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 // PID Response class for the TRD detector
17 // Based on 1D Likelihood approach
18 // Calculation of probabilities using Bayesian approach
19 // Attention: This method is only used to separate electrons from pions
22 // Markus Fasel <M.Fasel@gsi.de>
23 // Anton Andronic <A.Andronic@gsi.de>
27 #include <TDirectory.h>
32 #include <TObjArray.h>
39 #include "AliTRDPIDResponseObject.h"
40 //#include "AliTRDPIDParams.h"
41 //#include "AliTRDPIDReference.h"
42 #include "AliTRDPIDResponse.h"
43 #include "AliTRDTKDInterpolator.h"
45 ClassImp(AliTRDPIDResponse)
47 //____________________________________________________________
48 AliTRDPIDResponse::AliTRDPIDResponse():
50 ,fkPIDResponseObject(NULL)
51 ,fGainNormalisationFactor(1.)
55 // Default constructor
59 //____________________________________________________________
60 AliTRDPIDResponse::AliTRDPIDResponse(const AliTRDPIDResponse &ref):
62 ,fkPIDResponseObject(NULL)
63 ,fGainNormalisationFactor(ref.fGainNormalisationFactor)
64 ,fPIDmethod(ref.fPIDmethod)
71 //____________________________________________________________
72 AliTRDPIDResponse &AliTRDPIDResponse::operator=(const AliTRDPIDResponse &ref){
74 // Assignment operator
76 if(this == &ref) return *this;
79 TObject::operator=(ref);
80 fGainNormalisationFactor = ref.fGainNormalisationFactor;
81 fkPIDResponseObject = ref.fkPIDResponseObject;
82 fPIDmethod = ref.fPIDmethod;
87 //____________________________________________________________
88 AliTRDPIDResponse::~AliTRDPIDResponse(){
92 if(IsOwner()) delete fkPIDResponseObject;
95 //____________________________________________________________
96 Bool_t AliTRDPIDResponse::Load(const Char_t * filename){
98 // Load References into the toolkit
100 AliDebug(1, "Loading reference histos from root file");
101 TDirectory *owd = gDirectory;// store old working directory
104 filename = Form("%s/STEER/LQ1dRef_v1.root",gSystem->ExpandPathName("$ALICE_ROOT"));
105 TFile *in = TFile::Open(filename);
107 AliError("Ref file not available.");
112 fkPIDResponseObject = dynamic_cast<const AliTRDPIDResponseObject *>(in->Get("TRDPIDResponse")->Clone());
113 in->Close(); delete in;
115 SetBit(kIsOwner, kTRUE);
116 AliDebug(2, Form("Successfully loaded References for %d Momentum bins", fkPIDResponseObject->GetNumberOfMomentumBins()));
120 //____________________________________________________________
121 Bool_t AliTRDPIDResponse::GetResponse(Int_t n, const Double_t * const dedx, const Float_t * const p, Double_t prob[AliPID::kSPECIES], Bool_t kNorm) const
124 // Calculate TRD likelihood values for the track based on dedx and
125 // momentum values. The likelihoods are calculated by query the
126 // reference data depending on the PID method selected
129 // n - number of dedx slices/chamber
130 // dedx - array of dedx slices organized layer wise
131 // p - array of momentum measurements organized layer wise
134 // prob - probabilities allocated by TRD for particle specis
135 // kNorm - switch to normalize probabilities to 1. By default true. If false return not normalized prob.
