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10d100d4 | 1 | /************************************************************************** |
2 | * Copyright(c) 2005-2007, 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 | // ITS PID method # 1 | |
20 | // Implementation of the ITS PID class | |
21 | // Very naive one... Should be made better by the detector experts... | |
22 | // Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch | |
23 | //----------------------------------------------------------------- | |
24 | #include "TMath.h" | |
567624b5 | 25 | #include "AliVTrack.h" |
10d100d4 | 26 | #include "AliITSPIDResponse.h" |
27 | #include "AliITSPidParams.h" | |
28 | #include "AliExternalTrackParam.h" | |
29 | ||
10d100d4 | 30 | ClassImp(AliITSPIDResponse) |
31 | ||
15e979c9 | 32 | AliITSPIDResponse::AliITSPIDResponse(Bool_t isMC): |
10d100d4 | 33 | fRes(0.13), |
34 | fKp1(15.77), | |
35 | fKp2(4.95), | |
36 | fKp3(0.312), | |
37 | fKp4(2.14), | |
38 | fKp5(0.82) | |
39 | { | |
15e979c9 | 40 | if(!isMC){ |
41 | fBBtpcits[0]=0.73; | |
42 | fBBtpcits[1]=14.68; | |
43 | fBBtpcits[2]=0.905; | |
44 | fBBtpcits[3]=1.2; | |
45 | fBBtpcits[4]=6.6; | |
41cab740 | 46 | fBBdeu[0]=76.43; // parameters for the deuteron - tpcits - value from PbPb 2010 run (S.Trogolo - July 2014) |
47 | fBBdeu[1]=-34.21; | |
48 | fBBdeu[2]=113.2; | |
49 | fBBdeu[3]=-18.12; | |
50 | fBBdeu[4]=0.6019; | |
51 | fBBtri[0]=13.34; // parameters for the triton - tpcits - value from PbPb 2010 run (S.Trogolo - July 2014) | |
52 | fBBtri[1]=55.17; | |
53 | fBBtri[2]=66.41; | |
54 | fBBtri[3]=-6.601; | |
55 | fBBtri[4]=-0.4134; | |
62ccfebf | 56 | fBBsa[0]=2.73198E7; //pure PHOBOS parameterization |
88f46717 | 57 | fBBsa[1]=6.92389; |
58 | fBBsa[2]=1.90088E-6; | |
59 | fBBsa[3]=1.90088E-6; | |
60 | fBBsa[4]=3.40644E-7; | |
62ccfebf | 61 | fBBsaHybrid[0]=1.43505E7; //PHOBOS+Polinomial parameterization |
62 | fBBsaHybrid[1]=49.3402; | |
63 | fBBsaHybrid[2]=1.77741E-7; | |
64 | fBBsaHybrid[3]=1.77741E-7; | |
65 | fBBsaHybrid[4]=1.01311E-7; | |
66 | fBBsaHybrid[5]=77.2777; | |
67 | fBBsaHybrid[6]=33.4099; | |
68 | fBBsaHybrid[7]=46.0089; | |
69 | fBBsaHybrid[8]=-2.26583; | |
70 | fBBsaElectron[0]=4.05799E6; //electrons in the ITS | |
88f46717 | 71 | fBBsaElectron[1]=38.5713; |
72 | fBBsaElectron[2]=1.46462E-7; | |
73 | fBBsaElectron[3]=1.46462E-7; | |
74 | fBBsaElectron[4]=4.40284E-7; | |
8abeb05b | 75 | fResolSA[0]=1.; // 0 cluster tracks should not be used |
88f46717 | 76 | fResolSA[1]=0.25; // rough values for tracks with 1 |
77 | fResolSA[2]=0.131; // value from pp 2010 run (L. Milano, 16-Jun-11) | |
78 | fResolSA[3]=0.113; // value from pp 2010 run | |
8abeb05b | 79 | fResolSA[4]=0.104; // value from pp 2010 run |
15e979c9 | 80 | for(Int_t i=0; i<5;i++) fResolTPCITS[i]=0.13; |
41cab740 | 81 | fResolTPCITSDeu3[0]=0.06918; // deuteron resolution vs p |
