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 ///////////////////////////////////////////////////////////////////
19 // Parameterisation of pi, K, n and p eta and pt distributions //
20 // eta: according to HIJING (shadowing + quenching) //
21 // pT : according to CDF measurement at 1.8 TeV //
22 // Author: andreas.morsch@cern.ch //
24 ///////////////////////////////////////////////////////////////////
31 #include "AliGenEventHeader.h"
32 #include "AliGenHIJINGparaBa.h"
35 ClassImp(AliGenHIJINGparaBa)
38 static Double_t ptpi(Double_t *px, Double_t *)
41 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
42 // POWER LAW FOR PT > 500 MEV
43 // MT SCALING BELOW (T=160 MEV)
45 const Double_t kp0 = 1.3;
46 const Double_t kxn = 8.28;
47 const Double_t kxlim=0.5;
48 const Double_t kt=0.160;
49 const Double_t kxmpi=0.139;
51 Double_t y, y1, xmpi2, ynorm, a;
54 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
56 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt));
59 y=a*TMath::Power(kp0/(kp0+x),kxn);
61 y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt);
65 //_____________________________________________________________________________
66 static Double_t ptscal(Double_t pt, Int_t np)
68 // SCALING EN MASSE PAR RAPPORT A PTPI
69 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
70 const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
71 // VALUE MESON/PI AT 5 GEV
72 const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
74 Double_t f5=TMath::Power(((
75 sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
76 Double_t fmax2=f5/kfmax[np];
78 Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0);
79 Double_t fmtscal=TMath::Power(((
80 sqrt(pt*pt+0.018215)+2.)/ (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/
82 return fmtscal*ptpion;
85 //_____________________________________________________________________________
86 static Double_t ptka( Double_t *px, Double_t *)
89 // pt parametrisation for k
95 //_____________________________________________________________________________
96 static Double_t etapic( Double_t *py, Double_t *)
99 // eta parametrisation for pi
101 const Double_t ka1 = 4913.;
102 const Double_t ka2 = 1819.;
103 const Double_t keta1 = 0.22;
104 const Double_t keta2 = 3.66;
105 const Double_t kdeta1 = 1.47;
106 const Double_t kdeta2 = 1.51;
107 Double_t y=TMath::Abs(*py);
109 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
110 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
111 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
114 //_____________________________________________________________________________
115 static Double_t etakac( Double_t *py, Double_t *)
118 // eta parametrisation for ka
120 const Double_t ka1 = 497.6;
121 const Double_t ka2 = 215.6;
122 const Double_t keta1 = 0.79;
123 const Double_t keta2 = 4.09;
124 const Double_t kdeta1 = 1.54;
125 const Double_t kdeta2 = 1.40;
126 Double_t y=TMath::Abs(*py);
128 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
129 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
130 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
133 static Double_t ptbaryon( Double_t *px, Double_t *)
137 //____________________________________________________________
139 return ptscal(*px,7); // 7==> Baryon in the PtScal function
142 static Double_t etabaryon( Double_t *py, Double_t *)
145 //____________________________________________________________
146 const Float_t kp0 = 1.10343e+02;
147 const Float_t kp1 = 1.73247e+01;
148 const Float_t kp2 = -7.23808e+00;
149 const Float_t kp3 = 4.48334e-01;
150 const Double_t ky = TMath::Abs(*py);
152 return (kp0+kp1*ky+kp2*ky*ky+kp3*ky*ky*ky)/20.;
155 AliGenHIJINGparaBa::AliGenHIJINGparaBa()
161 // Default constructor
163 fName="HIGINGparaBa";
164 fTitle="HIJING Parametrisation Particle Generator with Baryons";
167 //_____________________________________________________________________________
168 AliGenHIJINGparaBa::AliGenHIJINGparaBa(Int_t npart)
169 :AliGenHIJINGpara(npart),
174 // Standard constructor
176 fName="HIGINGparaBa";
177 fTitle="HIJING Parametrisation Particle Generator with Baryons";
180 //_____________________________________________________________________________
181 AliGenHIJINGparaBa::~AliGenHIJINGparaBa()
184 // Standard destructor
190 //_____________________________________________________________________________
191 void AliGenHIJINGparaBa::Init()
