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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 | // 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 | |
20 | // | |
21 | // Authors: | |
22 | // Markus Fasel <M.Fasel@gsi.de> | |
23 | // Anton Andronic <A.Andronic@gsi.de> | |
24 | // | |
25 | #include <TAxis.h> | |
26 | #include <TClass.h> | |
27 | #include <TDirectory.h> | |
28 | #include <TFile.h> | |
29 | #include <TH1.h> | |
30 | #include <TKey.h> | |
31 | #include <TMath.h> | |
32 | #include <TObjArray.h> | |
33 | #include <TROOT.h> | |
34 | #include <TString.h> | |
35 | #include <TSystem.h> | |
36 | ||
37 | #include "AliLog.h" | |
38 | ||
39 | #include "AliTRDPIDParams.h" | |
40 | #include "AliTRDPIDReference.h" | |
41 | #include "AliTRDPIDResponse.h" | |
42 | ||
43 | ClassImp(AliTRDPIDResponse) | |
44 | ||
45 | //____________________________________________________________ | |
46 | AliTRDPIDResponse::AliTRDPIDResponse(): | |
47 | TObject() | |
48 | ,fkPIDReference(NULL) | |
49 | ,fkPIDParams(NULL) | |
50 | ,fGainNormalisationFactor(1.) | |
51 | ,fPIDmethod(kLQ1D) | |
52 | { | |
53 | // | |
54 | // Default constructor | |
55 | // | |
56 | } | |
57 | ||
58 | //____________________________________________________________ | |
59 | AliTRDPIDResponse::AliTRDPIDResponse(const AliTRDPIDResponse &ref): | |
60 | TObject(ref) | |
61 | ,fkPIDReference(ref.fkPIDReference) | |
62 | ,fkPIDParams(ref.fkPIDParams) | |
63 | ,fGainNormalisationFactor(ref.fGainNormalisationFactor) | |
64 | ,fPIDmethod(ref.fPIDmethod) | |
65 | { | |
66 | // | |
67 | // Copy constructor | |
68 | // | |
69 | } | |
70 | ||
71 | //____________________________________________________________ | |
72 | AliTRDPIDResponse &AliTRDPIDResponse::operator=(const AliTRDPIDResponse &ref){ | |
73 | // | |
74 | // Assignment operator | |
75 | // | |
76 | if(this == &ref) return *this; | |
77 | ||
78 | // Make copy | |
79 | TObject::operator=(ref); | |
80 | fGainNormalisationFactor = ref.fGainNormalisationFactor; | |
81 | fkPIDReference = ref.fkPIDReference; | |
82 | fkPIDParams = ref.fkPIDParams; | |
83 | fPIDmethod = ref.fPIDmethod; | |
84 | ||
85 | return *this; | |
86 | } | |
87 | ||
88 | //____________________________________________________________ | |
89 | AliTRDPIDResponse::~AliTRDPIDResponse(){ | |
90 | // | |
91 | // Destructor | |
92 | // | |
93 | if(IsOwner()) delete fkPIDReference; | |
94 | } | |
95 | ||
96 | //____________________________________________________________ | |
97 | Bool_t AliTRDPIDResponse::Load(const Char_t * filename, const Char_t *refName){ | |
98 | // | |
99 | // Load References into the toolkit | |
100 | // | |
101 | AliDebug(1, "Loading reference histos from root file"); | |
102 | TDirectory *owd = gDirectory;// store old working directory | |
103 | ||
104 | if(!filename) | |
105 | filename = Form("%s/STEER/LQ1dRef_v1.root",gSystem->ExpandPathName("$ALICE_ROOT")); | |
106 | TFile *in = TFile::Open(filename); | |
107 | if(!in){ | |
108 | AliError("Ref file not available."); | |
109 | return kFALSE; | |
110 | } | |
111 | ||
112 | gROOT->cd(); | |
113 | fkPIDReference = dynamic_cast<const AliTRDPIDReference *>(in->Get(refName)->Clone()); | |
114 | in->Close(); delete in; | |
115 | owd->cd(); | |