82 | fResolTPCITSDeu3[1]=0.02498; // 3 ITS clusters for PId | |
83 | fResolTPCITSDeu3[2]=1.1; // value from PbPb 2010 run (July 2014) | |
84 | fResolTPCITSDeu4[0]=0.06756;// deuteron resolution vs p | |
85 | fResolTPCITSDeu4[1]=0.02078; // 4 ITS clusters for PId | |
86 | fResolTPCITSDeu4[2]=1.05; // value from PbPb 2010 run (July 2014) | |
87 | fResolTPCITSTri3[0]=0.07239; // triton resolution vs p | |
88 | fResolTPCITSTri3[1]=0.0192; // 3 ITS clusters for PId | |
89 | fResolTPCITSTri3[2]=1.1; // value from PbPb 2010 run (July 2014) | |
90 | fResolTPCITSTri4[0]=0.06083; // triton resolution | |
91 | fResolTPCITSTri4[1]=0.02579; // 4 ITS clusters for PId | |
92 | fResolTPCITSTri4[2]=1.15; // value from PbPb 2010 run (July 2014) | |
15e979c9 | 93 | }else{ |
99daa709 | 94 | fBBtpcits[0]=1.04; |
95 | fBBtpcits[1]=27.14; | |
96 | fBBtpcits[2]=1.00; | |
97 | fBBtpcits[3]=0.964; | |
98 | fBBtpcits[4]=2.59; | |
62ccfebf | 99 | fBBsa[0]=2.02078E7; //pure PHOBOS parameterization |
88f46717 | 100 | fBBsa[1]=14.0724; |
101 | fBBsa[2]=3.84454E-7; | |
102 | fBBsa[3]=3.84454E-7; | |
103 | fBBsa[4]=2.43913E-7; | |
62ccfebf | 104 | fBBsaHybrid[0]=1.05381E7; //PHOBOS+Polinomial parameterization |
105 | fBBsaHybrid[1]=89.3933; | |
106 | fBBsaHybrid[2]=2.4831E-7; | |
107 | fBBsaHybrid[3]=2.4831E-7; | |
108 | fBBsaHybrid[4]=7.80591E-8; | |
109 | fBBsaHybrid[5]=62.9214; | |
110 | fBBsaHybrid[6]=32.347; | |
111 | fBBsaHybrid[7]=58.7661; | |
112 | fBBsaHybrid[8]=-3.39869; | |
113 | fBBsaElectron[0]=2.26807E6; //electrons in the ITS | |
88f46717 | 114 | fBBsaElectron[1]=99.985; |
115 | fBBsaElectron[2]=0.000714841; | |
116 | fBBsaElectron[3]=0.000259585; | |
117 | fBBsaElectron[4]=1.39412E-7; | |
8abeb05b | 118 | fResolSA[0]=1.; // 0 cluster tracks should not be used |
88f46717 | 119 | fResolSA[1]=0.25; // rough values for tracks with 1 |
120 | fResolSA[2]=0.126; // value from pp 2010 simulations (L. Milano, 16-Jun-11) | |
121 | fResolSA[3]=0.109; // value from pp 2010 simulations | |
122 | fResolSA[4]=0.097; // value from pp 2010 simulations | |
15e979c9 | 123 | for(Int_t i=0; i<5;i++) fResolTPCITS[i]=0.13; |
124 | } | |
10d100d4 | 125 | } |
126 | ||
56576f1e | 127 | /* |
10d100d4 | 128 | //_________________________________________________________________________ |
129 | AliITSPIDResponse::AliITSPIDResponse(Double_t *param): | |
9ebbddd4 | 130 | fRes(param[0]), |
10d100d4 | 131 | fKp1(15.77), |
132 | fKp2(4.95), | |
133 | fKp3(0.312), | |
134 | fKp4(2.14), | |
135 | fKp5(0.82) | |
136 | { | |
137 | // | |
138 | // The main constructor | |
139 | // | |
6b4634a4 | 140 | for (Int_t i=0; i<5;i++) { |
141 | fBBsa[i]=0.; | |
142 | fBBtpcits[i]=0.; | |
143 | fResolSA[i]=0.; | |
144 | fResolTPCITS[i]=0.; | |
145 | } | |
10d100d4 | 146 | } |
56576f1e | 147 | */ |
10d100d4 | 148 | |
