[u/mrichter/AliRoot.git] / STEER / STEERBase / AliITSPIDResponse.cxx

/**************************************************************************
 * Copyright(c) 2005-2007, 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.                  *
 **************************************************************************/

/* $Id$ */

//-----------------------------------------------------------------
// ITS PID method # 1
//           Implementation of the ITS PID class
// Very naive one... Should be made better by the detector experts...
//      Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
//-----------------------------------------------------------------
#include "TMath.h"
#include "AliVTrack.h"
#include "AliITSPIDResponse.h"
#include "AliITSPidParams.h"
#include "AliExternalTrackParam.h"

ClassImp(AliITSPIDResponse)

AliITSPIDResponse::AliITSPIDResponse(Bool_t isMC): 
  fRes(0.13),
  fKp1(15.77),
  fKp2(4.95),
  fKp3(0.312),
  fKp4(2.14),
  fKp5(0.82)
{
  if(!isMC){
    fBBtpcits[0]=0.73;
    fBBtpcits[1]=14.68;
    fBBtpcits[2]=0.905;
    fBBtpcits[3]=1.2;
    fBBtpcits[4]=6.6;
    fBBdeu[0]=76.43; // parameters for the deuteron - tpcits - value from PbPb 2010 run (S.Trogolo - July 2014)
    fBBdeu[1]=-34.21;
    fBBdeu[2]=113.2;
    fBBdeu[3]=-18.12;
    fBBdeu[4]=0.6019;
    fBBtri[0]=13.34; // parameters for the triton - tpcits - value from PbPb 2010 run (S.Trogolo - July 2014)
    fBBtri[1]=55.17;
    fBBtri[2]=66.41;
    fBBtri[3]=-6.601;
    fBBtri[4]=-0.4134;
    fBBsa[0]=2.73198E7; //pure PHOBOS parameterization
    fBBsa[1]=6.92389;
    fBBsa[2]=1.90088E-6;
    fBBsa[3]=1.90088E-6;
    fBBsa[4]=3.40644E-7;
    fBBsaHybrid[0]=1.43505E7;  //PHOBOS+Polinomial parameterization
    fBBsaHybrid[1]=49.3402;
    fBBsaHybrid[2]=1.77741E-7;
    fBBsaHybrid[3]=1.77741E-7;
    fBBsaHybrid[4]=1.01311E-7;
    fBBsaHybrid[5]=77.2777;
    fBBsaHybrid[6]=33.4099;
    fBBsaHybrid[7]=46.0089;
    fBBsaHybrid[8]=-2.26583;
    fBBsaElectron[0]=4.05799E6;  //electrons in the ITS
    fBBsaElectron[1]=38.5713;
    fBBsaElectron[2]=1.46462E-7;
    fBBsaElectron[3]=1.46462E-7;
    fBBsaElectron[4]=4.40284E-7; 
    fResolSA[0]=1.;   // 0 cluster tracks should not be used
    fResolSA[1]=0.25;  // rough values for tracks with 1
    fResolSA[2]=0.131;   // value from pp 2010 run (L. Milano, 16-Jun-11)
    fResolSA[3]=0.113; // value from pp 2010 run 
    fResolSA[4]=0.104; // value from pp 2010 run
    for(Int_t i=0; i<5;i++) fResolTPCITS[i]=0.13;
    fResolTPCITSDeu3[0]=0.06918; // deuteron resolution vs p
    fResolTPCITSDeu3[1]=0.02498; // 3 ITS clusters for PId
    fResolTPCITSDeu3[2]=1.1; // value from PbPb 2010 run (July 2014)
    fResolTPCITSDeu4[0]=0.06756;// deuteron resolution vs p
    fResolTPCITSDeu4[1]=0.02078; // 4 ITS clusters for PId
    fResolTPCITSDeu4[2]=1.05; // value from PbPb 2010 run (July 2014)
    fResolTPCITSTri3[0]=0.07239; // triton resolution vs p
    fResolTPCITSTri3[1]=0.0192; // 3 ITS clusters for PId
    fResolTPCITSTri3[2]=1.1; // value from PbPb 2010 run (July 2014)
    fResolTPCITSTri4[0]=0.06083; // triton resolution
    fResolTPCITSTri4[1]=0.02579; // 4 ITS clusters for PId
    fResolTPCITSTri4[2]=1.15; // value from PbPb 2010 run (July 2014)
  }else{
    fBBtpcits[0]=1.04;
    fBBtpcits[1]=27.14;
    fBBtpcits[2]=1.00;
    fBBtpcits[3]=0.964;
    fBBtpcits[4]=2.59;
    fBBsa[0]=2.02078E7; //pure PHOBOS parameterization
    fBBsa[1]=14.0724;
    fBBsa[2]=3.84454E-7;
    fBBsa[3]=3.84454E-7;
    fBBsa[4]=2.43913E-7;
    fBBsaHybrid[0]=1.05381E7; //PHOBOS+Polinomial parameterization
    fBBsaHybrid[1]=89.3933;
    fBBsaHybrid[2]=2.4831E-7;
    fBBsaHybrid[3]=2.4831E-7;
    fBBsaHybrid[4]=7.80591E-8;
    fBBsaHybrid[5]=62.9214;
    fBBsaHybrid[6]=32.347;
    fBBsaHybrid[7]=58.7661;
    fBBsaHybrid[8]=-3.39869;
    fBBsaElectron[0]=2.26807E6; //electrons in the ITS
    fBBsaElectron[1]=99.985;
    fBBsaElectron[2]=0.000714841;
    fBBsaElectron[3]=0.000259585;
    fBBsaElectron[4]=1.39412E-7;
    fResolSA[0]=1.;   // 0 cluster tracks should not be used
    fResolSA[1]=0.25;  // rough values for tracks with 1
    fResolSA[2]=0.126;   // value from pp 2010 simulations (L. Milano, 16-Jun-11)
    fResolSA[3]=0.109; // value from pp 2010 simulations
    fResolSA[4]=0.097; // value from pp 2010 simulations
    for(Int_t i=0; i<5;i++) fResolTPCITS[i]=0.13;
  }
}

