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 **************************************************************************/
20 ///////////////////////////////////////////////////////////////////
22 // Generate the final state of the interaction as the input //
23 // to the MonteCarlo //
27 <img src="picts/AliGeneratorClass.gif">
30 <font size=+2 color=red>
31 <p>The responsible person for this module is
32 <a href="mailto:andreas.morsch@cern.ch">Andreas Morsch</a>.
38 ///////////////////////////////////////////////////////////////////
40 #include "AliSimpleGen.h"
44 ClassImp(AliGenHIJINGpara)
46 //_____________________________________________________________________________
47 static Double_t ptpi(Double_t *px, Double_t *)
50 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
51 // POWER LAW FOR PT > 500 MEV
52 // MT SCALING BELOW (T=160 MEV)
54 const Double_t p0 = 1.3;
55 const Double_t xn = 8.28;
56 const Double_t xlim=0.5;
57 const Double_t t=0.160;
58 const Double_t xmpi=0.139;
60 Double_t y, y1, xmpi2, ynorm, a;
63 y1=TMath::Power(p0/(p0+xlim),xn);
65 ynorm=b*(TMath::Exp(-sqrt(xlim*xlim+xmpi2)/t));
68 y=a*TMath::Power(p0/(p0+x),xn);
70 y=b*TMath::Exp(-sqrt(x*x+xmpi2)/t);
74 //_____________________________________________________________________________
75 static Double_t ptscal(Double_t pt, Int_t np)
77 // SCALING EN MASSE PAR RAPPORT A PTPI
78 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
79 const Double_t hm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
80 // VALUE MESON/PI AT 5 GEV
81 const Double_t fmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
83 Double_t f5=TMath::Power(((sqrt(100.018215)+2.)/(sqrt(100.+hm[np]*hm[np])+2.0)),12.3);
84 Double_t fmax2=f5/fmax[np];
86 Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0);
87 Double_t fmtscal=TMath::Power(((sqrt(pt*pt+0.018215)+2.)/
88 (sqrt(pt*pt+hm[np]*hm[np])+2.0)),12.3)/ fmax2;
89 return fmtscal*ptpion;
92 //_____________________________________________________________________________
93 static Double_t ptka( Double_t *px, Double_t *)
96 // pt parametrisation for k
102 //_____________________________________________________________________________
103 static Double_t etapic( Double_t *py, Double_t *)
106 // eta parametrisation for pi
108 const Double_t a1 = 4913.;
109 const Double_t a2 = 1819.;
110 const Double_t eta1 = 0.22;
111 const Double_t eta2 = 3.66;
112 const Double_t deta1 = 1.47;
113 const Double_t deta2 = 1.51;
114 Double_t y=TMath::Abs(*py);
116 Double_t ex1 = (y-eta1)*(y-eta1)/(2*deta1*deta1);
117 Double_t ex2 = (y-eta2)*(y-eta2)/(2*deta2*deta2);
118 return a1*TMath::Exp(-ex1)+a2*TMath::Exp(-ex2);
121 //_____________________________________________________________________________
122 static Double_t etakac( Double_t *py, Double_t *)
125 // eta parametrisation for ka
127 const Double_t a1 = 497.6;
128 const Double_t a2 = 215.6;
129 const Double_t eta1 = 0.79;
130 const Double_t eta2 = 4.09;
131 const Double_t deta1 = 1.54;
132 const Double_t deta2 = 1.40;
133 Double_t y=TMath::Abs(*py);
135 Double_t ex1 = (y-eta1)*(y-eta1)/(2*deta1*deta1);
136 Double_t ex2 = (y-eta2)*(y-eta2)/(2*deta2*deta2);
137 return a1*TMath::Exp(-ex1)+a2*TMath::Exp(-ex2);
140 //_____________________________________________________________________________
141 AliGenHIJINGpara::AliGenHIJINGpara()
145 // Default constructor
153 //_____________________________________________________________________________
154 AliGenHIJINGpara::AliGenHIJINGpara(Int_t npart)
158 // Standard constructor
161 fTitle="HIJING Parametrisation Particle Generator";
168 //_____________________________________________________________________________
169 AliGenHIJINGpara::~AliGenHIJINGpara()
172 // Standard destructor
180 //_____________________________________________________________________________
181 void AliGenHIJINGpara::Init()
184 // Initialise the HIJING parametrisation
186 Float_t etaMin = -TMath::Log(TMath::Tan(TMath::Min((Double_t)fThetaMax/2,TMath::Pi()/2-1.e-10)));
187 Float_t etaMax = -TMath::Log(TMath::Tan(TMath::Max((Double_t)fThetaMin/2, 1.e-10)));
188 fPtpi = new TF1("ptpi",&ptpi,0,20,0);
189 fPtka = new TF1("ptka",&ptka,0,20,0);
190 fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0);
191 fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0);
192 TF1 *ETApic0 = new TF1("etapic",&etapic,-7,7,0);
193 TF1 *ETAkac0 = new TF1("etakac",&etakac,-7,7,0);
194 Float_t IntETApi = ETApic0->Integral(-0.5, 0.5);
