[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 "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;
    fBBsa[0]=2.73198E7;
    fBBsa[1]=6.92389;
    fBBsa[2]=1.90088E-6;
    fBBsa[3]=1.90088E-6;
    fBBsa[4]=3.40644E-7;
    fBBsaElectron[0]=4.05799E6;
    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;
  }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;
    fBBsa[1]=14.0724;
    fBBsa[2]=3.84454E-7;
    fBBsa[3]=3.84454E-7;
    fBBsa[4]=2.43913E-7;
    fBBsaElectron[0]=2.26807E6;
    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 p, Double_t mass, Bool_t isSA) const {
  //
  // returns AliExternalTrackParam::BetheBloch normalized to 
  // fgMIP at the minimum
  //

  Double_t bg=p/mass;
  Double_t beta = bg/TMath::Sqrt(1.+ bg*bg);
  Double_t gamma=bg/beta;
  Double_t par[5];
  if(isSA){
    if(mass>0.0005 && mass<0.00052){
      //if is an electron use a specific BB parameterization
      //To be used only between 100 and 160 MeV/c
      for(Int_t ip=0; ip<5;ip++) par[ip]=fBBsaElectron[ip];
    }else{
      for(Int_t ip=0; ip<5;ip++) par[ip]=fBBsa[ip];
    }
  }else{
    for(Int_t ip=0; ip<5;ip++) par[ip]=fBBtpcits[ip];
  }
  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];
  
  Double_t bb=0.;
  if(gamma>=0. && beta>0.){
    bb=(par[1]+2.0*TMath::Log(gamma)-beta*beta)*(par[0]/(beta*beta))*eff;
  }
  return bb;
}

//_________________________________________________________________________
Double_t AliITSPIDResponse::GetResolution(Double_t bethe, 
					  Int_t nPtsForPid, 
					  Bool_t isSA) const {
  // 
  // Calculate expected resolution for truncated mean
  //
  Float_t r;
  if(isSA) r=fResolSA[nPtsForPid];
  else r=fResolTPCITS[nPtsForPid];
  return r*bethe;
}


//_________________________________________________________________________
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 = 3;

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

  for (Int_t iLay = 0; iLay < nLay; iLay++) {
    if (qclu[iLay] <= 0)
      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);
    if (mom < 0.16) layProb=0.00001;
    itsProb[1] *= layProb;
    
    layProb = pars.GetLandauGausNorm(dedx,AliPID::kPion,mom,iLay+3);
    itsProb[2] *= layProb;
  }

