1 /**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
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 **************************************************************************/
19 ///////////////////////////////////////////////////////////////////
21 // Generate the final state of the interaction as the input //
22 // to the MonteCarlo //
26 <img src="picts/AliGeneratorClass.gif">
29 <font size=+2 color=red>
30 <p>The responsible person for this module is
31 <a href="mailto:andreas.morsch@cern.ch">Andreas Morsch</a>.
37 ///////////////////////////////////////////////////////////////////
39 #include "AliGenHIJINGpara.h"
44 ClassImp(AliGenHIJINGpara)
46 AliGenHIJINGpara::AliGenHIJINGpara(const AliGenHIJINGpara & para)
51 //_____________________________________________________________________________
52 static Double_t ptpi(Double_t *px, Double_t *)
55 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
56 // POWER LAW FOR PT > 500 MEV
57 // MT SCALING BELOW (T=160 MEV)
59 const Double_t kp0 = 1.3;
60 const Double_t kxn = 8.28;
61 const Double_t kxlim=0.5;
62 const Double_t kt=0.160;
63 const Double_t kxmpi=0.139;
65 Double_t y, y1, xmpi2, ynorm, a;
68 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
70 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt));
73 y=a*TMath::Power(kp0/(kp0+x),kxn);
75 y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt);
79 //_____________________________________________________________________________
80 static Double_t ptscal(Double_t pt, Int_t np)
82 // SCALING EN MASSE PAR RAPPORT A PTPI
83 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
84 const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
85 // VALUE MESON/PI AT 5 GEV
86 const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
88 Double_t f5=TMath::Power(((
89 sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
90 Double_t fmax2=f5/kfmax[np];
92 Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0);
93 Double_t fmtscal=TMath::Power(((
94 sqrt(pt*pt+0.018215)+2.)/ (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/
96 return fmtscal*ptpion;
99 //_____________________________________________________________________________
100 static Double_t ptka( Double_t *px, Double_t *)
103 // pt parametrisation for k
105 return ptscal(*px,2);
109 //_____________________________________________________________________________
110 static Double_t etapic( Double_t *py, Double_t *)
113 // eta parametrisation for pi
115 const Double_t ka1 = 4913.;
116 const Double_t ka2 = 1819.;
117 const Double_t keta1 = 0.22;
118 const Double_t keta2 = 3.66;
119 const Double_t kdeta1 = 1.47;
120 const Double_t kdeta2 = 1.51;
121 Double_t y=TMath::Abs(*py);
123 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
124 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
125 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
128 //_____________________________________________________________________________
129 static Double_t etakac( Double_t *py, Double_t *)
132 // eta parametrisation for ka
134 const Double_t ka1 = 497.6;
135 const Double_t ka2 = 215.6;
136 const Double_t keta1 = 0.79;
137 const Double_t keta2 = 4.09;
138 const Double_t kdeta1 = 1.54;
139 const Double_t kdeta2 = 1.40;
140 Double_t y=TMath::Abs(*py);
142 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
143 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
144 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
147 //_____________________________________________________________________________
148 AliGenHIJINGpara::AliGenHIJINGpara()
152 // Default constructor
160 //_____________________________________________________________________________
161 AliGenHIJINGpara::AliGenHIJINGpara(Int_t npart)
165 // Standard constructor
168 fTitle="HIJING Parametrisation Particle Generator";
175 //_____________________________________________________________________________
176 AliGenHIJINGpara::~AliGenHIJINGpara()
179 // Standard destructor
187 //_____________________________________________________________________________
188 void AliGenHIJINGpara::Init()
191 // Initialise the HIJING parametrisation
193 Float_t etaMin =-TMath::Log(TMath::Tan(
194 TMath::Min((Double_t)fThetaMax/2,TMath::Pi()/2-1.e-10)));
195 Float_t etaMax = -TMath::Log(TMath::Tan(
196 TMath::Max((Double_t)fThetaMin/2,1.e-10)));
197 fPtpi = new TF1("ptpi",&ptpi,0,20,0);
198 fPtka = new TF1("ptka",&ptka,0,20,0);
199 fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0);
200 fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0);
201 TF1 *etaPic0 = new TF1("etapic",&etapic,-7,7,0);
202 TF1 *etaKac0 = new TF1("etakac",&etakac,-7,7,0);
203 Float_t intETApi = etaPic0->Integral(-0.5, 0.5);
204 Float_t intETAka = etaKac0->Integral(-0.5, 0.5);
205 Float_t scalePi=7316/(intETApi/1.5);
206 Float_t scaleKa= 684/(intETAka/2.0);
208 Float_t intPt = (0.877*etaPic0->Integral(0, 15)+
209 0.123*etaKac0->Integral(0, 15));
210 Float_t intPtSel = (0.877*etaPic0->Integral(fPtMin, fPtMax)+
211 0.123*etaKac0->Integral(fPtMin, fPtMax));
212 Float_t ptFrac = intPtSel/intPt;
215 Float_t intETASel = (scalePi*etaPic0->Integral(etaMin, etaMax)+
216 scaleKa*etaKac0->Integral(etaMin, etaMax));
217 Float_t phiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi();
218 fParentWeight = Float_t(fNpart)/intETASel*ptFrac*phiFrac;
220 printf("\n The number of particles in the selected kinematic region corresponds to %f percent of a full event\n ", 100.*fParentWeight);
224 //_____________________________________________________________________________
225 void AliGenHIJINGpara::Generate()
228 // Generate one trigger
232 const Float_t kRaKpic=0.14;
233 const Float_t kBorne=1/(1+kRaKpic);
234 Float_t polar[3]= {0,0,0};
236 const Int_t kPions[3] = {kPi0, kPiPlus, kPiMinus};
237 const Int_t kKaons[4] = {kK0Long, kK0Short, kKPlus, kKMinus};
240 Float_t pt, pl, ptot;
243 Int_t i, part, nt, j;
250 for (j=0;j<3;j++) origin[j]=fOrigin[j];
251 if(fVertexSmear==perEvent) {
254 origin[j]+=fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
255 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
258 for(i=0;i<fNpart;i++) {
261 if(random[0]<kBorne) {
262 part=kPions[Int_t (random[1]*3)];
266 part=kKaons[Int_t (random[1]*4)];
270 phi=fPhiMin+random[2]*(fPhiMax-fPhiMin);
271 theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom()));
272 if(theta<fThetaMin || theta>fThetaMax) continue;
274 pl=pt/TMath::Tan(theta);
275 ptot=TMath::Sqrt(pt*pt+pl*pl);
276 if(ptot<fPMin || ptot>fPMax) continue;
277 p[0]=pt*TMath::Cos(phi);
278 p[1]=pt*TMath::Sin(phi);
280 if(fVertexSmear==perTrack) {
283 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
284 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
287 gAlice->SetTrack(fTrackIt,-1,part,p,origin,polar,0,"Primary",nt,fParentWeight);
293 AliGenHIJINGpara& AliGenHIJINGpara::operator=(const AliGenHIJINGpara& rhs)
295 // Assignment operator