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304864ab | 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 | /* $Id$ */ | |
17 | ||
18 | /////////////////////////////////////////////////////////////////////////////// | |
19 | // // | |
20 | // particle id probability densities // | |
21 | // // | |
22 | // The AliPID class stores the probability densities for the different // | |
23 | // particle type hypotheses electron, muon, pion, kaon, proton, photon, // | |
24 | // pi0, neutron, K0 and electron conversion. These probability densities // | |
25 | // are determined from the detector response functions. // | |
26 | // The * and *= operators are overloaded for AliPID to combine the PIDs // | |
27 | // from different detectors. // | |
28 | // // | |
29 | // The Bayesian probability to be a particle of a given type can be // | |
30 | // calculated from the probability densities, if the a priori probabilities // | |
31 | // (or abundences, concentrations) of particle species are known. These // | |
32 | // priors can be given as argument to the GetProbability or GetMostProbable // | |
33 | // method or they can be set globally by calling the static method // | |
34 | // SetPriors(). // | |
35 | // // | |
36 | // The implementation of this class is based on the note ... // | |
37 | // by Iouri Belikov and Karel Safarik. // | |
38 | // // | |
39 | /////////////////////////////////////////////////////////////////////////////// | |
40 | ||
a9bbb414 | 41 | #include <TClass.h> |
42 | #include <TDatabasePDG.h> | |
43 | #include <TPDGCode.h> | |
304864ab | 44 | |
304864ab | 45 | #include "AliLog.h" |
35f27279 | 46 | #include "AliPDG.h" |
a9bbb414 | 47 | #include "AliPID.h" |
304864ab | 48 | |
90e48c0c | 49 | #define M(PID) TDatabasePDG::Instance()->GetParticle(fgkParticleCode[(PID)])->Mass() |
304864ab | 50 | |
51 | ClassImp(AliPID) | |
52 | ||
35f27279 | 53 | const char* AliPID::fgkParticleName[AliPID::kSPECIESN+AliPID::kSPECIESLN+1] = { |
304864ab | 54 | "electron", |
55 | "muon", | |
56 | "pion", | |
57 | "kaon", | |
58 | "proton", | |
59 | "photon", | |
60 | "pi0", | |
61 | "neutron", | |
62 | "kaon0", | |
63 | "eleCon", | |
35f27279 | 64 | "deuteron", |
65 | "triton", | |
66 | "helium-3", | |
67 | "alpha", | |
304864ab | 68 | "unknown" |
69 | }; | |
70 | ||
35f27279 | 71 | const char* AliPID::fgkParticleShortName[AliPID::kSPECIESN+AliPID::kSPECIESLN+1] = { |
91dbd0dc | 72 | "e", |
73 | "mu", | |
74 | "pi", | |
75 | "K", | |
76 | "p", | |
77 | "photon", | |
78 | "pi0", | |
79 | "n", | |
80 | "K0", | |
81 | "eleCon", | |
35f27279 | 82 | "d", |
83 | "t", | |
84 | "he3", | |
85 | "alpha", | |
91dbd0dc | 86 | "unknown" |
87 | }; | |
88 | ||
35f27279 | 89 | const char* AliPID::fgkParticleLatexName[AliPID::kSPECIESN+AliPID::kSPECIESLN+1] = { |
91dbd0dc | 90 | "e", |
91 | "#mu", | |
92 | "#pi", | |
93 | "K", | |
94 | "p", | |
95 | "#gamma", | |
96 | "#pi_{0}", | |
97 | "n", | |
98 | "K_{0}", | |
99 | "eleCon", | |
35f27279 | 100 | "d", |
101 | "t", | |
102 | "he3", | |
103 | "#alpha", | |
91dbd0dc | 104 | "unknown" |
105 | }; | |
106 | ||
35f27279 | 107 | const Int_t AliPID::fgkParticleCode[AliPID::kSPECIESN+AliPID::kSPECIESLN+1] = { |
304864ab | 108 | ::kElectron, |
109 | ::kMuonMinus, | |
110 | ::kPiPlus, | |
111 | ::kKPlus, | |
112 | ::kProton, | |
113 | ::kGamma, | |
114 | ::kPi0, | |
115 | ::kNeutron, | |
116 | ::kK0, | |
0133aa88 | 117 | ::kElectron, |
35f27279 | 118 | 1000010020, |
