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c9a8628a | 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 | ||
803d1ab0 | 16 | /* $Id$ */ |
c9a8628a | 17 | |
c9a8628a | 18 | // |
ac3faee4 | 19 | // Experimental data inspired Gray Particle Model for p-Pb collisions |
c9a8628a | 20 | // The number of gray nucleons is proportional to the number of collisions. |
21 | // The number of black nucleons is proportional to the number of collisions | |
22 | // Fluctuations are calculated from a binomial distribution. | |
ac3faee4 | 23 | // Author: A.Morsch |
c9a8628a | 24 | // |
25 | ||
26 | #include "AliSlowNucleonModelExp.h" | |
27 | #include "AliCollisionGeometry.h" | |
28 | #include <TRandom.h> | |
58776b75 | 29 | #include <TMath.h> |
c9a8628a | 30 | |
706938e6 | 31 | ClassImp(AliSlowNucleonModelExp) |
c9a8628a | 32 | |
1c56e311 | 33 | |
34 | AliSlowNucleonModelExp::AliSlowNucleonModelExp(): | |
35 | fP(82), | |
58776b75 | 36 | fN (126), |
1ffc7bfa | 37 | fAlphaGray(2.3), |
38 | fAlphaBlack(3.6), | |
230d85c6 | 39 | fApplySaturation(kTRUE), |
40 | fnGraySaturation(15), | |
aa3eb8eb | 41 | fnBlackSaturation(28), |
c3e58d2c | 42 | fLCPparam(0.585), |
43 | fSigmaSmear(0.25) | |
c9a8628a | 44 | { |
ac3faee4 | 45 | // |
46 | // Default constructor | |
47 | // | |
1ffc7bfa | 48 | // |
aa3eb8eb | 49 | fSlownparam[0] = 60.; |
50 | fSlownparam[1] = 469.2; | |
51 | fSlownparam[2] = 8.762; | |
c3e58d2c | 52 | /*printf("\n\n ******** Initializing slow nucleon model with parameters:\n"); |
1ffc7bfa | 53 | printf(" \t alpha_{gray} %1.2f alpha_{black} %1.2f\n",fAlphaGray, fAlphaBlack); |
aa3eb8eb | 54 | printf(" \t SATURATION %d w. %d (gray) %d (black) \n\n",fApplySaturation,fnGraySaturation,fnBlackSaturation); |
c3e58d2c | 55 | printf(" \t LCP parameter %f Slown parameters = {%f, %f, |
56 | %f}\n\n",fLCPparam,fSlownparam[0],fSlownparam[1],fSlownparam[2]); */ | |
c9a8628a | 57 | } |
58 | ||
59 | ||
60 | void AliSlowNucleonModelExp::GetNumberOfSlowNucleons(AliCollisionGeometry* geo, | |
ac3faee4 | 61 | Int_t& ngp, Int_t& ngn, Int_t & nbp, Int_t & nbn) const |
c9a8628a | 62 | { |
63 | // | |
64 | // Return the number of black and gray nucleons | |
65 | // | |
66 | // Number of collisions | |
67 | ||
58776b75 | 68 | Float_t nu = geo->NN() + geo->NwN() + geo->NNw(); |
c9a8628a | 69 | |
70 | // Mean number of gray nucleons | |
71 | ||
72 | Float_t nGray = fAlphaGray * nu; | |
73 | Float_t nGrayNeutrons = nGray * fN / (fN + fP); | |
74 | Float_t nGrayProtons = nGray - nGrayNeutrons; | |
75 | ||
76 | // Mean number of black nucleons | |
230d85c6 | 77 | Float_t nBlack = 0.; |
78 | if(!fApplySaturation || (fApplySaturation && nGray<fnGraySaturation)) nBlack = fAlphaBlack * nu; | |
79 | else if(fApplySaturation && nGray>=fnGraySaturation) nBlack = fnBlackSaturation; | |
1ffc7bfa | 80 | Float_t nBlackNeutrons = nBlack * 0.84; |
c9a8628a | 81 | Float_t nBlackProtons = nBlack - nBlackNeutrons; |
82 | ||
83 | // Actual number (including fluctuations) from binomial distribution | |
84 | Double_t p; | |
85 | ||
86 | // gray neutrons | |
87 | p = nGrayNeutrons/fN; | |
88 | ngn = gRandom->Binomial((Int_t) fN, p); | |
89 | ||
90 | // gray protons | |
