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. *
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14 **************************************************************************/
18 Revision 1.8 2001/07/20 11:03:58 morsch
19 Issue warning message if used outside allowed eta range (-8 to 8).
21 Revision 1.7 2001/07/17 12:41:01 morsch
22 - Calculation of fraction of event corresponding to selected pt-range corrected
24 - Parent weight corrected.
26 Revision 1.6 2001/05/16 14:57:10 alibrary
27 New files for folders and Stack
29 Revision 1.5 2000/12/21 16:24:06 morsch
30 Coding convention clean-up
32 Revision 1.4 2000/11/30 07:12:50 alibrary
33 Introducing new Rndm and QA classes
35 Revision 1.3 2000/10/02 21:28:06 fca
36 Removal of useless dependecies via forward declarations
38 Revision 1.2 2000/07/11 18:24:55 fca
39 Coding convention corrections + few minor bug fixes
41 Revision 1.1 2000/06/09 20:20:30 morsch
42 Same class as previously in AliSimpleGen.cxx
43 All coding rule violations except RS3 corrected (AM)
47 // Parameterisation of pi and K, eta and pt distributions
48 // used for the ALICE TDRs.
49 // eta: according to HIJING (shadowing + quenching)
50 // pT : according to CDF measurement at 1.8 TeV
51 // Author: andreas.morsch@cern.ch
56 <img src="picts/AliGeneratorClass.gif">
59 <font size=+2 color=red>
60 <p>The responsible person for this module is
61 <a href="mailto:andreas.morsch@cern.ch">Andreas Morsch</a>.
67 ///////////////////////////////////////////////////////////////////
69 #include "AliGenHIJINGpara.h"
75 ClassImp(AliGenHIJINGpara)
77 AliGenHIJINGpara::AliGenHIJINGpara(const AliGenHIJINGpara & para)
82 //_____________________________________________________________________________
83 static Double_t ptpi(Double_t *px, Double_t *)
86 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
87 // POWER LAW FOR PT > 500 MEV
88 // MT SCALING BELOW (T=160 MEV)
90 const Double_t kp0 = 1.3;
91 const Double_t kxn = 8.28;
92 const Double_t kxlim=0.5;
93 const Double_t kt=0.160;
94 const Double_t kxmpi=0.139;
96 Double_t y, y1, xmpi2, ynorm, a;
99 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
101 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt));
104 y=a*TMath::Power(kp0/(kp0+x),kxn);
106 y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt);
110 //_____________________________________________________________________________
111 static Double_t ptscal(Double_t pt, Int_t np)
113 // SCALING EN MASSE PAR RAPPORT A PTPI
114 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
115 const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
116 // VALUE MESON/PI AT 5 GEV
117 const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
119 Double_t f5=TMath::Power(((
120 sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
121 Double_t fmax2=f5/kfmax[np];
123 Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0);
124 Double_t fmtscal=TMath::Power(((
125 sqrt(pt*pt+0.018215)+2.)/ (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/
127 return fmtscal*ptpion;
130 //_____________________________________________________________________________
131 static Double_t ptka( Double_t *px, Double_t *)
134 // pt parametrisation for k
136 return ptscal(*px,2);
140 //_____________________________________________________________________________
141 static Double_t etapic( Double_t *py, Double_t *)
144 // eta parametrisation for pi
146 const Double_t ka1 = 4913.;
147 const Double_t ka2 = 1819.;
148 const Double_t keta1 = 0.22;
149 const Double_t keta2 = 3.66;
150 const Double_t kdeta1 = 1.47;
151 const Double_t kdeta2 = 1.51;
152 Double_t y=TMath::Abs(*py);
154 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
155 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
156 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
159 //_____________________________________________________________________________
160 static Double_t etakac( Double_t *py, Double_t *)
163 // eta parametrisation for ka
165 const Double_t ka1 = 497.6;
166 const Double_t ka2 = 215.6;
167 const Double_t keta1 = 0.79;
168 const Double_t keta2 = 4.09;
169 const Double_t kdeta1 = 1.54;
170 const Double_t kdeta2 = 1.40;
171 Double_t y=TMath::Abs(*py);
173 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