119 | 1000010030, | |
120 | 1000020030, | |
121 | 1000020040, | |
304864ab | 122 | 0 |
123 | }; | |
124 | ||
35f27279 | 125 | /*const*/ Float_t AliPID::fgkParticleMass[AliPID::kSPECIESN+AliPID::kSPECIESLN+1] = { |
126 | 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 | |
a9bbb414 | 127 | /* |
90e48c0c | 128 | M(kElectron), // electron |
129 | M(kMuon), // muon | |
130 | M(kPion), // pion | |
131 | M(kKaon), // kaon | |
132 | M(kProton), // proton | |
133 | M(kPhoton), // photon | |
134 | M(kPi0), // pi0 | |
135 | M(kNeutron), // neutron | |
136 | M(kKaon0), // kaon0 | |
137 | M(kEleCon), // electron conversion | |
35f27279 | 138 | M(kDeuteron), // deuteron |
139 | M(kTriton), // triton | |
140 | M(kHe3), // he3 | |
141 | M(kAlpha), // alpha | |
90e48c0c | 142 | 0.00000 // unknown |
a9bbb414 | 143 | */ |
90e48c0c | 144 | }; |
304864ab | 145 | |
146 | Double_t AliPID::fgPrior[kSPECIESN] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0}; | |
147 | ||
148 | ||
149 | //_______________________________________________________________________ | |
90e48c0c | 150 | AliPID::AliPID() : |
151 | TObject(), | |
152 | fCharged(0) | |
304864ab | 153 | { |
a9bbb414 | 154 | // |
155 | // Default constructor | |
156 | // | |
157 | Init(); | |
158 | // set default values (= equal probabilities) | |
159 | for (Int_t i = 0; i < kSPECIESN; i++) | |
304864ab | 160 | fProbDensity[i] = 1./kSPECIESN; |
304864ab | 161 | } |
162 | ||
163 | //_______________________________________________________________________ | |
90e48c0c | 164 | AliPID::AliPID(const Double_t* probDensity, Bool_t charged) : |
165 | TObject(), | |
166 | fCharged(charged) | |
304864ab | 167 | { |
90e48c0c | 168 | // |
a9bbb414 | 169 | // Standard constructor |
90e48c0c | 170 | // |
a9bbb414 | 171 | Init(); |
172 | // set given probability densities | |
173 | for (Int_t i = 0; i < kSPECIES; i++) | |
304864ab | 174 | fProbDensity[i] = probDensity[i]; |
a9bbb414 | 175 | |
176 | for (Int_t i = kSPECIES; i < kSPECIESN; i++) | |
304864ab | 177 | fProbDensity[i] = ((charged) ? 0 : probDensity[i]); |
304864ab | 178 | } |
179 | ||
180 | //_______________________________________________________________________ | |
90e48c0c | 181 | AliPID::AliPID(const Float_t* probDensity, Bool_t charged) : |
182 | TObject(), | |
183 | fCharged(charged) | |
304864ab | 184 | { |
90e48c0c | 185 | // |
a9bbb414 | 186 | // Standard constructor |
90e48c0c | 187 | // |
a9bbb414 | 188 | Init(); |
189 | // set given probability densities | |
190 | for (Int_t i = 0; i < kSPECIES; i++) | |
304864ab | 191 | fProbDensity[i] = probDensity[i]; |
a9bbb414 | 192 | |
193 | for (Int_t i = kSPECIES; i < kSPECIESN; i++) | |
304864ab | 194 | fProbDensity[i] = ((charged) ? 0 : probDensity[i]); |
304864ab | 195 | } |
196 | ||
197 | //_______________________________________________________________________ | |
198 | AliPID::AliPID(const AliPID& pid) : | |
199 | TObject(pid), | |
200 | fCharged(pid.fCharged) | |
201 | { | |
90e48c0c | 202 | // |
203 | // copy constructor | |
204 | // | |
a9bbb414 | 205 | // We do not call init here, MUST already be done |
206 | for (Int_t i = 0; i < kSPECIESN; i++) | |
304864ab | 207 | fProbDensity[i] = pid.fProbDensity[i]; |
304864ab | 208 | } |
209 | ||
3088e2dd | 210 | //_______________________________________________________________________ |
211 | void AliPID::SetProbabilities(const Double_t* probDensity, Bool_t charged) | |
