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>
31 #include "AliGeometry.h"
46 fChildPhiMax(2. * TMath::Pi()),
48 fChildThetaMax(TMath::Pi()),
62 fGeometryAcceptance(0),
63 fPdgCodeParticleforAcceptanceCut(0),
64 fNumberOfAcceptedParticles(0),
67 // Default Constructor
70 AliGenMC::AliGenMC(Int_t npart)
81 fChildPhiMax(2. * TMath::Pi()),
83 fChildThetaMax(TMath::Pi()),
97 fGeometryAcceptance(0),
98 fPdgCodeParticleforAcceptanceCut(0),
99 fNumberOfAcceptedParticles(0),
104 for (Int_t i=0; i<8; i++) fParentSelect[i]=fChildSelect[i]=0;
107 AliGenMC::~AliGenMC()
112 void AliGenMC::Init()
116 switch (fForceDecay) {
117 case kBSemiElectronic:
118 case kSemiElectronic:
120 case kBJpsiDiElectron:
121 case kBPsiPrimeDiElectron:
122 fChildSelect[0] = kElectron;
129 case kBPsiPrimeDiMuon:
133 case kWToCharmToMuon:
136 fChildSelect[0]=kMuonMinus;
141 case kHadronicDWithout4Bodies:
142 fChildSelect[0]=kPiPlus;
143 fChildSelect[1]=kKPlus;
146 fChildSelect[0]=kKPlus;
160 if (fZTarget != 0 && fAProjectile != 0)
162 fDyBoost = - 0.5 * TMath::Log(Double_t(fZProjectile) * Double_t(fATarget) /
163 (Double_t(fZTarget) * Double_t(fAProjectile)));
168 Bool_t AliGenMC::ParentSelected(Int_t ip) const
170 // True if particle is in list of parent particles to be selected
171 for (Int_t i=0; i<8; i++)
173 if (fParentSelect.At(i) == ip) return kTRUE;
178 Bool_t AliGenMC::ChildSelected(Int_t ip) const
180 // True if particle is in list of decay products to be selected
181 for (Int_t i=0; i<5; i++)
183 if (fChildSelect.At(i) == ip) return kTRUE;
188 Bool_t AliGenMC::KinematicSelection(TParticle *particle, Int_t flag) const
190 // Perform kinematic selection
191 Float_t pz = particle->Pz();
192 Float_t e = particle->Energy();
193 Float_t pt = particle->Pt();
194 Float_t p = particle->P();
195 Float_t theta = particle->Theta();
196 Float_t mass = particle->GetCalcMass();
197 Float_t mt2 = pt * pt + mass * mass;
198 Float_t phi = particle->Phi();
202 if (TMath::Abs(pz) < e) {
203 y = 0.5*TMath::Log((e+pz)/(e-pz));
209 y0 = 0.5*TMath::Log((e+TMath::Abs(pz))*(e+TMath::Abs(pz))/mt2);
211 if (TMath::Abs(y) < 1.e10) {
218 y = (pz < 0) ? -y0 : y0;
222 // Primary particle cuts
224 // transverse momentum cut
225 if (pt > fPtMax || pt < fPtMin) {
226 // printf("\n failed pt cut %f %f %f \n",pt,fPtMin,fPtMax);
231 if (p > fPMax || p < fPMin) {
232 // printf("\n failed p cut %f %f %f \n",p,fPMin,fPMax);
237 if (theta > fThetaMax || theta < fThetaMin) {
238 // printf("\n failed theta cut %f %f %f \n",theta,fThetaMin,fThetaMax);
243 if (y > fYMax || y < fYMin) {
244 // printf("\n failed y cut %f %f %f \n",y,fYMin,fYMax);
249 if (phi > fPhiMax || phi < fPhiMin) {
250 // printf("\n failed phi cut %f %f %f \n",phi,fPhiMin,fPhiMax);
255 // Decay product cuts
257 // transverse momentum cut
258 if (pt > fChildPtMax || pt < fChildPtMin) {
259 // printf("\n failed pt cut %f %f %f \n",pt,fChildPtMin,fChildPtMax);
264 if (p > fChildPMax || p < fChildPMin) {
265 // printf("\n failed p cut %f %f %f \n",p,fChildPMin,fChildPMax);
270 if (theta > fChildThetaMax || theta < fChildThetaMin) {
271 // printf("\n failed theta cut %f %f %f \n",theta,fChildThetaMin,fChildThetaMax);
276 if (y > fChildYMax || y < fChildYMin) {
277 // printf("\n failed y cut %f %f %f \n",y,fChildYMin,fChildYMax);
282 if (phi > fChildPhiMax || phi < fChildPhiMin) {
283 // printf("\n failed phi cut %f %f %f \n",phi,fChildPhiMin,fChildPhiMax);
291 Bool_t AliGenMC::CheckAcceptanceGeometry(Int_t np, TClonesArray* particles)
293 // Check the geometrical acceptance for particle.
296 Int_t numberOfPdgCodeParticleforAcceptanceCut = 0;
297 Int_t numberOfAcceptedPdgCodeParticleforAcceptanceCut = 0;
298 TParticle * particle;
300 for (i = 0; i < np; i++) {
301 particle = (TParticle *) particles->At(i);
302 if( TMath::Abs( particle->GetPdgCode() ) == TMath::Abs( fPdgCodeParticleforAcceptanceCut ) ) {
303 numberOfPdgCodeParticleforAcceptanceCut++;
304 if (fGeometryAcceptance->Impact(particle)) numberOfAcceptedPdgCodeParticleforAcceptanceCut++;
307 if ( numberOfAcceptedPdgCodeParticleforAcceptanceCut > (fNumberOfAcceptedParticles-1) )
315 Int_t AliGenMC::CheckPDGCode(Int_t pdgcode) const
318 // If the particle is in a diffractive state, then take action accordingly
323 //rho_diff0 -- difficult to translate, return rho0
326 //pi_diffr+ -- change to pi+
329 //omega_di0 -- change to omega0
332 //phi_diff0 -- return phi0
335 //J/psi_di0 -- return J/psi
338 //n_diffr -- return neutron
341 //p_diffr+ -- return proton
344 //non diffractive state -- return code unchanged
348 void AliGenMC::Boost()
351 // Boost cms into LHC lab frame
354 Double_t beta = TMath::TanH(fDyBoost);
355 Double_t gamma = 1./TMath::Sqrt(1.-beta*beta);
356 Double_t gb = gamma * beta;
358 // printf("\n Boosting particles to lab frame %f %f %f", fDyBoost, beta, gamma);
361 Int_t np = fParticles->GetEntriesFast();
362 for (i = 0; i < np; i++)
364 TParticle* iparticle = (TParticle*) fParticles->At(i);
366 Double_t e = iparticle->Energy();
367 Double_t px = iparticle->Px();
368 Double_t py = iparticle->Py();
369 Double_t pz = iparticle->Pz();
371 Double_t eb = gamma * e - gb * pz;
372 Double_t pzb = -gb * e + gamma * pz;
374 iparticle->SetMomentum(px, py, pzb, eb);
378 void AliGenMC::AddHeader(AliGenEventHeader* header)
380 // Passes header either to the container or to gAlice
382 fContainer->AddHeader(header);
384 gAlice->SetGenEventHeader(header);