1 /**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
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 **************************************************************************/
16 //-----------------------------------------------------------------
17 // Implementation of the TPC PID class
18 // Very naive one... Should be made better by the detector experts...
19 // Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
20 // With many additions and modifications suggested by
21 // Alexander Kalweit, GSI, alexander.philipp.kalweit@cern.ch
22 // Dariusz Miskowiec, GSI, D.Miskowiec@gsi.de
23 //-----------------------------------------------------------------
25 #include "AliTPCPIDResponse.h"
26 #include "AliExternalTrackParam.h"
28 ClassImp(AliTPCPIDResponse)
30 //_________________________________________________________________________
31 AliTPCPIDResponse::AliTPCPIDResponse():
42 // The default constructor
46 //_________________________________________________________________________
47 AliTPCPIDResponse::AliTPCPIDResponse(Double_t *param):
58 // The main constructor
62 Double_t AliTPCPIDResponse::Bethe(Double_t betaGamma) const {
64 // This is the Bethe-Bloch function normalised to 1 at the minimum
66 // Simulated and reconstructed Bethe-Bloch differs
67 // Simulated curve is the dNprim/dx
68 // Reconstructed is proportianal dNtot/dx
69 // Temporary fix for production - Simple linear correction function
70 // Future 2 Bethe Bloch formulas needed
72 // 2. for reconstructed PID
74 // const Float_t kmeanCorrection =0.1;
76 AliExternalTrackParam::BetheBlochAleph(betaGamma,fKp1,fKp2,fKp3,fKp4,fKp5);
80 //_________________________________________________________________________
81 void AliTPCPIDResponse::SetBetheBlochParameters(Double_t kp1,
87 // Set the parameters of the ALEPH Bethe-Bloch formula
95 //_________________________________________________________________________
96 void AliTPCPIDResponse::SetSigma(Float_t res0, Float_t resN2) {
98 // Set the relative resolution sigma_rel = res0 * sqrt(1+resN2/npoint)
104 //_________________________________________________________________________
105 Double_t AliTPCPIDResponse::GetExpectedSignal(const Float_t mom,
106 AliPID::EParticleType n) const {
108 // Calculates the expected PID signal as the function of
109 // the information stored in the track, for the specified particle type
111 // At the moment, these signals are just the results of calling the
112 // Bethe-Bloch formula.
113 // This can be improved. By taking into account the number of
114 // assigned clusters and/or the track dip angle, for example.
117 Double_t mass=AliPID::ParticleMass(n);
118 return Bethe(mom/mass);
121 //_________________________________________________________________________
122 Double_t AliTPCPIDResponse::GetExpectedSigma(const Float_t mom,
124 AliPID::EParticleType n) const {
126 // Calculates the expected sigma of the PID signal as the function of
127 // the information stored in the track, for the specified particle type
132 return GetExpectedSignal(mom,n)*fRes0*sqrt(1. + fResN2/nPoints);
134 return GetExpectedSignal(mom,n)*fRes0;