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fe4da5cc | 1 | * |
2 | * $Id$ | |
3 | * | |
4 | * $Log$ | |
5 | * Revision 1.1.1.1 1995/10/24 10:21:41 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 GHELX3 (FIELD, STEP, VECT, VOUT) | |
13 | C. | |
14 | C. ****************************************************************** | |
15 | C. * * | |
16 | C. * Tracking routine in a constant field oriented * | |
17 | C. * along axis 3 * | |
18 | C. * Tracking is performed with a conventional * | |
19 | C. * helix step method * | |
20 | C. * * | |
21 | C. * ==>Called by : <USER>, GUSWIM * | |
22 | C. * Authors R.Brun, M.Hansroul ********* * | |
23 | C * Rewritten V.Perevoztchikov | |
24 | C. * * | |
25 | C. ****************************************************************** | |
26 | C. | |
27 | DIMENSION VECT(7),VOUT(7),HXP(3) | |
28 | PARAMETER (IX=1,IY=2,IZ=3,IPX=4,IPY=5,IPZ=6,IPP=7) | |
29 | PARAMETER (SIXTH = 1./6.) | |
30 | PARAMETER (EC=2.9979251E-4) | |
31 | C. | |
32 | C. ------------------------------------------------------------------ | |
33 | C. | |
34 | C units are kgauss,centimeters,gev/c | |
35 | C | |
36 | VOUT(IPP) = VECT(IPP) | |
37 | H4 = FIELD * EC | |
38 | * | |
39 | HXP(1) = - VECT(IPY) | |
40 | HXP(2) = + VECT(IPX) | |
41 | ||
42 | HP = VECT(IPZ) | |
43 | * | |
44 | RHO = -H4/VECT(IPP) | |
45 | TET = RHO * STEP | |
46 | IF (ABS(TET).GT.0.15) THEN | |
47 | SINT = SIN(TET) | |
48 | SINTT = (SINT/TET) | |
49 | TSINT = (TET-SINT)/TET | |
50 | COS1T = 2.*(SIN(0.5*TET))**2/TET | |
51 | ELSE | |
52 | TSINT = SIXTH*TET**2 | |
53 | SINTT = (1. - TSINT) | |
54 | SINT = TET*SINTT | |
55 | COS1T = 0.5*TET | |
56 | ENDIF | |
57 | * | |
58 | F1 = STEP * SINTT | |
59 | F2 = STEP * COS1T | |
60 | F3 = STEP * TSINT * HP | |
61 | F4 = -TET*COS1T | |
62 | F5 = SINT | |
63 | F6 = TET * COS1T * HP | |
64 | ||
65 | VOUT(IX) = VECT(IX) + (F1*VECT(IPX) + F2*HXP(1)) | |
66 | VOUT(IY) = VECT(IY) + (F1*VECT(IPY) + F2*HXP(2)) | |
67 | VOUT(IZ) = VECT(IZ) + (F1*VECT(IPZ) + F3) | |
68 | ||
69 | VOUT(IPX) = VECT(IPX) + (F4*VECT(IPX) + F5*HXP(1)) | |
70 | VOUT(IPY) = VECT(IPY) + (F4*VECT(IPY) + F5*HXP(2)) | |
71 | VOUT(IPZ) = VECT(IPZ) + (F4*VECT(IPZ) + F6) | |
72 | ||
73 | C | |
74 | 999 END |