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 // Base class for generators using external MC generators.
19 // For example AliGenPythia using Pythia.
20 // Provides basic functionality: setting of kinematic cuts on
21 // decay products and particle selection.
22 // andreas.morsch@cern.ch
24 #include <TClonesArray.h>
27 #include <TParticle.h>
28 #include <TLorentzVector.h>
33 #include "AliGeometry.h"
34 #include "AliDecayer.h"
40 fParticles("TParticle", 1000),
49 fChildPhiMax(2. * TMath::Pi()),
51 fChildThetaMax(TMath::Pi()),
59 fGeometryAcceptance(0),
60 fPdgCodeParticleforAcceptanceCut(0),
61 fNumberOfAcceptedParticles(0),
64 // Default Constructor
73 AliGenMC::AliGenMC(Int_t npart)
75 fParticles("TParticle", 1000),
84 fChildPhiMax(2. * TMath::Pi()),
86 fChildThetaMax(TMath::Pi()),
94 fGeometryAcceptance(0),
95 fPdgCodeParticleforAcceptanceCut(0),
96 fNumberOfAcceptedParticles(0),
107 for (Int_t i=0; i<8; i++) fParentSelect[i]=fChildSelect[i]=0;
110 AliGenMC::~AliGenMC()
115 void AliGenMC::Init()
119 switch (fForceDecay) {
120 case kBSemiElectronic:
121 case kSemiElectronic:
123 case kBJpsiDiElectron:
124 case kBPsiPrimeDiElectron:
127 fChildSelect[0] = kElectron;
135 case kBPsiPrimeDiMuon:
139 case kWToCharmToMuon:
142 fChildSelect[0]=kMuonMinus;
147 case kHadronicDWithout4Bodies:
148 fChildSelect[0]=kPiPlus;
149 fChildSelect[1]=kKPlus;
152 fChildSelect[0]=kKPlus;
155 fChildSelect[0]= 443;
157 case kChiToJpsiGammaToMuonMuon:
161 case kChiToJpsiGammaToElectronElectron:
166 fChildSelect[0]= kProton;
167 fChildSelect[1]= 211;
169 case kPsiPrimeJpsiDiElectron:
170 fChildSelect[0]= 211;
174 fChildSelect[0] = kGamma;
186 if (fZTarget != 0 && fAProjectile != 0)
188 fDyBoost = - 0.5 * TMath::Log(Double_t(fZProjectile) * Double_t(fATarget) /
189 (Double_t(fZTarget) * Double_t(fAProjectile)));
194 Bool_t AliGenMC::ParentSelected(Int_t ip) const
196 // True if particle is in list of parent particles to be selected
197 for (Int_t i=0; i<8; i++)
199 if (fParentSelect.At(i) == ip) return kTRUE;
204 Bool_t AliGenMC::ChildSelected(Int_t ip) const
206 // True if particle is in list of decay products to be selected
207 for (Int_t i=0; i<5; i++)
209 if (fChildSelect.At(i) == ip) return kTRUE;
214 Bool_t AliGenMC::KinematicSelection(const TParticle *particle, Int_t flag) const
216 // Perform kinematic selection
217 Double_t pz = particle->Pz();
218 Double_t pt = particle->Pt();
219 Double_t p = particle->P();
220 Double_t theta = particle->Theta();
221 Double_t mass = particle->GetCalcMass();
222 Double_t mt2 = pt * pt + mass * mass;
223 Double_t phi = particle->Phi();
224 Double_t e = particle->Energy();
227 e = TMath::Sqrt(p * p + mass * mass);
232 if (TMath::Abs(pz) < e) {
233 y = 0.5*TMath::Log((e+pz)/(e-pz));
239 y0 = 0.5*TMath::Log((e+TMath::Abs(pz))*(e+TMath::Abs(pz))/mt2);
241 if (TMath::Abs(y) < 1.e10) {
248 y = (pz < 0) ? -y0 : y0;
252 // Primary particle cuts
254 // transverse momentum cut
255 if (pt > fPtMax || pt < fPtMin) {
256 // printf("\n failed pt cut %f %f %f \n",pt,fPtMin,fPtMax);
261 if (p > fPMax || p < fPMin) {
262 // printf("\n failed p cut %f %f %f \n",p,fPMin,fPMax);
267 if (theta > fThetaMax || theta < fThetaMin) {
268 // printf("\n failed theta cut %f %f %f \n",theta,fThetaMin,fThetaMax);
273 if (y > fYMax || y < fYMin) {
274 // printf("\n failed y cut %f %f %f \n",y,fYMin,fYMax);
279 if (phi > fPhiMax || phi < fPhiMin) {
280 // printf("\n failed phi cut %f %f %f \n",phi,fPhiMin,fPhiMax);
285 // Decay product cuts
287 // transverse momentum cut
288 if (pt > fChildPtMax || pt < fChildPtMin) {
289 // printf("\n failed pt cut %f %f %f \n",pt,fChildPtMin,fChildPtMax);
294 if (p > fChildPMax || p < fChildPMin) {
295 // printf("\n failed p cut %f %f %f \n",p,fChildPMin,fChildPMax);
300 if (theta > fChildThetaMax || theta < fChildThetaMin) {
301 // printf("\n failed theta cut %f %f %f \n",theta,fChildThetaMin,fChildThetaMax);
306 if (y > fChildYMax || y < fChildYMin) {
307 // printf("\n failed y cut %f %f %f \n",y,fChildYMin,fChildYMax);
312 if (phi > fChildPhiMax || phi < fChildPhiMin) {
313 // printf("\n failed phi cut %f %f %f \n",phi,fChildPhiMin,fChildPhiMax);
321 Bool_t AliGenMC::CheckAcceptanceGeometry(Int_t np, TClonesArray* particles)
323 // Check the geometrical acceptance for particle.
