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fe4da5cc | 1 | * |
2 | * $Id$ | |
3 | * | |
4 | * $Log$ | |
5 | * Revision 1.1.1.1 1995/10/24 10:21:21 cernlib | |
6 | * Geant | |
7 | * | |
8 | * | |
9 | #include "geant321/pilot.h" | |
10 | *CMZ : 3.21/02 29/03/94 15.41.21 by S.Giani | |
11 | *-- Author : | |
12 | SUBROUTINE GANNII | |
13 | C. | |
14 | C. ****************************************************************** | |
15 | C. * * | |
16 | C. * Calculates cross-section in current material * | |
17 | C. * for positron annihilation * | |
18 | C. * * | |
19 | C. * ==>Called by : GPHYSI * | |
20 | C. * Authors R.Brun, L.Urban ********* * | |
21 | C. * 10/06/93: modified by Georges Azuelos (Vancouver) * | |
22 | C * to include 1-quantum annihilation * | |
23 | C. * * | |
24 | C. ****************************************************************** | |
25 | C. | |
26 | #include "geant321/gcbank.inc" | |
27 | #include "geant321/gctrak.inc" | |
28 | #include "geant321/gcmate.inc" | |
29 | #include "geant321/gconsp.inc" | |
30 | #include "geant321/gcjloc.inc" | |
31 | #include "geant321/gcmulo.inc" | |
32 | C. | |
33 | C. ------------------------------------------------------------------ | |
34 | C. | |
35 | SIG=0. | |
36 | IF(Z.GE.1.) THEN | |
37 | XE=ELOW(IEKBIN)+EMASS | |
38 | GAM=XE/EMASS | |
39 | GAM2=GAM**2 | |
40 | GAM1=MAX(GAM2-1.,0.) | |
41 | C=SQRT(GAM1) | |
42 | * | |
43 | SIG=(GAM2+4.*GAM+1.)*LOG(GAM+C)/GAM1-(GAM+3.)/C | |
44 | SIG=0.5*Q(JPROB+17)*SIG/(GAM+1.) | |
45 | PE=SQRT((XE-EMASS)*(XE+EMASS)) | |
46 | * | |
47 | GVE=PE/EMASS | |
48 | SIG1=GAM2+2.*(GAM+2.)/3.-(GAM+2.)/GVE*LOG(GAM+GVE) | |
49 | SIG1=2.*Q(JPROB+18)*SIG1/(GVE*(GAM+1.)**2) | |
50 | * | |
51 | SIG=SIG+SIG1 | |
52 | ENDIF | |
53 | IF(SIG.GT.0.)THEN | |
54 | Q(JANNI+IEKBIN)=1./SIG | |
55 | ELSE | |
56 | Q(JANNI+IEKBIN)=BIG | |
57 | ENDIF | |
58 | C | |
59 | END |