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 *
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12 * about the suitability of this software for any purpose. It is *
13 * provided "as is" without express or implied warranty. *
14 **************************************************************************/
19 ///////////////////////////////////////////////////////////////////
20 // Parameterisation of pi, K, n and p eta and pt distributions //
21 // eta: according to HIJING (shadowing + quenching) //
22 // pT : according to CDF measurement at 1.8 TeV //
23 // Author: andreas.morsch@cern.ch //
25 ///////////////////////////////////////////////////////////////////
27 #include "AliGenHIJINGparaBa.h"
28 #include "AliGenEventHeader.h"
36 ClassImp(AliGenHIJINGparaBa)
39 static Double_t ptpi(Double_t *px, Double_t *)
42 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
43 // POWER LAW FOR PT > 500 MEV
44 // MT SCALING BELOW (T=160 MEV)
46 const Double_t kp0 = 1.3;
47 const Double_t kxn = 8.28;
48 const Double_t kxlim=0.5;
49 const Double_t kt=0.160;
50 const Double_t kxmpi=0.139;
52 Double_t y, y1, xmpi2, ynorm, a;
55 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
57 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt));
60 y=a*TMath::Power(kp0/(kp0+x),kxn);
62 y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt);
66 //_____________________________________________________________________________
67 static Double_t ptscal(Double_t pt, Int_t np)
69 // SCALING EN MASSE PAR RAPPORT A PTPI
70 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
71 const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
72 // VALUE MESON/PI AT 5 GEV
73 const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
75 Double_t f5=TMath::Power(((
76 sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
77 Double_t fmax2=f5/kfmax[np];
79 Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0);
80 Double_t fmtscal=TMath::Power(((
81 sqrt(pt*pt+0.018215)+2.)/ (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/
83 return fmtscal*ptpion;
86 //_____________________________________________________________________________
87 static Double_t ptka( Double_t *px, Double_t *)
90 // pt parametrisation for k
96 //_____________________________________________________________________________
97 static Double_t etapic( Double_t *py, Double_t *)
100 // eta parametrisation for pi
102 const Double_t ka1 = 4913.;
103 const Double_t ka2 = 1819.;
104 const Double_t keta1 = 0.22;
105 const Double_t keta2 = 3.66;
106 const Double_t kdeta1 = 1.47;
107 const Double_t kdeta2 = 1.51;
108 Double_t y=TMath::Abs(*py);
110 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
111 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
112 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
115 //_____________________________________________________________________________
116 static Double_t etakac( Double_t *py, Double_t *)
119 // eta parametrisation for ka
121 const Double_t ka1 = 497.6;
122 const Double_t ka2 = 215.6;
123 const Double_t keta1 = 0.79;
124 const Double_t keta2 = 4.09;
125 const Double_t kdeta1 = 1.54;
126 const Double_t kdeta2 = 1.40;
127 Double_t y=TMath::Abs(*py);
129 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
130 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
131 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
134 static Double_t ptbaryon( Double_t *px, Double_t *)
138 //____________________________________________________________
140 return ptscal(*px,7); // 7==> Baryon in the PtScal function
143 static Double_t etabaryon( Double_t *py, Double_t *)
146 //____________________________________________________________
147 const Float_t p0 = 1.10343e+02;
148 const Float_t p1 = 1.73247e+01;
149 const Float_t p2 = -7.23808e+00;
150 const Float_t p3 = 4.48334e-01;
151 const Double_t y = TMath::Abs(*py);
153 return (p0+p1*y+p2*y*y+p3*y*y*y)/20.;
156 AliGenHIJINGparaBa::AliGenHIJINGparaBa()
160 // Default constructor
162 fName="HIGINGparaBa";
163 fTitle="HIJING Parametrisation Particle Generator with Baryons";
168 //_____________________________________________________________________________
169 AliGenHIJINGparaBa::AliGenHIJINGparaBa(Int_t npart)
170 :AliGenHIJINGpara(npart)
173 // Standard constructor
175 fName="HIGINGparaBa";
176 fTitle="HIJING Parametrisation Particle Generator with Baryons";