194 // Initialise the HIJING parametrisation
196 Float_t etaMin =-TMath::Log(TMath::Tan(
197 TMath::Min((Double_t)fThetaMax/2,TMath::Pi()/2-1.e-10)));
198 Float_t etaMax = -TMath::Log(TMath::Tan(
199 TMath::Max((Double_t)fThetaMin/2,1.e-10)));
200 fPtpi = new TF1("ptpi",&ptpi,0,20,0);
201 fPtka = new TF1("ptka",&ptka,0,20,0);
202 fPtba = new TF1("ptbaryon",&ptbaryon,0,20,0);
203 fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0);
204 fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0);
205 fETAba = new TF1("etabaryon",&etabaryon,etaMin,etaMax,0);
207 TF1 etaPic0("etapic(-7,7)",&etapic, -7, 7, 0);
208 TF1 etaKac0("etakac(-7,7)",&etakac, -7, 7, 0);
209 TF1 etaBar0("etabar(-7,7)",&etabaryon, -7, 7, 0);
211 TF1 ptPic0("ptpi(0,15)", &ptpi, 0., 15., 0);
212 TF1 ptKac0("ptka(0,15)", &ptka, 0., 15., 0);
213 TF1 ptBar0("ptbar(0,15)", &ptbaryon, 0., 15., 0);
215 Float_t intETApi = etaPic0.Integral(-0.5, 0.5);
216 Float_t intETAka = etaKac0.Integral(-0.5, 0.5);
217 Float_t intETAba = etaBar0.Integral(-0.5, 0.5);
219 Float_t scalePi = 6979./(intETApi/1.5);
220 Float_t scaleKa = 657./(intETAka/2.0);
221 Float_t scaleBa = 364./(intETAba/2.0);
223 // Fraction of events corresponding to the selected pt-range
224 Float_t intPt = (0.837*ptPic0.Integral(0, 15)+
225 0.105*ptKac0.Integral(0, 15)+
226 0.058*ptBar0.Integral(0, 15));
227 Float_t intPtSel = (0.837*ptPic0.Integral(fPtMin, fPtMax)+
228 0.105*ptKac0.Integral(fPtMin, fPtMax)+
229 0.058*ptBar0.Integral(fPtMin, fPtMax));
230 Float_t ptFrac = intPtSel/intPt;
232 // Fraction of events corresponding to the selected eta-range
233 Float_t intETASel = (scalePi*etaPic0.Integral(etaMin, etaMax)+
234 scaleKa*etaKac0.Integral(etaMin, etaMax)+
235 scaleBa*etaBar0.Integral(etaMin, etaMax));
236 // Fraction of events corresponding to the selected phi-range
237 Float_t phiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi();
239 fParentWeight = Float_t(fNpart)/(intETASel*ptFrac*phiFrac);
241 printf("%s: The number of particles in the selected kinematic region corresponds to %f percent of a full event \n",
242 ClassName(),100.*fParentWeight);
244 // Issue warning message if etaMin or etaMax are outside the alowed range
245 // of the parametrization
246 if (etaMin < -8.001 || etaMax > 8.001) {
247 printf("\n \n WARNING FROM AliGenHIJINGParaBa !");
248 printf("\n YOU ARE USING THE PARAMETERISATION OUTSIDE ");
249 printf("\n THE ALLOWED PSEUDORAPIDITY RANGE (-8. - 8.)");
250 printf("\n YOUR LIMITS: %f %f \n \n ", etaMin, etaMax);
254 //_____________________________________________________________________________
255 void AliGenHIJINGparaBa::Generate()
258 // Generate one trigger
262 const Float_t kBorne1 = 0.837;
263 const Float_t kBorne2 = kBorne1+0.105;
265 Float_t polar[3]= {0,0,0};
267 const Int_t kPions[3] = {kPi0, kPiPlus, kPiMinus};
268 const Int_t kKaons[4] = {kK0Long, kK0Short, kKPlus, kKMinus};
269 const Int_t kBaryons[4] = {kProton, kProtonBar, kNeutron, kNeutronBar};
272 Float_t pt, pl, ptot;
275 Int_t i, part, nt, j;
282 for (j=0;j<3;j++) origin[j]=fOrigin[j];
284 if(fVertexSmear == kPerEvent) {
287 while(TMath::Abs(dv[2]) > fCutVertexZ*fOsigma[2]) {
289 for (j=0; j < 3; j++) {
290 dv[j] = fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
291 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
294 for (j=0; j < 3; j++) origin[j] += dv[j];
298 eventVertex[0] = origin[0];
299 eventVertex[1] = origin[1];
300 eventVertex[2] = origin[2];
302 for(i=0;i<fNpart;i++) {
305 if(random[0] < kBorne1) {
306 part = kPions[Int_t (random[1]*3)];
309 } else if (random[0] < kBorne2) {
310 part = kKaons[Int_t (random[1]*4)];
314 part = kBaryons[Int_t (random[1]*4)];
319 phi=fPhiMin+random[2]*(fPhiMax-fPhiMin);
320 theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom()));
321 if(theta<fThetaMin || theta>fThetaMax) continue;
323 pl=pt/TMath::Tan(theta);
324 ptot=TMath::Sqrt(pt*pt+pl*pl);
325 if(ptot<fPMin || ptot>fPMax) continue;
326 p[0]=pt*TMath::Cos(phi);
327 p[1]=pt*TMath::Sin(phi);
329 if(fVertexSmear==kPerTrack) {
332 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
333 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
336 PushTrack(fTrackIt,-1,part,p,origin,polar,0,kPPrimary,nt,fParentWeight);
341 AliGenEventHeader* header = new AliGenEventHeader("HIJINGparam");
343 header->SetPrimaryVertex(eventVertex);
344 gAlice->SetGenEventHeader(header);