/*
//_________________________________________________________________________
AliITSPIDResponse::AliITSPIDResponse(Double_t *param): 
  fRes(param[0]),
  fKp1(15.77),
  fKp2(4.95),
  fKp3(0.312),
  fKp4(2.14),
  fKp5(0.82)
{
  //
  //  The main constructor
  //
  for (Int_t i=0; i<5;i++) {
      fBBsa[i]=0.; 
      fBBtpcits[i]=0.;
      fResolSA[i]=0.; 
      fResolTPCITS[i]=0.;
  }
}
*/

//_________________________________________________________________________
Double_t AliITSPIDResponse::BetheAleph(Double_t p, Double_t mass) const {
  //
  // returns AliExternalTrackParam::BetheBloch normalized to 
  // fgMIP at the minimum
  //
  
  Double_t bb=
    AliExternalTrackParam::BetheBlochAleph(p/mass,fKp1,fKp2,fKp3,fKp4,fKp5);
  return bb;
}

//_________________________________________________________________________
Double_t AliITSPIDResponse::Bethe(Double_t bg, const Double_t * const par, Bool_t isNuclei) const
{

  const Double_t beta = bg/TMath::Sqrt(1.+ bg*bg);
  const Double_t gamma=bg/beta;
  Double_t bb=1.;

  Double_t eff=1.0;
  if(bg<par[2])
    eff=(bg-par[3])*(bg-par[3])+par[4];
  else
    eff=(par[2]-par[3])*(par[2]-par[3])+par[4];
  
  if(gamma>=0. && beta>0.){
    if(isNuclei){
      //Parameterization for deuteron between 0.4 - 1.5 GeV/c; triton between 0.58 - 1.65 GeV/c
      bb=par[0] + par[1]/bg + par[2]/(bg*bg) + par[3]/(bg*bg*bg) + par[4]/(bg*bg*bg*bg);
    }else{ //Parameterization for pion, kaon, proton, electron
      bb=(par[1]+2.0*TMath::Log(gamma)-beta*beta)*(par[0]/(beta*beta))*eff;
    }
  }
  
  return bb;
}

//_________________________________________________________________________
Double_t AliITSPIDResponse::Bethe(Double_t p, Double_t mass, Bool_t isSA) const {

  //OLD - Mantained for backward compatibility
  //from the mass check --> Set the Particle Type
  //at the end use the method Bethe(Double_t p, AliPID::EParticleType species, Bool_t isSA) const to set the right parameter

  //
  // returns AliExternalTrackParam::BetheBloch normalized to 
  // fgMIP at the minimum
  //

  // NEW: Parameterization for Deuteron and Triton energy loss, reproduced with a polynomial in fixed p range
  // fBBdeu --> parameters for deuteron
  // fBBtri --> parameters for triton

  //NOTE
  //NOTE: if changes are made here, please also check the alternative function below
  //NOTE

  AliPID::EParticleType species = AliPID::kPion;

    if(TMath::AreEqualAbs(mass,AliPID::ParticleMass(0),0.00001)){
      //if is an electron use a specific BB parameterization
      //To be used only between 100 and 160 MeV/c
      species=AliPID::kElectron;
    }

    if(TMath::AreEqualAbs(mass,AliPID::ParticleMass(5),0.002)) species=AliPID::kDeuteron;
    if(TMath::AreEqualAbs(mass,AliPID::ParticleMass(6),0.001)) species=AliPID::kTriton;
  
    return Bethe(p,species,isSA);
}

//_________________________________________________________________________
Double_t AliITSPIDResponse::Bethe(Double_t p, AliPID::EParticleType species, Bool_t isSA) const
{
  // NEW - to be used
  // Alternative bethe function assuming a particle type not a mass
  // should be slightly faster
  //

  const Double_t m=AliPID::ParticleMassZ(species);
  const Double_t bg=p/m;
  Bool_t isNuclei=kFALSE;
  
