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4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
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18 Revision 1.4 2000/11/30 07:12:50 alibrary
19 Introducing new Rndm and QA classes
21 Revision 1.3 2000/10/02 21:28:06 fca
22 Removal of useless dependecies via forward declarations
24 Revision 1.2 2000/07/11 18:24:55 fca
25 Coding convention corrections + few minor bug fixes
27 Revision 1.1 2000/06/09 20:20:30 morsch
28 Same class as previously in AliSimpleGen.cxx
29 All coding rule violations except RS3 corrected (AM)
33 // Parameterisation of pi and K, eta and pt distributions
34 // used for the ALICE TDRs.
35 // eta: according to HIJING (shadowing + quenching)
36 // pT : according to CDF measurement at 1.8 TeV
37 // Author: andreas.morsch@cern.ch
42 <img src="picts/AliGeneratorClass.gif">
45 <font size=+2 color=red>
46 <p>The responsible person for this module is
47 <a href="mailto:andreas.morsch@cern.ch">Andreas Morsch</a>.
53 ///////////////////////////////////////////////////////////////////
55 #include "AliGenHIJINGpara.h"
61 ClassImp(AliGenHIJINGpara)
63 AliGenHIJINGpara::AliGenHIJINGpara(const AliGenHIJINGpara & para)
68 //_____________________________________________________________________________
69 static Double_t ptpi(Double_t *px, Double_t *)
72 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
73 // POWER LAW FOR PT > 500 MEV
74 // MT SCALING BELOW (T=160 MEV)
76 const Double_t kp0 = 1.3;
77 const Double_t kxn = 8.28;
78 const Double_t kxlim=0.5;
79 const Double_t kt=0.160;
80 const Double_t kxmpi=0.139;
82 Double_t y, y1, xmpi2, ynorm, a;
85 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
87 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt));
90 y=a*TMath::Power(kp0/(kp0+x),kxn);
92 y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt);
96 //_____________________________________________________________________________
97 static Double_t ptscal(Double_t pt, Int_t np)
99 // SCALING EN MASSE PAR RAPPORT A PTPI
100 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
101 const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
102 // VALUE MESON/PI AT 5 GEV
103 const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
105 Double_t f5=TMath::Power(((
106 sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
107 Double_t fmax2=f5/kfmax[np];
109 Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0);
110 Double_t fmtscal=TMath::Power(((
111 sqrt(pt*pt+0.018215)+2.)/ (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/
113 return fmtscal*ptpion;
116 //_____________________________________________________________________________
117 static Double_t ptka( Double_t *px, Double_t *)
120 // pt parametrisation for k
122 return ptscal(*px,2);
126 //_____________________________________________________________________________
127 static Double_t etapic( Double_t *py, Double_t *)
130 // eta parametrisation for pi
132 const Double_t ka1 = 4913.;
133 const Double_t ka2 = 1819.;
134 const Double_t keta1 = 0.22;
135 const Double_t keta2 = 3.66;
136 const Double_t kdeta1 = 1.47;
137 const Double_t kdeta2 = 1.51;
138 Double_t y=TMath::Abs(*py);
140 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
141 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
142 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
145 //_____________________________________________________________________________
146 static Double_t etakac( Double_t *py, Double_t *)
149 // eta parametrisation for ka
151 const Double_t ka1 = 497.6;
152 const Double_t ka2 = 215.6;
153 const Double_t keta1 = 0.79;
154 const Double_t keta2 = 4.09;
155 const Double_t kdeta1 = 1.54;