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

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

//_________________________________________________________________________
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"
	25	#include "AliITSPIDResponse.h"
	26	#include "AliITSPidParams.h"
	27	#include "AliExternalTrackParam.h"
	28
10d100d4	29	ClassImp(AliITSPIDResponse)
10d100d4	30
15e979c9	31	AliITSPIDResponse::AliITSPIDResponse(Bool_t isMC):
10d100d4	32	fRes(0.13),
	33	fKp1(15.77),
	34	fKp2(4.95),
	35	fKp3(0.312),
	36	fKp4(2.14),
	37	fKp5(0.82)
	38	{
15e979c9	39	if(!isMC){
	40	fBBtpcits[0]=0.73;
	41	fBBtpcits[1]=14.68;
	42	fBBtpcits[2]=0.905;
	43	fBBtpcits[3]=1.2;
	44	fBBtpcits[4]=6.6;
88f46717	45	fBBsa[0]=2.73198E7;
	46	fBBsa[1]=6.92389;
	47	fBBsa[2]=1.90088E-6;
	48	fBBsa[3]=1.90088E-6;
	49	fBBsa[4]=3.40644E-7;
	50	fBBsaElectron[0]=4.05799E6;
	51	fBBsaElectron[1]=38.5713;
	52	fBBsaElectron[2]=1.46462E-7;
	53	fBBsaElectron[3]=1.46462E-7;
	54	fBBsaElectron[4]=4.40284E-7;
8abeb05b	55	fResolSA[0]=1.; // 0 cluster tracks should not be used
88f46717	56	fResolSA[1]=0.25; // rough values for tracks with 1
	57	fResolSA[2]=0.131; // value from pp 2010 run (L. Milano, 16-Jun-11)
	58	fResolSA[3]=0.113; // value from pp 2010 run
8abeb05b	59	fResolSA[4]=0.104; // value from pp 2010 run
15e979c9	60	for(Int_t i=0; i<5;i++) fResolTPCITS[i]=0.13;
15e979c9	61	}else{
99daa709	62	fBBtpcits[0]=1.04;
	63	fBBtpcits[1]=27.14;
	64	fBBtpcits[2]=1.00;
	65	fBBtpcits[3]=0.964;
	66	fBBtpcits[4]=2.59;
88f46717	67	fBBsa[0]=2.02078E7;
	68	fBBsa[1]=14.0724;
	69	fBBsa[2]=3.84454E-7;
	70	fBBsa[3]=3.84454E-7;
	71	fBBsa[4]=2.43913E-7;
	72	fBBsaElectron[0]=2.26807E6;
	73	fBBsaElectron[1]=99.985;
	74	fBBsaElectron[2]=0.000714841;
	75	fBBsaElectron[3]=0.000259585;
	76	fBBsaElectron[4]=1.39412E-7;
8abeb05b	77	fResolSA[0]=1.; // 0 cluster tracks should not be used
88f46717	78	fResolSA[1]=0.25; // rough values for tracks with 1
	79	fResolSA[2]=0.126; // value from pp 2010 simulations (L. Milano, 16-Jun-11)
	80	fResolSA[3]=0.109; // value from pp 2010 simulations
	81	fResolSA[4]=0.097; // value from pp 2010 simulations
15e979c9	82	for(Int_t i=0; i<5;i++) fResolTPCITS[i]=0.13;
15e979c9	83	}
10d100d4	84	}
10d100d4	85
56576f1e	86	/*
10d100d4	87	//_________________________________________________________________________
10d100d4	88	AliITSPIDResponse::AliITSPIDResponse(Double_t *param):
9ebbddd4	89	fRes(param[0]),
10d100d4	90	fKp1(15.77),
	91	fKp2(4.95),
	92	fKp3(0.312),
	93	fKp4(2.14),
	94	fKp5(0.82)
	95	{
	96	//
	97	// The main constructor
	98	//
6b4634a4	99	for (Int_t i=0; i<5;i++) {
	100	fBBsa[i]=0.;
	101	fBBtpcits[i]=0.;
	102	fResolSA[i]=0.;
	103	fResolTPCITS[i]=0.;
	104	}
10d100d4	105	}
56576f1e	106	*/
10d100d4	107
8abeb05b	108	//_________________________________________________________________________
15e979c9	109	Double_t AliITSPIDResponse::BetheAleph(Double_t p, Double_t mass) const {
10d100d4	110	//
	111	// returns AliExternalTrackParam::BetheBloch normalized to
	112	// fgMIP at the minimum
	113	//
15e979c9	114
10d100d4	115	Double_t bb=
10d100d4	116	AliExternalTrackParam::BetheBlochAleph(p/mass,fKp1,fKp2,fKp3,fKp4,fKp5);
9ebbddd4	117	return bb;
10d100d4	118	}
10d100d4	119
8abeb05b	120	//_________________________________________________________________________
15e979c9	121	Double_t AliITSPIDResponse::Bethe(Double_t p, Double_t mass, Bool_t isSA) const {
	122	//
	123	// returns AliExternalTrackParam::BetheBloch normalized to
	124	// fgMIP at the minimum
	125	//
	126
	127	Double_t bg=p/mass;
	128	Double_t beta = bg/TMath::Sqrt(1.+ bg*bg);
	129	Double_t gamma=bg/beta;
	130	Double_t par[5];