116 | SetBit(kIsOwner, kTRUE); | |
117 | AliDebug(2, Form("Successfully loaded References for %d Momentum bins", fkPIDReference->GetNumberOfMomentumBins())); | |
118 | return kTRUE; | |
119 | } | |
120 | ||
121 | //____________________________________________________________ | |
122 | 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 | |
123 | { | |
124 | // | |
125 | // Calculate TRD likelihood values for the track based on dedx and | |
126 | // momentum values. The likelihoods are calculated by query the | |
127 | // reference data depending on the PID method selected | |
128 | // | |
129 | // Input parameter : | |
130 | // n - number of dedx slices/chamber | |
131 | // dedx - array of dedx slices organized layer wise | |
132 | // p - array of momentum measurements organized layer wise | |
133 | // | |
134 | // Return parameters | |
135 | // prob - probabilities allocated by TRD for particle specis | |
136 | // kNorm - switch to normalize probabilities to 1. By default true. If false return not normalized prob. | |
137 | // | |
138 | // Return value | |
139 | // true if calculation success | |
140 | // | |
141 | ||
142 | if(!fkPIDReference){ | |
143 | AliWarning("Missing reference data. PID calculation not possible."); | |
144 | return kFALSE; | |
145 | } | |
146 | ||
147 | for(Int_t is(AliPID::kSPECIES); is--;) prob[is]=.2; | |
148 | Double_t prLayer[AliPID::kSPECIES]; | |
149 | Double_t dE[10], s(0.); | |
150 | for(Int_t il(kNlayer); il--;){ | |
151 | memset(prLayer, 0, AliPID::kSPECIES*sizeof(Double_t)); | |
152 | if(!CookdEdx(n, &dedx[il*n], &dE[0])) continue; | |
153 | ||
154 | s=0.; | |
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 | s+=prLayer[is]; | |
159 | } | |
160 | if(s<1.e-30){ | |
161 | AliDebug(2, Form("Null all species prob layer[%d].", il)); | |
162 | continue; | |
163 | } | |
164 | for(Int_t is(AliPID::kSPECIES); is--;){ | |
165 | if(kNorm) prLayer[is] /= s; | |
166 | prob[is] *= prLayer[is]; | |
167 | } | |
168 | } | |
169 | if(!kNorm) return kTRUE; | |
170 | ||
171 | s=0.; | |
172 | for(Int_t is(AliPID::kSPECIES); is--;) s+=prob[is]; | |
173 | if(s<1.e-30){ | |
174 | AliDebug(2, "Null total prob."); | |
175 | return kFALSE; | |
176 | } | |
177 | for(Int_t is(AliPID::kSPECIES); is--;) prob[is]/=s; | |
178 | return kTRUE; | |
179 | } | |
180 | ||
181 | //____________________________________________________________ | |
182 | Double_t AliTRDPIDResponse::GetProbabilitySingleLayer(Int_t species, Double_t plocal, Double_t dEdx) const { | |
183 | // | |
184 | // Get the non-normalized probability for a certain particle species as coming | |
185 | // from the reference histogram | |
186 | // Interpolation between momentum bins | |
187 | // | |
188 | AliDebug(1, Form("Make Probability for Species %d with Momentum %f", species, plocal)); | |
189 | Float_t pLower, pUpper; | |
190 | Double_t probLayer = 0.; | |
191 | TH1 *refUpper = dynamic_cast<TH1 *>(fkPIDReference->GetUpperReference((AliPID::EParticleType)species, plocal, pUpper)), | |
192 | *refLower = dynamic_cast<TH1 *>(fkPIDReference->GetLowerReference((AliPID::EParticleType)species, plocal, pLower)); | |
193 | // Do Interpolation exept for underflow and overflow | |
194 | if(refLower && refUpper){ | |
