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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 | ||
00a38d07 | 53 | const char* AliPID::fgkParticleName[AliPID::kSPECIESCN+1] = { |
304864ab | 54 | "electron", |
55 | "muon", | |
56 | "pion", | |
00a38d07 | 57 | "kaon", |
304864ab | 58 | "proton", |
00a38d07 | 59 | |
60 | "deuteron", | |
61 | "triton", | |
62 | "helium-3", | |
63 | "alpha", | |
64 | ||
304864ab | 65 | "photon", |
66 | "pi0", | |
67 | "neutron", | |
68 | "kaon0", | |
69 | "eleCon", | |
00a38d07 | 70 | |
304864ab | 71 | "unknown" |
72 | }; | |
73 | ||
00a38d07 | 74 | const char* AliPID::fgkParticleShortName[AliPID::kSPECIESCN+1] = { |
91dbd0dc | 75 | "e", |
76 | "mu", | |
77 | "pi", | |
78 | "K", | |
79 | "p", | |
00a38d07 | 80 | |
81 | "d", | |
82 | "t", | |
83 | "he3", | |
84 | "alpha", | |
85 | ||
91dbd0dc | 86 | "photon", |
87 | "pi0", | |
88 | "n", | |
89 | "K0", | |
90 | "eleCon", | |
00a38d07 | 91 | |
91dbd0dc | 92 | "unknown" |
93 | }; | |
94 | ||
00a38d07 | 95 | const char* AliPID::fgkParticleLatexName[AliPID::kSPECIESCN+1] = { |
91dbd0dc | 96 | "e", |
97 | "#mu", | |
98 | "#pi", | |
99 | "K", | |
100 | "p", | |
00a38d07 | 101 | |
102 | "d", | |
103 | "t", | |
104 | "he3", | |
105 | "#alpha", | |
106 | ||
91dbd0dc | 107 | "#gamma", |
108 | "#pi_{0}", | |
109 | "n", | |
110 | "K_{0}", | |
111 | "eleCon", | |
00a38d07 | 112 | |
91dbd0dc | 113 | "unknown" |
114 | }; | |
115 | ||
00a38d07 | 116 | const Int_t AliPID::fgkParticleCode[AliPID::kSPECIESCN+1] = { |
304864ab | 117 | ::kElectron, |
118 | ::kMuonMinus, | |
119 | ::kPiPlus, | |
120 | ::kKPlus, | |
121 | ::kProton, | |
00a38d07 | 122 | |
123 | 1000010020, | |
124 | 1000010030, | |
125 | 1000020030, | |
126 | 1000020040, | |
127 | ||
304864ab | 128 | ::kGamma, |
129 | ::kPi0, | |
130 | ::kNeutron, | |
131 | ::kK0, | |
0133aa88 | 132 | ::kElectron, |
304864ab | 133 | 0 |
134 | }; | |
135 | ||
00a38d07 | 136 | /*const*/ Float_t AliPID::fgkParticleMass[AliPID::kSPECIESCN+1] = { |
35f27279 | 137 | 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 |
a9bbb414 | 138 | /* |
90e48c0c | 139 | M(kElectron), // electron |
140 | M(kMuon), // muon | |
141 | M(kPion), // pion | |
142 | M(kKaon), // kaon | |
143 | M(kProton), // proton | |
144 | M(kPhoton), // photon | |
145 | M(kPi0), // pi0 | |
146 | M(kNeutron), // neutron | |
147 | M(kKaon0), // kaon0 | |
148 | M(kEleCon), // electron conversion | |
35f27279 | 149 | M(kDeuteron), // deuteron |
150 | M(kTriton), // triton | |
151 | M(kHe3), // he3 | |
152 | M(kAlpha), // alpha | |
90e48c0c | 153 | 0.00000 // unknown |
a9bbb414 | 154 | */ |
90e48c0c | 155 | }; |
00a38d07 | 156 | /*const*/ Float_t AliPID::fgkParticleMassZ[AliPID::kSPECIESCN+1] = { |
67376d1d | 157 | 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 |
158 | /* | |
159 | M(kElectron), // electron | |
160 | M(kMuon), // muon | |
161 | M(kPion), // pion | |
162 | M(kKaon), // kaon | |
163 | M(kProton), // proton | |
164 | M(kPhoton), // photon | |
165 | M(kPi0), // pi0 | |
166 | M(kNeutron), // neutron | |
167 | M(kKaon0), // kaon0 | |
168 | M(kEleCon), // electron conversion | |
169 | M(kDeuteron), // deuteron | |
170 | M(kTriton), // triton | |
171 | M(kHe3)/2, // he3 | |
172 | M(kAlpha)/2, // alpha | |
173 | 0.00000 // unknown | |
174 | */ | |
175 | }; | |
304864ab | 176 | |
