1 /**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
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8 * documentation strictly for non-commercial purposes is hereby granted *
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11 * appear in the supporting documentation. The authors make no claims *
12 * about the suitability of this software for any purpose. It is *
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14 **************************************************************************/
19 // Library of generators for PMD
20 // providing y and pt parametrisation
21 // for generated tracks
22 // Specific for PMD needs
23 // Author: PMD Offline Group
29 #include "AliGenPMDlib.h"
31 ClassImp(AliGenPMDlib)
35 Double_t AliGenPMDlib::PtPi0(const Double_t *px, const Double_t */*dummy*/)
38 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
39 // POWER LAW FOR PT > 500 MEV
40 // MT SCALING BELOW (T=160 MEV)
42 const Double_t kp0 = 1.3;
43 const Double_t kxn = 8.28;
44 const Double_t kxlim=0.5;
45 const Double_t kt=0.160;
46 const Double_t kxmpi=0.139;
48 Double_t y, y1, xmpi2, ynorm, a;
51 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
53 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt));
56 y=a*TMath::Power(kp0/(kp0+x),kxn);
58 y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt);
65 Double_t AliGenPMDlib::YPi0( const Double_t *py, const Double_t */*dummy*/)
68 // y parametrisation for pi0
70 const Double_t ka1 = 4913.;
71 const Double_t ka2 = 1819.;
72 const Double_t keta1 = 0.22;
73 const Double_t keta2 = 3.66;
74 const Double_t kdeta1 = 1.47;
75 const Double_t kdeta2 = 1.51;
76 Double_t y=TMath::Abs(*py);
78 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
79 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
80 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
83 // particle composition
85 Int_t AliGenPMDlib::IpPi0(TRandom *)
91 //____________________________________________________________
95 Double_t AliGenPMDlib::PtScal(Double_t pt, Int_t np)
97 // SCALING EN MASSE PAR RAPPORT A PTPI
98 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
99 const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
100 // VALUE MESON/PI AT 5 GEV
101 const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
102 Double_t f5=TMath::Power(((sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
103 Double_t fmax2=f5/kfmax[np];
105 Double_t ptpion=100.*PtPi0(&pt, (Double_t*) 0);
106 Double_t fmtscal=TMath::Power(((sqrt(pt*pt+0.018215)+2.)/
107 (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/ fmax2;
108 return fmtscal*ptpion;
114 //____________________________________________________________
116 Double_t AliGenPMDlib::PtEta( const Double_t *px, const Double_t */*dummy*/)
119 return PtScal(*px, 1);
123 //____________________________________________________________
124 Double_t AliGenPMDlib::YEta( const Double_t *py, const Double_t */*dummy*/)
127 // y parametrisation for etas
129 const Double_t ka1 = 4913.;
130 const Double_t ka2 = 1819.;
131 const Double_t keta1 = 0.22;
132 const Double_t keta2 = 3.66;
133 const Double_t kdeta1 = 1.47;
134 const Double_t kdeta2 = 1.51;
135 Double_t y=TMath::Abs(*py);
137 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
138 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
139 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
142 // particle composition
144 Int_t AliGenPMDlib::IpEta(TRandom *)
150 typedef Double_t (*GenFunc) (const Double_t*, const Double_t*);
151 GenFunc AliGenPMDlib::GetPt(Int_t param, const char* /*tname*/) const
153 // Return pointer to pT parameterisation
165 printf("<AliGenPMDlib::GetPt> unknown parametrisation\n");
170 GenFunc AliGenPMDlib::GetY(Int_t param, const char* /*tname*/) const
172 // Return pointer to y- parameterisation
184 printf("<AliGenPMDlib::GetY> unknown parametrisation\n");
189 typedef Int_t (*GenFuncIp) (TRandom *);
190 GenFuncIp AliGenPMDlib::GetIp(Int_t param, const char* /*tname*/) const
192 // Return pointer to particle type parameterisation
203 printf("<AliGenPMDlib::GetIp> unknown parametrisation\n");