  //NOTE
  //NOTE: if changes are made here, please also check the alternative function above
  //NOTE
  const Double_t *par=fBBtpcits;
  if(isSA){
    if(species == AliPID::kElectron){
      //if is an electron use a specific BB parameterization
      //To be used only between 100 and 160 MeV/c
      par=fBBsaElectron;
    }else{
      par=fBBsa;
    }
  }else{
    if(species == AliPID::kDeuteron) {
      par=fBBdeu;
      isNuclei=kTRUE;
    }
    if(species == AliPID::kTriton  ) {
      par=fBBtri;
      isNuclei=kTRUE;
    }
  }

  return Bethe(bg, par, isNuclei);
}

//_________________________________________________________________________
Double_t AliITSPIDResponse::BetheITSsaHybrid(Double_t p, Double_t mass) const {
  //
  // returns AliExternalTrackParam::BetheBloch normalized to 
  // fgMIP at the minimum. The PHOBOS parameterization is used for beta*gamma>0.76. 
  // For beta*gamma<0.76 a polinomial function is used
  
  Double_t bg=p/mass;
  Double_t beta = bg/TMath::Sqrt(1.+ bg*bg);
  Double_t gamma=bg/beta;
  Double_t bb=1.;
  
  Double_t par[9];
  //parameters for pi, K, p
  for(Int_t ip=0; ip<9;ip++) par[ip]=fBBsaHybrid[ip];
  //if it is an electron the PHOBOS part of the parameterization is tuned for e
  //in the range used for identification beta*gamma is >0.76 for electrons
  //To be used only between 100 and 160 MeV/c
  if(mass>0.0005 && mass<0.00052)for(Int_t ip=0; ip<5;ip++) par[ip]=fBBsaElectron[ip]; 
  
  if(gamma>=0. && beta>0. && bg>0.1){
    if(bg>0.76){//PHOBOS
      Double_t eff=1.0;
      if(bg<par[2])
	eff=(bg-par[3])*(bg-par[3])+par[4];
      else
	eff=(par[2]-par[3])*(par[2]-par[3])+par[4];
      
      bb=(par[1]+2.0*TMath::Log(gamma)-beta*beta)*(par[0]/(beta*beta))*eff;
    }else{//Polinomial
      bb=par[5] + par[6]/bg + par[7]/(bg*bg) + par[8]/(bg*bg*bg);
    }
  }
  return bb; 
}

//_________________________________________________________________________
Double_t AliITSPIDResponse::GetResolution(Double_t bethe,
					  Int_t nPtsForPid, 
                                         Bool_t isSA,
                                         Double_t p,
                                         AliPID::EParticleType type) const {
  //
  // Calculate expected resolution for truncated mean
  //
  // NEW: Added new variables which are Double_t p and AliPID::EParticleType type
  // AliPID::EParticleType type is used to set the correct resolution for the different particles
  // default -> AliPID::EParticleType type = AliPID::kPion
  // Double_t p is used for the resolution of deuteron and triton, because they are function of the momentum
  // default -> Double_t p=0.

  Float_t r=0.f;
  Double_t c=1.; //this is a correction factor used for the nuclei resolution, while for pion/kaon/proton/electron is 1.

  if(isSA) r=fResolSA[nPtsForPid];
  else{
    const Double_t *par=0x0;
    if(type==AliPID::kDeuteron){
      if(nPtsForPid==3) par = fResolTPCITSDeu3;
      if(nPtsForPid==4) par = fResolTPCITSDeu4;
      c=par[2];
      r=par[0]+par[1]*p;
    } else if(type==AliPID::kTriton){
      if(nPtsForPid==3) par = fResolTPCITSTri3;
      if(nPtsForPid==4) par = fResolTPCITSTri4;
      c=par[2];
      r=par[0]+par[1]*p;
    } else{
      r=fResolTPCITS[nPtsForPid];
    }
  }

  return r*bethe*c;
}


//_________________________________________________________________________
void AliITSPIDResponse::GetITSProbabilities(Float_t mom, Double_t qclu[4], Double_t condprobfun[AliPID::kSPECIES], Bool_t isMC) const {
  //
  // Method to calculate PID probabilities for a single track
  // using the likelihood method
  //
  const Int_t nLay = 4;
  const Int_t nPart= 4;

  static AliITSPidParams pars(isMC);  // Pid parametrisation parameters
  
  Double_t itsProb[nPart] = {1,1,1,1}; // e, p, K, pi

  for (Int_t iLay = 0; iLay < nLay; iLay++) {
    if (qclu[iLay] <= 50.)
      continue;

    Float_t dedx = qclu[iLay];
    Float_t layProb = pars.GetLandauGausNorm(dedx,AliPID::kProton,mom,iLay+3);
    itsProb[0] *= layProb;
    
    layProb = pars.GetLandauGausNorm(dedx,AliPID::kKaon,mom,iLay+3);
    itsProb[1] *= layProb;
    
    layProb = pars.GetLandauGausNorm(dedx,AliPID::kPion,mom,iLay+3);
    itsProb[2] *= layProb;
   
    layProb = pars.GetLandauGausNorm(dedx,AliPID::kElectron,mom,iLay+3);
    itsProb[3] *= layProb;
  }