195 | Double_t probLower = refLower->GetBinContent(refLower->GetXaxis()->FindBin(dEdx)); | |
196 | Double_t probUpper = refUpper->GetBinContent(refUpper->GetXaxis()->FindBin(dEdx)); | |
197 | ||
198 | probLayer = probLower + (probUpper - probLower)/(pUpper-pLower) * (plocal - pLower); | |
199 | } else if(refLower){ | |
200 | // underflow | |
201 | probLayer = refLower->GetBinContent(refLower->GetXaxis()->FindBin(dEdx)); | |
202 | } else if(refUpper){ | |
203 | // overflow | |
204 | probLayer = refUpper->GetBinContent(refUpper->GetXaxis()->FindBin(dEdx)); | |
205 | } else { | |
206 | AliError("No references available"); | |
207 | } | |
208 | AliDebug(1, Form("Probability %f", probLayer)); | |
209 | return probLayer; | |
210 | } | |
211 | ||
212 | //____________________________________________________________ | |
213 | void AliTRDPIDResponse::SetOwner(){ | |
214 | // | |
215 | // Make Deep Copy of the Reference Histograms | |
216 | // | |
217 | if(!fkPIDReference || IsOwner()) return; | |
218 | const AliTRDPIDReference *tmp = fkPIDReference; | |
219 | fkPIDReference = dynamic_cast<const AliTRDPIDReference *>(tmp->Clone()); | |
220 | SetBit(kIsOwner, kTRUE); | |
221 | } | |
222 | ||
223 | //____________________________________________________________ | |
224 | Bool_t AliTRDPIDResponse::CookdEdx(Int_t nSlice, const Double_t * const in, Double_t *out) const | |
225 | { | |
226 | // | |
227 | // Recalculate dE/dx | |
228 | // | |
229 | switch(fPIDmethod){ | |
230 | case kNN: // NN | |
231 | break; | |
232 | case kLQ2D: // 2D LQ | |
233 | break; | |
234 | case kLQ1D: // 1D LQ | |
235 | out[0]= 0.; | |
236 | for(Int_t islice = 0; islice < nSlice; islice++) | |
237 | if(in[islice] > 0) out[0] += in[islice] * fGainNormalisationFactor; // Protect against negative values for slices having no dE/dx information | |
238 | if(out[0] < 1e-6) return kFALSE; | |
239 | break; | |
240 | default: | |
241 | return kFALSE; | |
242 | } | |
243 | return kTRUE; | |
244 | } | |
245 | ||
246 | //____________________________________________________________ | |
247 | Bool_t AliTRDPIDResponse::IdentifiedAsElectron(Int_t nTracklets, const Double_t *like, Double_t p, Double_t level) const { | |
248 | // | |
249 | // Check whether particle is identified as electron assuming a certain electron efficiency level | |
250 | // Only electron and pion hypothesis is taken into account | |
251 | // | |
252 | // Inputs: | |
253 | // Number of tracklets | |
254 | // Likelihood values | |
255 | // Momentum | |
256 | // Electron efficiency level | |
257 | // | |
258 | // If the function fails when the params are not accessible, the function returns true | |
259 | // | |
260 | if(!fkPIDParams){ | |
261 | AliError("No PID Param object available"); | |
262 | return kTRUE; | |
263 | } | |
264 | Double_t probEle = like[AliPID::kElectron]/(like[AliPID::kElectron] + like[AliPID::kPion]); | |
265 | Double_t params[4]; | |
266 | if(!fkPIDParams->GetThresholdParameters(nTracklets, level, params)){ | |
267 | AliError("No Params found for the given configuration"); | |
268 | return kTRUE; | |
269 | } | |
270 | Double_t threshold = 1. - params[0] - params[1] * p - params[2] * TMath::Exp(-params[3] * p); | |
271 | 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 | |
272 | return kFALSE; | |
273 | } | |
274 |