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>
30 #include "AliGeometry.h"
45 fChildPhiMax(2. * TMath::Pi()),
47 fChildThetaMax(TMath::Pi()),
61 fGeometryAcceptance(0),
62 fPdgCodeParticleforAcceptanceCut(0),
63 fNumberOfAcceptedParticles(2)
65 // Default Constructor
68 AliGenMC::AliGenMC(Int_t npart)
79 fChildPhiMax(2. * TMath::Pi()),
81 fChildThetaMax(TMath::Pi()),
95 fGeometryAcceptance(0),
96 fPdgCodeParticleforAcceptanceCut(0),
97 fNumberOfAcceptedParticles(2)
101 for (Int_t i=0; i<8; i++) fParentSelect[i]=fChildSelect[i]=0;
104 AliGenMC::~AliGenMC()
109 void AliGenMC::Init()
113 switch (fForceDecay) {
114 case kBSemiElectronic:
115 case kSemiElectronic:
117 case kBJpsiDiElectron:
118 case kBPsiPrimeDiElectron:
119 fChildSelect[0] = kElectron;
126 case kBPsiPrimeDiMuon:
130 case kWToCharmToMuon:
132 fChildSelect[0]=kMuonMinus;
137 case kHadronicDWithout4Bodies:
138 fChildSelect[0]=kPiPlus;
139 fChildSelect[1]=kKPlus;
142 fChildSelect[0]=kKPlus;
156 if (fZTarget != 0 && fAProjectile != 0)
158 fDyBoost = - 0.5 * TMath::Log(Double_t(fZProjectile) * Double_t(fATarget) /
159 (Double_t(fZTarget) * Double_t(fAProjectile)));
164 Bool_t AliGenMC::ParentSelected(Int_t ip) const
166 // True if particle is in list of parent particles to be selected
167 for (Int_t i=0; i<8; i++)
169 if (fParentSelect.At(i) == ip) return kTRUE;
174 Bool_t AliGenMC::ChildSelected(Int_t ip) const
176 // True if particle is in list of decay products to be selected
177 for (Int_t i=0; i<5; i++)
179 if (fChildSelect.At(i) == ip) return kTRUE;
184 Bool_t AliGenMC::KinematicSelection(TParticle *particle, Int_t flag) const
186 // Perform kinematic selection
187 Float_t pz = particle->Pz();
188 Float_t e = particle->Energy();
189 Float_t pt = particle->Pt();
190 Float_t p = particle->P();
191 Float_t theta = particle->Theta();
192 Float_t mass = particle->GetCalcMass();
193 Float_t mt2 = pt * pt + mass * mass;
194 Float_t phi = particle->Phi();
198 if (TMath::Abs(pz) < e) {
199 y = 0.5*TMath::Log((e+pz)/(e-pz));
205 y0 = 0.5*TMath::Log((e+TMath::Abs(pz))*(e+TMath::Abs(pz))/mt2);
207 if (TMath::Abs(y) < 1.e10) {
214 y = (pz < 0) ? -y0 : y0;
218 // Primary particle cuts
220 // transverse momentum cut
221 if (pt > fPtMax || pt < fPtMin) {
222 // printf("\n failed pt cut %f %f %f \n",pt,fPtMin,fPtMax);
227 if (p > fPMax || p < fPMin) {
228 // printf("\n failed p cut %f %f %f \n",p,fPMin,fPMax);
233 if (theta > fThetaMax || theta < fThetaMin) {
234 // printf("\n failed theta cut %f %f %f \n",theta,fThetaMin,fThetaMax);
239 if (y > fYMax || y < fYMin) {
240 // printf("\n failed y cut %f %f %f \n",y,fYMin,fYMax);
245 if (phi > fPhiMax || phi < fPhiMin) {
246 // printf("\n failed phi cut %f %f %f \n",phi,fPhiMin,fPhiMax);
251 // Decay product cuts
253 // transverse momentum cut
254 if (pt > fChildPtMax || pt < fChildPtMin) {
255 // printf("\n failed pt cut %f %f %f \n",pt,fChildPtMin,fChildPtMax);
260 if (p > fChildPMax || p < fChildPMin) {
261 // printf("\n failed p cut %f %f %f \n",p,fChildPMin,fChildPMax);
266 if (theta > fChildThetaMax || theta < fChildThetaMin) {
267 // printf("\n failed theta cut %f %f %f \n",theta,fChildThetaMin,fChildThetaMax);
272 if (y > fChildYMax || y < fChildYMin) {
273 // printf("\n failed y cut %f %f %f \n",y,fChildYMin,fChildYMax);
278 if (phi > fChildPhiMax || phi < fChildPhiMin) {
279 // printf("\n failed phi cut %f %f %f \n",phi,fChildPhiMin,fChildPhiMax);
287 Bool_t AliGenMC::CheckAcceptanceGeometry(Int_t np, TClonesArray* particles)
289 // Check the geometrical acceptance for particle.
292 Int_t numberOfPdgCodeParticleforAcceptanceCut = 0;
293 Int_t numberOfAcceptedPdgCodeParticleforAcceptanceCut = 0;
294 TParticle * particle;
296 for (i = 0; i < np; i++) {
297 particle = (TParticle *) particles->At(i);
298 if( TMath::Abs( particle->GetPdgCode() ) == TMath::Abs( fPdgCodeParticleforAcceptanceCut ) ) {
299 numberOfPdgCodeParticleforAcceptanceCut++;
300 if (fGeometryAcceptance->Impact(particle)) numberOfAcceptedPdgCodeParticleforAcceptanceCut++;
303 if ( numberOfAcceptedPdgCodeParticleforAcceptanceCut > (fNumberOfAcceptedParticles-1) )
311 Int_t AliGenMC::CheckPDGCode(Int_t pdgcode) const
314 // If the particle is in a diffractive state, then take action accordingly
319 //rho_diff0 -- difficult to translate, return rho0
322 //pi_diffr+ -- change to pi+
325 //omega_di0 -- change to omega0
328 //phi_diff0 -- return phi0
331 //J/psi_di0 -- return J/psi
334 //n_diffr -- return neutron
337 //p_diffr+ -- return proton
340 //non diffractive state -- return code unchanged
344 void AliGenMC::Boost()
347 // Boost cms into LHC lab frame
350 Double_t beta = TMath::TanH(fDyBoost);
351 Double_t gamma = 1./TMath::Sqrt(1.-beta*beta);
352 Double_t gb = gamma * beta;
354 // printf("\n Boosting particles to lab frame %f %f %f", fDyBoost, beta, gamma);
357 Int_t np = fParticles->GetEntriesFast();
358 for (i = 0; i < np; i++)
360 TParticle* iparticle = (TParticle*) fParticles->At(i);
362 Double_t e = iparticle->Energy();
363 Double_t px = iparticle->Px();
364 Double_t py = iparticle->Py();
365 Double_t pz = iparticle->Pz();
367 Double_t eb = gamma * e - gb * pz;
368 Double_t pzb = -gb * e + gamma * pz;
370 iparticle->SetMomentum(px, py, pzb, eb);