1d26da6d | 177 | Char_t AliPID::fgkParticleCharge[AliPID::kSPECIESCN+1] = { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 }; |
178 | ||
00a38d07 | 179 | Double_t AliPID::fgPrior[kSPECIESCN] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}; |
304864ab | 180 | |
181 | ||
182 | //_______________________________________________________________________ | |
90e48c0c | 183 | AliPID::AliPID() : |
184 | TObject(), | |
185 | fCharged(0) | |
304864ab | 186 | { |
a9bbb414 | 187 | // |
188 | // Default constructor | |
189 | // | |
190 | Init(); | |
191 | // set default values (= equal probabilities) | |
00a38d07 | 192 | for (Int_t i = 0; i < kSPECIESCN; i++) |
193 | fProbDensity[i] = 1./kSPECIESCN; | |
304864ab | 194 | } |
195 | ||
196 | //_______________________________________________________________________ | |
90e48c0c | 197 | AliPID::AliPID(const Double_t* probDensity, Bool_t charged) : |
198 | TObject(), | |
199 | fCharged(charged) | |
304864ab | 200 | { |
90e48c0c | 201 | // |
a9bbb414 | 202 | // Standard constructor |
90e48c0c | 203 | // |
a9bbb414 | 204 | Init(); |
205 | // set given probability densities | |
00a38d07 | 206 | for (Int_t i = 0; i < kSPECIESC; i++) |
304864ab | 207 | fProbDensity[i] = probDensity[i]; |
a9bbb414 | 208 | |
00a38d07 | 209 | for (Int_t i = kSPECIESC; i < kSPECIESCN; i++) |
304864ab | 210 | fProbDensity[i] = ((charged) ? 0 : probDensity[i]); |
304864ab | 211 | } |
212 | ||
213 | //_______________________________________________________________________ | |
90e48c0c | 214 | AliPID::AliPID(const Float_t* probDensity, Bool_t charged) : |
215 | TObject(), | |
216 | fCharged(charged) | |
304864ab | 217 | { |
90e48c0c | 218 | // |
a9bbb414 | 219 | // Standard constructor |
90e48c0c | 220 | // |
a9bbb414 | 221 | Init(); |
222 | // set given probability densities | |
00a38d07 | 223 | for (Int_t i = 0; i < kSPECIESC; i++) |
304864ab | 224 | fProbDensity[i] = probDensity[i]; |
a9bbb414 | 225 | |
00a38d07 | 226 | for (Int_t i = kSPECIESC; i < kSPECIESCN; i++) |
304864ab | 227 | fProbDensity[i] = ((charged) ? 0 : probDensity[i]); |
304864ab | 228 | } |
229 | ||
230 | //_______________________________________________________________________ | |
231 | AliPID::AliPID(const AliPID& pid) : | |
232 | TObject(pid), | |
233 | fCharged(pid.fCharged) | |
234 | { | |
90e48c0c | 235 | // |
236 | // copy constructor | |
237 | // | |
a9bbb414 | 238 | // We do not call init here, MUST already be done |
00a38d07 | 239 | for (Int_t i = 0; i < kSPECIESCN; i++) |
304864ab | 240 | fProbDensity[i] = pid.fProbDensity[i]; |
304864ab | 241 | } |
242 | ||
3088e2dd | 243 | //_______________________________________________________________________ |
244 | void AliPID::SetProbabilities(const Double_t* probDensity, Bool_t charged) | |
245 | { | |
246 | // | |
247 | // Set the probability densities | |
248 | // | |
00a38d07 | 249 | for (Int_t i = 0; i < kSPECIESC; i++) |
3088e2dd | 250 | fProbDensity[i] = probDensity[i]; |
251 | ||
00a38d07 | 252 | for (Int_t i = kSPECIESC; i < kSPECIESCN; i++) |
3088e2dd | 253 | fProbDensity[i] = ((charged) ? 0 : probDensity[i]); |
254 | } | |
255 | ||
304864ab | 256 | //_______________________________________________________________________ |
257 | AliPID& AliPID::operator = (const AliPID& pid) | |
258 | { | |
259 | // assignment operator | |
260 | ||
049e4804 | 261 | if(this != &pid) { |
262 | fCharged = pid.fCharged; | |
