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1 | /************************************************************************** | |
2 | * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. * | |
3 | * * | |
4 | * Author: The ALICE Off-line Project. * | |
5 | * Contributors are mentioned in the code where appropriate. * | |
6 | * * | |
7 | * Permission to use, copy, modify and distribute this software and its * | |
8 | * documentation strictly for non-commercial purposes is hereby granted * | |
9 | * without fee, provided that the above copyright notice appears in all * | |
10 | * copies and that both the copyright notice and this permission notice * | |
11 | * appear in the supporting documentation. The authors make no claims * | |
12 | * about the suitability of this software for any purpose. It is * | |
13 | * provided "as is" without express or implied warranty. * | |
14 | **************************************************************************/ | |
15 | ||
16 | /* $Id$ */ | |
17 | ||
18 | // | |
19 | // Generator to simulate beam gas interactions. | |
20 | // At present single interactions are read from an external file. | |
21 | // Several interactions are combined in one event. | |
22 | // By default the vertex is smeared between +/- 20 m | |
23 | // Author: andreas.morsch@cern.ch | |
24 | ||
25 | #include "AliGenBeamGas.h" | |
26 | ||
27 | #include <TParticle.h> | |
28 | ||
29 | ||
30 | ClassImp(AliGenBeamGas) | |
31 | ||
32 | AliGenBeamGas::AliGenBeamGas() | |
33 | :AliGenExtFile(), | |
34 | fInteractions(1) | |
35 | { | |
36 | // Constructor | |
37 | // | |
38 | fOsigma[0] = 0.; | |
39 | fOsigma[1] = 0.; | |
40 | fOsigma[2] = 2000.; | |
41 | } | |
42 | ||
43 | //____________________________________________________________ | |
44 | ||
45 | AliGenBeamGas::~AliGenBeamGas() | |
46 | { | |
47 | // Destructor | |
48 | delete fReader; | |
49 | } | |
50 | ||
51 | //___________________________________________________________ | |
52 | void AliGenBeamGas::Init() | |
53 | { | |
54 | // Initialize | |
55 | AliGenExtFile::Init(); | |
56 | } | |
57 | ||
58 | ||
59 | void AliGenBeamGas::Generate() | |
60 | { | |
61 | // Generate particles | |
62 | ||
63 | Float_t polar[3] = {0,0,0}; | |
64 | Float_t origin[3] = {0,0,0}; | |
65 | Float_t p[3]; | |
66 | Float_t random[2]; | |
67 | Int_t i, nt; | |
68 | Int_t nInt = 0; | |
69 | ||
70 | while(nInt < fInteractions) { | |
71 | // | |
72 | Rndm(random,2); | |
73 | // | |
74 | // Interaction vertex | |
75 | // | |
76 | origin[2] = 2. * fOsigma[2] * random[0] - fOsigma[2]; | |
77 | // | |
78 | // beam 1 or 2 | |
79 | // | |
80 | Float_t ibeam = (random[1] < 0.5) ? -1. : 1.; | |
81 | ||
82 | // | |
83 | // Read next event | |
84 | // | |
85 | Int_t nTracks = fReader->NextEvent(); | |
86 | if (nTracks == 0) { | |
87 | // printf("\n No more events !!! !\n"); | |
88 | Warning("AliGenBeamGas::Generate", | |
89 | "\nNo more events in external file!!!\n Last event may be empty or incomplete.\n"); | |
90 | return; | |
91 | } | |
92 | ||
93 | // | |
94 | // Stack filling loop | |
95 | // | |
96 | for (i = 0; i < nTracks; i++) { | |
97 | TParticle* iparticle = fReader->NextParticle(); | |
98 | p[0] = iparticle->Px(); | |
99 | p[1] = iparticle->Py(); | |
100 | p[2] = iparticle->Pz() * ibeam; | |
101 | ||
102 | Int_t idpart = iparticle->GetPdgCode(); | |
103 | Int_t decayed = iparticle->GetFirstDaughter(); | |
104 | Int_t doTracking = fTrackIt && (decayed < 0) && (TMath::Abs(idpart) > 10); | |
105 | PushTrack(doTracking,-1,idpart,p,origin,polar,0,kPPrimary,nt); | |
106 | KeepTrack(nt); | |
107 | } // track loop | |
108 | nInt++; | |
109 | } // event loop | |
110 | // | |
111 | SetHighWaterMark(nt); | |
112 | // | |
113 | CdEventFile(); | |
114 | } | |
115 | ||
116 | ||
117 | ||
118 | ||
119 |