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fe4da5cc | 1 | * |
2 | * $Id$ | |
3 | * | |
4 | * $Log$ | |
5 | * Revision 1.1.1.1 1995/10/24 10:21:33 cernlib | |
6 | * Geant | |
7 | * | |
8 | * | |
9 | #include "geant321/pilot.h" | |
10 | *CMZ : 3.21/02 29/03/94 15.41.23 by S.Giani | |
11 | *-- Author : | |
12 | SUBROUTINE GPRSGA | |
13 | C. | |
14 | C. ****************************************************************** | |
15 | C. * * | |
16 | C. * Calculates cross-section in current material * | |
17 | C. * for photon pair production and muon direct pair production. * | |
18 | C. * * | |
19 | C * semiempirical cross section formula of L.Urban is used * | |
20 | C * to estimate the photon mean free path in a given material * | |
21 | C * (see WRITEUP) * | |
22 | C. * * | |
23 | C. * ==>Called by : GPHYSI * | |
24 | C. * Authors R.Brun, G.Patrick, L.Urban ********* * | |
25 | C. * * | |
26 | C. ****************************************************************** | |
27 | C. | |
28 | #include "geant321/gcbank.inc" | |
29 | #include "geant321/gconsp.inc" | |
30 | #include "geant321/gctrak.inc" | |
31 | #include "geant321/gcmate.inc" | |
32 | #include "geant321/gcjloc.inc" | |
33 | #include "geant321/gcmulo.inc" | |
34 | #include "geant321/gccuts.inc" | |
35 | C. | |
36 | C. ------------------------------------------------------------------ | |
37 | C. | |
38 | C======> A, Pair production by photons | |
39 | C ========================== | |
40 | C Cut on threshold kinetic energy. Special case for vacuum | |
41 | C | |
42 | SST=0. | |
43 | IF(Z.LT.1.)GO TO 90 | |
44 | EGAM = ELOW(IEKBIN) | |
45 | IF (EGAM.LT.0.00099) GO TO 90 | |
46 | IF (EGAM.LT.0.00199) EGAM=0.0014 | |
47 | C | |
48 | JPROB=LQ(JMA-4) | |
49 | IF(JMIXT.EQ.0)THEN | |
50 | C | |
51 | C simple material (element) | |
52 | C | |
53 | SST=GPRSGG(Z,EGAM)/A | |
54 | ELSE | |
55 | C | |
56 | C compound or mixture | |
57 | C | |
58 | NLMAT=Q(JMA+11) | |
59 | NLM=IABS(NLMAT) | |
60 | DO 10 I=1,NLM | |
61 | II=JMIXT+NLM+I | |
62 | AA=Q(II-NLM) | |
63 | ZZ=Q(II) | |
64 | W=Q(II+NLM) | |
65 | SST=SST+W*GPRSGG(ZZ,EGAM)/AA | |
66 | 10 CONTINUE | |
67 | ENDIF | |
68 | C | |
69 | SST=AVO*DENS*SST | |
70 | C | |
71 | 90 IF(SST.GT.0.)THEN | |
72 | Q(JPAIR+IEKBIN)=1./SST | |
73 | ELSE | |
74 | Q(JPAIR+IEKBIN)=BIG | |
75 | ENDIF | |
76 | C | |
77 | C======> B, Direct pair production by muons | |
78 | C =============================== | |
79 | C | |
80 | SST=0. | |
81 | IF(Z.LT.1.)GO TO 190 | |
82 | T=ELOW(IEKBIN) | |
83 | IF(T.LT.1.)GO TO 190 | |
84 | IF(T.LE.PPCUTM)GO TO 190 | |
85 | IF(JMIXT.EQ.0)THEN | |
86 | C | |
87 | C Element | |
88 | C | |
89 | SST=GPRSGM(Z,T,PPCUTM) | |
90 | SST=SST/A | |
91 | ELSE | |
92 | C | |
93 | C Compound/Mixture | |
94 | C | |
95 | NLMAT=Q(JMA+11) | |
96 | NLM =IABS(NLMAT) | |
97 | SST =0. | |
98 | DO 110 I=1,NLM | |
99 | II = JMIXT+NLM+I | |
100 | AA = Q(II-NLM) | |
101 | ZZ = Q(II) | |
102 | WMAT = Q(II+NLM) | |
103 | SST = SST+WMAT*GPRSGM(ZZ,T,PPCUTM)/AA | |
104 | 110 CONTINUE | |
105 | ENDIF | |
106 | SST=AVO*DENS*SST | |
107 | C | |
108 | 190 IF(SST.GT.0.)THEN | |
109 | Q(JPAIR+IEKBIN+NEK1)=1./SST | |
110 | ELSE | |
111 | Q(JPAIR+IEKBIN+NEK1)=BIG | |
112 | ENDIF | |
113 | C | |
114 | END |