	131	if(isSA){
88f46717	132	if(mass>0.0005 && mass<0.00052){
	133	//if is an electron use a specific BB parameterization
	134	//To be used only between 100 and 160 MeV/c
	135	for(Int_t ip=0; ip<5;ip++) par[ip]=fBBsaElectron[ip];
	136	}else{
	137	for(Int_t ip=0; ip<5;ip++) par[ip]=fBBsa[ip];
	138	}
15e979c9	139	}else{
	140	for(Int_t ip=0; ip<5;ip++) par[ip]=fBBtpcits[ip];
	141	}
	142	Double_t eff=1.0;
	143	if(bg<par[2])
	144	eff=(bg-par[3])*(bg-par[3])+par[4];
	145	else
	146	eff=(par[2]-par[3])*(par[2]-par[3])+par[4];
88f46717	147
15e979c9	148	Double_t bb=0.;
	149	if(gamma>=0. && beta>0.){
	150	bb=(par[1]+2.0TMath::Log(gamma)-betabeta)(par[0]/(betabeta))*eff;
	151	}
	152	return bb;
	153	}
	154
8abeb05b	155	//_________________________________________________________________________
15e979c9	156	Double_t AliITSPIDResponse::GetResolution(Double_t bethe,
	157	Int_t nPtsForPid,
	158	Bool_t isSA) const {
10d100d4	159	//
	160	// Calculate expected resolution for truncated mean
	161	//
15e979c9	162	Float_t r;
	163	if(isSA) r=fResolSA[nPtsForPid];
	164	else r=fResolTPCITS[nPtsForPid];
	165	return r*bethe;
10d100d4	166	}
10d100d4	167
15e979c9	168
	169
	170
8abeb05b	171	//_________________________________________________________________________
b52bfc67	172	void AliITSPIDResponse::GetITSProbabilities(Float_t mom, Double_t qclu[4], Double_t condprobfun[AliPID::kSPECIES], Bool_t isMC) const {
10d100d4	173	//
	174	// Method to calculate PID probabilities for a single track
	175	// using the likelihood method
	176	//
	177	const Int_t nLay = 4;
	178	const Int_t nPart = 3;
	179
b52bfc67	180	static AliITSPidParams pars(isMC); // Pid parametrisation parameters
10d100d4	181
	182	Double_t itsProb[nPart] = {1,1,1}; // p, K, pi
	183
	184	for (Int_t iLay = 0; iLay < nLay; iLay++) {
	185	if (qclu[iLay] <= 0)
	186	continue;
	187
	188	Float_t dedx = qclu[iLay];
	189	Float_t layProb = pars.GetLandauGausNorm(dedx,AliPID::kProton,mom,iLay+3);
	190	itsProb[0] *= layProb;
	191
	192	layProb = pars.GetLandauGausNorm(dedx,AliPID::kKaon,mom,iLay+3);
	193	if (mom < 0.16) layProb=0.00001;
	194	itsProb[1] *= layProb;
	195
	196	layProb = pars.GetLandauGausNorm(dedx,AliPID::kPion,mom,iLay+3);
	197	itsProb[2] *= layProb;
	198	}
	199
	200	// Normalise probabilities
	201	Double_t sumProb = 0;
	202	for (Int_t iPart = 0; iPart < nPart; iPart++) {
	203	sumProb += itsProb[iPart];
	204	}
897a0e31	205	sumProb += 2*itsProb[2]; // muon and electron cannot be distinguished from pions
10d100d4	206
	207	for (Int_t iPart = 0; iPart < nPart; iPart++) {
	208	itsProb[iPart]/=sumProb;
	209	}
	210
897a0e31	211	condprobfun[AliPID::kElectron] = itsProb[2];
	212	condprobfun[AliPID::kMuon] = itsProb[2];
	213	condprobfun[AliPID::kPion] = itsProb[2];
10d100d4	214	condprobfun[AliPID::kKaon] = itsProb[1];
	215	condprobfun[AliPID::kProton] = itsProb[0];
	216	return;
	217	}
15e979c9	218
8abeb05b	219	//_________________________________________________________________________
	220	Int_t AliITSPIDResponse::GetParticleIdFromdEdxVsP(Float_t mom, Float_t signal, Bool_t isSA) const{
	221	// method to get particle identity with simple cuts on dE/dx vs. momentum
	222
	223	Double_t massp=AliPID::ParticleMass(AliPID::kProton);
	224	Double_t massk=AliPID::ParticleMass(AliPID::kKaon);
	225	Double_t bethep=Bethe(mom,massp,isSA);
	226	Double_t bethek=Bethe(mom,massk,isSA);
	227	if(signal>(0.5*(bethep+bethek))) return AliPID::kProton;
	228	Double_t masspi=AliPID::ParticleMass(AliPID::kPion);
	229	Double_t bethepi=Bethe(mom,masspi,isSA);
	230	if(signal>(0.5*(bethepi+bethek))) return AliPID::kKaon;
	231	return AliPID::kPion;
	232
	233	}