8abeb05b | 149 | //_________________________________________________________________________ |
15e979c9 | 150 | Double_t AliITSPIDResponse::BetheAleph(Double_t p, Double_t mass) const { |
10d100d4 | 151 | // |
152 | // returns AliExternalTrackParam::BetheBloch normalized to | |
153 | // fgMIP at the minimum | |
154 | // | |
15e979c9 | 155 | |
10d100d4 | 156 | Double_t bb= |
157 | AliExternalTrackParam::BetheBlochAleph(p/mass,fKp1,fKp2,fKp3,fKp4,fKp5); | |
9ebbddd4 | 158 | return bb; |
10d100d4 | 159 | } |
160 | ||
8abeb05b | 161 | //_________________________________________________________________________ |
41cab740 | 162 | Double_t AliITSPIDResponse::Bethe(Double_t p, Double_t mass, Bool_t isSA, Bool_t isNuclei) const { |
163 | ||
15e979c9 | 164 | // |
165 | // returns AliExternalTrackParam::BetheBloch normalized to | |
166 | // fgMIP at the minimum | |
167 | // | |
168 | ||
41cab740 | 169 | // NEW: Parameterization for Deuteron and Triton energy loss, reproduced with a polynomial in fixed p range |
170 | // fBBdeu --> parameters for deuteron | |
171 | // fBBtri --> parameters for triton | |
172 | ||
173 | ||
15e979c9 | 174 | Double_t bg=p/mass; |
175 | Double_t beta = bg/TMath::Sqrt(1.+ bg*bg); | |
176 | Double_t gamma=bg/beta; | |
62ccfebf | 177 | Double_t bb=1.; |
178 | ||
15e979c9 | 179 | Double_t par[5]; |
180 | if(isSA){ | |
41cab740 | 181 | if(TMath::AreEqualAbs(mass,AliPID::ParticleMass(0),0.00001)){ |
88f46717 | 182 | //if is an electron use a specific BB parameterization |
183 | //To be used only between 100 and 160 MeV/c | |
184 | for(Int_t ip=0; ip<5;ip++) par[ip]=fBBsaElectron[ip]; | |
185 | }else{ | |
186 | for(Int_t ip=0; ip<5;ip++) par[ip]=fBBsa[ip]; | |
187 | } | |
15e979c9 | 188 | }else{ |
41cab740 | 189 | if(isNuclei){ |
190 | if(TMath::AreEqualAbs(mass,AliPID::ParticleMass(5),0.002)) for(Int_t ip=0; ip<5;ip++) par[ip]=fBBdeu[ip]; | |
191 | if(TMath::AreEqualAbs(mass,AliPID::ParticleMass(6),0.001)) for(Int_t ip=0; ip<5;ip++) par[ip]=fBBtri[ip]; | |
192 | } | |
193 | else{ | |
194 | for(Int_t ip=0; ip<5;ip++) par[ip]=fBBtpcits[ip]; | |
195 | } | |
15e979c9 | 196 | } |
41cab740 | 197 | |
15e979c9 | 198 | Double_t eff=1.0; |
199 | if(bg<par[2]) | |
200 | eff=(bg-par[3])*(bg-par[3])+par[4]; | |
201 | else | |
202 | eff=(par[2]-par[3])*(par[2]-par[3])+par[4]; | |
88f46717 | 203 | |
15e979c9 | 204 | if(gamma>=0. && beta>0.){ |
41cab740 | 205 | if(isNuclei){ |
206 | //Parameterization for deuteron between 0.4 - 1.5 GeV/c; triton between 0.58 - 1.65 GeV/c | |
207 | bb=par[0] + par[1]/bg + par[2]/(bg*bg) + par[3]/(bg*bg*bg) + par[4]/(bg*bg*bg*bg); | |
208 | }else{ //Parameterization for pion, kaon, proton, electron | |
209 | bb=(par[1]+2.0*TMath::Log(gamma)-beta*beta)*(par[0]/(beta*beta))*eff; | |
210 | } | |
15e979c9 | 211 | } |
41cab740 | 212 | |
15e979c9 | 213 | return bb; |
214 | } | |
215 | ||
