1 /**************************************************************************
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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 1.6 2001/05/16 14:57:10 alibrary
19 New files for folders and Stack
21 Revision 1.5 2000/12/21 16:24:06 morsch
22 Coding convention clean-up
24 Revision 1.4 2000/11/30 07:12:50 alibrary
25 Introducing new Rndm and QA classes
27 Revision 1.3 2000/10/02 21:28:06 fca
28 Removal of useless dependecies via forward declarations
30 Revision 1.2 2000/07/11 18:24:55 fca
31 Coding convention corrections + few minor bug fixes
33 Revision 1.1 2000/06/09 20:20:30 morsch
34 Same class as previously in AliSimpleGen.cxx
35 All coding rule violations except RS3 corrected (AM)
39 // Parameterisation of pi and K, eta and pt distributions
40 // used for the ALICE TDRs.
41 // eta: according to HIJING (shadowing + quenching)
42 // pT : according to CDF measurement at 1.8 TeV
43 // Author: andreas.morsch@cern.ch
48 <img src="picts/AliGeneratorClass.gif">
51 <font size=+2 color=red>
52 <p>The responsible person for this module is
53 <a href="mailto:andreas.morsch@cern.ch">Andreas Morsch</a>.
59 ///////////////////////////////////////////////////////////////////
61 #include "AliGenHIJINGpara.h"
67 ClassImp(AliGenHIJINGpara)
69 AliGenHIJINGpara::AliGenHIJINGpara(const AliGenHIJINGpara & para)
74 //_____________________________________________________________________________
75 static Double_t ptpi(Double_t *px, Double_t *)
78 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
79 // POWER LAW FOR PT > 500 MEV
80 // MT SCALING BELOW (T=160 MEV)
82 const Double_t kp0 = 1.3;
83 const Double_t kxn = 8.28;
84 const Double_t kxlim=0.5;
85 const Double_t kt=0.160;
86 const Double_t kxmpi=0.139;
88 Double_t y, y1, xmpi2, ynorm, a;
91 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
93 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt));
96 y=a*TMath::Power(kp0/(kp0+x),kxn);
98 y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt);
102 //_____________________________________________________________________________
103 static Double_t ptscal(Double_t pt, Int_t np)
105 // SCALING EN MASSE PAR RAPPORT A PTPI
106 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
107 const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
108 // VALUE MESON/PI AT 5 GEV
109 const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
111 Double_t f5=TMath::Power(((
112 sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
113 Double_t fmax2=f5/kfmax[np];
115 Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0);
116 Double_t fmtscal=TMath::Power(((
117 sqrt(pt*pt+0.018215)+2.)/ (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/
119 return fmtscal*ptpion;
122 //_____________________________________________________________________________
123 static Double_t ptka( Double_t *px, Double_t *)
126 // pt parametrisation for k
128 return ptscal(*px,2);
132 //_____________________________________________________________________________
133 static Double_t etapic( Double_t *py, Double_t *)
136 // eta parametrisation for pi
138 const Double_t ka1 = 4913.;
139 const Double_t ka2 = 1819.;
140 const Double_t keta1 = 0.22;
141 const Double_t keta2 = 3.66;
142 const Double_t kdeta1 = 1.47;
143 const Double_t kdeta2 = 1.51;
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 static Double_t etakac( Double_t *py, Double_t *)
155 // eta parametrisation for ka
157 const Double_t ka1 = 497.6;
158 const Double_t ka2 = 215.6;
159 const Double_t keta1 = 0.79;
160 const Double_t keta2 = 4.09;
161 const Double_t kdeta1 = 1.54;
162 const Double_t kdeta2 = 1.40;
163 Double_t y=TMath::Abs(*py);
165 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
