--- /dev/null
+/**************************************************************************
+ * Copyright(c) 1998-2003, ALICE Experiment at CERN, All rights reserved. *
+ * *
+ * Author: The ALICE Off-line Project. *
+ * Contributors are mentioned in the code where appropriate. *
+ * *
+ * Permission to use, copy, modify and distribute this software and its *
+ * documentation strictly for non-commercial purposes is hereby granted *
+ * without fee, provided that the above copyright notice appears in all *
+ * copies and that both the copyright notice and this permission notice *
+ * appear in the supporting documentation. The authors make no claims *
+ * about the suitability of this software for any purpose. It is *
+ * provided "as is" without express or implied warranty. *
+ **************************************************************************/
+
+/* $Id$ */
+
+// --- AliRoot header files ---
+
+// Fast global reconstruction class.
+// It performes fast reconstruction for charged particles only,
+// assuming that they were detected by all central ALICE detectors but PHOS.
+// This class acts as a filter for primary particles, selects them
+// and deteriorates their 4-momenta.
+// The filter can recognize the primary particle list from different
+// event generators: Pythia, Hijing, HIJINGPara.
+//!
+// Usage:
+// rec = new AliPHOSGlobalReconstruction("galice.root");
+// rec->FastReconstruction(ievent);
+// TClonesArray *recList = rec->GetRecParticles();
+//!
+// See also $ALICE_ROOT/macros/TestGlobalReconstruction.C
+//!
+// Author: Yuri Kharlov. 17 April 2003
+
+#include "AliRun.h"
+#include "AliGenerator.h"
+#include "AliPHOSGetter.h"
+#include "AliPHOSFastGlobalReconstruction.h"
+
+ClassImp(AliPHOSFastGlobalReconstruction)
+
+//____________________________________________________________________________
+AliPHOSFastGlobalReconstruction::AliPHOSFastGlobalReconstruction(const char* headerFile )
+{
+ // Constructor of fast global reconstruction:
+ // create an instance of the PHOS getter,
+ // create an array or reconstructed particles.
+
+ gime = AliPHOSGetter::GetInstance(headerFile);
+ fGenerator = gAlice->Generator();
+ fParticles = new TClonesArray("TParticle",100);
+ fNParticles = 0;
+}
+
+//____________________________________________________________________________
+AliPHOSFastGlobalReconstruction::~AliPHOSFastGlobalReconstruction()
+{
+ // Destructor of fast global reconstruction:
+ // delete the array of reconstructed particles
+ if (fParticles != 0) {
+ delete fParticles;
+ fParticles = 0;
+ fNParticles = 0;
+ }
+}
+
+//____________________________________________________________________________
+void AliPHOSFastGlobalReconstruction::FastReconstruction(Int_t event)
+{
+ // Perform a fast global reconstruction of event numbered "event".
+ // Reconstructed particles will be stored into array recParticles
+
+ TParticle *primary;
+ TLorentzVector p,v;
+ Int_t kf,ks,imom1,imom2,idaug1,idaug2;
+
+ gime->Event(event,"P") ;
+ fParticles ->Clear();
+ fNParticles = 0;
+ Int_t nPrimaries = gime->NPrimaries();
+ TClonesArray *primaries = gime->Primaries();
+
+ for (Int_t iprim=0; iprim<nPrimaries; iprim++) {
+ primary = (TParticle*)primaries->At(iprim);
+ if ((strcmp(fGenerator->GetName(),"Pythia") ==0 && primary->GetStatusCode() == 1) ||
+ (strcmp(fGenerator->GetName(),"HIJINGpara")==0 && primary->GetFirstMother()==-1) ||
+ (strcmp(fGenerator->GetName(),"Hijing") ==0 && primary->GetStatusCode() == 3)) {
+ if (Detected(primary)) {
+ primary->Momentum(p);
+ primary->ProductionVertex(v);
+ kf = primary->GetPdgCode();
+ ks = primary->GetStatusCode();
+ imom1 = primary->GetFirstMother();
+ imom2 = primary->GetSecondMother();
+ idaug1 = primary->GetFirstDaughter();
+ idaug2 = primary->GetLastDaughter();
+ SmearMomentum(p);
+ new((*fParticles)[fNParticles]) TParticle(kf,ks,imom1,imom2,idaug1,idaug2,p,v);
+ fNParticles++;
+ }
+ }
+ }
+}
+
+//____________________________________________________________________________
+Bool_t AliPHOSFastGlobalReconstruction::Detected(TParticle *particle)
+{
+ // Returns kTRUE is a particle is reconstructed, kFALSE otherwise.
