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4 * Author: The ALICE Off-line Project. *
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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 //-----------------------------------------------------------------
22 #include "AliITSpidESD.h"
24 #include "AliESDtrack.h"
26 ClassImp(AliITSpidESD)
28 //_________________________________________________________________________
29 AliITSpidESD::AliITSpidESD(Double_t *param)
32 // The main constructor
39 Double_t AliITSpidESD::Bethe(Double_t bg) {
41 // This is the Bethe-Bloch function normalised to 1 at the minimum
44 Double_t bethe=(1.+ bg2)/bg2*(log(5940*bg2) - bg2/(1.+ bg2));
48 //_________________________________________________________________________
49 Int_t AliITSpidESD::MakePID(AliESD *event)
52 // This function calculates the "detector response" PID probabilities
54 static const Double_t masses[]={
55 0.000511, 0.105658, 0.139570, 0.493677, 0.938272, 1.875613
57 Int_t ntrk=event->GetNumberOfTracks();
58 for (Int_t i=0; i<ntrk; i++) {
59 AliESDtrack *t=event->GetTrack(i);
60 if ((t->GetStatus()&AliESDtrack::kITSin )==0)
61 if ((t->GetStatus()&AliESDtrack::kITSout)==0) continue;
62 Int_t ns=AliESDtrack::kSPECIES;
64 for (Int_t j=0; j<ns; j++) {
65 Double_t mass=masses[j];
66 Double_t mom=t->GetP();
67 Double_t dedx=t->GetITSsignal()/fMIP;
68 Double_t bethe=Bethe(mom/mass);
69 Double_t sigma=fRes*bethe;
70 if (TMath::Abs(dedx-bethe) > fRange*sigma) {
71 p[j]=TMath::Exp(-0.5*fRange*fRange);
74 p[j]=TMath::Exp(-0.5*(dedx-bethe)*(dedx-bethe)/(sigma*sigma));