166 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
167 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
170 //_____________________________________________________________________________
171 AliGenHIJINGpara::AliGenHIJINGpara()
175 // Default constructor
183 //_____________________________________________________________________________
184 AliGenHIJINGpara::AliGenHIJINGpara(Int_t npart)
188 // Standard constructor
191 fTitle="HIJING Parametrisation Particle Generator";
198 //_____________________________________________________________________________
199 AliGenHIJINGpara::~AliGenHIJINGpara()
202 // Standard destructor
210 //_____________________________________________________________________________
211 void AliGenHIJINGpara::Init()
214 // Initialise the HIJING parametrisation
216 Float_t etaMin =-TMath::Log(TMath::Tan(
217 TMath::Min((Double_t)fThetaMax/2,TMath::Pi()/2-1.e-10)));
218 Float_t etaMax = -TMath::Log(TMath::Tan(
219 TMath::Max((Double_t)fThetaMin/2,1.e-10)));
220 fPtpi = new TF1("ptpi",&ptpi,0,20,0);
221 fPtka = new TF1("ptka",&ptka,0,20,0);
222 fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0);
223 fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0);
225 TF1 *etaPic0 = new TF1("etapic",&etapic,-7,7,0);
226 TF1 *etaKac0 = new TF1("etakac",&etakac,-7,7,0);
228 TF1 *ptPic0 = new TF1("ptpi",&ptpi,0.,15.,0);
229 TF1 *ptKac0 = new TF1("ptka",&ptka,0.,15.,0);
231 Float_t intETApi = etaPic0->Integral(-0.5, 0.5);
232 Float_t intETAka = etaKac0->Integral(-0.5, 0.5);
233 Float_t scalePi = 7316/(intETApi/1.5);
234 Float_t scaleKa = 684/(intETAka/2.0);
236 // Fraction of events corresponding to the selected pt-range
237 Float_t intPt = (0.877*ptPic0->Integral(0, 15)+
238 0.123*ptKac0->Integral(0, 15));
239 Float_t intPtSel = (0.877*ptPic0->Integral(fPtMin, fPtMax)+
240 0.123*ptKac0->Integral(fPtMin, fPtMax));
241 Float_t ptFrac = intPtSel/intPt;
243 // Fraction of events corresponding to the selected eta-range
244 Float_t intETASel = (scalePi*etaPic0->Integral(etaMin, etaMax)+
245 scaleKa*etaKac0->Integral(etaMin, etaMax));
246 // Fraction of events corresponding to the selected phi-range
247 Float_t phiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi();
249 fParentWeight = Float_t(fNpart)/(intETASel*ptFrac*phiFrac);
251 printf("%s: The number of particles in the selected kinematic region corresponds to %f percent of a full event\n ",
252 ClassName(),100.*fParentWeight);
256 //_____________________________________________________________________________
257 void AliGenHIJINGpara::Generate()
260 // Generate one trigger
264 const Float_t kRaKpic=0.14;
265 const Float_t kBorne=1/(1+kRaKpic);
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};
272 Float_t pt, pl, ptot;
275 Int_t i, part, nt, j;
282 for (j=0;j<3;j++) origin[j]=fOrigin[j];
283 if(fVertexSmear==kPerEvent) {
286 origin[j]+=fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
287 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
290 for(i=0;i<fNpart;i++) {
293 if(random[0]<kBorne) {
294 part=kPions[Int_t (random[1]*3)];
298 part=kKaons[Int_t (random[1]*4)];
302 phi=fPhiMin+random[2]*(fPhiMax-fPhiMin);
303 theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom()));
304 if(theta<fThetaMin || theta>fThetaMax) continue;
306 pl=pt/TMath::Tan(theta);
307 ptot=TMath::Sqrt(pt*pt+pl*pl);
308 if(ptot<fPMin || ptot>fPMax) continue;
309 p[0]=pt*TMath::Cos(phi);
310 p[1]=pt*TMath::Sin(phi);
312 if(fVertexSmear==kPerTrack) {
315 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
316 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
319 gAlice->SetTrack(fTrackIt,-1,part,p,origin,polar,0,kPPrimary,nt,fParentWeight);
325 AliGenHIJINGpara& AliGenHIJINGpara::operator=(const AliGenHIJINGpara& rhs)
327 // Assignment operator