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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 | //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ | |
f21fc003 | 31 | AliHMPIDPid::AliHMPIDPid():TNamed("HMPIDrec","HMPIDPid") |
3278403b | 32 | { |
33 | //.. | |
34 | //init of data members | |
35 | //.. | |
36 | } | |
37 | //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ | |
b7a2d22d | 38 | void AliHMPIDPid::FindPid(AliESDtrack *pTrk,Double_t nmean,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(); |
ac66a50d | 45 | |
6ba13ae0 | 46 | Double_t thetaCerExp = -999.; |
47 | if(pTrk->GetHMPIDsignal()<=0) thetaCerExp = pTrk->GetHMPIDsignal(); | |
48 | else thetaCerExp = pTrk->GetHMPIDsignal() - (Int_t)pTrk->GetHMPIDsignal(); // measured thetaCherenkov | |
49 | ||
50 | if(thetaCerExp<=0){ //HMPID does not find anything reasonable for this track, assign 0.2 for all species | |
dac53a45 | 51 | for(Int_t iPart=0;iPart<nsp;iPart++) prob[iPart]=1.0/(Float_t)nsp; |
89e82ce1 | 52 | delete pPid ; pPid=0x0; return; |
9eb30f08 | 53 | } |
122305ea | 54 | |
55 | Double_t p[3] = {0}, pmod = 0; | |
56 | if(pTrk->GetOuterHmpPxPyPz(p)) pmod = TMath::Sqrt(p[0]*p[0]+p[1]*p[1]+p[2]*p[2]); // Momentum of the charged particle | |
57 | ||
58 | else { | |
59 | for(Int_t iPart=0;iPart<nsp;iPart++) prob[iPart]=1.0/(Float_t)nsp; | |
89e82ce1 | 60 | delete pPid ; pPid=0x0; return; |
122305ea | 61 | } |
62 | ||
ac66a50d | 63 | Double_t hTot=0; // Initialize the total height of the amplitude method |
64 | Double_t *h = new Double_t [nsp]; // number of charged particles to be considered | |
9eb30f08 | 65 | |
ac66a50d | 66 | Bool_t desert = kTRUE; // Flag to evaluate if ThetaC is far ("desert") from the given Gaussians |
67 | ||
68 | for(Int_t iPart=0;iPart<nsp;iPart++){ // for each particle | |
69 | ||
70 | h[iPart] = 0; // reset the height | |
71 | Double_t mass = pPid->ParticleMass(iPart); // with the given mass | |
b7a2d22d | 72 | Double_t cosThetaTh = TMath::Sqrt(mass*mass+pmod*pmod)/(nmean*pmod); // evaluate the theor. Theta Cherenkov |
ac66a50d | 73 | if(cosThetaTh>1) continue; // no light emitted, zero height |
74 | Double_t thetaCerTh = TMath::ACos(cosThetaTh); // theoretical Theta Cherenkov | |
94d2d456 | 75 | Double_t sigmaRing = Resolution(iPart,thetaCerTh,pTrk); |
ac66a50d | 76 | |
6068c9c3 | 77 | if(sigmaRing==0) continue; |
78 | ||
ac66a50d | 79 | if(TMath::Abs(thetaCerExp-thetaCerTh)<4*sigmaRing) desert = kFALSE; // |
80 | h[iPart] =TMath::Gaus(thetaCerTh,thetaCerExp,sigmaRing,kTRUE); | |
9eb30f08 | 81 | hTot +=h[iPart]; //total height of all theoretical heights for normalization |
ac66a50d | 82 | |
9eb30f08 | 83 | }//species loop |
84 | ||
