Line data Source code
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 : #include "AliGenReader.h"
27 :
28 : #include <TParticle.h>
29 :
30 :
31 6 : ClassImp(AliGenBeamGas)
32 :
33 : AliGenBeamGas::AliGenBeamGas()
34 0 : :AliGenExtFile(),
35 0 : fInteractions(1)
36 0 : {
37 : // Constructor
38 : //
39 0 : fOsigma[0] = 0.;
40 0 : fOsigma[1] = 0.;
41 0 : fOsigma[2] = 2000.;
42 0 : }
43 :
44 : //____________________________________________________________
45 :
46 0 : AliGenBeamGas::~AliGenBeamGas()
47 0 : {
48 : // Destructor
49 0 : delete fReader;
50 0 : }
51 :
52 : //___________________________________________________________
53 : void AliGenBeamGas::Init()
54 : {
55 : // Initialize
56 0 : AliGenExtFile::Init();
57 0 : }
58 :
59 :
60 : void AliGenBeamGas::Generate()
61 : {
62 : // Generate particles
63 :
64 0 : Float_t polar[3] = {0,0,0};
65 0 : Float_t origin[3] = {0,0,0};
66 0 : Float_t p[3];
67 0 : Float_t random[2];
68 0 : Int_t i, nt;
69 : Int_t nInt = 0;
70 :
71 0 : while(nInt < fInteractions) {
72 : //
73 0 : Rndm(random,2);
74 : //
75 : // Interaction vertex
76 : //
77 0 : origin[2] = 2. * fOsigma[2] * random[0] - fOsigma[2];
78 : //
79 : // beam 1 or 2
80 : //
81 0 : Float_t ibeam = (random[1] < 0.5) ? -1. : 1.;
82 :
83 : // Interaction time
84 0 : Float_t time = origin[2]/TMath::Ccgs()*ibeam;
85 : //
86 : // Read next event
87 : //
88 0 : Int_t nTracks = fReader->NextEvent();
89 0 : if (nTracks == 0) {
90 : // printf("\n No more events !!! !\n");
91 0 : Warning("AliGenBeamGas::Generate",
92 : "\nNo more events in external file!!!\n Last event may be empty or incomplete.\n");
93 0 : return;
94 : }
95 :
96 : //
97 : // Stack filling loop
98 : //
99 0 : for (i = 0; i < nTracks; i++) {
100 0 : TParticle* iparticle = fReader->NextParticle();
101 0 : p[0] = iparticle->Px();
102 0 : p[1] = iparticle->Py();
103 0 : p[2] = iparticle->Pz() * ibeam;
104 :
105 0 : Int_t idpart = iparticle->GetPdgCode();
106 0 : Int_t decayed = iparticle->GetFirstDaughter();
107 0 : Int_t doTracking = fTrackIt && (decayed < 0) && (TMath::Abs(idpart) > 10);
108 0 : PushTrack(doTracking,-1,idpart,p,origin,polar,time,kPPrimary,nt);
109 0 : KeepTrack(nt);
110 : } // track loop
111 0 : nInt++;
112 0 : } // event loop
113 : //
114 0 : SetHighWaterMark(nt);
115 : //
116 0 : CdEventFile();
117 0 : }
118 :
119 :
120 :
121 :
122 :
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