/02 29/03/94 15.41.22 by S.Giani | |
11 | *-- Author : | |
12 | SUBROUTINE GPAIRM | |
13 | C. | |
14 | C. ****************************************************************** | |
15 | C. * * | |
16 | C. * Simulates direct pair production by muons * | |
17 | C. * * | |
18 | C. * ==>Called by : GTMUON * | |
19 | C. * Author L.Urban ********* * | |
20 | C. * * | |
21 | C. ****************************************************************** | |
22 | C. | |
23 | #include "geant321/gcbank.inc" | |
24 | #include "geant321/gconsp.inc" | |
25 | #include "geant321/gctrak.inc" | |
26 | #include "geant321/gcmate.inc" | |
27 | #include "geant321/gckine.inc" | |
28 | #include "geant321/gcking.inc" | |
29 | #include "geant321/gcphys.inc" | |
30 | #include "geant321/gccuts.inc" | |
31 | DIMENSION RNDM(2) | |
32 | LOGICAL ROTATE | |
33 | C | |
34 | C CVM= 3*SQRT(e)*EMMU/4 | |
35 | C EM6= 6*EMMU**2 | |
36 | DATA CVM,EM6/0.130652,0.066983/ | |
37 | DATA AL10T/9.212/ | |
38 | C. | |
39 | C. ------------------------------------------------------------------ | |
40 | C. | |
41 | IF(GEKIN.LE.PPCUTM)GO TO 900 | |
42 | EEM1=GETOT | |
43 | KCASE=NAMEC(6) | |
44 | C | |
45 | VMIN=4*EMASS/EEM1 | |
46 | VMAX=1.-CVM*Z**0.333333/EEM1 | |
47 | IF(VMAX.LE.VMIN)GO TO 900 | |
48 | VC = PPCUTM/EEM1 | |
49 | ALE=LOG(EEM1) | |
50 | ALFA=1.+ALE/AL10T | |
51 | V0=0.18*(4.+ALE/AL10T)*ALFA*(ALFA*VMIN)**0.6666667 | |
52 | BETA=0.1*(1.+3.*ALE/AL10T) | |
53 | B=0.9/(1.+0.4*ALE+0.022*ALE*ALE) | |
54 | AA=1.+2.*B*LOG(VC/V0) | |
55 | IF(AA.LE.1.) AA=1.05 | |
56 | A1=1.-AA | |
57 | CC=EXP(-0.25*A1*A1/B) | |
58 | A1R=1./A1 | |
59 | C1=VMAX**A1 | |
60 | C2=VC**A1 | |
61 | C | |
62 | C SAMPLE V AND RO | |
63 | C | |
64 | 50 CALL GRNDM(RNDM,2) | |
65 | R=RNDM(1) | |
66 | V=(R*C1+(1.-R)*C2)**A1R | |
67 | IF(V.LE.VMIN) GOTO 50 | |
68 | IF(V.LT.V0) THEN | |
69 | SCREJ=CC*((V-VMIN)/(V0-VMIN))**BETA*(V0/V)**A1 | |
70 | ELSE | |
71 | SCREJ=CC*(V0/V)**(A1+B*LOG(V/V0)) | |
72 | ENDIF | |
73 | IF(RNDM(2).GT.SCREJ) GOTO 50 | |
74 | R0MAX= SCREJ*(1.-EM6/(EEM1**2*(1.-V))) | |
75 | CALL GRNDM(RNDM,2) | |
76 | R0 = R0MAX*(2.*RNDM(1)-1.) | |
77 | C | |
78 | C Energies | |
79 | C | |
80 | EPP = V*EEM1 | |
81 | IF(IPAIR.NE.1)THEN | |
82 | NGKINE=0 | |
83 | DESTEP=DESTEP+EPP | |
84 | GO TO 60 | |
85 | ENDIF | |
86 | EPOS = 0.5*EPP*(1.+R0) | |
87 | EMIN = EPP-EPOS | |
88 | C | |
89 | C Angles | |
90 | C | |
91 | THETA = AMASS/EEM1 | |
92 | SINTH = SIN(THETA) | |
93 | COSTH = COS(THETA) | |
94 | PHI = TWOPI*RNDM(2) | |
95 | COSPHI= COS(PHI) | |
96 | SINPHI= SIN(PHI) | |
97 | C | |
98 | CALL GFANG(VECT(4),COSAL,SINAL,COSBT,SINBT,ROTATE) | |
99 | C | |
100 | C Positron | |
101 | C | |
102 | NGKINE = 0 | |
103 | TPOS = EPOS-EMASS | |
104 | IF(TPOS.GT.CUTELE)THEN | |
105 | PPOS = SQRT((EPOS+EMASS)*TPOS) | |
106 | NGKINE= NGKINE+1 | |
107 | GKIN(1,NGKINE)=PPOS*SINTH*COSPHI | |
108 | GKIN(2,NGKINE)=PPOS*SINTH*SINPHI | |
109 | GKIN(3,NGKINE)=PPOS*COSTH | |
110 | GKIN(4,NGKINE)=EPOS | |
111 | GKIN(5,NGKINE)=2. | |
112 | TOFD(NGKINE)=0. | |
113 | GPOS(1,NGKINE) = VECT(1) | |
114 | GPOS(2,NGKINE) = VECT(2) | |
115 | GPOS(3,NGKINE) = VECT(3) | |
116 | IF(ROTATE) | |
117 | + CALL GDROT(GKIN(1,NGKINE),COSAL,SINAL,COSBT,SINBT) | |
118 | ELSE | |
119 | DESTEP=DESTEP+TPOS | |
120 | CALL GANNI2 | |
121 | ENDIF | |
122 | C | |
123 | C Electron | |
124 | C | |
125 | TMIN=EMIN-EMASS | |
126 | IF(TMIN.GT.CUTELE)THEN | |
127 | PMIN = SQRT((EMIN+EMASS)*TMIN) | |
128 | NGKINE= NGKINE+1 | |
129 | GKIN(1,NGKINE)=-PMIN*SINTH*COSPHI | |
130 | GKIN(2,NGKINE)=-PMIN*SINTH*SINPHI | |
131 | GKIN(3,NGKINE)=PMIN*COSTH | |
132 | GKIN(4,NGKINE)=EMIN | |
133 | GKIN(5,NGKINE)=3. | |
134 | TOFD(NGKINE)=0. | |
135 | GPOS(1,NGKINE) = VECT(1) | |
136 | GPOS(2,NGKINE) = VECT(2) | |
137 | GPOS(3,NGKINE) = VECT(3) | |
138 | IF(ROTATE) | |
139 | + CALL GDROT(GKIN(1,NGKINE),COSAL,SINAL,COSBT,SINBT) | |
140 | ELSE | |
141 | DESTEP=DESTEP+TMIN | |
142 | ENDIF | |
143 | C | |
144 | C Correct muon track | |
145 | C | |
146 | 60 GEKIN = GEKIN-EPP | |
147 | GETOT = GEKIN+AMASS | |
148 | VECT(7)= SQRT((GETOT+AMASS)*GEKIN) | |
149 | CALL GEKBIN | |
150 | C | |
151 | C Update probabilities | |
152 | C | |
153 | 900 CALL GRNDM(RNDM,1) | |
154 | ZINTPA = -LOG(RNDM(1)) | |
155 | SLPAIR = SLENG | |
156 | STEPPA = BIG | |
157 | C | |
158 | END |