1 ///////////////////////////////////////////////////////////////////
3 // Generate the final state of the interaction as the input //
4 // to the MonteCarlo //
8 <img src="picts/AliGeneratorClass.gif">
11 <font size=+2 color=red>
12 <p>The responsible person for this module is
13 <a href="mailto:andreas.morsch@cern.ch">Andreas Morsch</a>.
19 ///////////////////////////////////////////////////////////////////
21 #include "AliSimpleGen.h"
25 ClassImp(AliGenHIJINGpara)
27 //_____________________________________________________________________________
28 static Double_t ptpi(Double_t *px, Double_t *)
31 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
32 // POWER LAW FOR PT > 500 MEV
33 // MT SCALING BELOW (T=160 MEV)
35 const Double_t p0 = 1.3;
36 const Double_t xn = 8.28;
37 const Double_t xlim=0.5;
38 const Double_t t=0.160;
39 const Double_t xmpi=0.139;
41 Double_t y, y1, xmpi2, ynorm, a;
44 y1=TMath::Power(p0/(p0+xlim),xn);
46 ynorm=b*(TMath::Exp(-sqrt(xlim*xlim+xmpi2)/t));
49 y=a*TMath::Power(p0/(p0+x),xn);
51 y=b*TMath::Exp(-sqrt(x*x+xmpi2)/t);
55 //_____________________________________________________________________________
56 static Double_t ptscal(Double_t pt, Int_t np)
58 // SCALING EN MASSE PAR RAPPORT A PTPI
59 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
60 const Double_t hm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
61 // VALUE MESON/PI AT 5 GEV
62 const Double_t fmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
64 Double_t f5=TMath::Power(((sqrt(100.018215)+2.)/(sqrt(100.+hm[np]*hm[np])+2.0)),12.3);
65 Double_t fmax2=f5/fmax[np];
67 Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0);
68 Double_t fmtscal=TMath::Power(((sqrt(pt*pt+0.018215)+2.)/
69 (sqrt(pt*pt+hm[np]*hm[np])+2.0)),12.3)/ fmax2;
70 return fmtscal*ptpion;
73 //_____________________________________________________________________________
74 static Double_t ptka( Double_t *px, Double_t *)
77 // pt parametrisation for k
83 //_____________________________________________________________________________
84 static Double_t etapic( Double_t *py, Double_t *)
87 // eta parametrisation for pi
89 const Double_t a1 = 4913.;
90 const Double_t a2 = 1819.;
91 const Double_t eta1 = 0.22;
92 const Double_t eta2 = 3.66;
93 const Double_t deta1 = 1.47;
94 const Double_t deta2 = 1.51;
95 Double_t y=TMath::Abs(*py);
97 Double_t ex1 = (y-eta1)*(y-eta1)/(2*deta1*deta1);
98 Double_t ex2 = (y-eta2)*(y-eta2)/(2*deta2*deta2);
99 return a1*TMath::Exp(-ex1)+a2*TMath::Exp(-ex2);
102 //_____________________________________________________________________________
103 static Double_t etakac( Double_t *py, Double_t *)
106 // eta parametrisation for ka
108 const Double_t a1 = 497.6;
109 const Double_t a2 = 215.6;
110 const Double_t eta1 = 0.79;
111 const Double_t eta2 = 4.09;
112 const Double_t deta1 = 1.54;
113 const Double_t deta2 = 1.40;
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 AliGenHIJINGpara::AliGenHIJINGpara()
126 // Default constructor
134 //_____________________________________________________________________________
135 AliGenHIJINGpara::AliGenHIJINGpara(Int_t npart)
139 // Standard constructor
142 fTitle="HIJING Parametrisation Particle Generator";
149 //_____________________________________________________________________________
150 AliGenHIJINGpara::~AliGenHIJINGpara()
153 // Standard destructor
161 //_____________________________________________________________________________
162 void AliGenHIJINGpara::Init()
165 // Initialise the HIJING parametrisation
167 Float_t etaMin = -TMath::Log(TMath::Tan(TMath::Min((Double_t)fThetaMax/2,TMath::Pi()/2-1.e-10)));
168 Float_t etaMax = -TMath::Log(TMath::Tan(TMath::Max((Double_t)fThetaMin/2, 1.e-10)));
169 fPtpi = new TF1("ptpi",&ptpi,0,20,0);
170 fPtka = new TF1("ptka",&ptka,0,20,0);
171 fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0);
172 fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0);
173 TF1 *ETApic0 = new TF1("etapic",&etapic,-7,7,0);
174 TF1 *ETAkac0 = new TF1("etakac",&etakac,-7,7,0);
175 Float_t IntETApi = ETApic0->Integral(-0.5, 0.5);
176 Float_t IntETAka = ETAkac0->Integral(-0.5, 0.5);
177 Float_t scalePi=7316/(IntETApi/1.5);
178 Float_t scaleKa= 684/(IntETAka/2.0);
180 Float_t IntPt = (0.877*ETApic0->Integral(0, 15)+