  // Normalise probabilities
  Double_t sumProb = 0;
  for (Int_t iPart = 0; iPart < nPart; iPart++) {
    sumProb += itsProb[iPart];
  }
  sumProb += itsProb[2]; // muon cannot be distinguished from pions

  for (Int_t iPart = 0; iPart < nPart; iPart++) {
    itsProb[iPart]/=sumProb;
  }
  condprobfun[AliPID::kElectron] = itsProb[3];
  condprobfun[AliPID::kMuon] = itsProb[2];
  condprobfun[AliPID::kPion] = itsProb[2];
  condprobfun[AliPID::kKaon] = itsProb[1];
  condprobfun[AliPID::kProton] = itsProb[0];
  return;
}

//_________________________________________________________________________
Double_t AliITSPIDResponse::GetNumberOfSigmas( const AliVTrack* track, AliPID::EParticleType type) const
{
  //
  // number of sigmas
  //
  UChar_t clumap=track->GetITSClusterMap();
  Int_t nPointsForPid=0;
  for(Int_t i=2; i<6; i++){
    if(clumap&(1<<i)) ++nPointsForPid;
  }
  Float_t mom=track->P();

  //check for ITS standalone tracks
  Bool_t isSA=kTRUE;
  if( track->GetStatus() & AliVTrack::kTPCin ) isSA=kFALSE;
  
  const Float_t dEdx=track->GetITSsignal();
  
  //TODO: in case of the electron, use the SA parametrisation,
  //      this needs to be changed if ITS provides a parametrisation
  //      for electrons also for ITS+TPC tracks
  return GetNumberOfSigmas(mom,dEdx,type,nPointsForPid,isSA || (type==AliPID::kElectron));
}

//_________________________________________________________________________
Double_t AliITSPIDResponse::GetSignalDelta( const AliVTrack* track, AliPID::EParticleType type, Bool_t ratio/*=kFALSE*/) const
{
  //
  // Signal - expected
  //
  const Float_t mom=track->P();
  const Double_t chargeFactor = TMath::Power(AliPID::ParticleCharge(type),2.);
  Bool_t isSA=kTRUE;
  if( track->GetStatus() & AliVTrack::kTPCin ) isSA=kFALSE;
  
  const Float_t dEdx=track->GetITSsignal();
  
  //TODO: in case of the electron, use the SA parametrisation,
  //      this needs to be changed if ITS provides a parametrisation
  //      for electrons also for ITS+TPC tracks
  
  const Float_t bethe = Bethe(mom,AliPID::ParticleMassZ(type), isSA || (type==AliPID::kElectron))*chargeFactor;

  Double_t delta=-9999.;
  if (!ratio) delta=dEdx-bethe;
  else if (bethe>1.e-20) delta=dEdx/bethe;
  
  return delta;
}

//_________________________________________________________________________
Int_t AliITSPIDResponse::GetParticleIdFromdEdxVsP(Float_t mom, Float_t signal, Bool_t isSA) const{
  // method to get particle identity with simple cuts on dE/dx vs. momentum

  Double_t massp=AliPID::ParticleMass(AliPID::kProton);
  Double_t massk=AliPID::ParticleMass(AliPID::kKaon);
  Double_t bethep=Bethe(mom,massp,isSA);
  Double_t bethek=Bethe(mom,massk,isSA);
  if(signal>(0.5*(bethep+bethek))) return AliPID::kProton;
  Double_t masspi=AliPID::ParticleMass(AliPID::kPion);
  Double_t bethepi=Bethe(mom,masspi,isSA);
  if(signal>(0.5*(bethepi+bethek))) return AliPID::kKaon;
  return AliPID::kPion;
    