00a38d07 | 263 | for (Int_t i = 0; i < kSPECIESCN; i++) { |
049e4804 | 264 | fProbDensity[i] = pid.fProbDensity[i]; |
265 | } | |
304864ab | 266 | } |
267 | return *this; | |
268 | } | |
269 | ||
a9bbb414 | 270 | //_______________________________________________________________________ |
271 | void AliPID::Init() | |
272 | { | |
273 | // | |
1d26da6d | 274 | // Initialise the masses, charges |
a9bbb414 | 275 | // |
276 | // Initialise only once... | |
35f27279 | 277 | if(!fgkParticleMass[0]) { |
278 | AliPDG::AddParticlesToPdgDataBase(); | |
00a38d07 | 279 | for (Int_t i = 0; i < kSPECIESC; i++) { |
374ef46b | 280 | fgkParticleMass[i] = M(i); |
1d26da6d | 281 | if (i == kHe3 || i == kAlpha) { |
282 | fgkParticleMassZ[i] = M(i)/2.; | |
283 | fgkParticleCharge[i] = 2; | |
284 | } | |
285 | else { | |
286 | fgkParticleMassZ[i]=M(i); | |
287 | fgkParticleCharge[i]=1; | |
288 | } | |
67376d1d | 289 | } |
35f27279 | 290 | } |
a9bbb414 | 291 | } |
304864ab | 292 | |
293 | //_____________________________________________________________________________ | |
294 | Double_t AliPID::GetProbability(EParticleType iType, | |
295 | const Double_t* prior) const | |
296 | { | |
a9bbb414 | 297 | // |
298 | // Get the probability to be a particle of type "iType" | |
299 | // assuming the a priori probabilities "prior" | |
300 | // | |
304864ab | 301 | Double_t sum = 0.; |
00a38d07 | 302 | Int_t nSpecies = ((fCharged) ? kSPECIESC : kSPECIESCN); |
304864ab | 303 | for (Int_t i = 0; i < nSpecies; i++) { |
304 | sum += fProbDensity[i] * prior[i]; | |
305 | } | |
306 | if (sum <= 0) { | |
307 | AliError("Invalid probability densities or priors"); | |
308 | return -1; | |
309 | } | |
310 | return fProbDensity[iType] * prior[iType] / sum; | |
311 | } | |
312 | ||
313 | //_____________________________________________________________________________ | |
314 | Double_t AliPID::GetProbability(EParticleType iType) const | |
315 | { | |
316 | // get the probability to be a particle of type "iType" | |
317 | // assuming the globaly set a priori probabilities | |
318 | ||
319 | return GetProbability(iType, fgPrior); | |
320 | } | |
321 | ||
322 | //_____________________________________________________________________________ | |
323 | void AliPID::GetProbabilities(Double_t* probabilities, | |
324 | const Double_t* prior) const | |
325 | { | |
326 | // get the probabilities to be a particle of given type | |
327 | // assuming the a priori probabilities "prior" | |
328 | ||
329 | Double_t sum = 0.; | |
00a38d07 | 330 | Int_t nSpecies = ((fCharged) ? kSPECIESC : kSPECIESCN); |
304864ab | 331 | for (Int_t i = 0; i < nSpecies; i++) { |
332 | sum += fProbDensity[i] * prior[i]; | |
333 | } | |
334 | if (sum <= 0) { | |
335 | AliError("Invalid probability densities or priors"); | |
336 | for (Int_t i = 0; i < nSpecies; i++) probabilities[i] = -1; | |
337 | return; | |
338 | } | |
339 | for (Int_t i = 0; i < nSpecies; i++) { | |
340 | probabilities[i] = fProbDensity[i] * prior[i] / sum; | |
341 | } | |
342 | } | |
343 | ||
344 | //_____________________________________________________________________________ | |
345 | void AliPID::GetProbabilities(Double_t* probabilities) const | |
346 | { | |
347 | // get the probabilities to be a particle of given type | |
348 | // assuming the globaly set a priori probabilities | |
349 | ||
350 | GetProbabilities(probabilities, fgPrior); | |