181 0.123*ETAkac0->Integral(0, 15));
182 Float_t IntPtSel = (0.877*ETApic0->Integral(fPtMin, fPtMax)+
183 0.123*ETAkac0->Integral(fPtMin, fPtMax));
184 Float_t PtFrac = IntPtSel/IntPt;
187 Float_t IntETASel = (scalePi*ETApic0->Integral(etaMin, etaMax)+
188 scaleKa*ETAkac0->Integral(etaMin, etaMax));
189 Float_t PhiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi();
190 fParentWeight = Float_t(fNpart)/IntETASel*PtFrac*PhiFrac;
192 printf("\n The number of particles in the selected kinematic region corresponds to %f percent of a full event\n ", 100.*fParentWeight);
196 //_____________________________________________________________________________
197 void AliGenHIJINGpara::Generate()
200 // Generate one trigger
204 const Float_t raKpic=0.14;
205 const Float_t borne=1/(1+raKpic);
206 Float_t polar[3]= {0,0,0};
208 const Int_t pions[3] = {kPi0, kPiPlus, kPiMinus};
209 const Int_t kaons[4] = {kK0Long, kK0Short, kKPlus, kKMinus};
212 Float_t pt, pl, ptot;
215 Int_t i, part, nt, j;
222 for (j=0;j<3;j++) origin[j]=fOrigin[j];
223 if(fVertexSmear==perEvent) {
226 origin[j]+=fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
227 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
230 for(i=0;i<fNpart;i++) {
233 if(random[0]<borne) {
234 part=pions[Int_t (random[1]*3)];
238 part=kaons[Int_t (random[1]*4)];
242 phi=2*random[2]*TMath::Pi();
243 if(phi<fPhiMin || phi>fPhiMax) continue;
244 theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom()));
245 if(theta<fThetaMin || theta>fThetaMax) continue;
247 pl=pt/TMath::Tan(theta);
248 ptot=TMath::Sqrt(pt*pt+pl*pl);
249 if(ptot<fPMin || ptot>fPMax) continue;
250 p[0]=pt*TMath::Cos(phi);
251 p[1]=pt*TMath::Sin(phi);
253 if(fVertexSmear==perTrack) {
256 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
257 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
260 gAlice->SetTrack(1,-1,part,p,origin,polar,0,"Primary",nt,fParentWeight);
266 ClassImp(AliGenFixed)
268 //_____________________________________________________________________________
269 AliGenFixed::AliGenFixed()
273 // Default constructor
278 //_____________________________________________________________________________
279 AliGenFixed::AliGenFixed(Int_t npart)
283 // Standard constructor
286 fTitle="Fixed Particle Generator";
287 // Generate Proton by default
291 //_____________________________________________________________________________
292 void AliGenFixed::Generate()
295 // Generate one trigger
297 Float_t polar[3]= {0,0,0};
298 Float_t p[3] = {fPMin*TMath::Cos(fPhiMin)*TMath::Sin(fThetaMin),
299 fPMin*TMath::Sin(fPhiMin)*TMath::Sin(fThetaMin),
300 fPMin*TMath::Cos(fThetaMin)};
303 for(i=0;i<fNpart;i++) {
304 gAlice->SetTrack(1,-1,fIpart,p,fOrigin.GetArray(),polar,0,"Primary",nt);
308 //_____________________________________________________________________________
309 void AliGenFixed::SetSigma(Float_t, Float_t, Float_t)
312 // Set the interaction point sigma
314 printf("Vertex smearing not implemented for fixed generator\n");
320 //_____________________________________________________________________________
321 AliGenBox::AliGenBox()
325 // Default constructor
330 //_____________________________________________________________________________
331 AliGenBox::AliGenBox(Int_t npart)
335 // Standard constructor
338 fTitle="Box particle generator";
339 // Generate Proton by default
343 //_____________________________________________________________________________
344 void AliGenBox::Generate()
347 // Generate one trigger
350 Float_t polar[3]= {0,0,0};
355 Float_t pmom, theta, phi;
359 for (j=0;j<3;j++) origin[j]=fOrigin[j];
360 if(fVertexSmear==perEvent) {
363 origin[j]+=fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
364 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
367 for(i=0;i<fNpart;i++) {
369 pmom=fPMin+random[0]*(fPMax-fPMin);
370 theta=fThetaMin+random[1]*(fThetaMax-fThetaMin);
371 phi=fPhiMin+random[2]*(fPhiMax-fPhiMin);
372 p[0] = pmom*TMath::Cos(phi)*TMath::Sin(theta);
373 p[1] = pmom*TMath::Sin(phi)*TMath::Sin(theta);
374 p[2] = pmom*TMath::Cos(theta);
375 if(fVertexSmear==perTrack) {
378 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
379 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
382 gAlice->SetTrack(1,-1,fIpart,p,origin,polar,0,"Primary",nt);