1 ///////////////////////////////////////////////////////////////////
3 // Generate the final state of the interaction as the input //
4 // to the MonteCarlo //
8 <img src="gif/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"
24 ClassImp(AliGenHIJINGpara)
26 //_____________________________________________________________________________
27 static Double_t ptpi(Double_t *px, Double_t *)
30 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
31 // POWER LAW FOR PT > 500 MEV
32 // MT SCALING BELOW (T=160 MEV)
34 const Double_t p0 = 1.3;
35 const Double_t xn = 8.28;
36 const Double_t xlim=0.5;
37 const Double_t t=0.160;
38 const Double_t xmpi=0.139;
40 Double_t y, y1, xmpi2, ynorm, a;
43 y1=TMath::Power(p0/(p0+xlim),xn);
45 ynorm=b*(TMath::Exp(-sqrt(xlim*xlim+xmpi2)/t));
48 y=a*TMath::Power(p0/(p0+x),xn);
50 y=b*TMath::Exp(-sqrt(x*x+xmpi2)/t);
54 //_____________________________________________________________________________
55 static Double_t ptscal(Double_t pt, Int_t np)
57 // SCALING EN MASSE PAR RAPPORT A PTPI
58 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
59 const Double_t hm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
60 // VALUE MESON/PI AT 5 GEV
61 const Double_t fmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
63 Double_t f5=TMath::Power(((sqrt(100.018215)+2.)/(sqrt(100.+hm[np]*hm[np])+2.0)),12.3);
64 Double_t fmax2=f5/fmax[np];
66 Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0);
67 Double_t fmtscal=TMath::Power(((sqrt(pt*pt+0.018215)+2.)/
68 (sqrt(pt*pt+hm[np]*hm[np])+2.0)),12.3)/ fmax2;
69 return fmtscal*ptpion;
72 //_____________________________________________________________________________
73 static Double_t ptka( Double_t *px, Double_t *)
76 // pt parametrisation for k
82 //_____________________________________________________________________________
83 static Double_t etapic( Double_t *py, Double_t *)
86 // eta parametrisation for pi
88 const Double_t a1 = 4913.;
89 const Double_t a2 = 1819.;
90 const Double_t eta1 = 0.22;
91 const Double_t eta2 = 3.66;
92 const Double_t deta1 = 1.47;
93 const Double_t deta2 = 1.51;
94 Double_t y=TMath::Abs(*py);
96 Double_t ex1 = (y-eta1)*(y-eta1)/(2*deta1*deta1);
97 Double_t ex2 = (y-eta2)*(y-eta2)/(2*deta2*deta2);
98 return a1*TMath::Exp(-ex1)+a2*TMath::Exp(-ex2);
101 //_____________________________________________________________________________
102 static Double_t etakac( Double_t *py, Double_t *)
105 // eta parametrisation for ka
107 const Double_t a1 = 497.6;
108 const Double_t a2 = 215.6;
109 const Double_t eta1 = 0.79;
110 const Double_t eta2 = 4.09;
111 const Double_t deta1 = 1.54;
112 const Double_t deta2 = 1.40;
113 Double_t y=TMath::Abs(*py);
115 Double_t ex1 = (y-eta1)*(y-eta1)/(2*deta1*deta1);
116 Double_t ex2 = (y-eta2)*(y-eta2)/(2*deta2*deta2);
117 return a1*TMath::Exp(-ex1)+a2*TMath::Exp(-ex2);
120 //_____________________________________________________________________________
121 AliGenHIJINGpara::AliGenHIJINGpara()
125 // Default constructor
133 //_____________________________________________________________________________
134 AliGenHIJINGpara::AliGenHIJINGpara(Int_t npart)
138 // Standard constructor
141 fTitle="HIJING Parametrisation Particle Generator";
148 //_____________________________________________________________________________
149 AliGenHIJINGpara::~AliGenHIJINGpara()
152 // Standard destructor
160 //_____________________________________________________________________________
161 void AliGenHIJINGpara::Init()
164 // Initialise the HIJING parametrisation
166 Float_t etaMin = -TMath::Log(TMath::Tan(TMath::Min((Double_t)fThetaMax/2,TMath::Pi()/2-1.e-10)));
167 Float_t etaMax = -TMath::Log(TMath::Tan(TMath::Max((Double_t)fThetaMin/2, 1.e-10)));
168 fPtpi = new TF1("ptpi",&ptpi,0,20,0);
169 fPtka = new TF1("ptka",&ptka,0,20,0);
170 fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0);
171 fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0);
172 TF1 *ETApic0 = new TF1("etapic",&etapic,-7,7,0);
173 TF1 *ETAkac0 = new TF1("etakac",&etakac,-7,7,0);
174 Float_t IntETApi = ETApic0->Integral(-0.5, 0.5);
175 Float_t IntETAka = ETAkac0->Integral(-0.5, 0.5);
176 Float_t scalePi=7316/(IntETApi/1.5);
177 Float_t scaleKa= 684/(IntETAka/2.0);
179 Float_t IntPt = (0.877*ETApic0->Integral(0, 15)+
180 0.123*ETAkac0->Integral(0, 15));
181 Float_t IntPtSel = (0.877*ETApic0->Integral(fPtMin, fPtMax)+