}
Commit	Line	Data
10d100d4	1	/**************************************************************************
	2	* Copyright(c) 2005-2007, 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	//-----------------------------------------------------------------
	19	// ITS PID method # 1
	20	// Implementation of the ITS PID class
	21	// Very naive one... Should be made better by the detector experts...
	22	// Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
	23	//-----------------------------------------------------------------
	24	#include "TMath.h"
567624b5	25	#include "AliVTrack.h"
10d100d4	26	#include "AliITSPIDResponse.h"
	27	#include "AliITSPidParams.h"
	28	#include "AliExternalTrackParam.h"
	29
10d100d4	30	ClassImp(AliITSPIDResponse)
10d100d4	31
15e979c9	32	AliITSPIDResponse::AliITSPIDResponse(Bool_t isMC):
10d100d4	33	fRes(0.13),
	34	fKp1(15.77),
	35	fKp2(4.95),
	36	fKp3(0.312),
	37	fKp4(2.14),
	38	fKp5(0.82)
	39	{
15e979c9	40	if(!isMC){
	41	fBBtpcits[0]=0.73;
	42	fBBtpcits[1]=14.68;
	43	fBBtpcits[2]=0.905;
	44	fBBtpcits[3]=1.2;
	45	fBBtpcits[4]=6.6;
41cab740	46	fBBdeu[0]=76.43; // parameters for the deuteron - tpcits - value from PbPb 2010 run (S.Trogolo - July 2014)
	47	fBBdeu[1]=-34.21;
	48	fBBdeu[2]=113.2;
	49	fBBdeu[3]=-18.12;
	50	fBBdeu[4]=0.6019;
	51	fBBtri[0]=13.34; // parameters for the triton - tpcits - value from PbPb 2010 run (S.Trogolo - July 2014)
	52	fBBtri[1]=55.17;
	53	fBBtri[2]=66.41;
	54	fBBtri[3]=-6.601;
	55	fBBtri[4]=-0.4134;
62ccfebf	56	fBBsa[0]=2.73198E7; //pure PHOBOS parameterization
88f46717	57	fBBsa[1]=6.92389;
	58	fBBsa[2]=1.90088E-6;
	59	fBBsa[3]=1.90088E-6;
	60	fBBsa[4]=3.40644E-7;
62ccfebf	61	fBBsaHybrid[0]=1.43505E7; //PHOBOS+Polinomial parameterization
	62	fBBsaHybrid[1]=49.3402;
	63	fBBsaHybrid[2]=1.77741E-7;
	64	fBBsaHybrid[3]=1.77741E-7;
	65	fBBsaHybrid[4]=1.01311E-7;
	66	fBBsaHybrid[5]=77.2777;
	67	fBBsaHybrid[6]=33.4099;
	68	fBBsaHybrid[7]=46.0089;
	69	fBBsaHybrid[8]=-2.26583;
	70	fBBsaElectron[0]=4.05799E6; //electrons in the ITS
88f46717	71	fBBsaElectron[1]=38.5713;
	72	fBBsaElectron[2]=1.46462E-7;
	73	fBBsaElectron[3]=1.46462E-7;
	74	fBBsaElectron[4]=4.40284E-7;
8abeb05b	75	fResolSA[0]=1.; // 0 cluster tracks should not be used
88f46717	76	fResolSA[1]=0.25; // rough values for tracks with 1
	77	fResolSA[2]=0.131; // value from pp 2010 run (L. Milano, 16-Jun-11)
	78	fResolSA[3]=0.113; // value from pp 2010 run
8abeb05b	79	fResolSA[4]=0.104; // value from pp 2010 run
15e979c9	80	for(Int_t i=0; i<5;i++) fResolTPCITS[i]=0.13;
41cab740	81	fResolTPCITSDeu3[0]=0.06918; // deuteron resolution vs p
	82	fResolTPCITSDeu3[1]=0.02498; // 3 ITS clusters for PId
	83	fResolTPCITSDeu3[2]=1.1; // value from PbPb 2010 run (July 2014)
	84	fResolTPCITSDeu4[0]=0.06756;// deuteron resolution vs p
	85	fResolTPCITSDeu4[1]=0.02078; // 4 ITS clusters for PId
	86	fResolTPCITSDeu4[2]=1.05; // value from PbPb 2010 run (July 2014)
	87	fResolTPCITSTri3[0]=0.07239; // triton resolution vs p
	88	fResolTPCITSTri3[1]=0.0192; // 3 ITS clusters for PId
	89	fResolTPCITSTri3[2]=1.1; // value from PbPb 2010 run (July 2014)
	90	fResolTPCITSTri4[0]=0.06083; // triton resolution
	91	fResolTPCITSTri4[1]=0.02579; // 4 ITS clusters for PId
	92	fResolTPCITSTri4[2]=1.15; // value from PbPb 2010 run (July 2014)
15e979c9	93	}else{
99daa709	94	fBBtpcits[0]=1.04;
	95	fBBtpcits[1]=27.14;
	96	fBBtpcits[2]=1.00;
	97	fBBtpcits[3]=0.964;
	98	fBBtpcits[4]=2.59;
62ccfebf	99	fBBsa[0]=2.02078E7; //pure PHOBOS parameterization
88f46717	100	fBBsa[1]=14.0724;
	101	fBBsa[2]=3.84454E-7;
	102	fBBsa[3]=3.84454E-7;
	103	fBBsa[4]=2.43913E-7;
62ccfebf	104	fBBsaHybrid[0]=1.05381E7; //PHOBOS+Polinomial parameterization
	105	fBBsaHybrid[1]=89.3933;
	106	fBBsaHybrid[2]=2.4831E-7;
	107	fBBsaHybrid[3]=2.4831E-7;
	108	fBBsaHybrid[4]=7.80591E-8;
	109	fBBsaHybrid[5]=62.9214;
	110	fBBsaHybrid[6]=32.347;
	111	fBBsaHybrid[7]=58.7661;
	112	fBBsaHybrid[8]=-3.39869;
	113	fBBsaElectron[0]=2.26807E6; //electrons in the ITS
88f46717	114	fBBsaElectron[1]=99.985;
	115	fBBsaElectron[2]=0.000714841;
	116	fBBsaElectron[3]=0.000259585;
	117	fBBsaElectron[4]=1.39412E-7;
