New generator for the krypton runs of TPC (Marek)
[u/mrichter/AliRoot.git] / EVGEN / AliGenKrypton.cxx
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d02055c6 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/*
17$Log$
18*/
19
20//
21// generates single Kr decay, in order to generate the calibration data
22// one should use it together with the AliGenCocktail class
23//
24#include "AliGenKrypton.h"
25#include "TPDGCode.h"
26//
27ClassImp(AliGenKrypton)
28
29//________________________________________________________________________
30AliGenKrypton::AliGenKrypton(){
31 //
32 // Default constructor
33 //
34}
35//________________________________________________________________________
36void AliGenKrypton::Generate(){
37 Double_t eelectron[6];
38 Double_t egamma[2];
39 Float_t polar[3]={0.,0.,0.};
40 Int_t nelectron, ngamma;
41 Int_t nt;
42 //
43 // generate decay vertex within the gas TPC volume
44 //
45 Float_t rmin,rmax,zmax;
46 zmax=249.7;
47 rmin=78.8;
48 rmax=258.;
49 Float_t me=511.e-6;
50 Double_t rnd;
51 //
52 rnd=gRandom->Rndm();
53 Float_t r = (rmax-rmin)*rnd+rmin;
54 rnd=gRandom->Rndm();
55 Float_t phi=TMath::TwoPi()*rnd;
56 //
57 Float_t origin[3];
58 //
59 rnd=gRandom->Rndm();
60 origin[2]=zmax*(2.*rnd-1.);
61 origin[0]=r*TMath::Cos(phi);
62 origin[1]=r*TMath::Sin(phi);
63 //
64 Float_t ptot,p[3];
65 //
66 // generate decay
67 //
68 KrDecay(nelectron,ngamma,eelectron,egamma);
69 //
70 // electrons
71 //
72 for(Int_t i=0;i<nelectron;i++){
73 rnd=gRandom->Rndm();
74 phi=TMath::TwoPi()*rnd;
75 ptot=TMath::Sqrt(eelectron[i]*(eelectron[i]+2.*me));
76 p[0]=ptot*TMath::Cos(phi);
77 p[1]=ptot*TMath::Sin(phi);
78 rnd=gRandom->Rndm();
79 p[2]=ptot*TMath::Cos(TMath::Pi()*rnd);
80 //
81 // her push particle
82 //
83 PushTrack(fTrackIt,-1,kElectron,p,origin,polar,0,kPPrimary,nt);
84 }
85 //
86 // gammas
87 //
88 for(Int_t i=0;i<ngamma;i++){
89 rnd=gRandom->Rndm();
90 phi=TMath::TwoPi()*rnd;
91 ptot=egamma[i];
92 p[0]=ptot*TMath::Cos(phi);
93 p[1]=ptot*TMath::Sin(phi);
94 rnd=gRandom->Rndm();
95 p[2]=ptot*TMath::Cos(TMath::Pi()*rnd);
96 //
97 // her push particle
98 //
99 PushTrack(fTrackIt,-1,kGamma,p,origin,polar,0,kPPrimary,nt);
100 }
101}
102//________________________________________________________________________
103void AliGenKrypton::KrDecay(Int_t &nelectron, Int_t &ngamma, Double_t *eelectron, Double_t *egamma)
104{
105 Double_t prob1[2]={0.76,0.88}; // 0.76, 0.12, 0.12
106 Double_t prob2=0.95; // 0.95, 0.05
107 nelectron=0;
108 ngamma=0;
109
110 Double_t rnd;
111 rnd = gRandom->Rndm();
112 //
113 //
114 // first decay - 32 keV
115 //
116 if(rnd < prob1[0]) {
117 // 2 electrons
118 nelectron = 2;
119 eelectron[0]=30.e-6;
120 eelectron[1]=1.8e-6;
121 }
122 else if (rnd > prob1[1]){
123 // 4 electrons
124 nelectron=4;
125 eelectron[0]=18.e-6;
126 eelectron[1]=10.e-6;
127 eelectron[2]=1.8e-6;
128 eelectron[3]=1.8e-6;
129 }
130 else {
131 // 2 electrons + 1 gamma
132 nelectron = 2;
133 ngamma = 1;
134 eelectron[0]=18.e-6;
135 eelectron[1]=1.8e-6;
136 egamma[0]=12.e-6;
137 }
138 //
139 // second decay - 9 keV
140 //
141 rnd=gRandom->Rndm();
142 //
143 if(rnd < prob2){
144 // 2 electrons
145 nelectron+=2;
146 eelectron[nelectron-2]=7.6e-6;
147 eelectron[nelectron-1]=1.8e-6;
148 }
149 else {
150 ngamma++;
151 egamma[ngamma-1]=9.e-6;
152 }
153}
154//________________________________________________________________________