62ccfebf | 216 | //_________________________________________________________________________ |
217 | Double_t AliITSPIDResponse::BetheITSsaHybrid(Double_t p, Double_t mass) const { | |
218 | // | |
219 | // returns AliExternalTrackParam::BetheBloch normalized to | |
220 | // fgMIP at the minimum. The PHOBOS parameterization is used for beta*gamma>0.76. | |
221 | // For beta*gamma<0.76 a polinomial function is used | |
222 | ||
223 | Double_t bg=p/mass; | |
224 | Double_t beta = bg/TMath::Sqrt(1.+ bg*bg); | |
225 | Double_t gamma=bg/beta; | |
226 | Double_t bb=1.; | |
227 | ||
228 | Double_t par[9]; | |
229 | //parameters for pi, K, p | |
230 | for(Int_t ip=0; ip<9;ip++) par[ip]=fBBsaHybrid[ip]; | |
231 | //if it is an electron the PHOBOS part of the parameterization is tuned for e | |
232 | //in the range used for identification beta*gamma is >0.76 for electrons | |
233 | //To be used only between 100 and 160 MeV/c | |
234 | if(mass>0.0005 && mass<0.00052)for(Int_t ip=0; ip<5;ip++) par[ip]=fBBsaElectron[ip]; | |
235 | ||
236 | if(gamma>=0. && beta>0. && bg>0.1){ | |
237 | if(bg>0.76){//PHOBOS | |
238 | Double_t eff=1.0; | |
239 | if(bg<par[2]) | |
240 | eff=(bg-par[3])*(bg-par[3])+par[4]; | |
241 | else | |
242 | eff=(par[2]-par[3])*(par[2]-par[3])+par[4]; | |
243 | ||
244 | bb=(par[1]+2.0*TMath::Log(gamma)-beta*beta)*(par[0]/(beta*beta))*eff; | |
245 | }else{//Polinomial | |
246 | bb=par[5] + par[6]/bg + par[7]/(bg*bg) + par[8]/(bg*bg*bg); | |
247 | } | |
248 | } | |
249 | return bb; | |
250 | } | |
251 | ||
8abeb05b | 252 | //_________________________________________________________________________ |
41cab740 | 253 | Double_t AliITSPIDResponse::GetResolution(Double_t bethe, |
15e979c9 | 254 | Int_t nPtsForPid, |
41cab740 | 255 | Bool_t isSA, |
256 | Double_t p, | |
257 | AliPID::EParticleType type) const { | |
258 | // | |
10d100d4 | 259 | // Calculate expected resolution for truncated mean |
260 | // | |
41cab740 | 261 | // NEW: Added new variables which are Double_t p and AliPID::EParticleType type |
262 | // AliPID::EParticleType type is used to set the correct resolution for the different particles | |
263 | // default -> AliPID::EParticleType type = AliPID::kPion | |
264 | // Double_t p is used for the resolution of deuteron and triton, because they are function of the momentum | |
265 | // default -> Double_t p=0. | |
266 | ||
15e979c9 | 267 | Float_t r; |
41cab740 | 268 | Float_t c=1.; //this is a correction factor used for the nuclei resolution, while for pion/kaon/proton/electron is 1. |
269 | Double_t par[3]; | |
270 | ||
15e979c9 | 271 | if(isSA) r=fResolSA[nPtsForPid]; |
41cab740 | 272 | else{ |
273 | if(AliPID::ParticleMass(type)>=AliPID::ParticleMass(5)){ //if mass >= mass_deu -->resolution for nuclei is selected | |
274 | if(type==AliPID::kDeuteron){ | |
