Further fixes to the par file generation
[u/mrichter/AliRoot.git] / HMPID / AliHMPIDPid.cxx
CommitLineData
3278403b 1/**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
3 * *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
6 * *
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 **************************************************************************/
15
16//////////////////////////////////////////////////////////////////////////
17// //
18// AliHMPIDPid //
19// //
20// HMPID class to perfom particle identification //
21// //
22//////////////////////////////////////////////////////////////////////////
23
24#include "AliHMPIDPid.h" //class header
25#include "AliHMPIDParam.h" //class header
ac66a50d 26#include "AliHMPIDRecon.h" //class header
9eb30f08 27#include <AliESDtrack.h> //FindPid()
ac66a50d 28#include <TRandom.h> //Resolution()
3278403b 29
30//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
31AliHMPIDPid::AliHMPIDPid():TTask("HMPIDrec","HMPIDPid")
32{
33//..
34//init of data members
35//..
36}
37//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
dac53a45 38void AliHMPIDPid::FindPid(AliESDtrack *pTrk,Int_t nsp,Double_t *prob)
3278403b 39{
ac66a50d 40// Calculates probability to be a electron-muon-pion-kaon-proton with the "amplitude" method
3278403b 41// from the given Cerenkov angle and momentum assuming no initial particle composition
42// (i.e. apriory probability to be the particle of the given sort is the same for all sorts)
43
ac66a50d 44 AliPID *pPid = new AliPID();
45 Double_t thetaCerExp = pTrk->GetHMPIDsignal(); // measured thetaCherenkov
46
47 if(thetaCerExp<=0){ //HMPID does not find anything reasonable for this track, assign 0.2 for all species
dac53a45 48 for(Int_t iPart=0;iPart<nsp;iPart++) prob[iPart]=1.0/(Float_t)nsp;
9eb30f08 49 return;
50 }
51
ac66a50d 52 Double_t pmod = pTrk->GetP(); // Momentum of the charged particle
53 Double_t hTot=0; // Initialize the total height of the amplitude method
54 Double_t *h = new Double_t [nsp]; // number of charged particles to be considered
9eb30f08 55
ac66a50d 56 Bool_t desert = kTRUE; // Flag to evaluate if ThetaC is far ("desert") from the given Gaussians
57
58 for(Int_t iPart=0;iPart<nsp;iPart++){ // for each particle
59
60 h[iPart] = 0; // reset the height
61 Double_t mass = pPid->ParticleMass(iPart); // with the given mass
62 Double_t cosThetaTh = TMath::Sqrt(mass*mass+pmod*pmod)/(AliHMPIDParam::Instance()->MeanIdxRad()*pmod); // evaluate the theor. Theta Cherenkov
63 if(cosThetaTh>1) continue; // no light emitted, zero height
64 Double_t thetaCerTh = TMath::ACos(cosThetaTh); // theoretical Theta Cherenkov
65 Double_t sigmaRing = Resolution(thetaCerTh,pTrk);
66
67 if(sigmaRing==0) {
68 for(Int_t jPart=0;jPart<nsp;jPart++) prob[jPart]=1.0/(Float_t)nsp;
69 return;
70 }
71
72 if(TMath::Abs(thetaCerExp-thetaCerTh)<4*sigmaRing) desert = kFALSE; //
73 h[iPart] =TMath::Gaus(thetaCerTh,thetaCerExp,sigmaRing,kTRUE);
9eb30f08 74 hTot +=h[iPart]; //total height of all theoretical heights for normalization
ac66a50d 75
9eb30f08 76 }//species loop
77
dac53a45 78 for(Int_t iPart=0;iPart<nsp;iPart++) {//species loop to assign probabilities
ac66a50d 79
80 if(!desert) prob[iPart]=h[iPart]/hTot;
dac53a45 81 else prob[iPart]=1.0/(Float_t)nsp; //all theoretical values are far away from experemental one
ac66a50d 82
9eb30f08 83 }
ac66a50d 84
dac53a45 85 delete [] h;
ac66a50d 86 delete pPid ; pPid=0x0;
3278403b 87}
88//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
ac66a50d 89Double_t AliHMPIDPid::Resolution(Double_t thetaCerTh, AliESDtrack *pTrk)
90{
91 AliHMPIDParam *pParam = AliHMPIDParam::Instance();
92
93 AliHMPIDRecon rec;
94 Float_t xRa,yRa,thRa,phRa;
95 pTrk->GetHMPIDtrk(xRa,yRa,thRa,phRa);
96 rec.SetTrack(xRa,yRa,thRa,phRa);
97 Double_t thetaMax = TMath::ACos(1./pParam->MeanIdxRad());
98 Int_t nPhots = (Int_t)(21.*TMath::Sin(thetaCerTh)*TMath::Sin(thetaCerTh)/(TMath::Sin(thetaMax)*TMath::Sin(thetaMax))+0.01);
99
100 Double_t sigmatot = 0;
101 Int_t nTrks = 20;
102 for(Int_t iTrk=0;iTrk<nTrks;iTrk++) {
103 Double_t invSigma = 0;
104 Int_t nPhotsAcc = 0;
105 for(Int_t j=0;j<nPhots;j++){
106 Double_t phi = gRandom->Rndm()*TMath::TwoPi();
107 TVector2 pos; pos=rec.TracePhot(thetaCerTh,phi);
108 if(!pParam->IsInside(pos.X(),pos.Y())) continue;
109 if(pParam->IsInDead(pos.X(),pos.Y())) continue;
110 Double_t sigma2 = pParam->Sigma2(thRa,phRa,thetaCerTh,phi);//photon candidate sigma^2
111 if(sigma2!=0) {
112 invSigma += 1./sigma2;
113 nPhotsAcc++;
114 }
115 }
116 if(invSigma!=0) sigmatot += 1./TMath::Sqrt(invSigma);
117 }
118 return sigmatot/nTrks;
119}