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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 | ||
16 | /* | |
17 | $Log$ | |
65fb704d | 18 | Revision 1.1 2000/09/08 15:37:58 morsch |
19 | pt and y-parameterisations for PMD physics simulation. | |
20 | THIS VERSION IS JUST A TEMPLATE THE PT AND Y DISTRIBUTIONS HAVE TO BE CORRECTED !!!!. | |
21 | ||
0ed0a0a2 | 22 | */ |
23 | ||
24 | #include "AliGenPMDlib.h" | |
0ed0a0a2 | 25 | #include "AliPDG.h" |
65fb704d | 26 | #include "TMath.h" |
0ed0a0a2 | 27 | |
28 | ClassImp(AliGenPMDlib) | |
29 | // | |
30 | // Neutral Pions | |
31 | ||
32 | Double_t AliGenPMDlib::PtPi0(Double_t *px, Double_t *dummy) | |
33 | { | |
34 | // | |
35 | // PT-PARAMETERIZATION CDF, PRL 61(88) 1819 | |
36 | // POWER LAW FOR PT > 500 MEV | |
37 | // MT SCALING BELOW (T=160 MEV) | |
38 | // | |
39 | const Double_t kp0 = 1.3; | |
40 | const Double_t kxn = 8.28; | |
41 | const Double_t kxlim=0.5; | |
42 | const Double_t kt=0.160; | |
43 | const Double_t kxmpi=0.139; | |
44 | const Double_t kb=1.; | |
45 | Double_t y, y1, xmpi2, ynorm, a; | |
46 | Double_t x=*px; | |
47 | // | |
48 | y1=TMath::Power(kp0/(kp0+kxlim),kxn); | |
49 | xmpi2=kxmpi*kxmpi; | |
50 | ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt)); | |
51 | a=ynorm/y1; | |
52 | if (x > kxlim) | |
53 | y=a*TMath::Power(kp0/(kp0+x),kxn); | |
54 | else | |
55 | y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt); | |
56 | return y*x; | |
57 | } | |
58 | ||
59 | // | |
60 | // y-distribution | |
61 | // | |
62 | Double_t AliGenPMDlib::YPi0( Double_t *py, Double_t *dummy) | |
63 | { | |
64 | // | |
65 | // y parametrisation for pi0 | |
66 | // | |
67 | const Double_t ka1 = 4913.; | |
68 | const Double_t ka2 = 1819.; | |
69 | const Double_t keta1 = 0.22; | |
70 | const Double_t keta2 = 3.66; | |
71 | const Double_t kdeta1 = 1.47; | |
72 | const Double_t kdeta2 = 1.51; | |
73 | Double_t y=TMath::Abs(*py); | |
74 | // | |
75 | Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1); | |
76 | Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2); | |
77 | return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2); | |
78 | } | |
79 | ||
80 | // particle composition | |
81 | // | |
65fb704d | 82 | Int_t AliGenPMDlib::IpPi0(TRandom *) |
0ed0a0a2 | 83 | { |
84 | // Pi0 | |
85 | return kPi0; | |
86 | } | |
87 | ||
88 | //____________________________________________________________ | |
89 | // | |
90 | // Mt-scaling | |
91 | ||
92 | Double_t AliGenPMDlib::PtScal(Double_t pt, Int_t np) | |
93 | { | |
94 | // SCALING EN MASSE PAR RAPPORT A PTPI | |
95 | // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI | |
96 | const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0}; | |
97 | // VALUE MESON/PI AT 5 GEV | |
98 | const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0}; | |
99 | np--; | |
100 | Double_t f5=TMath::Power(((sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3); | |
101 | Double_t fmax2=f5/kfmax[np]; | |
102 | // PIONS | |
103 | Double_t ptpion=100.*PtPi0(&pt, (Double_t*) 0); | |
104 | Double_t fmtscal=TMath::Power(((sqrt(pt*pt+0.018215)+2.)/ | |
105 | (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/ fmax2; | |
106 | return fmtscal*ptpion; | |
107 | } | |
108 | // | |
109 | // kaon | |
110 | // | |
111 | // pt-distribution | |
112 | //____________________________________________________________ | |
113 | ||
114 | Double_t AliGenPMDlib::PtEta( Double_t *px, Double_t *dummy) | |
115 | { | |
116 | // Kaon pT | |
117 | return PtScal(*px,3); | |
118 | } | |
119 | ||
120 | // y-distribution | |
121 | //____________________________________________________________ | |
122 | Double_t AliGenPMDlib::YEta( Double_t *py, Double_t *dummy) | |
123 | { | |
124 | // | |
125 | // y parametrisation for etas | |
126 | // | |
127 | const Double_t ka1 = 4913.; | |
128 | const Double_t ka2 = 1819.; | |
129 | const Double_t keta1 = 0.22; | |
130 | const Double_t keta2 = 3.66; | |
131 | const Double_t kdeta1 = 1.47; | |
132 | const Double_t kdeta2 = 1.51; | |
133 | Double_t y=TMath::Abs(*py); | |
134 | // | |
135 | Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1); | |
136 | Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2); | |
137 | return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2); | |
138 | } | |
139 | ||
140 | // particle composition | |
141 | // | |
65fb704d | 142 | Int_t AliGenPMDlib::IpEta(TRandom *) |
0ed0a0a2 | 143 | { |
144 | return 221; | |
145 | } | |
146 | ||
147 | ||
148 | typedef Double_t (*GenFunc) (Double_t*, Double_t*); | |
149 | GenFunc AliGenPMDlib::GetPt(Param_t param, const char* tname) | |
150 | { | |
151 | // Return pointer to pT parameterisation | |
152 | GenFunc func=NULL; | |
153 | switch (param) | |
154 | { | |
155 | case Pion: | |
156 | func=PtPi0; | |
157 | break; | |
158 | case Eta: | |
159 | func=PtEta; | |
160 | break; | |
161 | default: | |
162 | func=0; | |
163 | printf("<AliGenPMDlib::GetPt> unknown parametrisation\n"); | |
164 | } | |
165 | return func; | |
166 | } | |
167 | ||
168 | GenFunc AliGenPMDlib::GetY(Param_t param, const char* tname) | |
169 | { | |
170 | // Return pointer to y- parameterisation | |
171 | GenFunc func=NULL; | |
172 | switch (param) | |
173 | { | |
174 | case Pion: | |
175 | func=YPi0; | |
176 | break; | |
177 | case Eta: | |
178 | func=YEta; | |
179 | break; | |
180 | default: | |
181 | func=0; | |
182 | printf("<AliGenPMDlib::GetY> unknown parametrisation\n"); | |
183 | } | |
184 | return func; | |
185 | ||
186 | } | |
65fb704d | 187 | typedef Int_t (*GenFuncIp) (TRandom *); |
0ed0a0a2 | 188 | GenFuncIp AliGenPMDlib::GetIp(Param_t param, const char* tname) |
189 | { | |
190 | // Return pointer to particle type parameterisation | |
191 | GenFuncIp func=NULL; | |
192 | switch (param) | |
193 | { | |
194 | case Pion: | |
195 | func=IpPi0; | |
196 | break; | |
197 | case Eta: | |
198 | func=IpEta; | |
199 | break; | |
200 | default: | |
201 | printf("<AliGenPMDlib::GetIp> unknown parametrisation\n"); | |
202 | } | |
203 | return func; | |
204 | } | |
205 | ||
206 | ||
207 | ||
208 |