In AliMUONAlignment
[u/mrichter/AliRoot.git] / EVGEN / AliGenBeamGas.cxx
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4bda3bc1 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
88cb7938 16/* $Id$ */
4bda3bc1 17
508eeb68 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.
0af12c00 22// By default the vertex is smeared between +/- 20 m
23// Author: andreas.morsch@cern.ch
4bda3bc1 24
25#include "AliGenBeamGas.h"
4bda3bc1 26
27#include <TParticle.h>
4bda3bc1 28
29
198bb1c7 30ClassImp(AliGenBeamGas)
4bda3bc1 31
32AliGenBeamGas::AliGenBeamGas()
1c56e311 33 :AliGenExtFile(),
34 fInteractions(1)
4bda3bc1 35{
36// Constructor
37//
508eeb68 38 fOsigma[0] = 0.;
39 fOsigma[1] = 0.;
40 fOsigma[2] = 2000.;
4bda3bc1 41}
42
4bda3bc1 43//____________________________________________________________
44
45AliGenBeamGas::~AliGenBeamGas()
46{
47// Destructor
48 delete fReader;
49}
50
51//___________________________________________________________
52void AliGenBeamGas::Init()
53{
54// Initialize
55 AliGenExtFile::Init();
56}
57
58
59void 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//
508eeb68 76 origin[2] = 2. * fOsigma[2] * random[0] - fOsigma[2];
4bda3bc1 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);
642f15cf 105 PushTrack(doTracking,-1,idpart,p,origin,polar,0,kPPrimary,nt);
4bda3bc1 106 KeepTrack(nt);
107 } // track loop
108 nInt++;
109 } // event loop
110//
111 SetHighWaterMark(nt);
112//
113 CdEventFile();
114}
115
116
4bda3bc1 117
4bda3bc1 118
119