dac53a45 | 85 | for(Int_t iPart=0;iPart<nsp;iPart++) {//species loop to assign probabilities |
ac66a50d | 86 | |
87 | if(!desert) prob[iPart]=h[iPart]/hTot; | |
dac53a45 | 88 | else prob[iPart]=1.0/(Float_t)nsp; //all theoretical values are far away from experemental one |
ac66a50d | 89 | |
9eb30f08 | 90 | } |
ac66a50d | 91 | |
dac53a45 | 92 | delete [] h; |
ac66a50d | 93 | delete pPid ; pPid=0x0; |
3278403b | 94 | } |
95 | //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ | |
94d2d456 | 96 | Double_t AliHMPIDPid::Resolution(Int_t iPart, Double_t thetaCerTh, AliESDtrack *pTrk) |
ac66a50d | 97 | { |
98 | AliHMPIDParam *pParam = AliHMPIDParam::Instance(); | |
99 | ||
100 | AliHMPIDRecon rec; | |
b018f09d | 101 | Float_t xPc,yPc,thRa,phRa; |
94d2d456 | 102 | Float_t x, y; |
103 | Int_t q, nph; | |
b018f09d | 104 | pTrk->GetHMPIDtrk(xPc,yPc,thRa,phRa); |
94d2d456 | 105 | pTrk->GetHMPIDmip(x,y,q,nph); |
b018f09d | 106 | |
107 | Double_t xRa = xPc - (pParam->RadThick()+pParam->WinThick()+pParam->GapThick())*TMath::Cos(phRa)*TMath::Tan(thRa); //just linear extrapolation back to RAD | |
108 | Double_t yRa = yPc - (pParam->RadThick()+pParam->WinThick()+pParam->GapThick())*TMath::Sin(phRa)*TMath::Tan(thRa); //just linear extrapolation back to RAD | |
ac66a50d | 109 | rec.SetTrack(xRa,yRa,thRa,phRa); |
b018f09d | 110 | |
111 | Double_t occupancy = pTrk->GetHMPIDoccupancy(); | |
ac66a50d | 112 | Double_t thetaMax = TMath::ACos(1./pParam->MeanIdxRad()); |
94d2d456 | 113 | Int_t nPhotsTh = (Int_t)(12.*TMath::Sin(thetaCerTh)*TMath::Sin(thetaCerTh)/(TMath::Sin(thetaMax)*TMath::Sin(thetaMax))+0.01); |
ac66a50d | 114 | |
115 | Double_t sigmatot = 0; | |
116 | Int_t nTrks = 20; | |
94d2d456 | 117 | |
ac66a50d | 118 | for(Int_t iTrk=0;iTrk<nTrks;iTrk++) { |
119 | Double_t invSigma = 0; | |
120 | Int_t nPhotsAcc = 0; | |
94d2d456 | 121 | |
122 | Int_t nPhots = 0; | |
123 | if(nph<nPhotsTh+TMath::Sqrt(nPhotsTh) && nph>nPhotsTh-TMath::Sqrt(nPhotsTh)) nPhots = nph; | |
124 | else nPhots = gRandom->Poisson(nPhotsTh); | |
125 | ||
ac66a50d | 126 | for(Int_t j=0;j<nPhots;j++){ |
127 | Double_t phi = gRandom->Rndm()*TMath::TwoPi(); | |
128 | TVector2 pos; pos=rec.TracePhot(thetaCerTh,phi); | |
129 | if(!pParam->IsInside(pos.X(),pos.Y())) continue; | |
94d2d456 | 130 | if(pParam->IsInDead(pos.X(),pos.Y())) continue; |
ac66a50d | 131 | Double_t sigma2 = pParam->Sigma2(thRa,phRa,thetaCerTh,phi);//photon candidate sigma^2 |
132 | if(sigma2!=0) { | |
133 | invSigma += 1./sigma2; | |
134 | nPhotsAcc++; | |
135 | } | |
136 | } | |
137 | if(invSigma!=0) sigmatot += 1./TMath::Sqrt(invSigma); | |
138 | } | |
94d2d456 | 139 | |
140 | return (sigmatot/nTrks)*pParam->SigmaCorrFact(iPart,occupancy); | |
ac66a50d | 141 | } |