212 | { | |
213 | // | |
214 | // Set the probability densities | |
215 | // | |
216 | for (Int_t i = 0; i < kSPECIES; i++) | |
217 | fProbDensity[i] = probDensity[i]; | |
218 | ||
219 | for (Int_t i = kSPECIES; i < kSPECIESN; i++) | |
220 | fProbDensity[i] = ((charged) ? 0 : probDensity[i]); | |
221 | } | |
222 | ||
304864ab | 223 | //_______________________________________________________________________ |
224 | AliPID& AliPID::operator = (const AliPID& pid) | |
225 | { | |
226 | // assignment operator | |
227 | ||
228 | fCharged = pid.fCharged; | |
229 | for (Int_t i = 0; i < kSPECIESN; i++) { | |
230 | fProbDensity[i] = pid.fProbDensity[i]; | |
231 | } | |
232 | return *this; | |
233 | } | |
234 | ||
a9bbb414 | 235 | //_______________________________________________________________________ |
236 | void AliPID::Init() | |
237 | { | |
238 | // | |
239 | // Initialise the masses | |
240 | // | |
241 | // Initialise only once... | |
35f27279 | 242 | if(!fgkParticleMass[0]) { |
243 | AliPDG::AddParticlesToPdgDataBase(); | |
244 | for (Int_t i = 0; i < kSPECIESN + kSPECIESLN; i++) | |
374ef46b | 245 | fgkParticleMass[i] = M(i); |
35f27279 | 246 | } |
a9bbb414 | 247 | } |
304864ab | 248 | |
249 | //_____________________________________________________________________________ | |
250 | Double_t AliPID::GetProbability(EParticleType iType, | |
251 | const Double_t* prior) const | |
252 | { | |
a9bbb414 | 253 | // |
254 | // Get the probability to be a particle of type "iType" | |
255 | // assuming the a priori probabilities "prior" | |
256 | // | |
304864ab | 257 | Double_t sum = 0.; |
258 | Int_t nSpecies = ((fCharged) ? kSPECIES : kSPECIESN); | |
259 | for (Int_t i = 0; i < nSpecies; i++) { | |
260 | sum += fProbDensity[i] * prior[i]; | |
261 | } | |
262 | if (sum <= 0) { | |
263 | AliError("Invalid probability densities or priors"); | |
264 | return -1; | |
265 | } | |
266 | return fProbDensity[iType] * prior[iType] / sum; | |
267 | } | |
268 | ||
269 | //_____________________________________________________________________________ | |
270 | Double_t AliPID::GetProbability(EParticleType iType) const | |
271 | { | |
272 | // get the probability to be a particle of type "iType" | |
273 | // assuming the globaly set a priori probabilities | |
274 | ||
275 | return GetProbability(iType, fgPrior); | |
276 | } | |
277 | ||
278 | //_____________________________________________________________________________ | |
279 | void AliPID::GetProbabilities(Double_t* probabilities, | |
280 | const Double_t* prior) const | |
281 | { | |
282 | // get the probabilities to be a particle of given type | |
283 | // assuming the a priori probabilities "prior" | |
284 | ||
285 | Double_t sum = 0.; | |
286 | Int_t nSpecies = ((fCharged) ? kSPECIES : kSPECIESN); | |
287 | for (Int_t i = 0; i < nSpecies; i++) { | |
288 | sum += fProbDensity[i] * prior[i]; | |
289 | } | |
290 | if (sum <= 0) { | |
291 | AliError("Invalid probability densities or priors"); | |
292 | for (Int_t i = 0; i < nSpecies; i++) probabilities[i] = -1; | |
293 | return; | |
294 | } | |
295 | for (Int_t i = 0; i < nSpecies; i++) { | |
296 | probabilities[i] = fProbDensity[i] * prior[i] / sum; | |
297 | } | |
298 | } | |
299 | ||
300 | //_____________________________________________________________________________ | |
301 | void AliPID::GetProbabilities(Double_t* probabilities) const | |
302 | { | |
303 | // get the probabilities to be a particle of given type | |
