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"
39 fParticles("TParticle", 1000),
48 fChildPhiMax(2. * TMath::Pi()),
50 fChildThetaMax(TMath::Pi()),
58 fGeometryAcceptance(0),
59 fPdgCodeParticleforAcceptanceCut(0),
60 fNumberOfAcceptedParticles(0),
63 // Default Constructor
72 AliGenMC::AliGenMC(Int_t npart)
74 fParticles("TParticle", 1000),
83 fChildPhiMax(2. * TMath::Pi()),
85 fChildThetaMax(TMath::Pi()),
93 fGeometryAcceptance(0),
94 fPdgCodeParticleforAcceptanceCut(0),
95 fNumberOfAcceptedParticles(0),
106 for (Int_t i=0; i<8; i++) fParentSelect[i]=fChildSelect[i]=0;
109 AliGenMC::~AliGenMC()
114 void AliGenMC::Init()
118 switch (fForceDecay) {
119 case kBSemiElectronic:
120 case kSemiElectronic:
122 case kBJpsiDiElectron:
123 case kBPsiPrimeDiElectron:
124 fChildSelect[0] = kElectron;
131 case kBPsiPrimeDiMuon:
135 case kWToCharmToMuon:
138 fChildSelect[0]=kMuonMinus;
143 case kHadronicDWithout4Bodies:
144 fChildSelect[0]=kPiPlus;
145 fChildSelect[1]=kKPlus;
148 fChildSelect[0]=kKPlus;
151 fChildSelect[0]= 443;
153 case kChiToJpsiGammaToMuonMuon:
157 case kChiToJpsiGammaToElectronElectron:
162 fChildSelect[0]= kProton;
163 fChildSelect[1]= 211;
165 case kPsiPrimeJpsiDiElectron:
166 fChildSelect[0]= 211;
179 if (fZTarget != 0 && fAProjectile != 0)
181 fDyBoost = - 0.5 * TMath::Log(Double_t(fZProjectile) * Double_t(fATarget) /
182 (Double_t(fZTarget) * Double_t(fAProjectile)));
187 Bool_t AliGenMC::ParentSelected(Int_t ip) const
189 // True if particle is in list of parent particles to be selected
190 for (Int_t i=0; i<8; i++)
192 if (fParentSelect.At(i) == ip) return kTRUE;
197 Bool_t AliGenMC::ChildSelected(Int_t ip) const
199 // True if particle is in list of decay products to be selected
200 for (Int_t i=0; i<5; i++)
202 if (fChildSelect.At(i) == ip) return kTRUE;
207 Bool_t AliGenMC::KinematicSelection(TParticle *particle, Int_t flag) const
209 // Perform kinematic selection
210 Double_t pz = particle->Pz();
211 Double_t pt = particle->Pt();
212 Double_t p = particle->P();
213 Double_t theta = particle->Theta();
214 Double_t mass = particle->GetCalcMass();
215 Double_t mt2 = pt * pt + mass * mass;
216 Double_t phi = particle->Phi();
217 Double_t e = particle->Energy();
220 e = TMath::Sqrt(p * p + mass * mass);
225 if (TMath::Abs(pz) < e) {
226 y = 0.5*TMath::Log((e+pz)/(e-pz));
232 y0 = 0.5*TMath::Log((e+TMath::Abs(pz))*(e+TMath::Abs(pz))/mt2);
234 if (TMath::Abs(y) < 1.e10) {
241 y = (pz < 0) ? -y0 : y0;
245 // Primary particle cuts
247 // transverse momentum cut
248 if (pt > fPtMax || pt < fPtMin) {
249 // printf("\n failed pt cut %f %f %f \n",pt,fPtMin,fPtMax);
254 if (p > fPMax || p < fPMin) {
255 // printf("\n failed p cut %f %f %f \n",p,fPMin,fPMax);
260 if (theta > fThetaMax || theta < fThetaMin) {
261 // printf("\n failed theta cut %f %f %f \n",theta,fThetaMin,fThetaMax);
266 if (y > fYMax || y < fYMin) {
267 // printf("\n failed y cut %f %f %f \n",y,fYMin,fYMax);
272 if (phi > fPhiMax || phi < fPhiMin) {
273 // printf("\n failed phi cut %f %f %f \n",phi,fPhiMin,fPhiMax);
278 // Decay product cuts
280 // transverse momentum cut
281 if (pt > fChildPtMax || pt < fChildPtMin) {
282 // printf("\n failed pt cut %f %f %f \n",pt,fChildPtMin,fChildPtMax);
287 if (p > fChildPMax || p < fChildPMin) {
288 // printf("\n failed p cut %f %f %f \n",p,fChildPMin,fChildPMax);
293 if (theta > fChildThetaMax || theta < fChildThetaMin) {
294 // printf("\n failed theta cut %f %f %f \n",theta,fChildThetaMin,fChildThetaMax);
299 if (y > fChildYMax || y < fChildYMin) {
300 // printf("\n failed y cut %f %f %f \n",y,fChildYMin,fChildYMax);
305 if (phi > fChildPhiMax || phi < fChildPhiMin) {
306 // printf("\n failed phi cut %f %f %f \n",phi,fChildPhiMin,fChildPhiMax);
314 Bool_t AliGenMC::CheckAcceptanceGeometry(Int_t np, TClonesArray* particles)
316 // Check the geometrical acceptance for particle.