8abeb05b	118	fResolSA[0]=1.; // 0 cluster tracks should not be used
88f46717	119	fResolSA[1]=0.25; // rough values for tracks with 1
	120	fResolSA[2]=0.126; // value from pp 2010 simulations (L. Milano, 16-Jun-11)
	121	fResolSA[3]=0.109; // value from pp 2010 simulations
	122	fResolSA[4]=0.097; // value from pp 2010 simulations
15e979c9	123	for(Int_t i=0; i<5;i++) fResolTPCITS[i]=0.13;
15e979c9	124	}
10d100d4	125	}
10d100d4	126
56576f1e	127	/*
10d100d4	128	//_________________________________________________________________________
10d100d4	129	AliITSPIDResponse::AliITSPIDResponse(Double_t *param):
9ebbddd4	130	fRes(param[0]),
10d100d4	131	fKp1(15.77),
	132	fKp2(4.95),
	133	fKp3(0.312),
	134	fKp4(2.14),
	135	fKp5(0.82)
	136	{
	137	//
	138	// The main constructor
	139	//
6b4634a4	140	for (Int_t i=0; i<5;i++) {
	141	fBBsa[i]=0.;
	142	fBBtpcits[i]=0.;
	143	fResolSA[i]=0.;
	144	fResolTPCITS[i]=0.;
	145	}
10d100d4	146	}
56576f1e	147	*/
10d100d4	148
8abeb05b	149	//_________________________________________________________________________
15e979c9	150	Double_t AliITSPIDResponse::BetheAleph(Double_t p, Double_t mass) const {
10d100d4	151	//
	152	// returns AliExternalTrackParam::BetheBloch normalized to
	153	// fgMIP at the minimum
	154	//
15e979c9	155
10d100d4	156	Double_t bb=
10d100d4	157	AliExternalTrackParam::BetheBlochAleph(p/mass,fKp1,fKp2,fKp3,fKp4,fKp5);
9ebbddd4	158	return bb;
10d100d4	159	}
10d100d4	160
4bd62e52	161	//_________________________________________________________________________
	162	Double_t AliITSPIDResponse::Bethe(Double_t bg, const Double_t * const par, Bool_t isNuclei) const
	163	{
	164
	165	const Double_t beta = bg/TMath::Sqrt(1.+ bg*bg);
	166	const Double_t gamma=bg/beta;
	167	Double_t bb=1.;
	168
	169	Double_t eff=1.0;
	170	if(bg<par[2])
	171	eff=(bg-par[3])*(bg-par[3])+par[4];
	172	else
	173	eff=(par[2]-par[3])*(par[2]-par[3])+par[4];
	174
	175	if(gamma>=0. && beta>0.){
	176	if(isNuclei){
	177	//Parameterization for deuteron between 0.4 - 1.5 GeV/c; triton between 0.58 - 1.65 GeV/c
	178	bb=par[0] + par[1]/bg + par[2]/(bgbg) + par[3]/(bgbgbg) + par[4]/(bgbgbgbg);
	179	}else{ //Parameterization for pion, kaon, proton, electron
	180	bb=(par[1]+2.0TMath::Log(gamma)-betabeta)(par[0]/(betabeta))*eff;
	181	}
	182	}
	183
	184	return bb;
	185	}
	186
8abeb05b	187	//_________________________________________________________________________
bb40433d	188	Double_t AliITSPIDResponse::Bethe(Double_t p, Double_t mass, Bool_t isSA) const {
	189
	190	//OLD - Mantained for backward compatibility
	191	//from the mass check --> Set the Particle Type
	192	//at the end use the method Bethe(Double_t p, AliPID::EParticleType species, Bool_t isSA) const to set the right parameter
41cab740	193
15e979c9	194	//
	195	// returns AliExternalTrackParam::BetheBloch normalized to
	196	// fgMIP at the minimum
	197	//
	198
41cab740	199	// NEW: Parameterization for Deuteron and Triton energy loss, reproduced with a polynomial in fixed p range
	200	// fBBdeu --> parameters for deuteron
	201	// fBBtri --> parameters for triton
	202
4bd62e52	203	//NOTE
	204	//NOTE: if changes are made here, please also check the alternative function below
	205	//NOTE
bb40433d	206
	207	AliPID::EParticleType species = AliPID::kPion;
	208
41cab740	209	if(TMath::AreEqualAbs(mass,AliPID::ParticleMass(0),0.00001)){
88f46717	210	//if is an electron use a specific BB parameterization
88f46717	211	//To be used only between 100 and 160 MeV/c
bb40433d	212	species=AliPID::kElectron;
88f46717	213	}
41cab740	214
bb40433d	215	if(TMath::AreEqualAbs(mass,AliPID::ParticleMass(5),0.002)) species=AliPID::kDeuteron;
	216	if(TMath::AreEqualAbs(mass,AliPID::ParticleMass(6),0.001)) species=AliPID::kTriton;
	217
	218	return Bethe(p,species,isSA);
4bd62e52	219	}
	220
	221	//_________________________________________________________________________
	222	Double_t AliITSPIDResponse::Bethe(Double_t p, AliPID::EParticleType species, Bool_t isSA) const
	223	{
bb40433d	224	// NEW - to be used
bb40433d	225	// Alternative bethe function assuming a particle type not a mass
4bd62e52	226	// should be slightly faster
	227	//
	228
