+++ /dev/null
-/**************************************************************************
- * Copyright(c) 1998-1999, 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. *
- **************************************************************************/
-
-//-----------------------------------------------------------------
-// Implementation of the TPC PID class
-// Very naive one... Should be made better by the detector experts...
-// Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
-// With many additions and modifications suggested by
-// Alexander Kalweit, GSI, alexander.philipp.kalweit@cern.ch
-// Dariusz Miskowiec, GSI, D.Miskowiec@gsi.de
-//-----------------------------------------------------------------
-
-#include "AliTPCpidESD.h"
-#include "AliESDEvent.h"
-#include "AliESDtrack.h"
-#include "AliMathBase.h"
-
-ClassImp(AliTPCpidESD)
-
-//_________________________________________________________________________
-AliTPCpidESD::AliTPCpidESD():
- fMIP(50.),
- fRes(0.07),
- fRange(5.),
- fKp1(0.76176e-1),
- fKp2(10.632),
- fKp3(0.13279e-4),
- fKp4(1.8631),
- fKp5(1.9479)
-{
- //
- // The default constructor
- //
-}
-
-//_________________________________________________________________________
-AliTPCpidESD::AliTPCpidESD(Double_t *param):
- fMIP(param[0]),
- fRes(param[1]),
- fRange(param[2]),
- fKp1(0.76176e-1),
- fKp2(10.632),
- fKp3(0.13279e-4),
- fKp4(1.8631),
- fKp5(1.9479)
-{
- //
- // The main constructor
- //
-}
-
-Double_t AliTPCpidESD::Bethe(Double_t betaGamma) const {
- //
- // This is the Bethe-Bloch function normalised to 1 at the minimum
- // WARNING
- // Simulated and reconstructed Bethe-Bloch differs
- // Simulated curve is the dNprim/dx
- // Reconstructed is proportianal dNtot/dx
- // Temporary fix for production - Simple linear correction function
- // Future 2 Bethe Bloch formulas needed
- // 1. for simulation
- // 2. for reconstructed PID
- //
- const Float_t kmeanCorrection =0.1;
- Double_t bb=AliMathBase::BetheBlochAleph(betaGamma,fKp1,fKp2,fKp3,fKp4,fKp5);
- Double_t meanCorrection =(1+(bb-1)*kmeanCorrection);
- bb *= meanCorrection;
- return bb;
-}
-
-//_________________________________________________________________________
-void AliTPCpidESD::SetBetheBlochParameters(Double_t kp1,
- Double_t kp2,
- Double_t kp3,
- Double_t kp4,
- Double_t kp5) {
- //
- // Set the parameters of the ALEPH Bethe-Bloch formula
- //
- fKp1=kp1;
- fKp2=kp2;
- fKp3=kp3;
- fKp4=kp4;
- fKp5=kp5;
-}
-
-//_________________________________________________________________________
-Bool_t AliTPCpidESD::ExpectedSigmas(const AliESDtrack *t,
- Double_t s[],
- Int_t n) const {
- //
- // Calculate the expected dE/dx resolution as the function of
- // the information stored in the track.
- //
- // At the moment, this resolution is just proportional to the expected
- // signal. This can be improved. By taking into account the number of
- // assigned clusters, for example.
- //
- Bool_t ok=kFALSE;
- Double_t signals[AliPID::kSPECIESN];
- if (ExpectedSignals(t,signals,n)) {
- for (Int_t i=0; i<n; i++) s[i] = fRes*signals[i];
- ok=kTRUE;
- }
- return ok;
-}
-
-//_________________________________________________________________________
-Bool_t AliTPCpidESD::NumberOfSigmas(const AliESDtrack *t,
- Double_t s[],
- Int_t n) const {
- //
- // Calculate the deviation of the actual PID signal from the expected
- // signal, in units of expected sigmas.
- //
- Bool_t ok=kFALSE;
-
- Double_t dedx=t->GetTPCsignal()/fMIP;
- Double_t sigmas[AliPID::kSPECIESN];
- if (ExpectedSigmas(t,sigmas,n)) {
- Double_t signals[AliPID::kSPECIESN];
- if (ExpectedSignals(t,signals,n)) {
- for (Int_t i=0; i<n; i++) s[i] = (signals[i] - dedx)/sigmas[i];
- ok=kTRUE;
- }
- }
- return ok;
-}
-
-//_________________________________________________________________________
-Bool_t AliTPCpidESD::ExpectedSignals(const AliESDtrack *t,
- Double_t s[],
- Int_t n) const {
- //
- // Calculates the expected PID signals as the function of
- // the information stored in the track.
