add dimuon trigger efficiency
[u/mrichter/AliRoot.git] / TRD / AliTRDpidESD.cxx
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b0f03c34 1/**************************************************************************
2 * Copyright(c) 1998-1999, 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//-----------------------------------------------------------------
17// Implementation of the TRD PID class
bd50219c 18// Assigns the electron and pion liklihoods for each ESD track.
19// The AliTRDprobdist class is instantiated here.
20// The function MakePID(AliESD *event) calculates the probability
21// of having dedx and the probability of having timbin at a given
22// momentum (mom) and particle type k (0 for e) and (2 for pi)
23// from the precalculated timbin distributions.
24// Prashant Shukla <shukla@pi0.physi.uni-heidelberg.de>
b0f03c34 25//-----------------------------------------------------------------
26
27#include "AliTRDpidESD.h"
28#include "AliESD.h"
29#include "AliESDtrack.h"
bd50219c 30#include "AliTRDprobdist.h"
b0f03c34 31
32ClassImp(AliTRDpidESD)
33
34//_________________________________________________________________________
35AliTRDpidESD::AliTRDpidESD(Double_t *param)
36{
37 //
38 // The main constructor
39 //
40 fMIP=param[0]; // MIP signal
41 fRes=param[1]; // relative resolution
42 fRange=param[2]; // PID "range" (in sigmas)
43}
44
eab5961e 45Double_t AliTRDpidESD::Bethe(Double_t bg)
46{
b0f03c34 47 //
eab5961e 48 // Parametrization of the Bethe-Bloch-curve
49 // The parametrization is the same as for the TPC and is taken from Lehrhaus.
b0f03c34 50 //
eab5961e 51
52 // This parameters have been adjusted to averaged values from GEANT
53 const Double_t kP1 = 7.17960e-02;
54 const Double_t kP2 = 8.54196;
55 const Double_t kP3 = 1.38065e-06;
56 const Double_t kP4 = 5.30972;
57 const Double_t kP5 = 2.83798;
58
59 // This parameters have been adjusted to Xe-data found in:
60 // Allison & Cobb, Ann. Rev. Nucl. Sci. (1980), 30, 253
61 //const Double_t kP1 = 0.76176E-1;
62 //const Double_t kP2 = 10.632;
63 //const Double_t kP3 = 3.17983E-6;
64 //const Double_t kP4 = 1.8631;
65 //const Double_t kP5 = 1.9479;
66
67 // Lower cutoff of the Bethe-Bloch-curve to limit step sizes
68 const Double_t kBgMin = 0.8;
69 const Double_t kBBMax = 6.83298;
70 //const Double_t kBgMin = 0.6;
71 //const Double_t kBBMax = 17.2809;
72 //const Double_t kBgMin = 0.4;
73 //const Double_t kBBMax = 82.0;
74
75 if (bg > kBgMin) {
76 Double_t yy = bg / TMath::Sqrt(1. + bg*bg);
77 Double_t aa = TMath::Power(yy,kP4);
78 Double_t bb = TMath::Power((1./bg),kP5);
79 bb = TMath::Log(kP3 + bb);
80 return ((kP2 - aa - bb)*kP1 / aa);
81 }
82 else {
83 return kBBMax;
84 }
85
b0f03c34 86}
87
88//_________________________________________________________________________
89Int_t AliTRDpidESD::MakePID(AliESD *event)
90{
91 //
92 // This function calculates the "detector response" PID probabilities
93 //
bd50219c 94 // The class AliTRDprobdist contains precalculated prob dis.
95 AliTRDprobdist *pd = new AliTRDprobdist();
defc9040 96 pd->SetADCNorm(1.0); // The factor is the ratio of Mean of pi charge dist.
97 // for the New TRD code divided by the Mean of pi charge
98 // dist. given in AliTRDprobdist object
99
100 // Example to get mean for particle 2 (pi) and momentum number 4 (2 GeV)
101 // printf("%.2f \n", pd->GetMean(2, 4));
102 // Example of use of Copy Constructor
103 // AliTRDprobdist *pd1 = new AliTRDprobdist(*pd);
bd50219c 104
105 Int_t ntrk=event->GetNumberOfTracks();
106 for (Int_t i=0; i<ntrk; i++) {
107 AliESDtrack *t=event->GetTrack(i);
108 if ((t->GetStatus()&AliESDtrack::kTRDin)==0)
1642e650 109 if ((t->GetStatus()&AliESDtrack::kTRDout)==0)
110 if ((t->GetStatus()&AliESDtrack::kTRDrefit)==0) continue;
111 if(t->GetTRDsignal()==0) continue;
bd50219c 112 // Int_t ns=AliESDtrack::kSPECIES;
113 Int_t ns=AliPID::kSPECIES;
114 Double_t p[10];
115 Double_t mom=t->GetP();
eee41b89 116 Double_t probTotal=0.0;
bd50219c 117 for (Int_t j=0; j<ns; j++) {
118 p[j]=1.;
119 for (Int_t ilayer=0; ilayer <6; ilayer++) {
120 Double_t dedx=t->GetTRDsignals(ilayer);
121 Int_t timbin=t->GetTRDTimBin(ilayer);
eee41b89 122 p[j]*= pd->GetProbability(j,mom,dedx);
123 p[j]*= pd->GetProbabilityT(j,mom,timbin);
124 p[j]*= 100;
bd50219c 125 } // loop over layers
eee41b89 126 probTotal+=p[j];
bd50219c 127 } //loop over particle species
5f8ccb35 128 // printf(" %f %d %f %f %f \n", mom, timbin, p[0], p[1], p[2]);
b0f03c34 129 for (Int_t j=0; j<ns; j++) {
eee41b89 130 if(probTotal) p[j]/= probTotal;
131 else p[j]=1.0;
5f8ccb35 132 // p[j]=1.;
eee41b89 133 } //loop over particle species
b0f03c34 134 t->SetTRDpid(p);
eee41b89 135 } //loop over tracks
136 delete pd;
b0f03c34 137 return 0;
138}