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0ed0a0a2 | 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 | /* $Id$ */ |
0ed0a0a2 | 17 | |
ac3faee4 | 18 | // |
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 | |
24 | // | |
25 | ||
116cbefd | 26 | #include <TMath.h> |
27 | #include <TPDGCode.h> | |
28 | ||
0ed0a0a2 | 29 | #include "AliGenPMDlib.h" |
0ed0a0a2 | 30 | |
31 | ClassImp(AliGenPMDlib) | |
32 | // | |
33 | // Neutral Pions | |
34 | ||
75e0cc59 | 35 | Double_t AliGenPMDlib::PtPi0(const Double_t *px, const Double_t */*dummy*/) |
0ed0a0a2 | 36 | { |
37 | // | |
38 | // PT-PARAMETERIZATION CDF, PRL 61(88) 1819 | |
39 | // POWER LAW FOR PT > 500 MEV | |
40 | // MT SCALING BELOW (T=160 MEV) | |
41 | // | |
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; | |
47 | const Double_t kb=1.; | |
48 | Double_t y, y1, xmpi2, ynorm, a; | |
49 | Double_t x=*px; | |
50 | // | |
51 | y1=TMath::Power(kp0/(kp0+kxlim),kxn); | |
52 | xmpi2=kxmpi*kxmpi; | |
53 | ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt)); | |
54 | a=ynorm/y1; | |
55 | if (x > kxlim) | |
56 | y=a*TMath::Power(kp0/(kp0+x),kxn); | |
57 | else | |
58 | y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt); | |
59 | return y*x; | |
60 | } | |
61 | ||
62 | // | |
63 | // y-distribution | |
64 | // | |
75e0cc59 | 65 | Double_t AliGenPMDlib::YPi0( const Double_t *py, const Double_t */*dummy*/) |
0ed0a0a2 | 66 | { |
67 | // | |
68 | // y parametrisation for pi0 | |
69 | // | |
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); | |
77 | // | |
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); | |
81 | } | |
82 | ||
83 | // particle composition | |
84 | // | |
65fb704d | 85 | Int_t AliGenPMDlib::IpPi0(TRandom *) |
0ed0a0a2 | 86 | { |
87 | // Pi0 | |
88 | return kPi0; | |
89 | } | |
90 | ||
91 | //____________________________________________________________ | |
92 | // | |
93 | // Mt-scaling | |
94 | ||
95 | Double_t AliGenPMDlib::PtScal(Double_t pt, Int_t np) | |
96 | { | |
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 | np--; | |
103 | Double_t f5=TMath::Power(((sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3); | |
104 | Double_t fmax2=f5/kfmax[np]; | |
105 | // PIONS | |
106 | Double_t ptpion=100.*PtPi0(&pt, (Double_t*) 0); | |
107 | Double_t fmtscal=TMath::Power(((sqrt(pt*pt+0.018215)+2.)/ | |
108 | (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/ fmax2; | |
109 | return fmtscal*ptpion; | |
110 | } | |
111 | // | |
112 | // kaon | |
113 | // | |
114 | // pt-distribution | |
115 | //____________________________________________________________ | |
116 | ||
75e0cc59 | 117 | Double_t AliGenPMDlib::PtEta( const Double_t *px, const Double_t */*dummy*/) |
0ed0a0a2 | 118 | { |
119 | // Kaon pT | |
120 | return PtScal(*px,3); | |
121 | } | |
122 | ||
123 | // y-distribution | |
124 | //____________________________________________________________ | |
75e0cc59 | 125 | Double_t AliGenPMDlib::YEta( const Double_t *py, const Double_t */*dummy*/) |
0ed0a0a2 | 126 | { |
127 | // | |
128 | // y parametrisation for etas | |
129 | // | |
130 | const Double_t ka1 = 4913.; | |
131 | const Double_t ka2 = 1819.; | |
132 | const Double_t keta1 = 0.22; | |
133 | const Double_t keta2 = 3.66; | |
134 | const Double_t kdeta1 = 1.47; | |
135 | const Double_t kdeta2 = 1.51; | |
136 | Double_t y=TMath::Abs(*py); | |
137 | // | |
138 | Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1); | |
139 | Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2); | |
140 | return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2); | |
141 | } | |
142 | ||
143 | // particle composition | |
144 | // | |
65fb704d | 145 | Int_t AliGenPMDlib::IpEta(TRandom *) |
0ed0a0a2 | 146 | { |
147 | return 221; | |
148 | } | |
149 | ||
150 | ||
75e0cc59 | 151 | typedef Double_t (*GenFunc) (const Double_t*, const Double_t*); |
198bb1c7 | 152 | GenFunc AliGenPMDlib::GetPt(Int_t param, const char* /*tname*/) const |
0ed0a0a2 | 153 | { |
154 | // Return pointer to pT parameterisation | |
155 | GenFunc func=NULL; | |
156 | switch (param) | |
157 | { | |
34f60c01 | 158 | case kPion: |
0ed0a0a2 | 159 | func=PtPi0; |
160 | break; | |
34f60c01 | 161 | case kEta: |
0ed0a0a2 | 162 | func=PtEta; |
163 | break; | |
164 | default: | |
165 | func=0; | |
166 | printf("<AliGenPMDlib::GetPt> unknown parametrisation\n"); | |
167 | } | |
168 | return func; | |
169 | } | |
170 | ||
198bb1c7 | 171 | GenFunc AliGenPMDlib::GetY(Int_t param, const char* /*tname*/) const |
0ed0a0a2 | 172 | { |
173 | // Return pointer to y- parameterisation | |
174 | GenFunc func=NULL; | |
175 | switch (param) | |
176 | { | |
34f60c01 | 177 | case kPion: |
0ed0a0a2 | 178 | func=YPi0; |
179 | break; | |
34f60c01 | 180 | case kEta: |
0ed0a0a2 | 181 | func=YEta; |
182 | break; | |
183 | default: | |
184 | func=0; | |
185 | printf("<AliGenPMDlib::GetY> unknown parametrisation\n"); | |
186 | } | |
187 | return func; | |
188 | ||
189 | } | |
65fb704d | 190 | typedef Int_t (*GenFuncIp) (TRandom *); |
198bb1c7 | 191 | GenFuncIp AliGenPMDlib::GetIp(Int_t param, const char* /*tname*/) const |
0ed0a0a2 | 192 | { |
193 | // Return pointer to particle type parameterisation | |
194 | GenFuncIp func=NULL; | |
195 | switch (param) | |
196 | { | |
34f60c01 | 197 | case kPion: |
0ed0a0a2 | 198 | func=IpPi0; |
199 | break; | |
34f60c01 | 200 | case kEta: |
0ed0a0a2 | 201 | func=IpEta; |
202 | break; | |
203 | default: | |
204 | printf("<AliGenPMDlib::GetIp> unknown parametrisation\n"); | |
205 | } | |
206 | return func; | |
207 | } | |
208 | ||
209 | ||
210 | ||
211 |