- //
- // At the moment, these signals are just the results of calling the
- // Bethe-Bloch formula.
- // This can be improved. By taking into account the number of
- // assigned clusters and/or the track dip angle, for example.
- //
-
- Double_t mom=t->GetP();
- const AliExternalTrackParam *in=t->GetInnerParam();
- if (in) mom=in->GetP();
-
- for (Int_t i=0; i<n; i++) {
- Double_t mass=AliPID::ParticleMass(i);
- s[i]=Bethe(mom/mass);
- }
-
- return kTRUE;
-}
-
-//_________________________________________________________________________
-Double_t AliTPCpidESD::GetExpectedSignal(const AliESDtrack *t,
- AliPID::EParticleType n) const {
- //
- // Calculates the expected PID signal as the function of
- // the information stored in the track, for the specified particle type
- //
- // At the moment, these signals are just the results of calling the
- // Bethe-Bloch formula.
- // This can be improved. By taking into account the number of
- // assigned clusters and/or the track dip angle, for example.
- //
-
- Double_t mom=t->GetP();
- const AliExternalTrackParam *in=t->GetInnerParam();
- if (in) mom=in->GetP();
-
- Double_t mass=AliPID::ParticleMass(n);
- return Bethe(mom/mass);
-}
-
-//_________________________________________________________________________
-Double_t AliTPCpidESD::GetExpectedSigma(const AliESDtrack *t,
- AliPID::EParticleType n) const {
- //
- // Calculates the expected sigma of the PID signal as the function of
- // the information stored in the track, for the specified particle type
- //
- //
- // At the moment, this sigma is just proportional to the expected
- // signal. This can be improved. By taking into account the number of
- // assigned clusters, for example.
- //
-
- return fRes*GetExpectedSignal(t,n);
-}
-
-//_________________________________________________________________________
-Double_t AliTPCpidESD::GetNumberOfSigmas(const AliESDtrack *t,
- AliPID::EParticleType n) const {
- //
- // Calculate the deviation of the actual PID signal from the expected
- // signal, in units of expected sigmas, for the specified particle type
- //
-
- Double_t dedx=t->GetTPCsignal()/fMIP;
- return (dedx - GetExpectedSignal(t,n))/GetExpectedSigma(t,n);
-}
-
-//_________________________________________________________________________
-Int_t AliTPCpidESD::MakePID(AliESDEvent *event)
-{
- //
- // This function calculates the "detector response" PID probabilities
- //
- Int_t ntrk=event->GetNumberOfTracks();
- for (Int_t i=0; i<ntrk; i++) {
- AliESDtrack *t=event->GetTrack(i);
- if ((t->GetStatus()&AliESDtrack::kTPCin )==0)
- if ((t->GetStatus()&AliESDtrack::kTPCout)==0) continue;
- Double_t p[10];
- Double_t dedx=t->GetTPCsignal()/fMIP;
- Bool_t mismatch=kTRUE, heavy=kTRUE;
- for (Int_t j=0; j<AliPID::kSPECIES; j++) {
- AliPID::EParticleType type=AliPID::EParticleType(j);
- Double_t bethe=GetExpectedSignal(t,type);
- Double_t sigma=GetExpectedSigma(t,type);
- if (TMath::Abs(dedx-bethe) > fRange*sigma) {
- p[j]=TMath::Exp(-0.5*fRange*fRange)/sigma;
- } else {
- p[j]=TMath::Exp(-0.5*(dedx-bethe)*(dedx-bethe)/(sigma*sigma))/sigma;
- mismatch=kFALSE;
- }
-
- // Check for particles heavier than (AliPID::kSPECIES - 1)
- if (dedx < (bethe + fRange*sigma)) heavy=kFALSE;
-
- }
-
- if (mismatch)
- for (Int_t j=0; j<AliPID::kSPECIES; j++) p[j]=1/AliPID::kSPECIES;
-
- t->SetTPCpid(p);
-
- if (heavy) t->ResetStatus(AliESDtrack::kTPCpid);
-
- }
- return 0;
-}
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