	229	const Double_t m=AliPID::ParticleMassZ(species);
	230	const Double_t bg=p/m;
	231	Bool_t isNuclei=kFALSE;
88f46717	232
4bd62e52	233	//NOTE
	234	//NOTE: if changes are made here, please also check the alternative function above
	235	//NOTE
	236	const Double_t *par=fBBtpcits;
	237	if(isSA){
	238	if(species == AliPID::kElectron){
	239	//if is an electron use a specific BB parameterization
	240	//To be used only between 100 and 160 MeV/c
	241	par=fBBsaElectron;
	242	}else{
	243	par=fBBsa;
	244	}
	245	}else{
	246	if(species == AliPID::kDeuteron) {
	247	par=fBBdeu;
	248	isNuclei=kTRUE;
	249	}
	250	if(species == AliPID::kTriton ) {
	251	par=fBBtri;
	252	isNuclei=kTRUE;
41cab740	253	}
15e979c9	254	}
41cab740	255
4bd62e52	256	return Bethe(bg, par, isNuclei);
15e979c9	257	}
15e979c9	258
62ccfebf	259	//_________________________________________________________________________
	260	Double_t AliITSPIDResponse::BetheITSsaHybrid(Double_t p, Double_t mass) const {
	261	//
	262	// returns AliExternalTrackParam::BetheBloch normalized to
	263	// fgMIP at the minimum. The PHOBOS parameterization is used for beta*gamma>0.76.
	264	// For beta*gamma<0.76 a polinomial function is used
	265
	266	Double_t bg=p/mass;
	267	Double_t beta = bg/TMath::Sqrt(1.+ bg*bg);
	268	Double_t gamma=bg/beta;
	269	Double_t bb=1.;
	270
	271	Double_t par[9];
	272	//parameters for pi, K, p
	273	for(Int_t ip=0; ip<9;ip++) par[ip]=fBBsaHybrid[ip];
	274	//if it is an electron the PHOBOS part of the parameterization is tuned for e
	275	//in the range used for identification beta*gamma is >0.76 for electrons
	276	//To be used only between 100 and 160 MeV/c
	277	if(mass>0.0005 && mass<0.00052)for(Int_t ip=0; ip<5;ip++) par[ip]=fBBsaElectron[ip];
	278
	279	if(gamma>=0. && beta>0. && bg>0.1){
	280	if(bg>0.76){//PHOBOS
	281	Double_t eff=1.0;
	282	if(bg<par[2])
	283	eff=(bg-par[3])*(bg-par[3])+par[4];
	284	else
	285	eff=(par[2]-par[3])*(par[2]-par[3])+par[4];
	286
	287	bb=(par[1]+2.0TMath::Log(gamma)-betabeta)(par[0]/(betabeta))*eff;
	288	}else{//Polinomial
	289	bb=par[5] + par[6]/bg + par[7]/(bgbg) + par[8]/(bgbg*bg);
	290	}
	291	}
	292	return bb;
	293	}
	294
8abeb05b	295	//_________________________________________________________________________
41cab740	296	Double_t AliITSPIDResponse::GetResolution(Double_t bethe,
15e979c9	297	Int_t nPtsForPid,
41cab740	298	Bool_t isSA,
	299	Double_t p,
	300	AliPID::EParticleType type) const {
	301	//
10d100d4	302	// Calculate expected resolution for truncated mean
10d100d4	303	//
41cab740	304	// NEW: Added new variables which are Double_t p and AliPID::EParticleType type
	305	// AliPID::EParticleType type is used to set the correct resolution for the different particles
	306	// default -> AliPID::EParticleType type = AliPID::kPion
	307	// Double_t p is used for the resolution of deuteron and triton, because they are function of the momentum
	308	// default -> Double_t p=0.
	309
4bd62e52	310	Float_t r=0.f;
4bd62e52	311	Double_t c=1.; //this is a correction factor used for the nuclei resolution, while for pion/kaon/proton/electron is 1.
41cab740	312
15e979c9	313	if(isSA) r=fResolSA[nPtsForPid];
41cab740	314	else{
4bd62e52	315	const Double_t *par=0x0;
	316	if(type==AliPID::kDeuteron){
	317	if(nPtsForPid==3) par = fResolTPCITSDeu3;
	318	if(nPtsForPid==4) par = fResolTPCITSDeu4;
	319	c=par[2];
	320	r=par[0]+par[1]*p;
	321	} else if(type==AliPID::kTriton){
	322	if(nPtsForPid==3) par = fResolTPCITSTri3;
	323	if(nPtsForPid==4) par = fResolTPCITSTri4;
	324	c=par[2];
41cab740	325	r=par[0]+par[1]*p;
4bd62e52	326	} else{
4bd62e52	327	r=fResolTPCITS[nPtsForPid];
41cab740	328	}
41cab740	329	}
15e979c9	330
41cab740	331	return rbethec;
41cab740	332	}
15e979c9	333
15e979c9	334
8abeb05b	335	//_________________________________________________________________________
b52bfc67	336	void AliITSPIDResponse::GetITSProbabilities(Float_t mom, Double_t qclu[4], Double_t condprobfun[AliPID::kSPECIES], Bool_t isMC) const {
10d100d4	337	//
	338	// Method to calculate PID probabilities for a single track
	339	// using the likelihood method
	340	//
	341	const Int_t nLay = 4;
2ca1f4ee	342	const Int_t nPart= 4;