182 0.123*ETAkac0->Integral(fPtMin, fPtMax));
183 Float_t PtFrac = IntPtSel/IntPt;
186 Float_t IntETASel = (scalePi*ETApic0->Integral(etaMin, etaMax)+
187 scaleKa*ETAkac0->Integral(etaMin, etaMax));
188 Float_t PhiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi();
189 fParentWeight = Float_t(fNpart)/IntETASel*PtFrac*PhiFrac;
191 printf("\n The number of particles in the selected kinematic region corresponds to %f percent of a full event\n ", 100.*fParentWeight);
195 //_____________________________________________________________________________
196 void AliGenHIJINGpara::Generate()
199 // Generate one trigger
202 AliMC* pMC = AliMC::GetMC();
204 const Float_t raKpic=0.14;
205 const Float_t borne=1/(1+raKpic);
206 Float_t polar[3]= {0,0,0};
209 const Int_t piplus=8;
210 const Int_t piminus=9;
213 const Int_t kplus=11;
214 const Int_t kminus=12;
216 const Int_t pions[3] = {pi0, piplus, piminus};
217 const Int_t kaons[4] = {k0l, k0s, kplus, kminus};
220 Float_t pt, pl, ptot;
223 Int_t i, part, nt, j;
230 for (j=0;j<3;j++) origin[j]=fOrigin[j];
231 if(fVertexSmear==perEvent) {
234 origin[j]+=fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
235 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
238 for(i=0;i<fNpart;i++) {
241 if(random[0]<borne) {
242 part=pions[Int_t (random[1]*3)];
246 part=kaons[Int_t (random[1]*4)];
250 phi=2*random[2]*TMath::Pi();
251 if(phi<fPhiMin || phi>fPhiMax) continue;
252 theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom()));
253 if(theta<fThetaMin || theta>fThetaMax) continue;
255 pl=pt/TMath::Tan(theta);
256 ptot=TMath::Sqrt(pt*pt+pl*pl);
257 if(ptot<fPMin || ptot>fPMax) continue;
258 p[0]=pt*TMath::Cos(phi);
259 p[1]=pt*TMath::Sin(phi);
261 if(fVertexSmear==perTrack) {
264 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
265 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
268 gAlice->SetTrack(1,-1,part,p,origin,polar,0,"Primary",nt,fParentWeight);
274 ClassImp(AliGenFixed)
276 //_____________________________________________________________________________
277 AliGenFixed::AliGenFixed()
281 // Default constructor
286 //_____________________________________________________________________________
287 AliGenFixed::AliGenFixed(Int_t npart)
291 // Standard constructor
294 fTitle="Fixed Particle Generator";
295 // Generate Proton by default
299 //_____________________________________________________________________________
300 void AliGenFixed::Generate()
303 // Generate one trigger
305 Float_t polar[3]= {0,0,0};
306 Float_t p[3] = {fPMin*TMath::Cos(fPhiMin)*TMath::Sin(fThetaMin),
307 fPMin*TMath::Sin(fPhiMin)*TMath::Sin(fThetaMin),
308 fPMin*TMath::Cos(fThetaMin)};
311 for(i=0;i<fNpart;i++) {
312 gAlice->SetTrack(1,-1,fIpart,p,fOrigin.GetArray(),polar,0,"Primary",nt);
316 //_____________________________________________________________________________
317 void AliGenFixed::SetSigma(Float_t, Float_t, Float_t)
320 // Set the interaction point sigma
322 printf("Vertex smearing not implemented for fixed generator\n");
328 //_____________________________________________________________________________
329 AliGenBox::AliGenBox()
333 // Default constructor
338 //_____________________________________________________________________________
339 AliGenBox::AliGenBox(Int_t npart)
343 // Standard constructor
346 fTitle="Box particle generator";
347 // Generate Proton by default
351 //_____________________________________________________________________________
352 void AliGenBox::Generate()
355 // Generate one trigger
357 AliMC* pMC = AliMC::GetMC();
359 Float_t polar[3]= {0,0,0};
364 Float_t pmom, theta, phi;
368 for (j=0;j<3;j++) origin[j]=fOrigin[j];
369 if(fVertexSmear==perEvent) {
372 origin[j]+=fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
373 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
376 for(i=0;i<fNpart;i++) {
378 pmom=fPMin+random[0]*(fPMax-fPMin);
379 theta=fThetaMin+random[1]*(fThetaMax-fThetaMin);
380 phi=fPhiMin+random[2]*(fPhiMax-fPhiMin);
381 p[0] = pmom*TMath::Cos(phi)*TMath::Sin(theta);
382 p[1] = pmom*TMath::Sin(phi)*TMath::Sin(theta);
383 p[2] = pmom*TMath::Cos(theta);
384 if(fVertexSmear==perTrack) {
387 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
388 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
391 gAlice->SetTrack(1,-1,fIpart,p,origin,polar,0,"Primary",nt);