1 /**************************************************************************
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4 * Author: The ALICE Off-line Project. *
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14 **************************************************************************/
16 //-----------------------------------------------------------------//
18 // Implementation of the TOF PID class //
19 // Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch //
21 //-----------------------------------------------------------------//
26 #include "AliTOFPIDResponse.h"
28 ClassImp(AliTOFPIDResponse)
30 //_________________________________________________________________________
31 AliTOFPIDResponse::AliTOFPIDResponse():
33 fPmax(0), // zero at 0.5 GeV/c for pp
37 //_________________________________________________________________________
38 AliTOFPIDResponse::AliTOFPIDResponse(Double_t *param):
40 fPmax(0), // zero at 0.5 GeV/c for pp
44 // The main constructor
48 //fPmax=TMath::Exp(-0.5*3*3)/fSigma; // ~3 sigma at 0.5 GeV/c for PbPb
50 //_________________________________________________________________________
52 AliTOFPIDResponse::GetMismatchProbability(Double_t p, Double_t mass) const {
54 // Returns the probability of mismatching
55 // assuming 1/(p*beta)^2 scaling
57 const Double_t km=0.5; // "reference" momentum (GeV/c)
59 Double_t ref2=km*km*km*km/(km*km + mass*mass);// "reference" (p*beta)^2
60 Double_t p2beta2=p*p*p*p/(p*p + mass*mass);
62 return fPmax*ref2/p2beta2;
64 //_________________________________________________________________________
65 Double_t AliTOFPIDResponse::GetExpectedSigma(Float_t mom, Float_t time, Float_t mass) const {
67 // Return the expected sigma of the PID signal for the specified
69 // If the operation is not possible, return a negative value.
72 Double_t dpp = 0.01; //mean relative pt resolution;
73 if (mom>0.5) dpp = 0.01*mom;
76 Double_t sigma = dpp*time/(1.+ mom*mom/(mass*mass));
78 return TMath::Sqrt(sigma*sigma + fSigma*fSigma);