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. *
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8 * documentation strictly for non-commercial purposes is hereby granted *
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14 **************************************************************************/
16 //-----------------------------------------------------------------
17 // Implementation of the ITS PID class
18 // Very naive one... Should be made better by the detector experts...
19 // Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
20 //-----------------------------------------------------------------
24 #include "AliITSpidESD.h"
25 #include "AliESDtrack.h"
27 ClassImp(AliITSpidESD)
30 //______________________________________________________________________
31 AliITSpidESD::AliITSpidESD():TObject(){
36 Double_t AliITSpidESD::Bethe(Double_t p,Double_t mass) {
38 Double_t mom=p*1000;//MeV
39 Double_t Mass=mass*1000;//Mev
40 Float_t dens =2.33; //g cm-3
41 Double_t K=0.307075;//MeVcm^2/g
42 Double_t ZovA=0.49848;
43 Double_t me=0.511;//MeV/c^2
44 Double_t I=173./1000000.;//MeV
45 Double_t En=TMath::Sqrt(mom*mom+Mass*Mass);//MeV
46 Double_t gamma=En/Mass;
48 Double_t Tmax=2*me*beta*beta*gamma*gamma/(1+2*gamma*me/Mass+(me/Mass)*(me/Mass));
49 Double_t deltaover2=28.816*1e-6*TMath::Sqrt(dens*ZovA)+TMath::Log(beta*gamma)-0.5;
50 return K*ZovA*1/(beta*beta)*(0.5*TMath::Log(2*me*beta*beta*gamma*gamma*Tmax/(I*I))-beta*beta-deltaover2)*2.33*1000*0.03-37;