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 **************************************************************************/
18 // Class to generate particles from using paramtrized pT and y distributions.
19 // Distributions are obtained from pointer to object of type AliGenLib.
20 // (For example AliGenMUONlib)
21 // Decays are performed using Pythia.
22 // andreas.morsch@cern.ch
24 #include "AliGenParam.h"
25 #include "AliDecayer.h"
26 #include "AliGenMUONlib.h"
28 #include <TParticle.h>
29 #include <TParticlePDG.h>
30 #include <TDatabasePDG.h>
31 #include <TLorentzVector.h>
32 #include <TVirtualMC.h>
41 //------------------------------------------------------------
45 <img src="picts/AliGenParam.gif">
49 //____________________________________________________________
50 //____________________________________________________________
51 AliGenParam::AliGenParam()
53 // Deafault constructor
64 AliGenParam::AliGenParam(Int_t npart, AliGenLib * Library, Int_t param, char* tname):AliGenMC(npart)
66 // Constructor using number of particles parameterisation id and library
68 fTitle= "Particle Generator using pT and y parameterisation";
70 fPtParaFunc = Library->GetPt(param, tname);
71 fYParaFunc = Library->GetY (param, tname);
72 fIpParaFunc = Library->GetIp(param, tname);
82 //____________________________________________________________
84 AliGenParam::AliGenParam(Int_t npart, Int_t param, char* tname):AliGenMC(npart)
86 // Constructor using parameterisation id and number of particles
89 fTitle= "Particle Generator using pT and y parameterisation";
91 AliGenLib* pLibrary = new AliGenMUONlib();
93 fPtParaFunc = pLibrary->GetPt(param, tname);
94 fYParaFunc = pLibrary->GetY (param, tname);
95 fIpParaFunc = pLibrary->GetIp(param, tname);
102 for (Int_t i=0; i<5; i++) fChildSelect[i]=0;
105 SetChildMomentumRange();
108 SetChildThetaRange();
112 AliGenParam::AliGenParam(Int_t npart, Int_t param,
113 Double_t (*PtPara) (Double_t*, Double_t*),
114 Double_t (*YPara ) (Double_t* ,Double_t*),
115 Int_t (*IpPara) (TRandom *))
119 // Gines Martinez 1/10/99
121 fTitle= "Particle Generator using pT and y parameterisation";
123 fPtParaFunc = PtPara;
125 fIpParaFunc = IpPara;
132 for (Int_t i=0; i<5; i++) fChildSelect[i]=0;
135 SetChildMomentumRange();
138 SetChildThetaRange();
143 AliGenParam::AliGenParam(const AliGenParam & Param)
150 //____________________________________________________________
151 AliGenParam::~AliGenParam()
158 //____________________________________________________________
159 void AliGenParam::Init()
163 if (gMC) fDecayer = gMC->GetDecayer();
166 <img src="picts/AliGenParam.gif">
170 fPtPara = new TF1("Pt-Parametrization",fPtParaFunc,fPtMin,fPtMax,0);
171 // Set representation precision to 10 MeV
172 Int_t npx= Int_t((fPtMax-fPtMin)/fDeltaPt);
174 fPtPara->SetNpx(npx);
176 fYPara = new TF1("Y-Parametrization",fYParaFunc,fYMin,fYMax,0);
177 TF1 ptPara("Pt-Parametrization(0,15)",fPtParaFunc,0,15,0);
178 TF1 yPara("Y-Parametrization(-6,6)",fYParaFunc,-6,6,0);
185 fdNdy0=fYParaFunc(&y1,&y2);
187 // Integral over generation region
188 Float_t intYS = yPara.Integral(fYMin, fYMax);
189 Float_t intPt0 = ptPara.Integral(0,15);
190 Float_t intPtS = ptPara.Integral(fPtMin,fPtMax);
191 Float_t phiWgt=(fPhiMax-fPhiMin)/2./TMath::Pi();
192 if (fAnalog == kAnalog) {
193 fYWgt = intYS/fdNdy0;
194 fPtWgt = intPtS/intPt0;
195 fParentWeight = fYWgt*fPtWgt*phiWgt/fNpart;
197 fYWgt = intYS/fdNdy0;
198 fPtWgt = (fPtMax-fPtMin)/intPt0;
199 fParentWeight = fYWgt*fPtWgt*phiWgt/fNpart;
202 // particle decay related initialization
203 fDecayer->SetForceDecay(fForceDecay);
210 //____________________________________________________________
211 void AliGenParam::Generate()
214 // Generate 'npart' of light and heavy mesons (J/Psi, upsilon or phi, Pion,
215 // Kaons, Etas, Omegas) and Baryons (proton, antiprotons, neutrons and
216 // antineutrons in the the desired theta, phi and momentum windows;
217 // Gaussian smearing on the vertex is done if selected.