91 | p = nGrayProtons/fP; | |
92 | ngp = gRandom->Binomial((Int_t) fP, p); | |
93 | ||
94 | // black neutrons | |
95 | p = nBlackNeutrons/fN; | |
96 | nbn = gRandom->Binomial((Int_t) fN, p); | |
97 | ||
98 | // black protons | |
99 | p = nBlackProtons/fP; | |
100 | nbp = gRandom->Binomial((Int_t) fP, p); | |
58776b75 | 101 | |
102 | } | |
103 | ||
104 | void AliSlowNucleonModelExp::GetNumberOfSlowNucleons2(AliCollisionGeometry* geo, | |
105 | Int_t& ngp, Int_t& ngn, Int_t & nbp, Int_t & nbn) const | |
106 | { | |
107 | // | |
108 | // Return the number of black and gray nucleons | |
109 | // | |
110 | // Number of collisions | |
111 | ||
112 | // based on E910 model ================================================================ | |
113 | ||
114 | Float_t nu = (Float_t) (geo->NN() + geo->NwN() + geo->NNw()); | |
115 | // | |
c3e58d2c | 116 | //nu = nu+1.*gRandom->Rndm(); |
117 | nu = gRandom->Gaus(nu, 0.5); | |
118 | if(nu<0.) nu=0.; | |
58776b75 | 119 | // |
120 | Float_t poverpd = 0.843; | |
121 | Float_t zAu2zPb = 82./79.; | |
122 | Float_t nGrayp = (-0.27 + 0.63 * nu - 0.0008 *nu *nu)*poverpd*zAu2zPb; | |
123 | ||
124 | // gray protons | |
125 | Double_t p; | |
126 | p = nGrayp/fP; | |
127 | ngp = gRandom->Binomial((Int_t) fP, p); | |
128 | //ngp = gRandom->Gaus(nGrayp, TMath::Sqrt(fP*p*(1-p))); | |
129 | if(nGrayp<0.) ngp=0; | |
130 | ||
131 | //Float_t blackovergray = 3./7.;// from spallation | |
132 | Float_t blackovergray = 0.65; // from COSY | |
133 | Float_t nBlackp = blackovergray*nGrayp; | |
134 | ||
135 | // black protons | |
136 | p = nBlackp/fP; | |
137 | nbp = gRandom->Binomial((Int_t) fP, p); | |
138 | //nbp = gRandom->Gaus(nBlackp, TMath::Sqrt(fP*p*(1-p))); | |
139 | if(nBlackp<0.) nbp=0; | |
140 | ||
141 | if(nu<3.){ | |
142 | nGrayp = -0.836 + 0.9112 *nu - 0.05381 *nu *nu; | |
143 | nBlackp = blackovergray*nGrayp; | |
144 | } | |
145 | ||
aa3eb8eb | 146 | //printf(" \t Using LCP parameter %f Slown parameters = {%f, %f, %f}\n\n",fLCPparam,fSlownparam[0],fSlownparam[1],fSlownparam[2]); |
58776b75 | 147 | Float_t nGrayNeutrons = 0.; |
148 | Float_t nBlackNeutrons = 0.; | |
aa3eb8eb | 149 | Float_t cp = (nGrayp+nBlackp)/fLCPparam; |
58776b75 | 150 | |
151 | if(cp>0.){ | |
aa3eb8eb | 152 | Float_t nSlow = fSlownparam[0]+fSlownparam[1]/(-fSlownparam[2]-cp); |
153 | Float_t paramRetta = fSlownparam[0]+fSlownparam[1]/(-fSlownparam[2]-3); | |
154 | if(cp<3.) nSlow = 0.+(paramRetta-0.)/(3.-0.)*(cp-0.); | |
58776b75 | 155 | |
156 | nGrayNeutrons = nSlow * 0.1; | |
157 | nBlackNeutrons = nSlow - nGrayNeutrons; | |
158 | } | |
159 | else{ | |
aa3eb8eb | 160 | // Sikler "pasturato" (qui non entra mai!!!!) |
58776b75 | 161 | nGrayNeutrons = 0.47 * fAlphaGray * nu; |
162 | nBlackNeutrons = 0.88 * fAlphaBlack * nu; | |
c3e58d2c | 163 | //printf("nslowp=0 -> ncoll = %1.0f -> ngrayn = %1.0f nblackn = %1.0f \n", nu, nGrayNeutrons, nBlackNeutrons); |
58776b75 | 164 | } |
165 | ||
166 | // gray neutrons | |
167 | p = nGrayNeutrons/fN; | |
168 | // ngn = gRandom->Binomial((Int_t) fN, p); | |
169 | ngn = gRandom->Gaus(nGrayNeutrons, TMath::Sqrt(fN*p*(1-p))); | |
170 | ||
171 | // black neutrons | |
172 | p = nBlackNeutrons/fN; | |