319 Int_t numberOfPdgCodeParticleforAcceptanceCut = 0;
320 Int_t numberOfAcceptedPdgCodeParticleforAcceptanceCut = 0;
321 TParticle * particle;
323 for (i = 0; i < np; i++) {
324 particle = (TParticle *) particles->At(i);
325 if( TMath::Abs( particle->GetPdgCode() ) == TMath::Abs( fPdgCodeParticleforAcceptanceCut ) ) {
326 numberOfPdgCodeParticleforAcceptanceCut++;
327 if (fGeometryAcceptance->Impact(particle)) numberOfAcceptedPdgCodeParticleforAcceptanceCut++;
330 if ( numberOfAcceptedPdgCodeParticleforAcceptanceCut > (fNumberOfAcceptedParticles-1) )
338 Int_t AliGenMC::CheckPDGCode(Int_t pdgcode) const
341 // If the particle is in a diffractive state, then take action accordingly
346 //rho_diff0 -- difficult to translate, return rho0
349 //pi_diffr+ -- change to pi+
352 //omega_di0 -- change to omega0
355 //phi_diff0 -- return phi0
358 //J/psi_di0 -- return J/psi
361 //n_diffr -- return neutron
364 //p_diffr+ -- return proton
367 //non diffractive state -- return code unchanged
371 void AliGenMC::Boost()
374 // Boost cms into LHC lab frame
377 Double_t beta = TMath::TanH(fDyBoost);
378 Double_t gamma = 1./TMath::Sqrt((1.-beta)*(1.+beta));
379 Double_t gb = gamma * beta;
381 // printf("\n Boosting particles to lab frame %f %f %f", fDyBoost, beta, gamma);
384 Int_t np = fParticles.GetEntriesFast();
385 for (i = 0; i < np; i++)
387 TParticle* iparticle = (TParticle*) fParticles.At(i);
389 Double_t e = iparticle->Energy();
390 Double_t px = iparticle->Px();
391 Double_t py = iparticle->Py();
392 Double_t pz = iparticle->Pz();
394 Double_t eb = gamma * e - gb * pz;
395 Double_t pzb = -gb * e + gamma * pz;
397 iparticle->SetMomentum(px, py, pzb, eb);
401 void AliGenMC::BeamCrossAngle()
403 // Applies a boost in the y-direction in order to take into account the
404 // beam crossing angle
406 Double_t thetaPr0, phiPr0, pyPr2, pzPr2;
409 thetaPr0 = fXingAngleY / 2.;
412 // Momentum of the CMS system
413 pyPr2 = TMath::Sqrt(fEnergyCMS * fEnergyCMS/ 4 - 0.938 * 0.938) * TMath::Sin(thetaPr0);
414 pzPr2 = TMath::Sqrt(fEnergyCMS * fEnergyCMS/ 4 - 0.938 * 0.938) * TMath::Cos(thetaPr0);
416 TLorentzVector proj1Vect, proj2Vect, projVect;
417 proj1Vect.SetPxPyPzE(0., pyPr2, pzPr2, fEnergyCMS/2);
418 proj2Vect.SetPxPyPzE(0., pyPr2,-pzPr2, fEnergyCMS/2);
419 projVect = proj1Vect + proj2Vect;
420 beta=(1. / projVect.E()) * (projVect.Vect());
423 Int_t np = fParticles.GetEntriesFast();
424 for (i = 0; i < np; i++)
426 TParticle* iparticle = (TParticle*) fParticles.At(i);
428 Double_t e = iparticle->Energy();
429 Double_t px = iparticle->Px();
430 Double_t py = iparticle->Py();
431 Double_t pz = iparticle->Pz();
433 TLorentzVector partIn;
434 partIn.SetPxPyPzE(px,py,pz,e);
436 iparticle->SetMomentum(partIn.Px(),partIn.Py(),partIn.Pz(),partIn.E());
441 void AliGenMC::AddHeader(AliGenEventHeader* header)
443 // Passes header either to the container or to gAlice
445 fContainer->AddHeader(header);
447 gAlice->SetGenEventHeader(header);