304 | // assuming the globaly set a priori probabilities | |
305 | ||
306 | GetProbabilities(probabilities, fgPrior); | |
307 | } | |
308 | ||
309 | //_____________________________________________________________________________ | |
310 | AliPID::EParticleType AliPID::GetMostProbable(const Double_t* prior) const | |
311 | { | |
312 | // get the most probable particle id hypothesis | |
313 | // assuming the a priori probabilities "prior" | |
314 | ||
315 | Double_t max = 0.; | |
316 | EParticleType id = kPion; | |
317 | Int_t nSpecies = ((fCharged) ? kSPECIES : kSPECIESN); | |
318 | for (Int_t i = 0; i < nSpecies; i++) { | |
319 | Double_t prob = fProbDensity[i] * prior[i]; | |
320 | if (prob > max) { | |
321 | max = prob; | |
322 | id = EParticleType(i); | |
323 | } | |
324 | } | |
325 | if (max == 0) { | |
326 | AliError("Invalid probability densities or priors"); | |
327 | } | |
328 | return id; | |
329 | } | |
330 | ||
331 | //_____________________________________________________________________________ | |
332 | AliPID::EParticleType AliPID::GetMostProbable() const | |
333 | { | |
334 | // get the most probable particle id hypothesis | |
335 | // assuming the globaly set a priori probabilities | |
336 | ||
337 | return GetMostProbable(fgPrior); | |
338 | } | |
339 | ||
340 | ||
341 | //_____________________________________________________________________________ | |
342 | void AliPID::SetPriors(const Double_t* prior, Bool_t charged) | |
343 | { | |
344 | // use the given priors as global a priori probabilities | |
345 | ||
346 | Double_t sum = 0; | |
347 | for (Int_t i = 0; i < kSPECIESN; i++) { | |
348 | if (charged && (i >= kSPECIES)) { | |
349 | fgPrior[i] = 0; | |
350 | } else { | |
351 | if (prior[i] < 0) { | |
352 | AliWarningClass(Form("negative prior (%g) for %ss. " | |
353 | "Using 0 instead.", prior[i], | |
354 | fgkParticleName[i])); | |
355 | fgPrior[i] = 0; | |
356 | } else { | |
357 | fgPrior[i] = prior[i]; | |
358 | } | |
359 | } | |
360 | sum += prior[i]; | |
361 | } | |
362 | if (sum == 0) { | |
363 | AliWarningClass("all priors are zero."); | |
364 | } | |
365 | } | |
366 | ||
367 | //_____________________________________________________________________________ | |
368 | void AliPID::SetPrior(EParticleType iType, Double_t prior) | |
369 | { | |
370 | // use the given prior as global a priori probability for particles | |
371 | // of type "iType" | |
372 | ||
373 | if (prior < 0) { | |
374 | AliWarningClass(Form("negative prior (%g) for %ss. Using 0 instead.", | |
375 | prior, fgkParticleName[iType])); | |
376 | prior = 0; | |
377 | } | |
378 | fgPrior[iType] = prior; | |
379 | } | |
380 | ||
381 | ||
304864ab | 382 | //_____________________________________________________________________________ |
383 | AliPID& AliPID::operator *= (const AliPID& pid) | |
384 | { | |
385 | // combine this probability densities with the one of "pid" | |
386 | ||
387 | for (Int_t i = 0; i < kSPECIESN; i++) { | |
388 | fProbDensity[i] *= pid.fProbDensity[i]; | |
389 | } | |
390 | return *this; | |
391 | } | |
392 | ||
393 | //_____________________________________________________________________________ | |
394 | AliPID operator * (const AliPID& pid1, const AliPID& pid2) | |
395 | { | |
396 | // combine the two probability densities | |
397 | ||
398 | AliPID result; | |
399 | result *= pid1; | |
400 | result *= pid2; | |
401 | return result; | |
402 | } |