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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 | |
116cbefd | 18 | #include <TMath.h> |
19 | #include <TPDGCode.h> | |
20 | ||
0ed0a0a2 | 21 | #include "AliGenPMDlib.h" |
0ed0a0a2 | 22 | |
23 | ClassImp(AliGenPMDlib) | |
24 | // | |
25 | // Neutral Pions | |
26 | ||
198bb1c7 | 27 | Double_t AliGenPMDlib::PtPi0(Double_t *px, Double_t */*dummy*/) |
0ed0a0a2 | 28 | { |
29 | // | |
30 | // PT-PARAMETERIZATION CDF, PRL 61(88) 1819 | |
31 | // POWER LAW FOR PT > 500 MEV | |
32 | // MT SCALING BELOW (T=160 MEV) | |
33 | // | |
34 | const Double_t kp0 = 1.3; | |
35 | const Double_t kxn = 8.28; | |
36 | const Double_t kxlim=0.5; | |
37 | const Double_t kt=0.160; | |
38 | const Double_t kxmpi=0.139; | |
39 | const Double_t kb=1.; | |
40 | Double_t y, y1, xmpi2, ynorm, a; | |
41 | Double_t x=*px; | |
42 | // | |
43 | y1=TMath::Power(kp0/(kp0+kxlim),kxn); | |
44 | xmpi2=kxmpi*kxmpi; | |
45 | ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt)); | |
46 | a=ynorm/y1; | |
47 | if (x > kxlim) | |
48 | y=a*TMath::Power(kp0/(kp0+x),kxn); | |
49 | else | |
50 | y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt); | |
51 | return y*x; | |
52 | } | |
53 | ||
54 | // | |
55 | // y-distribution | |
56 | // | |
198bb1c7 | 57 | Double_t AliGenPMDlib::YPi0( Double_t *py, Double_t */*dummy*/) |
0ed0a0a2 | 58 | { |
59 | // | |
60 | // y parametrisation for pi0 | |
61 | // | |
62 | const Double_t ka1 = 4913.; | |
63 | const Double_t ka2 = 1819.; | |
64 | const Double_t keta1 = 0.22; | |
65 | const Double_t keta2 = 3.66; | |
66 | const Double_t kdeta1 = 1.47; | |
67 | const Double_t kdeta2 = 1.51; | |
68 | Double_t y=TMath::Abs(*py); | |
69 | // | |
70 | Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1); | |
71 | Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2); | |
72 | return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2); | |
73 | } | |
74 | ||
75 | // particle composition | |
76 | // | |
65fb704d | 77 | Int_t AliGenPMDlib::IpPi0(TRandom *) |
0ed0a0a2 | 78 | { |
79 | // Pi0 | |
80 | return kPi0; | |
81 | } | |
82 | ||
83 | //____________________________________________________________ | |
84 | // | |
85 | // Mt-scaling | |
86 | ||
87 | Double_t AliGenPMDlib::PtScal(Double_t pt, Int_t np) | |
88 | { | |
89 | // SCALING EN MASSE PAR RAPPORT A PTPI | |
90 | // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI | |
91 | const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0}; | |
92 | // VALUE MESON/PI AT 5 GEV | |
93 | const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0}; | |
94 | np--; | |
95 | Double_t f5=TMath::Power(((sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3); | |
96 | Double_t fmax2=f5/kfmax[np]; | |
97 | // PIONS | |
98 | Double_t ptpion=100.*PtPi0(&pt, (Double_t*) 0); | |
99 | Double_t fmtscal=TMath::Power(((sqrt(pt*pt+0.018215)+2.)/ | |
100 | (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/ fmax2; | |
101 | return fmtscal*ptpion; | |
102 | } | |
103 | // | |
104 | // kaon | |
105 | // | |
106 | // pt-distribution | |
107 | //____________________________________________________________ | |
108 | ||
198bb1c7 | 109 | Double_t AliGenPMDlib::PtEta( Double_t *px, Double_t */*dummy*/) |
0ed0a0a2 | 110 | { |
111 | // Kaon pT | |
112 | return PtScal(*px,3); | |
113 | } | |
114 | ||
115 | // y-distribution | |
116 | //____________________________________________________________ | |
198bb1c7 | 117 | Double_t AliGenPMDlib::YEta( Double_t *py, Double_t */*dummy*/) |
0ed0a0a2 | 118 | { |
119 | // | |
120 | // y parametrisation for etas | |
121 | // | |
122 | const Double_t ka1 = 4913.; | |
123 | const Double_t ka2 = 1819.; | |
124 | const Double_t keta1 = 0.22; | |
125 | const Double_t keta2 = 3.66; | |
126 | const Double_t kdeta1 = 1.47; | |
127 | const Double_t kdeta2 = 1.51; | |
128 | Double_t y=TMath::Abs(*py); | |
129 | // | |
130 | Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1); | |
131 | Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2); | |
132 | return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2); | |
133 | } | |
134 | ||
135 | // particle composition | |
136 | // | |
65fb704d | 137 | Int_t AliGenPMDlib::IpEta(TRandom *) |
0ed0a0a2 | 138 | { |
139 | return 221; | |
140 | } | |
141 | ||
142 | ||
143 | typedef Double_t (*GenFunc) (Double_t*, Double_t*); | |
198bb1c7 | 144 | GenFunc AliGenPMDlib::GetPt(Int_t param, const char* /*tname*/) const |
0ed0a0a2 | 145 | { |
146 | // Return pointer to pT parameterisation | |
147 | GenFunc func=NULL; | |
148 | switch (param) | |
149 | { | |
34f60c01 | 150 | case kPion: |
0ed0a0a2 | 151 | func=PtPi0; |
152 | break; | |
34f60c01 | 153 | case kEta: |
0ed0a0a2 | 154 | func=PtEta; |
155 | break; | |
156 | default: | |
157 | func=0; | |
158 | printf("<AliGenPMDlib::GetPt> unknown parametrisation\n"); | |
159 | } | |
160 | return func; | |
161 | } | |
162 | ||
198bb1c7 | 163 | GenFunc AliGenPMDlib::GetY(Int_t param, const char* /*tname*/) const |
0ed0a0a2 | 164 | { |
165 | // Return pointer to y- parameterisation | |
166 | GenFunc func=NULL; | |
167 | switch (param) | |
168 | { | |
34f60c01 | 169 | case kPion: |
0ed0a0a2 | 170 | func=YPi0; |
171 | break; | |
34f60c01 | 172 | case kEta: |
0ed0a0a2 | 173 | func=YEta; |
174 | break; | |
175 | default: | |
176 | func=0; | |
177 | printf("<AliGenPMDlib::GetY> unknown parametrisation\n"); | |
178 | } | |
179 | return func; | |
180 | ||
181 | } | |
65fb704d | 182 | typedef Int_t (*GenFuncIp) (TRandom *); |
198bb1c7 | 183 | GenFuncIp AliGenPMDlib::GetIp(Int_t param, const char* /*tname*/) const |
0ed0a0a2 | 184 | { |
185 | // Return pointer to particle type parameterisation | |
186 | GenFuncIp func=NULL; | |
187 | switch (param) | |
188 | { | |
34f60c01 | 189 | case kPion: |
0ed0a0a2 | 190 | func=IpPi0; |
191 | break; | |
34f60c01 | 192 | case kEta: |
0ed0a0a2 | 193 | func=IpEta; |
194 | break; | |
195 | default: | |
196 | printf("<AliGenPMDlib::GetIp> unknown parametrisation\n"); | |
197 | } | |
198 | return func; | |
199 | } | |
200 | ||
201 | ||
202 | ||
203 |