326 Int_t numberOfPdgCodeParticleforAcceptanceCut = 0;
327 Int_t numberOfAcceptedPdgCodeParticleforAcceptanceCut = 0;
328 TParticle * particle;
330 for (i = 0; i < np; i++) {
331 particle = (TParticle *) particles->At(i);
332 if( TMath::Abs( particle->GetPdgCode() ) == TMath::Abs( fPdgCodeParticleforAcceptanceCut ) ) {
333 numberOfPdgCodeParticleforAcceptanceCut++;
334 if (fGeometryAcceptance->Impact(particle)) numberOfAcceptedPdgCodeParticleforAcceptanceCut++;
337 if ( numberOfAcceptedPdgCodeParticleforAcceptanceCut > (fNumberOfAcceptedParticles-1) )
345 Int_t AliGenMC::CheckPDGCode(Int_t pdgcode) const
348 // If the particle is in a diffractive state, then take action accordingly
353 //rho_diff0 -- difficult to translate, return rho0
356 //pi_diffr+ -- change to pi+
359 //omega_di0 -- change to omega0
362 //phi_diff0 -- return phi0
365 //J/psi_di0 -- return J/psi
368 //n_diffr -- return neutron
371 //p_diffr+ -- return proton
374 //non diffractive state -- return code unchanged
378 void AliGenMC::Boost()
381 // Boost cms into LHC lab frame
384 Double_t beta = TMath::TanH(fDyBoost);
385 Double_t gamma = 1./TMath::Sqrt((1.-beta)*(1.+beta));
386 Double_t gb = gamma * beta;
388 // printf("\n Boosting particles to lab frame %f %f %f", fDyBoost, beta, gamma);
391 Int_t np = fParticles.GetEntriesFast();
392 for (i = 0; i < np; i++)
394 TParticle* iparticle = (TParticle*) fParticles.At(i);
396 Double_t e = iparticle->Energy();
397 Double_t px = iparticle->Px();
398 Double_t py = iparticle->Py();
399 Double_t pz = iparticle->Pz();
401 Double_t eb = gamma * e - gb * pz;
402 Double_t pzb = -gb * e + gamma * pz;
404 iparticle->SetMomentum(px, py, pzb, eb);
408 void AliGenMC::BeamCrossAngle()
410 // Applies a boost in the y-direction in order to take into account the
411 // beam crossing angle
413 Double_t thetaPr0, phiPr0, pyPr2, pzPr2;
416 thetaPr0 = fXingAngleY / 2.;
419 // Momentum of the CMS system
420 pyPr2 = TMath::Sqrt(fEnergyCMS * fEnergyCMS/ 4 - 0.938 * 0.938) * TMath::Sin(thetaPr0);
421 pzPr2 = TMath::Sqrt(fEnergyCMS * fEnergyCMS/ 4 - 0.938 * 0.938) * TMath::Cos(thetaPr0);
423 TLorentzVector proj1Vect, proj2Vect, projVect;
424 proj1Vect.SetPxPyPzE(0., pyPr2, pzPr2, fEnergyCMS/2);
425 proj2Vect.SetPxPyPzE(0., pyPr2,-pzPr2, fEnergyCMS/2);
426 projVect = proj1Vect + proj2Vect;
427 beta=(1. / projVect.E()) * (projVect.Vect());
430 Int_t np = fParticles.GetEntriesFast();
431 for (i = 0; i < np; i++)
433 TParticle* iparticle = (TParticle*) fParticles.At(i);
435 Double_t e = iparticle->Energy();
436 Double_t px = iparticle->Px();
437 Double_t py = iparticle->Py();
438 Double_t pz = iparticle->Pz();
440 TLorentzVector partIn;
441 partIn.SetPxPyPzE(px,py,pz,e);
443 iparticle->SetMomentum(partIn.Px(),partIn.Py(),partIn.Pz(),partIn.E());
448 void AliGenMC::AddHeader(AliGenEventHeader* header)
450 // Passes header either to the container or to gAlice
452 fContainer->AddHeader(header);
454 gAlice->SetGenEventHeader(header);