10d100d4	343
b52bfc67	344	static AliITSPidParams pars(isMC); // Pid parametrisation parameters
10d100d4	345
2ca1f4ee	346	Double_t itsProb[nPart] = {1,1,1,1}; // e, p, K, pi
10d100d4	347
10d100d4	348	for (Int_t iLay = 0; iLay < nLay; iLay++) {
2ca1f4ee	349	if (qclu[iLay] <= 50.)
10d100d4	350	continue;
	351
	352	Float_t dedx = qclu[iLay];
	353	Float_t layProb = pars.GetLandauGausNorm(dedx,AliPID::kProton,mom,iLay+3);
	354	itsProb[0] *= layProb;
	355
	356	layProb = pars.GetLandauGausNorm(dedx,AliPID::kKaon,mom,iLay+3);
10d100d4	357	itsProb[1] *= layProb;
	358
	359	layProb = pars.GetLandauGausNorm(dedx,AliPID::kPion,mom,iLay+3);
	360	itsProb[2] *= layProb;
2ca1f4ee	361
	362	layProb = pars.GetLandauGausNorm(dedx,AliPID::kElectron,mom,iLay+3);
	363	itsProb[3] *= layProb;
10d100d4	364	}
	365
	366	// Normalise probabilities
	367	Double_t sumProb = 0;
	368	for (Int_t iPart = 0; iPart < nPart; iPart++) {
	369	sumProb += itsProb[iPart];
	370	}
2ca1f4ee	371	sumProb += itsProb[2]; // muon cannot be distinguished from pions
10d100d4	372
	373	for (Int_t iPart = 0; iPart < nPart; iPart++) {
	374	itsProb[iPart]/=sumProb;
	375	}
2ca1f4ee	376	condprobfun[AliPID::kElectron] = itsProb[3];
897a0e31	377	condprobfun[AliPID::kMuon] = itsProb[2];
897a0e31	378	condprobfun[AliPID::kPion] = itsProb[2];
10d100d4	379	condprobfun[AliPID::kKaon] = itsProb[1];
	380	condprobfun[AliPID::kProton] = itsProb[0];
	381	return;
	382	}
15e979c9	383
567624b5	384	//_________________________________________________________________________
	385	Double_t AliITSPIDResponse::GetNumberOfSigmas( const AliVTrack* track, AliPID::EParticleType type) const
	386	{
	387	//
	388	// number of sigmas
	389	//
	390	UChar_t clumap=track->GetITSClusterMap();
	391	Int_t nPointsForPid=0;
	392	for(Int_t i=2; i<6; i++){
	393	if(clumap&(1<<i)) ++nPointsForPid;
	394	}
	395	Float_t mom=track->P();
bb40433d	396
567624b5	397	//check for ITS standalone tracks
	398	Bool_t isSA=kTRUE;
	399	if( track->GetStatus() & AliVTrack::kTPCin ) isSA=kFALSE;
	400
	401	const Float_t dEdx=track->GetITSsignal();
	402
	403	//TODO: in case of the electron, use the SA parametrisation,
	404	// this needs to be changed if ITS provides a parametrisation
	405	// for electrons also for ITS+TPC tracks
	406	return GetNumberOfSigmas(mom,dEdx,type,nPointsForPid,isSA \|\| (type==AliPID::kElectron));
	407	}
	408
	409	//_________________________________________________________________________
1d59271b	410	Double_t AliITSPIDResponse::GetSignalDelta( const AliVTrack* track, AliPID::EParticleType type, Bool_t ratio/=kFALSE/) const
567624b5	411	{
	412	//
	413	// Signal - expected
	414	//
	415	const Float_t mom=track->P();
	416	const Double_t chargeFactor = TMath::Power(AliPID::ParticleCharge(type),2.);
	417	Bool_t isSA=kTRUE;
	418	if( track->GetStatus() & AliVTrack::kTPCin ) isSA=kFALSE;
	419
	420	const Float_t dEdx=track->GetITSsignal();
	421
	422	//TODO: in case of the electron, use the SA parametrisation,
	423	// this needs to be changed if ITS provides a parametrisation
	424	// for electrons also for ITS+TPC tracks
	425
1d59271b	426	const Float_t bethe = Bethe(mom,AliPID::ParticleMassZ(type), isSA \|\| (type==AliPID::kElectron))*chargeFactor;
	427
	428	Double_t delta=-9999.;
	429	if (!ratio) delta=dEdx-bethe;
	430	else if (bethe>1.e-20) delta=dEdx/bethe;
	431
	432	return delta;
567624b5	433	}
567624b5	434
8abeb05b	435	//_________________________________________________________________________
	436	Int_t AliITSPIDResponse::GetParticleIdFromdEdxVsP(Float_t mom, Float_t signal, Bool_t isSA) const{
	437	// method to get particle identity with simple cuts on dE/dx vs. momentum
	438
	439	Double_t massp=AliPID::ParticleMass(AliPID::kProton);
	440	Double_t massk=AliPID::ParticleMass(AliPID::kKaon);
	441	Double_t bethep=Bethe(mom,massp,isSA);
	442	Double_t bethek=Bethe(mom,massk,isSA);
	443	if(signal>(0.5*(bethep+bethek))) return AliPID::kProton;
	444	Double_t masspi=AliPID::ParticleMass(AliPID::kPion);
	445	Double_t bethepi=Bethe(mom,masspi,isSA);
	446	if(signal>(0.5*(bethepi+bethek))) return AliPID::kKaon;
	447	return AliPID::kPion;
	448
	449	}