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 **************************************************************************/
18 Revision 1.1 2000/06/09 20:20:30 morsch
19 Same class as previously in AliSimpleGen.cxx
20 All coding rule violations except RS3 corrected (AM)
23 ///////////////////////////////////////////////////////////////////
25 // Generate the final state of the interaction as the input //
26 // to the MonteCarlo //
30 <img src="picts/AliGeneratorClass.gif">
33 <font size=+2 color=red>
34 <p>The responsible person for this module is
35 <a href="mailto:andreas.morsch@cern.ch">Andreas Morsch</a>.
41 ///////////////////////////////////////////////////////////////////
43 #include "AliGenHIJINGpara.h"
48 ClassImp(AliGenHIJINGpara)
50 AliGenHIJINGpara::AliGenHIJINGpara(const AliGenHIJINGpara & para)
55 //_____________________________________________________________________________
56 static Double_t ptpi(Double_t *px, Double_t *)
59 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
60 // POWER LAW FOR PT > 500 MEV
61 // MT SCALING BELOW (T=160 MEV)
63 const Double_t kp0 = 1.3;
64 const Double_t kxn = 8.28;
65 const Double_t kxlim=0.5;
66 const Double_t kt=0.160;
67 const Double_t kxmpi=0.139;
69 Double_t y, y1, xmpi2, ynorm, a;
72 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
74 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt));
77 y=a*TMath::Power(kp0/(kp0+x),kxn);
79 y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt);
83 //_____________________________________________________________________________
84 static Double_t ptscal(Double_t pt, Int_t np)
86 // SCALING EN MASSE PAR RAPPORT A PTPI
87 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
88 const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
89 // VALUE MESON/PI AT 5 GEV
90 const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
92 Double_t f5=TMath::Power(((
93 sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
94 Double_t fmax2=f5/kfmax[np];
96 Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0);
97 Double_t fmtscal=TMath::Power(((
98 sqrt(pt*pt+0.018215)+2.)/ (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/
100 return fmtscal*ptpion;
103 //_____________________________________________________________________________
104 static Double_t ptka( Double_t *px, Double_t *)
107 // pt parametrisation for k
109 return ptscal(*px,2);
113 //_____________________________________________________________________________
114 static Double_t etapic( Double_t *py, Double_t *)
117 // eta parametrisation for pi
119 const Double_t ka1 = 4913.;
120 const Double_t ka2 = 1819.;
121 const Double_t keta1 = 0.22;
122 const Double_t keta2 = 3.66;
123 const Double_t kdeta1 = 1.47;
124 const Double_t kdeta2 = 1.51;
125 Double_t y=TMath::Abs(*py);
127 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
128 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
129 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
132 //_____________________________________________________________________________
133 static Double_t etakac( Double_t *py, Double_t *)
136 // eta parametrisation for ka
138 const Double_t ka1 = 497.6;
139 const Double_t ka2 = 215.6;
140 const Double_t keta1 = 0.79;
141 const Double_t keta2 = 4.09;
142 const Double_t kdeta1 = 1.54;
143 const Double_t kdeta2 = 1.40;
144 Double_t y=TMath::Abs(*py);
146 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
147 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
148 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
151 //_____________________________________________________________________________
152 AliGenHIJINGpara::AliGenHIJINGpara()
156 // Default constructor
164 //_____________________________________________________________________________
165 AliGenHIJINGpara::AliGenHIJINGpara(Int_t npart)
169 // Standard constructor
172 fTitle="HIJING Parametrisation Particle Generator";
179 //_____________________________________________________________________________
180 AliGenHIJINGpara::~AliGenHIJINGpara()
183 // Standard destructor
191 //_____________________________________________________________________________
192 void AliGenHIJINGpara::Init()
195 // Initialise the HIJING parametrisation
197 Float_t etaMin =-TMath::Log(TMath::Tan(
198 TMath::Min((Double_t)fThetaMax/2,TMath::Pi()/2-1.e-10)));
199 Float_t etaMax = -TMath::Log(TMath::Tan(
200 TMath::Max((Double_t)fThetaMin/2,1.e-10)));
201 fPtpi = new TF1("ptpi",&ptpi,0,20,0);
202 fPtka = new TF1("ptka",&ptka,0,20,0);
203 fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0);
204 fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0);
205 TF1 *etaPic0 = new TF1("etapic",&etapic,-7,7,0);
206 TF1 *etaKac0 = new TF1("etakac",&etakac,-7,7,0);
207 Float_t intETApi = etaPic0->Integral(-0.5, 0.5);
208 Float_t intETAka = etaKac0->Integral(-0.5, 0.5);
209 Float_t scalePi=7316/(intETApi/1.5);
210 Float_t scaleKa= 684/(intETAka/2.0);
212 Float_t intPt = (0.877*etaPic0->Integral(0, 15)+
213 0.123*etaKac0->Integral(0, 15));
214 Float_t intPtSel = (0.877*etaPic0->Integral(fPtMin, fPtMax)+
215 0.123*etaKac0->Integral(fPtMin, fPtMax));
216 Float_t ptFrac = intPtSel/intPt;
219 Float_t intETASel = (scalePi*etaPic0->Integral(etaMin, etaMax)+
220 scaleKa*etaKac0->Integral(etaMin, etaMax));
221 Float_t phiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi();
222 fParentWeight = Float_t(fNpart)/intETASel*ptFrac*phiFrac;
224 printf("\n The number of particles in the selected kinematic region corresponds to %f percent of a full event\n ", 100.*fParentWeight);
228 //_____________________________________________________________________________
229 void AliGenHIJINGpara::Generate()
232 // Generate one trigger
236 const Float_t kRaKpic=0.14;
237 const Float_t kBorne=1/(1+kRaKpic);
238 Float_t polar[3]= {0,0,0};
240 const Int_t kPions[3] = {kPi0, kPiPlus, kPiMinus};
241 const Int_t kKaons[4] = {kK0Long, kK0Short, kKPlus, kKMinus};
244 Float_t pt, pl, ptot;
247 Int_t i, part, nt, j;
254 for (j=0;j<3;j++) origin[j]=fOrigin[j];
255 if(fVertexSmear==kPerEvent) {
258 origin[j]+=fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
259 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
262 for(i=0;i<fNpart;i++) {
265 if(random[0]<kBorne) {
266 part=kPions[Int_t (random[1]*3)];
270 part=kKaons[Int_t (random[1]*4)];
274 phi=fPhiMin+random[2]*(fPhiMax-fPhiMin);
275 theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom()));
276 if(theta<fThetaMin || theta>fThetaMax) continue;
278 pl=pt/TMath::Tan(theta);
279 ptot=TMath::Sqrt(pt*pt+pl*pl);
280 if(ptot<fPMin || ptot>fPMax) continue;
281 p[0]=pt*TMath::Cos(phi);
282 p[1]=pt*TMath::Sin(phi);
284 if(fVertexSmear==kPerTrack) {
287 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
288 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
291 gAlice->SetTrack(fTrackIt,-1,part,p,origin,polar,0,"Primary",nt,fParentWeight);
297 AliGenHIJINGpara& AliGenHIJINGpara::operator=(const AliGenHIJINGpara& rhs)
299 // Assignment operator