218 // The decay of heavy mesons is done using lujet,
219 // and the childern particle are tracked by GEANT
220 // However, light mesons are directly tracked by GEANT
221 // setting fForceDecay = nodecay (SetForceDecay(nodecay))
224 // Reinitialize decayer
227 Float_t polar[3]= {0,0,0}; // Polarisation of the parent particle (for GEANT tracking)
228 Float_t origin0[3]; // Origin of the generated parent particle (for GEANT tracking)
229 Float_t pt, pl, ptot; // Transverse, logitudinal and total momenta of the parent particle
230 Float_t phi, theta; // Phi and theta spherical angles of the parent particle momentum
232 och[3]; // Momentum, polarisation and origin of the children particles from lujet
237 static TClonesArray *particles;
239 if(!particles) particles = new TClonesArray("TParticle",1000);
241 TDatabasePDG *pDataBase = TDatabasePDG::Instance();
245 // Calculating vertex position per event
246 for (j=0;j<3;j++) origin0[j]=fOrigin[j];
247 if(fVertexSmear==kPerEvent) {
249 for (j=0;j<3;j++) origin0[j]=fVertex[j];
254 // Generating fNpart particles
259 Int_t iPart = fIpParaFunc(fRandom);
260 fChildWeight=(fDecayer->GetPartialBranchingRatio(iPart))*fParentWeight;
261 TParticlePDG *particle = pDataBase->GetParticle(iPart);
262 Float_t am = particle->Mass();
267 phi=fPhiMin+random[0]*(fPhiMax-fPhiMin);
270 ty = TMath::TanH(fYPara->GetRandom());
273 if (fAnalog == kAnalog) {
274 pt=fPtPara->GetRandom();
278 pt=fPtMin+random[1]*(fPtMax-fPtMin);
280 wgtp=fParentWeight*fPtParaFunc(& ptd, &dummy);
281 wgtch=fChildWeight*fPtParaFunc(& ptd, &dummy);
283 xmt=sqrt(pt*pt+am*am);
284 if (TMath::Abs(ty)==1.) {
287 "Division by 0: Please check you rapidity range !");
290 pl=xmt*ty/sqrt(1.-ty*ty);
291 theta=TMath::ATan2(pt,pl);
293 if(theta<fThetaMin || theta>fThetaMax) continue;
294 ptot=TMath::Sqrt(pt*pt+pl*pl);
296 if(ptot<fPMin || ptot>fPMax) continue;
298 p[0]=pt*TMath::Cos(phi);
299 p[1]=pt*TMath::Sin(phi);
301 if(fVertexSmear==kPerTrack) {
305 fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
306 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
310 // Looking at fForceDecay :
311 // if fForceDecay != none Primary particle decays using
312 // AliPythia and children are tracked by GEANT
314 // if fForceDecay == none Primary particle is tracked by GEANT
315 // (In the latest, make sure that GEANT actually does all the decays you want)
318 if (fForceDecay != kNoDecay) {
319 // Using lujet to decay particle
320 Float_t energy=TMath::Sqrt(ptot*ptot+am*am);
321 TLorentzVector pmom(p[0], p[1], p[2], energy);
322 fDecayer->Decay(iPart,&pmom);
324 // select decay particles
325 Int_t np=fDecayer->ImportParticles(particles);
327 // Selecting GeometryAcceptance for particles fPdgCodeParticleforAcceptanceCut;