195 Float_t IntETAka = ETAkac0->Integral(-0.5, 0.5);
196 Float_t scalePi=7316/(IntETApi/1.5);
197 Float_t scaleKa= 684/(IntETAka/2.0);
199 Float_t IntPt = (0.877*ETApic0->Integral(0, 15)+
200 0.123*ETAkac0->Integral(0, 15));
201 Float_t IntPtSel = (0.877*ETApic0->Integral(fPtMin, fPtMax)+
202 0.123*ETAkac0->Integral(fPtMin, fPtMax));
203 Float_t PtFrac = IntPtSel/IntPt;
206 Float_t IntETASel = (scalePi*ETApic0->Integral(etaMin, etaMax)+
207 scaleKa*ETAkac0->Integral(etaMin, etaMax));
208 Float_t PhiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi();
209 fParentWeight = Float_t(fNpart)/IntETASel*PtFrac*PhiFrac;
211 printf("\n The number of particles in the selected kinematic region corresponds to %f percent of a full event\n ", 100.*fParentWeight);
215 //_____________________________________________________________________________
216 void AliGenHIJINGpara::Generate()
219 // Generate one trigger
223 const Float_t raKpic=0.14;
224 const Float_t borne=1/(1+raKpic);
225 Float_t polar[3]= {0,0,0};
227 const Int_t pions[3] = {kPi0, kPiPlus, kPiMinus};
228 const Int_t kaons[4] = {kK0Long, kK0Short, kKPlus, kKMinus};
231 Float_t pt, pl, ptot;
234 Int_t i, part, nt, j;
241 for (j=0;j<3;j++) origin[j]=fOrigin[j];
242 if(fVertexSmear==perEvent) {
245 origin[j]+=fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
246 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
249 for(i=0;i<fNpart;i++) {
252 if(random[0]<borne) {
253 part=pions[Int_t (random[1]*3)];
257 part=kaons[Int_t (random[1]*4)];
261 phi=2*random[2]*TMath::Pi();
262 if(phi<fPhiMin || phi>fPhiMax) continue;
263 theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom()));
264 if(theta<fThetaMin || theta>fThetaMax) continue;
266 pl=pt/TMath::Tan(theta);
267 ptot=TMath::Sqrt(pt*pt+pl*pl);
268 if(ptot<fPMin || ptot>fPMax) continue;
269 p[0]=pt*TMath::Cos(phi);
270 p[1]=pt*TMath::Sin(phi);
272 if(fVertexSmear==perTrack) {
275 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
276 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
279 gAlice->SetTrack(1,-1,part,p,origin,polar,0,"Primary",nt,fParentWeight);
285 ClassImp(AliGenFixed)
287 //_____________________________________________________________________________
288 AliGenFixed::AliGenFixed()
292 // Default constructor
297 //_____________________________________________________________________________
298 AliGenFixed::AliGenFixed(Int_t npart)
302 // Standard constructor
305 fTitle="Fixed Particle Generator";
306 // Generate Proton by default
310 //_____________________________________________________________________________
311 void AliGenFixed::Generate()
314 // Generate one trigger
316 Float_t polar[3]= {0,0,0};
317 Float_t p[3] = {fPMin*TMath::Cos(fPhiMin)*TMath::Sin(fThetaMin),
318 fPMin*TMath::Sin(fPhiMin)*TMath::Sin(fThetaMin),
319 fPMin*TMath::Cos(fThetaMin)};
322 for(i=0;i<fNpart;i++) {
323 gAlice->SetTrack(1,-1,fIpart,p,fOrigin.GetArray(),polar,0,"Primary",nt);
327 //_____________________________________________________________________________
328 void AliGenFixed::SetSigma(Float_t, Float_t, Float_t)
331 // Set the interaction point sigma
333 printf("Vertex smearing not implemented for fixed generator\n");
339 //_____________________________________________________________________________
340 AliGenBox::AliGenBox()
344 // Default constructor
349 //_____________________________________________________________________________
350 AliGenBox::AliGenBox(Int_t npart)
354 // Standard constructor
357 fTitle="Box particle generator";
358 // Generate Proton by default
362 //_____________________________________________________________________________
363 void AliGenBox::Generate()
366 // Generate one trigger
369 Float_t polar[3]= {0,0,0};
374 Float_t pmom, theta, phi;
378 for (j=0;j<3;j++) origin[j]=fOrigin[j];
379 if(fVertexSmear==perEvent) {
382 origin[j]+=fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
383 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
386 for(i=0;i<fNpart;i++) {
388 pmom=fPMin+random[0]*(fPMax-fPMin);
389 theta=fThetaMin+random[1]*(fThetaMax-fThetaMin);
390 phi=fPhiMin+random[2]*(fPhiMax-fPhiMin);
391 p[0] = pmom*TMath::Cos(phi)*TMath::Sin(theta);
392 p[1] = pmom*TMath::Sin(phi)*TMath::Sin(theta);
393 p[2] = pmom*TMath::Cos(theta);
394 if(fVertexSmear==perTrack) {
397 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
398 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
401 gAlice->SetTrack(1,-1,fIpart,p,origin,polar,0,"Primary",nt);