138 // true if calculation success
141 if(!fkPIDResponseObject){
142 AliWarning("Missing reference data. PID calculation not possible.");
146 for(Int_t is(AliPID::kSPECIES); is--;) prob[is]=.2;
147 Double_t prLayer[AliPID::kSPECIES];
148 Double_t dE[10], s(0.);
149 for(Int_t il(kNlayer); il--;){
150 memset(prLayer, 0, AliPID::kSPECIES*sizeof(Double_t));
151 if(!CookdEdx(n, &dedx[il*n], &dE[0])) continue;
155 for(Int_t is(AliPID::kSPECIES); is--;){
156 if((dE[0] > 0.) && (p[il] > 0.)) prLayer[is] = GetProbabilitySingleLayer(is, p[il], &dE[0]);
157 AliDebug(3, Form("Probability for Species %d in Layer %d: %f", is, il, prLayer[is]));
158 if(prLayer[is]<1.e-30){
159 AliDebug(2, Form("Null for species %d species prob layer[%d].",is,il));
169 AliDebug(2, Form("Null all species prob layer[%d].", il));
172 for(Int_t is(AliPID::kSPECIES); is--;){
173 if(kNorm) prLayer[is] /= s;
174 prob[is] *= prLayer[is];
177 if(!kNorm) return kTRUE;
180 for(Int_t is(AliPID::kSPECIES); is--;) s+=prob[is];
182 AliDebug(2, "Null total prob.");
185 for(Int_t is(AliPID::kSPECIES); is--;) prob[is]/=s;
189 //____________________________________________________________
190 Double_t AliTRDPIDResponse::GetProbabilitySingleLayer(Int_t species, Double_t plocal, Double_t *dEdx) const {
192 // Get the non-normalized probability for a certain particle species as coming
193 // from the reference histogram
194 // Interpolation between momentum bins
196 AliDebug(1, Form("Make Probability for Species %d with Momentum %f", species, plocal));
198 Double_t probLayer = 0.;
199 Float_t pLower, pUpper;
207 Double_t point[kNslicesLQ2D];
208 for(Int_t idim=0;idim<kNslicesLQ2D;idim++){point[idim]=dEdx[idim];}
210 AliTRDTKDInterpolator *refLower = dynamic_cast<AliTRDTKDInterpolator*>(fkPIDResponseObject->GetLowerReference((AliPID::EParticleType)species, plocal, pLower,kLQ2D));
213 refLower->Eval(point,probLayer,error);
216 AliError("No references available");
222 TH1 *refUpper = dynamic_cast<TH1 *>(fkPIDResponseObject->GetUpperReference((AliPID::EParticleType)species, plocal, pUpper,kLQ1D)),
223 *refLower = dynamic_cast<TH1 *>(fkPIDResponseObject->GetLowerReference((AliPID::EParticleType)species, plocal, pLower,kLQ1D));
224 // Do Interpolation exept for underflow and overflow
225 if(refLower && refUpper){
226 Double_t probLower = refLower->GetBinContent(refLower->GetXaxis()->FindBin(dEdx[0]));
227 Double_t probUpper = refUpper->GetBinContent(refUpper->GetXaxis()->FindBin(dEdx[0]));
229 probLayer = probLower + (probUpper - probLower)/(pUpper-pLower) * (plocal - pLower);
232 probLayer = refLower->GetBinContent(refLower->GetXaxis()->FindBin(dEdx[0]));
235 probLayer = refUpper->GetBinContent(refUpper->GetXaxis()->FindBin(dEdx[0]));
237 AliError("No references available");
239 AliDebug(1, Form("Probability %f", probLayer));
248 //____________________________________________________________
249 void AliTRDPIDResponse::SetOwner(){
251 // Make Deep Copy of the Reference Histograms
253 if(!fkPIDResponseObject || IsOwner()) return;
254 const AliTRDPIDResponseObject *tmp = fkPIDResponseObject;
255 fkPIDResponseObject = dynamic_cast<const AliTRDPIDResponseObject *>(tmp->Clone());
256 SetBit(kIsOwner, kTRUE);
259 //____________________________________________________________
260 Bool_t AliTRDPIDResponse::CookdEdx(Int_t nSlice, const Double_t * const in, Double_t *out) const
271 for(Int_t islice = 0; islice < nSlice; islice++){
272 if(islice<fkPIDResponseObject->GetNSlicesQ0())out[0]+= in[islice];
273 else out[1]+= in[islice];
278 for(Int_t islice = 0; islice < nSlice; islice++)
279 if(in[islice] > 0) out[0] += in[islice] * fGainNormalisationFactor; // Protect against negative values for slices having no dE/dx information
280 if(out[0] < 1e-6) return kFALSE;
289 //____________________________________________________________
290 Bool_t AliTRDPIDResponse::IdentifiedAsElectron(Int_t nTracklets, const Double_t *like, Double_t p, Double_t level) const {
292 // Check whether particle is identified as electron assuming a certain electron efficiency level
293 // Only electron and pion hypothesis is taken into account
296 // Number of tracklets
299 // Electron efficiency level
301 // If the function fails when the params are not accessible, the function returns true
303 if(!fkPIDResponseObject){
304 AliError("No PID Param object available");
307 Double_t probEle = like[AliPID::kElectron]/(like[AliPID::kElectron] + like[AliPID::kPion]);
309 if(!fkPIDResponseObject->GetThresholdParameters(nTracklets, level, params,fPIDmethod)){
310 AliError("No Params found for the given configuration");
313 Double_t threshold = 1. - params[0] - params[1] * p - params[2] * TMath::Exp(-params[3] * p);
314 if(probEle > TMath::Max(TMath::Min(threshold, 0.99), 0.2)) return kTRUE; // truncate the threshold upperwards to 0.999 and lowerwards to 0.2 and exclude unphysical values