174 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
175 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
178 //_____________________________________________________________________________
179 AliGenHIJINGpara::AliGenHIJINGpara()
183 // Default constructor
191 //_____________________________________________________________________________
192 AliGenHIJINGpara::AliGenHIJINGpara(Int_t npart)
196 // Standard constructor
199 fTitle="HIJING Parametrisation Particle Generator";
206 //_____________________________________________________________________________
207 AliGenHIJINGpara::~AliGenHIJINGpara()
210 // Standard destructor
218 //_____________________________________________________________________________
219 void AliGenHIJINGpara::Init()
222 // Initialise the HIJING parametrisation
224 Float_t etaMin =-TMath::Log(TMath::Tan(
225 TMath::Min((Double_t)fThetaMax/2,TMath::Pi()/2-1.e-10)));
226 Float_t etaMax = -TMath::Log(TMath::Tan(
227 TMath::Max((Double_t)fThetaMin/2,1.e-10)));
228 fPtpi = new TF1("ptpi",&ptpi,0,20,0);
229 fPtka = new TF1("ptka",&ptka,0,20,0);
230 fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0);
231 fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0);
233 TF1 *etaPic0 = new TF1("etapic",&etapic,-7,7,0);
234 TF1 *etaKac0 = new TF1("etakac",&etakac,-7,7,0);
236 TF1 *ptPic0 = new TF1("ptpi",&ptpi,0.,15.,0);
237 TF1 *ptKac0 = new TF1("ptka",&ptka,0.,15.,0);
239 Float_t intETApi = etaPic0->Integral(-0.5, 0.5);
240 Float_t intETAka = etaKac0->Integral(-0.5, 0.5);
241 Float_t scalePi = 7316/(intETApi/1.5);
242 Float_t scaleKa = 684/(intETAka/2.0);
244 // Fraction of events corresponding to the selected pt-range
245 Float_t intPt = (0.877*ptPic0->Integral(0, 15)+
246 0.123*ptKac0->Integral(0, 15));
247 Float_t intPtSel = (0.877*ptPic0->Integral(fPtMin, fPtMax)+
248 0.123*ptKac0->Integral(fPtMin, fPtMax));
249 Float_t ptFrac = intPtSel/intPt;
251 // Fraction of events corresponding to the selected eta-range
252 Float_t intETASel = (scalePi*etaPic0->Integral(etaMin, etaMax)+
253 scaleKa*etaKac0->Integral(etaMin, etaMax));
254 // Fraction of events corresponding to the selected phi-range
255 Float_t phiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi();
257 fParentWeight = Float_t(fNpart)/(intETASel*ptFrac*phiFrac);
259 printf("%s: The number of particles in the selected kinematic region corresponds to %f percent of a full event\n ",
260 ClassName(),100.*fParentWeight);
262 // Issue warning message if etaMin or etaMax are outside the alowed range
263 // of the parametrization
264 if (etaMin < -8.001 || etaMax > 8.001) {
265 printf("\n \n WARNING FROM AliGenHIJINGPara !");
266 printf("\n YOU ARE USING THE PARAMETERISATION OUTSIDE ");
267 printf("\n THE ALLOWED PSEUDORAPIDITY RANGE (-8. - 8.)");
268 printf("\n YOUR LIMITS: %f %f \n \n ", etaMin, etaMax);
272 //_____________________________________________________________________________
273 void AliGenHIJINGpara::Generate()
276 // Generate one trigger
280 const Float_t kRaKpic=0.14;
281 const Float_t kBorne=1/(1+kRaKpic);
282 Float_t polar[3]= {0,0,0};
284 const Int_t kPions[3] = {kPi0, kPiPlus, kPiMinus};
285 const Int_t kKaons[4] = {kK0Long, kK0Short, kKPlus, kKMinus};
288 Float_t pt, pl, ptot;
291 Int_t i, part, nt, j;
298 for (j=0;j<3;j++) origin[j]=fOrigin[j];
299 if(fVertexSmear==kPerEvent) {
302 origin[j]+=fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
303 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
306 for(i=0;i<fNpart;i++) {
309 if(random[0]<kBorne) {
310 part=kPions[Int_t (random[1]*3)];
314 part=kKaons[Int_t (random[1]*4)];
318 phi=fPhiMin+random[2]*(fPhiMax-fPhiMin);
319 theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom()));
320 if(theta<fThetaMin || theta>fThetaMax) continue;
322 pl=pt/TMath::Tan(theta);
323 ptot=TMath::Sqrt(pt*pt+pl*pl);
324 if(ptot<fPMin || ptot>fPMax) continue;
325 p[0]=pt*TMath::Cos(phi);
326 p[1]=pt*TMath::Sin(phi);
328 if(fVertexSmear==kPerTrack) {
331 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
332 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
335 SetTrack(fTrackIt,-1,part,p,origin,polar,0,kPPrimary,nt,fParentWeight);
341 AliGenHIJINGpara& AliGenHIJINGpara::operator=(const AliGenHIJINGpara& rhs)
343 // Assignment operator