275 | if(nPtsForPid==3) for(Int_t j=0; j<3; j++) par[j] = fResolTPCITSDeu3[j]; | |
276 | if(nPtsForPid==4) for(Int_t j=0; j<3; j++) par[j] = fResolTPCITSDeu4[j]; | |
277 | c=par[2]; | |
278 | } | |
279 | if(type==AliPID::kTriton){ | |
280 | if(nPtsForPid==3) for(Int_t j=0; j<3; j++) par[j] = fResolTPCITSTri3[j]; | |
281 | if(nPtsForPid==4) for(Int_t j=0; j<3; j++) par[j] = fResolTPCITSTri4[j]; | |
282 | c=par[2]; | |
283 | } | |
10d100d4 | 284 | |
41cab740 | 285 | r=par[0]+par[1]*p; |
286 | } | |
287 | else r=fResolTPCITS[nPtsForPid]; | |
288 | } | |
15e979c9 | 289 | |
41cab740 | 290 | return r*bethe*c; |
291 | } | |
15e979c9 | 292 | |
293 | ||
8abeb05b | 294 | //_________________________________________________________________________ |
b52bfc67 | 295 | void AliITSPIDResponse::GetITSProbabilities(Float_t mom, Double_t qclu[4], Double_t condprobfun[AliPID::kSPECIES], Bool_t isMC) const { |
10d100d4 | 296 | // |
297 | // Method to calculate PID probabilities for a single track | |
298 | // using the likelihood method | |
299 | // | |
300 | const Int_t nLay = 4; | |
2ca1f4ee | 301 | const Int_t nPart= 4; |
10d100d4 | 302 | |
b52bfc67 | 303 | static AliITSPidParams pars(isMC); // Pid parametrisation parameters |
10d100d4 | 304 | |
2ca1f4ee | 305 | Double_t itsProb[nPart] = {1,1,1,1}; // e, p, K, pi |
10d100d4 | 306 | |
307 | for (Int_t iLay = 0; iLay < nLay; iLay++) { | |
2ca1f4ee | 308 | if (qclu[iLay] <= 50.) |
10d100d4 | 309 | continue; |
310 | ||
311 | Float_t dedx = qclu[iLay]; | |
312 | Float_t layProb = pars.GetLandauGausNorm(dedx,AliPID::kProton,mom,iLay+3); | |
313 | itsProb[0] *= layProb; | |
314 | ||
315 | layProb = pars.GetLandauGausNorm(dedx,AliPID::kKaon,mom,iLay+3); | |
10d100d4 | 316 | itsProb[1] *= layProb; |
317 | ||
318 | layProb = pars.GetLandauGausNorm(dedx,AliPID::kPion,mom,iLay+3); | |
319 | itsProb[2] *= layProb; | |
2ca1f4ee | 320 | |
321 | layProb = pars.GetLandauGausNorm(dedx,AliPID::kElectron,mom,iLay+3); | |
322 | itsProb[3] *= layProb; | |
10d100d4 | 323 | } |
324 | ||
325 | // Normalise probabilities | |
326 | Double_t sumProb = 0; | |
327 | for (Int_t iPart = 0; iPart < nPart; iPart++) { | |
328 | sumProb += itsProb[iPart]; | |
329 | } | |
2ca1f4ee | 330 | sumProb += itsProb[2]; // muon cannot be distinguished from pions |
10d100d4 | 331 | |
332 | for (Int_t iPart = 0; iPart < nPart; iPart++) { | |
333 | itsProb[iPart]/=sumProb; | |
334 | } | |
2ca1f4ee | 335 | condprobfun[AliPID::kElectron] = itsProb[3]; |
897a0e31 | 336 | condprobfun[AliPID::kMuon] = itsProb[2]; |
337 | condprobfun[AliPID::kPion] = itsProb[2]; | |
10d100d4 | 338 | condprobfun[AliPID::kKaon] = itsProb[1]; |
339 | condprobfun[AliPID::kProton] = itsProb[0]; | |
340 | return; | |
341 | } | |
15e979c9 | 342 | |
567624b5 | 343 | //_________________________________________________________________________ |