351 | } | |
352 | ||
353 | //_____________________________________________________________________________ | |
354 | AliPID::EParticleType AliPID::GetMostProbable(const Double_t* prior) const | |
355 | { | |
356 | // get the most probable particle id hypothesis | |
357 | // assuming the a priori probabilities "prior" | |
358 | ||
359 | Double_t max = 0.; | |
360 | EParticleType id = kPion; | |
00a38d07 | 361 | Int_t nSpecies = ((fCharged) ? kSPECIESC : kSPECIESCN); |
304864ab | 362 | for (Int_t i = 0; i < nSpecies; i++) { |
363 | Double_t prob = fProbDensity[i] * prior[i]; | |
364 | if (prob > max) { | |
365 | max = prob; | |
366 | id = EParticleType(i); | |
367 | } | |
368 | } | |
369 | if (max == 0) { | |
370 | AliError("Invalid probability densities or priors"); | |
371 | } | |
372 | return id; | |
373 | } | |
374 | ||
375 | //_____________________________________________________________________________ | |
376 | AliPID::EParticleType AliPID::GetMostProbable() const | |
377 | { | |
378 | // get the most probable particle id hypothesis | |
379 | // assuming the globaly set a priori probabilities | |
380 | ||
381 | return GetMostProbable(fgPrior); | |
382 | } | |
383 | ||
384 | ||
385 | //_____________________________________________________________________________ | |
386 | void AliPID::SetPriors(const Double_t* prior, Bool_t charged) | |
387 | { | |
388 | // use the given priors as global a priori probabilities | |
389 | ||
390 | Double_t sum = 0; | |
00a38d07 | 391 | for (Int_t i = 0; i < kSPECIESCN; i++) { |
392 | if (charged && (i >= kSPECIESC)) { | |
304864ab | 393 | fgPrior[i] = 0; |
394 | } else { | |
395 | if (prior[i] < 0) { | |
396 | AliWarningClass(Form("negative prior (%g) for %ss. " | |
397 | "Using 0 instead.", prior[i], | |
398 | fgkParticleName[i])); | |
399 | fgPrior[i] = 0; | |
400 | } else { | |
401 | fgPrior[i] = prior[i]; | |
402 | } | |
403 | } | |
404 | sum += prior[i]; | |
405 | } | |
406 | if (sum == 0) { | |
407 | AliWarningClass("all priors are zero."); | |
408 | } | |
409 | } | |
410 | ||
411 | //_____________________________________________________________________________ | |
412 | void AliPID::SetPrior(EParticleType iType, Double_t prior) | |
413 | { | |
414 | // use the given prior as global a priori probability for particles | |
415 | // of type "iType" | |
416 | ||
417 | if (prior < 0) { | |
418 | AliWarningClass(Form("negative prior (%g) for %ss. Using 0 instead.", | |
419 | prior, fgkParticleName[iType])); | |
420 | prior = 0; | |
421 | } | |
422 | fgPrior[iType] = prior; | |
423 | } | |
424 | ||
425 | ||
304864ab | 426 | //_____________________________________________________________________________ |
427 | AliPID& AliPID::operator *= (const AliPID& pid) | |
428 | { | |
429 | // combine this probability densities with the one of "pid" | |
430 | ||
00a38d07 | 431 | for (Int_t i = 0; i < kSPECIESCN; i++) { |
304864ab | 432 | fProbDensity[i] *= pid.fProbDensity[i]; |
433 | } | |
434 | return *this; | |
435 | } | |
436 | ||
437 | //_____________________________________________________________________________ | |
438 | AliPID operator * (const AliPID& pid1, const AliPID& pid2) | |
439 | { | |
440 | // combine the two probability densities | |
441 | ||
442 | AliPID result; | |
443 | result *= pid1; | |
444 | result *= pid2; | |
445 | return result; | |
446 | } |