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4 * Author: The ALICE Off-line Project. *
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14 **************************************************************************/
16 //-----------------------------------------------------------------
17 // Implementation of the TPC PID class
18 // Very naive one... Should be made better by the detector experts...
19 // Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
20 //-----------------------------------------------------------------
22 #include "AliTPCpidESD.h"
23 #include "AliESDEvent.h"
24 #include "AliESDtrack.h"
25 #include "AliMathBase.h"
27 ClassImp(AliTPCpidESD)
29 //_________________________________________________________________________
30 AliTPCpidESD::AliTPCpidESD(Double_t *param):
36 // The main constructor
43 Double_t AliTPCpidESD::Bethe(Double_t betaGamma) {
45 // This is the Bethe-Bloch function normalised to 1 at the minimum
47 // Simulated and reconstructed Bethe-Bloch differs
48 // Simulated curve is the dNprim/dx
49 // Reconstructed is proportianal dNtot/dx
50 // Temporary fix for production - Simple linear correction function
51 // Future 2 Bethe Bloch formulas needed
53 // 2. for reconstructed PID
55 const Float_t kmeanCorrection =0.1;
56 Double_t bb = AliMathBase::BetheBlochAleph(betaGamma);
57 Double_t meanCorrection =(1+(bb-1)*kmeanCorrection);
62 //_________________________________________________________________________
63 Int_t AliTPCpidESD::MakePID(AliESDEvent *event)
66 // This function calculates the "detector response" PID probabilities
68 Int_t ntrk=event->GetNumberOfTracks();
69 for (Int_t i=0; i<ntrk; i++) {
70 AliESDtrack *t=event->GetTrack(i);
71 if ((t->GetStatus()&AliESDtrack::kTPCin )==0)
72 if ((t->GetStatus()&AliESDtrack::kTPCout)==0) continue;
74 Double_t mom=t->GetP();
75 const AliExternalTrackParam *in=t->GetInnerParam();
76 if (in) mom=in->GetP();
77 Double_t dedx=t->GetTPCsignal()/fMIP;
78 Bool_t mismatch=kTRUE, heavy=kTRUE;
79 for (Int_t j=0; j<AliPID::kSPECIES; j++) {
80 Double_t mass=AliPID::ParticleMass(j);
81 Double_t bethe=Bethe(mom/mass);
82 Double_t sigma=fRes*bethe;
83 if (TMath::Abs(dedx-bethe) > fRange*sigma) {
84 p[j]=TMath::Exp(-0.5*fRange*fRange)/sigma;
86 p[j]=TMath::Exp(-0.5*(dedx-bethe)*(dedx-bethe)/(sigma*sigma))/sigma;
90 // Check for particles heavier than (AliPID::kSPECIES - 1)
91 if (dedx < (bethe + fRange*sigma)) heavy=kFALSE;
96 for (Int_t j=0; j<AliPID::kSPECIES; j++) p[j]=1/AliPID::kSPECIES;
100 if (heavy) t->ResetStatus(AliESDtrack::kTPCpid);