* add tuned on data functionality for TOF (non-gaussian tails)

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

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//-----------------------------------------------------------------//
//                                                                 //
//           Implementation of the TOF PID class                   //
//      Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch         //
//                                                                 //
//-----------------------------------------------------------------//

#include "TMath.h"
#include "AliLog.h"
#include "TF1.h"

#include "AliTOFPIDResponse.h"

ClassImp(AliTOFPIDResponse)

TF1 *AliTOFPIDResponse::fTOFtailResponse = NULL; // function to generate a TOF tail

//_________________________________________________________________________
AliTOFPIDResponse::AliTOFPIDResponse(): 
  fSigma(0),
  fPmax(0),         // zero at 0.5 GeV/c for pp
  fTime0(0)
{
  fPar[0] = 0.008;
  fPar[1] = 0.008;
  fPar[2] = 0.002;
  fPar[3] = 40.0;

  if(!fTOFtailResponse){
    fTOFtailResponse = new TF1("fTOFtail","[0]*TMath::Exp(-(x-[1])*(x-[1])/2/[2]/[2])* (x < [1]+[3]*[2]) + (x > [1]+[3]*[2])*[0]*TMath::Exp(-(x-[1]-[3]*[2]*0.5)*[3]/[2] * 0.0111)*0.01818",-1000,1000);
    fTOFtailResponse->SetParameter(0,1);
    fTOFtailResponse->SetParameter(1,-25);
    fTOFtailResponse->SetParameter(2,1);
    fTOFtailResponse->SetParameter(3,1.1);
    fTOFtailResponse->SetNpx(10000);
  }
    

  // Reset T0 info
  ResetT0info();
  SetMomBoundary();
}
//_________________________________________________________________________
AliTOFPIDResponse::AliTOFPIDResponse(Double_t *param):
  fSigma(param[0]),
  fPmax(0),          // zero at 0.5 GeV/c for pp
  fTime0(0)
{
  //
  //  The main constructor
  //
  //

  //fPmax=TMath::Exp(-0.5*3*3)/fSigma; // ~3 sigma at 0.5 GeV/c for PbPb 

  fPar[0] = 0.008;
  fPar[1] = 0.008;
  fPar[2] = 0.002;
  fPar[3] = 40.0;

  // Reset T0 info
  ResetT0info();
  SetMomBoundary();
}
//_________________________________________________________________________
Double_t 
AliTOFPIDResponse::GetMismatchProbability(Double_t p, Double_t mass) const {
  //
  // Returns the probability of mismatching 
  // assuming 1/(p*beta)^2 scaling
  //
  const Double_t km=0.5;                   // "reference" momentum (GeV/c)

  Double_t ref2=km*km*km*km/(km*km + mass*mass);// "reference" (p*beta)^2
  Double_t p2beta2=p*p*p*p/(p*p + mass*mass);

  return fPmax*ref2/p2beta2;
}
//_________________________________________________________________________
Double_t AliTOFPIDResponse::GetExpectedSigma(Float_t mom, Float_t time, Float_t mass) const {
  //
  // Return the expected sigma of the PID signal for the specified
  // particle mass/Z.
  // If the operation is not possible, return a negative value.
  //

  Double_t dpp=fPar[0] + fPar[1]*mom + fPar[2]*mass/mom;      //mean relative pt resolution;

 
  Double_t sigma = dpp*time/(1.+ mom*mom/(mass*mass));
  
  Int_t index = GetMomBin(mom);

  Double_t t0res = fT0resolution[index];

  return TMath::Sqrt(sigma*sigma + fPar[3]*fPar[3]/mom/mom + fSigma*fSigma + t0res*t0res);

}
//_________________________________________________________________________
Double_t AliTOFPIDResponse::GetExpectedSigma(Float_t mom, Float_t time, AliPID::EParticleType  type) const {
  //
  // Return the expected sigma of the PID signal for the specified
  // particle type.
  // If the operation is not possible, return a negative value.
  //
  
  Double_t mass = AliPID::ParticleMassZ(type);
  Double_t dpp=fPar[0] + fPar[1]*mom + fPar[2]*mass/mom;      //mean relative pt resolution;

 
  Double_t sigma = dpp*time/(1.+ mom*mom/(mass*mass));
  
  Int_t index = GetMomBin(mom);

  Double_t t0res = fT0resolution[index];

  return TMath::Sqrt(sigma*sigma + fPar[3]*fPar[3]/mom/mom + fSigma*fSigma + t0res*t0res);

}
//_________________________________________________________________________
Double_t AliTOFPIDResponse::GetExpectedSignal(const AliVTrack* track,AliPID::EParticleType type) const {
  //
  // Return the expected signal of the PID signal for the particle type
  // If the operation is not possible, return a negative value.
  //
  Double_t expt[5];
  track->GetIntegratedTimes(expt);
  if (type<=AliPID::kProton) return expt[type];
  else {
    Double_t p = track->P();
    Double_t massZ = AliPID::ParticleMassZ(type);
    return expt[0]/p*massZ*TMath::Sqrt(1.+p*p/massZ/massZ);
  }
}
//_________________________________________________________________________
Int_t AliTOFPIDResponse::GetMomBin(Float_t p) const{
  //
  // Returns the momentum bin index
  //

  Int_t i=0;
  while(p > fPCutMin[i] && i < fNmomBins) i++;
  if(i > 0) i--;

  return i;
}
//_________________________________________________________________________
void AliTOFPIDResponse::SetMomBoundary(){
  //
  // Set boundaries for momentum bins
  //

  fPCutMin[0] = 0.3;
  fPCutMin[1] = 0.5;
  fPCutMin[2] = 0.6;
  fPCutMin[3] = 0.7;
  fPCutMin[4] = 0.8;
  fPCutMin[5] = 0.9;
  fPCutMin[6] = 1;
  fPCutMin[7] = 1.2;
  fPCutMin[8] = 1.5;
  fPCutMin[9] = 2;
  fPCutMin[10] = 3;  
}
//_________________________________________________________________________
Float_t AliTOFPIDResponse::GetStartTime(Float_t mom) const {
  //
  // Returns event_time value as estimated by TOF combinatorial algorithm
  //

  Int_t ibin = GetMomBin(mom);
  return GetT0bin(ibin);

}
//_________________________________________________________________________
Float_t AliTOFPIDResponse::GetStartTimeRes(Float_t mom) const {
  //
  // Returns event_time resolution as estimated by TOF combinatorial algorithm
  //

  Int_t ibin = GetMomBin(mom);
  return GetT0binRes(ibin);

}
//_________________________________________________________________________
Int_t AliTOFPIDResponse::GetStartTimeMask(Float_t mom) const {
  //
  // Returns event_time mask
  //

  Int_t ibin = GetMomBin(mom);
  return GetT0binMask(ibin);

}
//_________________________________________________________________________
Double_t AliTOFPIDResponse::GetTailRandomValue() const // generate a random value to add a tail to TOF time (for MC analyses)
{
  if(fTOFtailResponse)
    return fTOFtailResponse->GetRandom();
  else
    return 0.0;
}