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[u/mrichter/AliRoot.git] / EVGEN / AliSlowNucleonModelExp.cxx
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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 31ClassImp(AliSlowNucleonModelExp)
c9a8628a 32
1c56e311 33
34AliSlowNucleonModelExp::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
60void 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
104void 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 179void 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 251void AliSlowNucleonModelExp::SetParameters(Float_t alpha1, Float_t alpha2)
252{
253 // Set the model parameters
254 fAlphaGray = alpha1;
255 fAlphaBlack = alpha2;
256}
230d85c6 257