+ // A particle is reconstructed if it is charged and accepted with the
+ // probability Efficiency(pt,eta) depending on pt and eta.
+
+ Bool_t detected = kFALSE;
+ if (particle->GetPDG()->Charge() != 0) {
+ Float_t pt = particle->Pt();
+ Float_t eta = particle->Eta();
+ if (gRandom->Rndm() < Efficiency(pt,eta)) detected = kTRUE;
+ }
+ return detected;
+}
+
+//____________________________________________________________________________
+Float_t AliPHOSFastGlobalReconstruction::Efficiency(Float_t pt, Float_t eta)
+{
+ // Detection probability vs. pt and eta, i.e. a probability to detect
+ // a particle with transverse momentum pt and speudorapidity eta.
+ // For the moment assume that charged particles are detected with
+ // 80% efficiency within |eta|<0.9 and pt>0.15 GeV, and with 0% efficiency
+ // beyond that acceptance
+
+ const Float_t kEtaLimit = 0.9;
+ const Float_t kPtLimit = 0.15;
+ Float_t efficiency = 0.0;
+ if (TMath::Abs(eta) < kEtaLimit && pt > kPtLimit) efficiency = 0.80;
+ return efficiency;
+}
+
+//____________________________________________________________________________
+void AliPHOSFastGlobalReconstruction::SmearMomentum(TLorentzVector &p)
+{
+ // Smear 4-momentum according to known resolution (2% for the moment)
+
+ const Float_t kAngleResolution = 0.02;
+ const Float_t kMomentumResolution = 0.02;
+ Double_t mass = p.M();
+ for (Int_t i=0; i<3; i++) {
+ p[i] *= gRandom->Gaus(1.,kAngleResolution );
+ p[i] *= gRandom->Gaus(1.,kMomentumResolution);
+ }
+ p[3] = TMath::Sqrt(p.P()*p.P() + mass*mass);
+}
--- /dev/null
+#ifndef ALIPHOSFASTGLOBALRECONSTRUCTION_H
+#define ALIPHOSFASTGLOBALRECONSTRUCTION_H
+/* Copyright(c) 1998-2003, ALICE Experiment at CERN, All rights reserved. *
+ * See cxx source for full Copyright notice */
+
+/* $Id$ */
+
+// Fast global reconstruction class.
+// It performes fast reconstruction for charged particles only,
+// assuming that they were detected by all central ALICE detectors but PHOS.
+// This class acts as a filter for primary particles, selects them
+// and deteriorates their 4-momenta.
+//!
+// Author: Yuri Kharlov. 17 April 2003
+
+//_________________________________________________________________________
+class AliGenerator;
+class TClonesArray;
+class AliPHOSGetter;
+
+class AliPHOSFastGlobalReconstruction : public TObject {
+
+public:
+ AliPHOSFastGlobalReconstruction() {};
+ AliPHOSFastGlobalReconstruction(const char* headerFile);
+ virtual ~AliPHOSFastGlobalReconstruction();
+ void FastReconstruction(Int_t event);
+ TClonesArray *GetRecParticles() const {return fParticles;}
+
+private:
+ Bool_t Detected(TParticle *particle);
+ Float_t Efficiency(Float_t pt, Float_t eta);
+ void SmearMomentum(TLorentzVector &p);
+
+private:
+ AliPHOSGetter *gime; //! Instance of the PHOS getter
+ AliGenerator *fGenerator; //! MC generator used in simulation
+ TClonesArray *fParticles; //! Array of reconstructed particles
+ Int_t fNParticles; //! Number of reconstructed particles
+
+ClassDef(AliPHOSFastGlobalReconstruction,1) // Fast global reconstruction
+};
+
+#endif // AliPHOSFASTGLOBALRECONSTRUCTION_H
git://git.uio.no / u / mrichter / AliRoot.git / commitdiff