173 | // nbn = gRandom->Binomial((Int_t) fN, p); | |
174 | nbn = gRandom->Gaus(nBlackNeutrons, TMath::Sqrt(fN*p*(1-p))); | |
175 | ||
176 | ||
c9a8628a | 177 | } |
178 | ||
c3e58d2c | 179 | void AliSlowNucleonModelExp::GetNumberOfSlowNucleons2s(AliCollisionGeometry* geo, |
180 | Int_t& ngp, Int_t& ngn, Int_t & nbp, Int_t & nbn) const | |
181 | { | |
182 | // | |
183 | // Return the number of black and gray nucleons | |
184 | // | |
185 | // Number of collisions | |
186 | ||
187 | // based on E910 model ================================================================ | |
188 | ||
189 | Float_t nu = (Float_t) (geo->NN() + geo->NwN() + geo->NNw()); | |
190 | // | |
191 | Float_t poverpd = 0.843; | |
192 | Float_t zAu2zPb = 82./79.; | |
193 | Float_t grayp = (-0.27 + 0.63 * nu - 0.0008 *nu *nu)*poverpd*zAu2zPb; | |
194 | Float_t nGrayp = gRandom->Gaus(grayp, fSigmaSmear); | |
195 | if(nGrayp<0.) nGrayp=0.; | |
196 | ||
197 | // gray protons | |
198 | Double_t p=0.; | |
199 | p = nGrayp/fP; | |
200 | ngp = gRandom->Binomial((Int_t) fP, p); | |
201 | //ngp = gRandom->Gaus(nGrayp, TMath::Sqrt(fP*p*(1-p))); | |
202 | if(nGrayp<0.) ngp=0; | |
203 | ||
204 | //Float_t blackovergray = 3./7.;// from spallation | |
205 | Float_t blackovergray = 0.65; // from COSY | |
206 | //Float_t blackp = blackovergray*grayp; | |
207 | //Float_t nBlackp = gRandom->Gaus(nblackp, fSigmaSmear); | |
208 | Float_t nBlackp = blackovergray*nGrayp; | |
209 | if(nBlackp<0.) nBlackp=0.; | |
210 | ||
211 | // black protons | |
212 | p = nBlackp/fP; | |
213 | nbp = gRandom->Binomial((Int_t) fP, p); | |
214 | //nbp = gRandom->Gaus(nBlackp, TMath::Sqrt(fP*p*(1-p))); | |
215 | if(nBlackp<0.) nbp=0; | |
216 | ||
217 | Float_t nGrayNeutrons = 0.; | |
218 | Float_t nBlackNeutrons = 0.; | |
219 | Float_t cp = (nGrayp+nBlackp)/fLCPparam; | |
220 | ||
221 | if(cp>0.){ | |
222 | Float_t nSlow = fSlownparam[0]+fSlownparam[1]/(-fSlownparam[2]-cp); | |
223 | ||
224 | nGrayNeutrons = nSlow * 0.1; | |
225 | nBlackNeutrons = nSlow - nGrayNeutrons; | |
226 | } | |
227 | else{ | |
228 | // Sikler "pasturato" (qui non entra mai!!!!) | |
229 | nGrayNeutrons = 0.47 * fAlphaGray * nu; | |
230 | nBlackNeutrons = 0.88 * fAlphaBlack * nu; | |
231 | //printf("nslowp=0 -> ncoll = %1.0f -> ngrayn = %1.0f nblackn = %1.0f \n", nu, nGrayNeutrons, nBlackNeutrons); | |
232 | } | |
233 | // | |
234 | if(nGrayNeutrons<0.) nGrayNeutrons=0.; | |
235 | if(nBlackNeutrons<0.) nBlackNeutrons=0.; | |
236 | ||
237 | // gray neutrons | |
238 | p = nGrayNeutrons/fN; | |
239 | // ngn = gRandom->Binomial((Int_t) fN, p); | |
240 | ngn = gRandom->Gaus(nGrayNeutrons, TMath::Sqrt(fN*p*(1-p))); | |
241 | if(nGrayNeutrons<0.) ngn=0; | |
242 | ||
243 | // black neutrons | |
244 | p = nBlackNeutrons/fN; | |
245 | // nbn = gRandom->Binomial((Int_t) fN, p); | |
246 | nbn = gRandom->Gaus(nBlackNeutrons, TMath::Sqrt(fN*p*(1-p))); | |
247 | if(nBlackNeutrons<0.) nbn=0; | |
248 | ||
249 | } | |
250 | ||
c9a8628a | 251 | void AliSlowNucleonModelExp::SetParameters(Float_t alpha1, Float_t alpha2) |
252 | { | |
253 | // Set the model parameters | |
254 | fAlphaGray = alpha1; | |
255 | fAlphaBlack = alpha2; | |
256 | } | |
230d85c6 | 257 |