Bugfix in AliPoints2Memory
[u/mrichter/AliRoot.git] / GEANT321 / gphys / gcompi.F
CommitLineData
fe4da5cc 1*
2* $Id$
3*
4* $Log$
5* Revision 1.1.1.1 1995/10/24 10:21:23 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 GCOMPI
13C.
14C. ******************************************************************
15C. * *
16C. * Calculates cross-section in current material *
17C. * for COMPTON scattering. *
18C. * *
19C. * The total cross-section of L.Urban is used to estimate the *
20C. * photon mean free path. *
21C. * It gives a good description of the data from 10KeV to *
22C. * 100/Z GeV *
23C. * *
24C. * ==>Called by : GPHYSI *
25C. * Authors R.Brun, L.Urban ********* *
26C. * *
27C. ******************************************************************
28C.
29#include "geant321/gcbank.inc"
30#include "geant321/gctrak.inc"
31#include "geant321/gconsp.inc"
32#include "geant321/gcmate.inc"
33#include "geant321/gcjloc.inc"
34#include "geant321/gcmulo.inc"
35 DIMENSION PCOMP(12),P(4)
36 DATA AC,BC,CC/20.,230.,440./
37 DATA PCOMP/ 0.27965,-0.18300,0.67527E+1,-0.19798E+2,
38 + 0.19756E-4,-0.10205E-1,-0.73913E-1,0.27079E-1,
39 + -0.39178E-6,0.68241E-4,0.60480E-4,0.30274E-3/
40 DATA PI2R2I/2.004275/
41C.
42C. ------------------------------------------------------------------
43C.
44C Energy cut-off above which we ignore COMPTON scattering.
45C
46 SIG=0.
47 IF(Z.LT.1.)GO TO 90
48 EGAM = ELOW(IEKBIN)
49 X=EGAM/EMASS
50 IF(EGAM.GT.(100./Z))GO TO 90
51 X2=X*X
52 JPROB=LQ(JMA-4)
53C
54 DO 20 I=1,4
55 C=1.
56 P(I)=0.
57 DO 10 J=1,3
58 JJ=4*J+I-4
59 P(I)=P(I)+C*PCOMP(JJ)
60 C=C*Z
61 10 CONTINUE
62 20 CONTINUE
63C
64 SIG=P(1)*LOG(1.+2.*X)/X
65 SIG=SIG+(P(2)+P(3)*X+P(4)*X2)/(1.+AC*X+BC*X2+CC*X2*X)
66 SIG=PI2R2I*Q(JPROB+17)*SIG
67C
68 90 IF(SIG.GT.0.)THEN
69 Q(JCOMP+IEKBIN)=1./SIG
70 ELSE
71 Q(JCOMP+IEKBIN)=BIG
72 ENDIF
73C
74 END