344 | Double_t AliITSPIDResponse::GetNumberOfSigmas( const AliVTrack* track, AliPID::EParticleType type) const | |
345 | { | |
346 | // | |
347 | // number of sigmas | |
348 | // | |
349 | UChar_t clumap=track->GetITSClusterMap(); | |
350 | Int_t nPointsForPid=0; | |
351 | for(Int_t i=2; i<6; i++){ | |
352 | if(clumap&(1<<i)) ++nPointsForPid; | |
353 | } | |
354 | Float_t mom=track->P(); | |
355 | ||
356 | //check for ITS standalone tracks | |
357 | Bool_t isSA=kTRUE; | |
358 | if( track->GetStatus() & AliVTrack::kTPCin ) isSA=kFALSE; | |
359 | ||
360 | const Float_t dEdx=track->GetITSsignal(); | |
361 | ||
362 | //TODO: in case of the electron, use the SA parametrisation, | |
363 | // this needs to be changed if ITS provides a parametrisation | |
364 | // for electrons also for ITS+TPC tracks | |
365 | return GetNumberOfSigmas(mom,dEdx,type,nPointsForPid,isSA || (type==AliPID::kElectron)); | |
366 | } | |
367 | ||
368 | //_________________________________________________________________________ | |
1d59271b | 369 | Double_t AliITSPIDResponse::GetSignalDelta( const AliVTrack* track, AliPID::EParticleType type, Bool_t ratio/*=kFALSE*/) const |
567624b5 | 370 | { |
371 | // | |
372 | // Signal - expected | |
373 | // | |
374 | const Float_t mom=track->P(); | |
375 | const Double_t chargeFactor = TMath::Power(AliPID::ParticleCharge(type),2.); | |
376 | Bool_t isSA=kTRUE; | |
377 | if( track->GetStatus() & AliVTrack::kTPCin ) isSA=kFALSE; | |
378 | ||
379 | const Float_t dEdx=track->GetITSsignal(); | |
380 | ||
381 | //TODO: in case of the electron, use the SA parametrisation, | |
382 | // this needs to be changed if ITS provides a parametrisation | |
383 | // for electrons also for ITS+TPC tracks | |
384 | ||
1d59271b | 385 | const Float_t bethe = Bethe(mom,AliPID::ParticleMassZ(type), isSA || (type==AliPID::kElectron))*chargeFactor; |
386 | ||
387 | Double_t delta=-9999.; | |
388 | if (!ratio) delta=dEdx-bethe; | |
389 | else if (bethe>1.e-20) delta=dEdx/bethe; | |
390 | ||
391 | return delta; | |
567624b5 | 392 | } |
393 | ||
8abeb05b | 394 | //_________________________________________________________________________ |
395 | Int_t AliITSPIDResponse::GetParticleIdFromdEdxVsP(Float_t mom, Float_t signal, Bool_t isSA) const{ | |
396 | // method to get particle identity with simple cuts on dE/dx vs. momentum | |
397 | ||
398 | Double_t massp=AliPID::ParticleMass(AliPID::kProton); | |
399 | Double_t massk=AliPID::ParticleMass(AliPID::kKaon); | |
400 | Double_t bethep=Bethe(mom,massp,isSA); | |
401 | Double_t bethek=Bethe(mom,massk,isSA); | |
402 | if(signal>(0.5*(bethep+bethek))) return AliPID::kProton; | |
403 | Double_t masspi=AliPID::ParticleMass(AliPID::kPion); | |
404 | Double_t bethepi=Bethe(mom,masspi,isSA); | |
405 | if(signal>(0.5*(bethepi+bethek))) return AliPID::kKaon; | |
406 | return AliPID::kPion; | |
407 | ||
408 | } |