328 if (fGeometryAcceptance)
329 if (!CheckAcceptanceGeometry(np,particles)) continue;
331 Int_t* pFlag = new Int_t[np];
332 Int_t* pParent = new Int_t[np];
333 Int_t* pSelected = new Int_t[np];
334 Int_t* trackIt = new Int_t[np];
336 for (i=0; i<np; i++) {
343 TParticle* iparticle = (TParticle *) particles->At(0);
345 for (i = 1; i<np ; i++) {
347 iparticle = (TParticle *) particles->At(i);
348 Int_t kf = iparticle->GetPdgCode();
349 Int_t ks = iparticle->GetStatusCode();
353 ipF = iparticle->GetFirstDaughter();
354 ipL = iparticle->GetLastDaughter();
355 if (ipF > 0) for (j=ipF-1; j<ipL; j++) pFlag[j]=1;
359 // flag decay products of particles with long life-time (c tau > .3 mum)
362 // TParticlePDG *particle = pDataBase->GetParticle(kf);
364 Double_t lifeTime = fDecayer->GetLifetime(kf);
365 // Double_t mass = particle->Mass();
366 // Double_t width = particle->Width();
367 if (lifeTime > (Double_t) fMaxLifeTime) {
368 ipF = iparticle->GetFirstDaughter();
369 ipL = iparticle->GetLastDaughter();
370 if (ipF > 0) for (j=ipF-1; j<ipL; j++) pFlag[j]=1;
379 if (ChildSelected(TMath::Abs(kf)) || fForceDecay == kAll && trackIt[i])
382 pc[0]=iparticle->Px();
383 pc[1]=iparticle->Py();
384 pc[2]=iparticle->Pz();
385 Bool_t childok = KinematicSelection(iparticle, 1);
396 } // if child selection
398 } // decay particle loop
399 } // if decay products
402 if ((fCutOnChild && ncsel >0) || !fCutOnChild){
406 PushTrack(0, -1, iPart, p, origin0, polar, 0, kPPrimary, nt, wgtp);
412 for (i = 1; i < np; i++) {
414 TParticle* iparticle = (TParticle *) particles->At(i);
415 Int_t kf = iparticle->GetPdgCode();
416 Int_t ipa = iparticle->GetFirstMother()-1;
418 och[0] = origin0[0]+iparticle->Vx()/10;
419 och[1] = origin0[1]+iparticle->Vy()/10;
420 och[2] = origin0[2]+iparticle->Vz()/10;
421 pc[0] = iparticle->Px();
422 pc[1] = iparticle->Py();
423 pc[2] = iparticle->Pz();
426 iparent = pParent[ipa];
431 PushTrack(fTrackIt*trackIt[i], iparent, kf,
433 0, kPDecay, nt, wgtch);
440 if (pFlag) delete[] pFlag;
441 if (pParent) delete[] pParent;
442 if (pSelected) delete[] pSelected;
443 if (trackIt) delete[] trackIt;
444 } // kinematic selection
445 else // nodecay option, so parent will be tracked by GEANT (pions, kaons, eta, omegas, baryons)
448 PushTrack(fTrackIt,-1,iPart,p,origin0,polar,0,kPPrimary,nt,wgtp);
454 SetHighWaterMark(nt);
457 void AliGenParam::Draw()
460 // Draw the pT and y Distributions
462 TCanvas *c0 = new TCanvas("c0","Canvas 0",400,10,600,700);
466 fPtPara->GetHistogram()->SetXTitle("p_{T} (GeV)");
469 fYPara->GetHistogram()->SetXTitle("y");
472 AliGenParam& AliGenParam::operator=(const AliGenParam& rhs)
474 // Assignment operator