181 //_____________________________________________________________________________
182 AliGenHIJINGparaBa::~AliGenHIJINGparaBa()
185 // Standard destructor
191 //_____________________________________________________________________________
192 void AliGenHIJINGparaBa::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 fPtba = new TF1("ptbaryon",&ptbaryon,0,20,0);
204 fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0);
205 fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0);
206 fETAba = new TF1("etabaryon",&etabaryon,etaMin,etaMax,0);
208 TF1 *etaPic0 = new TF1("etapic",&etapic, -7, 7, 0);
209 TF1 *etaKac0 = new TF1("etakac",&etakac, -7, 7, 0);
210 TF1 *etaBar0 = new TF1("etabar",&etabaryon, -7, 7, 0);
212 TF1 *ptPic0 = new TF1("ptpi", &ptpi, 0., 15., 0);
213 TF1 *ptKac0 = new TF1("ptka", &ptka, 0., 15., 0);
214 TF1 *ptBar0 = new TF1("ptbar", &ptbaryon, 0., 15., 0);
216 Float_t intETApi = etaPic0->Integral(-0.5, 0.5);
217 Float_t intETAka = etaKac0->Integral(-0.5, 0.5);
218 Float_t intETAba = etaBar0->Integral(-0.5, 0.5);
220 Float_t scalePi = 6979./(intETApi/1.5);
221 Float_t scaleKa = 657./(intETAka/2.0);
222 Float_t scaleBa = 364./(intETAba/2.0);
224 // Fraction of events corresponding to the selected pt-range
225 Float_t intPt = (0.837*ptPic0->Integral(0, 15)+
226 0.105*ptKac0->Integral(0, 15)+
227 0.058*ptBar0->Integral(0, 15));
228 Float_t intPtSel = (0.837*ptPic0->Integral(fPtMin, fPtMax)+
229 0.105*ptKac0->Integral(fPtMin, fPtMax)+
230 0.058*ptBar0->Integral(fPtMin, fPtMax));
231 Float_t ptFrac = intPtSel/intPt;
233 // Fraction of events corresponding to the selected eta-range
234 Float_t intETASel = (scalePi*etaPic0->Integral(etaMin, etaMax)+
235 scaleKa*etaKac0->Integral(etaMin, etaMax)+
236 scaleBa*etaBar0->Integral(etaMin, etaMax));
237 // Fraction of events corresponding to the selected phi-range
238 Float_t phiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi();
240 fParentWeight = Float_t(fNpart)/(intETASel*ptFrac*phiFrac);
242 printf("%s: The number of particles in the selected kinematic region corresponds to %f percent of a full event \n",
243 ClassName(),100.*fParentWeight);
245 // Issue warning message if etaMin or etaMax are outside the alowed range
246 // of the parametrization
247 if (etaMin < -8.001 || etaMax > 8.001) {
248 printf("\n \n WARNING FROM AliGenHIJINGParaBa !");
249 printf("\n YOU ARE USING THE PARAMETERISATION OUTSIDE ");
250 printf("\n THE ALLOWED PSEUDORAPIDITY RANGE (-8. - 8.)");
251 printf("\n YOUR LIMITS: %f %f \n \n ", etaMin, etaMax);
255 //_____________________________________________________________________________
256 void AliGenHIJINGparaBa::Generate()
259 // Generate one trigger
263 const Float_t kBorne1 = 0.837;
264 const Float_t kBorne2 = kBorne1+0.105;
266 Float_t polar[3]= {0,0,0};
268 const Int_t kPions[3] = {kPi0, kPiPlus, kPiMinus};
269 const Int_t kKaons[4] = {kK0Long, kK0Short, kKPlus, kKMinus};
270 const Int_t kBaryons[4] = {kProton, kProtonBar, kNeutron, kNeutronBar};
273 Float_t pt, pl, ptot;
276 Int_t i, part, nt, j;
283 for (j=0;j<3;j++) origin[j]=fOrigin[j];
285 if(fVertexSmear == kPerEvent) {
288 while(TMath::Abs(dv[2]) > fCutVertexZ*fOsigma[2]) {
290 for (j=0; j < 3; j++) {
291 dv[j] = fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
292 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
295 for (j=0; j < 3; j++) origin[j] += dv[j];
299 eventVertex[0] = origin[0];
300 eventVertex[1] = origin[1];
301 eventVertex[2] = origin[2];
303 for(i=0;i<fNpart;i++) {
306 if(random[0] < kBorne1) {
307 part = kPions[Int_t (random[1]*3)];
310 } else if (random[0] < kBorne2) {
311 part = kKaons[Int_t (random[1]*4)];
315 part = kBaryons[Int_t (random[1]*4)];
320 phi=fPhiMin+random[2]*(fPhiMax-fPhiMin);
321 theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom()));
322 if(theta<fThetaMin || theta>fThetaMax) continue;
324 pl=pt/TMath::Tan(theta);
325 ptot=TMath::Sqrt(pt*pt+pl*pl);
326 if(ptot<fPMin || ptot>fPMax) continue;
327 p[0]=pt*TMath::Cos(phi);
328 p[1]=pt*TMath::Sin(phi);
330 if(fVertexSmear==kPerTrack) {
333 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
334 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
337 SetTrack(fTrackIt,-1,part,p,origin,polar,0,kPPrimary,nt,fParentWeight);
342 AliGenEventHeader* header = new AliGenEventHeader("HIJINGparam");
344 header->SetPrimaryVertex(eventVertex);
345 gAlice->SetGenEventHeader(header);