156 const Double_t kdeta2 = 1.40;
157 Double_t y=TMath::Abs(*py);
159 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
160 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
161 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
164 //_____________________________________________________________________________
165 AliGenHIJINGpara::AliGenHIJINGpara()
169 // Default constructor
177 //_____________________________________________________________________________
178 AliGenHIJINGpara::AliGenHIJINGpara(Int_t npart)
182 // Standard constructor
185 fTitle="HIJING Parametrisation Particle Generator";
192 //_____________________________________________________________________________
193 AliGenHIJINGpara::~AliGenHIJINGpara()
196 // Standard destructor
204 //_____________________________________________________________________________
205 void AliGenHIJINGpara::Init()
208 // Initialise the HIJING parametrisation
210 Float_t etaMin =-TMath::Log(TMath::Tan(
211 TMath::Min((Double_t)fThetaMax/2,TMath::Pi()/2-1.e-10)));
212 Float_t etaMax = -TMath::Log(TMath::Tan(
213 TMath::Max((Double_t)fThetaMin/2,1.e-10)));
214 fPtpi = new TF1("ptpi",&ptpi,0,20,0);
215 fPtka = new TF1("ptka",&ptka,0,20,0);
216 fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0);
217 fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0);
218 TF1 *etaPic0 = new TF1("etapic",&etapic,-7,7,0);
219 TF1 *etaKac0 = new TF1("etakac",&etakac,-7,7,0);
220 Float_t intETApi = etaPic0->Integral(-0.5, 0.5);
221 Float_t intETAka = etaKac0->Integral(-0.5, 0.5);
222 Float_t scalePi=7316/(intETApi/1.5);
223 Float_t scaleKa= 684/(intETAka/2.0);
225 Float_t intPt = (0.877*etaPic0->Integral(0, 15)+
226 0.123*etaKac0->Integral(0, 15));
227 Float_t intPtSel = (0.877*etaPic0->Integral(fPtMin, fPtMax)+
228 0.123*etaKac0->Integral(fPtMin, fPtMax));
229 Float_t ptFrac = intPtSel/intPt;
232 Float_t intETASel = (scalePi*etaPic0->Integral(etaMin, etaMax)+
233 scaleKa*etaKac0->Integral(etaMin, etaMax));
234 Float_t phiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi();
235 fParentWeight = Float_t(fNpart)/intETASel*ptFrac*phiFrac;
237 printf("\n The number of particles in the selected kinematic region corresponds to %f percent of a full event\n ", 100.*fParentWeight);
241 //_____________________________________________________________________________
242 void AliGenHIJINGpara::Generate()
245 // Generate one trigger
249 const Float_t kRaKpic=0.14;
250 const Float_t kBorne=1/(1+kRaKpic);
251 Float_t polar[3]= {0,0,0};
253 const Int_t kPions[3] = {kPi0, kPiPlus, kPiMinus};
254 const Int_t kKaons[4] = {kK0Long, kK0Short, kKPlus, kKMinus};
257 Float_t pt, pl, ptot;
260 Int_t i, part, nt, j;
267 for (j=0;j<3;j++) origin[j]=fOrigin[j];
268 if(fVertexSmear==kPerEvent) {
271 origin[j]+=fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
272 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
275 for(i=0;i<fNpart;i++) {
278 if(random[0]<kBorne) {
279 part=kPions[Int_t (random[1]*3)];
283 part=kKaons[Int_t (random[1]*4)];
287 phi=fPhiMin+random[2]*(fPhiMax-fPhiMin);
288 theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom()));
289 if(theta<fThetaMin || theta>fThetaMax) continue;
291 pl=pt/TMath::Tan(theta);
292 ptot=TMath::Sqrt(pt*pt+pl*pl);
293 if(ptot<fPMin || ptot>fPMax) continue;
294 p[0]=pt*TMath::Cos(phi);
295 p[1]=pt*TMath::Sin(phi);
297 if(fVertexSmear==kPerTrack) {
300 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
301 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
304 gAlice->SetTrack(fTrackIt,-1,part,p,origin,polar,0,kPPrimary,nt,fParentWeight);
310 AliGenHIJINGpara& AliGenHIJINGpara::operator=(const AliGenHIJINGpara& rhs)
312 // Assignment operator