Coding rule violations corrected.
[u/mrichter/AliRoot.git] / PHOS / AliPHOSFastGlobalReconstruction.cxx
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8b2df7ae 1/**************************************************************************
2 * Copyright(c) 1998-2003, ALICE Experiment at CERN, All rights reserved. *
3 * *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
6 * *
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 **************************************************************************/
15
16/* $Id$ */
17
18// --- AliRoot header files ---
19
20// Fast global reconstruction class.
21// It performes fast reconstruction for charged particles only,
22// assuming that they were detected by all central ALICE detectors but PHOS.
23// This class acts as a filter for primary particles, selects them
24// and deteriorates their 4-momenta.
25// The filter can recognize the primary particle list from different
26// event generators: Pythia, Hijing, HIJINGPara.
27//!
28// Usage:
29// rec = new AliPHOSGlobalReconstruction("galice.root");
30// rec->FastReconstruction(ievent);
31// TClonesArray *recList = rec->GetRecParticles();
32//!
33// See also $ALICE_ROOT/macros/TestGlobalReconstruction.C
34//!
35// Author: Yuri Kharlov. 17 April 2003
36
37#include "AliRun.h"
38#include "AliGenerator.h"
39#include "AliPHOSGetter.h"
40#include "AliPHOSFastGlobalReconstruction.h"
41
42ClassImp(AliPHOSFastGlobalReconstruction)
43
44//____________________________________________________________________________
45AliPHOSFastGlobalReconstruction::AliPHOSFastGlobalReconstruction(const char* headerFile )
46{
47 // Constructor of fast global reconstruction:
48 // create an instance of the PHOS getter,
49 // create an array or reconstructed particles.
50
88cb7938 51 gime = AliPHOSGetter::Instance(headerFile);
8b2df7ae 52 fGenerator = gAlice->Generator();
53 fParticles = new TClonesArray("TParticle",100);
54 fNParticles = 0;
55}
56
57//____________________________________________________________________________
58AliPHOSFastGlobalReconstruction::~AliPHOSFastGlobalReconstruction()
59{
60 // Destructor of fast global reconstruction:
61 // delete the array of reconstructed particles
62 if (fParticles != 0) {
63 delete fParticles;
64 fParticles = 0;
65 fNParticles = 0;
66 }
67}
68
69//____________________________________________________________________________
70void AliPHOSFastGlobalReconstruction::FastReconstruction(Int_t event)
71{
72 // Perform a fast global reconstruction of event numbered "event".
73 // Reconstructed particles will be stored into array recParticles
74
75 TParticle *primary;
76 TLorentzVector p,v;
77 Int_t kf,ks,imom1,imom2,idaug1,idaug2;
78
88cb7938 79 gime->Event(event,"X") ;
8b2df7ae 80 fParticles ->Clear();
81 fNParticles = 0;
82 Int_t nPrimaries = gime->NPrimaries();
83 TClonesArray *primaries = gime->Primaries();
84
85 for (Int_t iprim=0; iprim<nPrimaries; iprim++) {
86 primary = (TParticle*)primaries->At(iprim);
87 if ((strcmp(fGenerator->GetName(),"Pythia") ==0 && primary->GetStatusCode() == 1) ||
88 (strcmp(fGenerator->GetName(),"HIJINGpara")==0 && primary->GetFirstMother()==-1) ||
89 (strcmp(fGenerator->GetName(),"Hijing") ==0 && primary->GetStatusCode() == 3)) {
90 if (Detected(primary)) {
91 primary->Momentum(p);
92 primary->ProductionVertex(v);
93 kf = primary->GetPdgCode();
94 ks = primary->GetStatusCode();
95 imom1 = primary->GetFirstMother();
96 imom2 = primary->GetSecondMother();
97 idaug1 = primary->GetFirstDaughter();
98 idaug2 = primary->GetLastDaughter();
99 SmearMomentum(p);
100 new((*fParticles)[fNParticles]) TParticle(kf,ks,imom1,imom2,idaug1,idaug2,p,v);
101 fNParticles++;
102 }
103 }
104 }
105}
106
107//____________________________________________________________________________
108Bool_t AliPHOSFastGlobalReconstruction::Detected(TParticle *particle)
109{
110 // Returns kTRUE is a particle is reconstructed, kFALSE otherwise.
111 // A particle is reconstructed if it is charged and accepted with the
112 // probability Efficiency(pt,eta) depending on pt and eta.
113
114 Bool_t detected = kFALSE;
115 if (particle->GetPDG()->Charge() != 0) {
116 Float_t pt = particle->Pt();
117 Float_t eta = particle->Eta();
118 if (gRandom->Rndm() < Efficiency(pt,eta)) detected = kTRUE;
119 }
120 return detected;
121}
122
123//____________________________________________________________________________
124Float_t AliPHOSFastGlobalReconstruction::Efficiency(Float_t pt, Float_t eta)
125{
126 // Detection probability vs. pt and eta, i.e. a probability to detect
127 // a particle with transverse momentum pt and speudorapidity eta.
128 // For the moment assume that charged particles are detected with
129 // 80% efficiency within |eta|<0.9 and pt>0.15 GeV, and with 0% efficiency
130 // beyond that acceptance
131
132 const Float_t kEtaLimit = 0.9;
133 const Float_t kPtLimit = 0.15;
134 Float_t efficiency = 0.0;
135 if (TMath::Abs(eta) < kEtaLimit && pt > kPtLimit) efficiency = 0.80;
136 return efficiency;
137}
138
139//____________________________________________________________________________
140void AliPHOSFastGlobalReconstruction::SmearMomentum(TLorentzVector &p)
141{
142 // Smear 4-momentum according to known resolution (2% for the moment)
143
144 const Float_t kAngleResolution = 0.02;
145 const Float_t kMomentumResolution = 0.02;
146 Double_t mass = p.M();
147 for (Int_t i=0; i<3; i++) {
148 p[i] *= gRandom->Gaus(1.,kAngleResolution );
149 p[i] *= gRandom->Gaus(1.,kMomentumResolution);
150 }
151 p[3] = TMath::Sqrt(p.P()*p.P() + mass*mass);
152}