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b0f03c34 | 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 | ||
dab811d0 | 16 | /* $Id$ */ |
17 | ||
b52cb1b6 | 18 | //////////////////////////////////////////////////////////////////////////// |
19 | // // | |
20 | // Implementation of the TRD PID class // | |
21 | // // | |
22 | // Assigns the electron and pion likelihoods to each ESD track. // | |
af885e0f | 23 | // The function MakePID(AliESDEvent *event) calculates the probability // |
b52cb1b6 | 24 | // of having dedx and a maximum timbin at a given // |
25 | // momentum (mom) and particle type k // | |
26 | // from the precalculated distributions. // | |
27 | // // | |
dab811d0 | 28 | // Authors : // |
29 | // Prashant Shukla <shukla@pi0.physi.uni-heidelberg.de> (Original version)// | |
30 | // Alex Bercuci (a.bercuci@gsi.de) // | |
b52cb1b6 | 31 | // // |
32 | //////////////////////////////////////////////////////////////////////////// | |
b0f03c34 | 33 | |
b52cb1b6 | 34 | #include "AliLog.h" |
af885e0f | 35 | #include "AliESDEvent.h" |
b0f03c34 | 36 | #include "AliESDtrack.h" |
c6011b06 | 37 | #include "AliTracker.h" |
b52cb1b6 | 38 | |
39 | #include "AliTRDpidESD.h" | |
40 | #include "AliTRDgeometry.h" | |
cc7cef99 | 41 | #include "AliTRDcalibDB.h" |
dab811d0 | 42 | #include "AliRun.h" |
43 | #include "AliTRDtrack.h" | |
720a0a16 | 44 | #include "Cal/AliTRDCalPID.h" |
b0f03c34 | 45 | |
c6011b06 | 46 | |
b0f03c34 | 47 | ClassImp(AliTRDpidESD) |
48 | ||
df34b21e | 49 | Bool_t AliTRDpidESD::fCheckTrackStatus = kTRUE; |
50 | Bool_t AliTRDpidESD::fCheckKinkStatus = kFALSE; | |
85815482 | 51 | Int_t AliTRDpidESD::fMinPlane = 0; |
df34b21e | 52 | |
b52cb1b6 | 53 | //_____________________________________________________________________________ |
dab811d0 | 54 | AliTRDpidESD::AliTRDpidESD() |
c6011b06 | 55 | :TObject(), fTrack(0x0) |
b0f03c34 | 56 | { |
57 | // | |
b52cb1b6 | 58 | // Default constructor |
b0f03c34 | 59 | // |
b52cb1b6 | 60 | |
b0f03c34 | 61 | } |
62 | ||
b52cb1b6 | 63 | //_____________________________________________________________________________ |
dab811d0 | 64 | AliTRDpidESD::AliTRDpidESD(const AliTRDpidESD &p) |
c6011b06 | 65 | :TObject(p), fTrack(0x0) |
eab5961e | 66 | { |
b0f03c34 | 67 | // |
b52cb1b6 | 68 | // AliTRDpidESD copy constructor |
b0f03c34 | 69 | // |
eab5961e | 70 | |
b52cb1b6 | 71 | ((AliTRDpidESD &) p).Copy(*this); |
72 | ||
73 | } | |
74 | ||
c6011b06 | 75 | //_____________________________________________________________________________ |
76 | AliTRDpidESD::~AliTRDpidESD() | |
77 | { | |
78 | // | |
79 | // Destructor | |
80 | // | |
81 | if(fTrack) delete fTrack; | |
82 | } | |
83 | ||
b52cb1b6 | 84 | //_____________________________________________________________________________ |
85 | AliTRDpidESD &AliTRDpidESD::operator=(const AliTRDpidESD &p) | |
86 | { | |
87 | // | |
88 | // Assignment operator | |
89 | // | |
90 | ||
91 | if (this != &p) ((AliTRDpidESD &) p).Copy(*this); | |
92 | return *this; | |
93 | ||
94 | } | |
95 | ||
96 | //_____________________________________________________________________________ | |
97 | void AliTRDpidESD::Copy(TObject &p) const | |
98 | { | |
99 | // | |
100 | // Copy function | |
101 | // | |
102 | ||
25ca55ce | 103 | ((AliTRDpidESD &) p).fCheckTrackStatus = fCheckTrackStatus; |
104 | ((AliTRDpidESD &) p).fCheckKinkStatus = fCheckKinkStatus; | |
105 | ((AliTRDpidESD &) p).fMinPlane = fMinPlane; | |
c6011b06 | 106 | ((AliTRDpidESD &) p).fTrack = 0x0; |
107 | ||
b0f03c34 | 108 | } |
109 | ||
b52cb1b6 | 110 | //_____________________________________________________________________________ |
af885e0f | 111 | Int_t AliTRDpidESD::MakePID(AliESDEvent *event) |
bd50219c | 112 | { |
113 | // | |
b52cb1b6 | 114 | // This function calculates the PID probabilities based on TRD signals |
bd50219c | 115 | // |
dab811d0 | 116 | // The method produces probabilities based on the charge |
117 | // and the position of the maximum time bin in each layer. | |
118 | // The dE/dx information can be used as global charge or 2 to 3 | |
720a0a16 | 119 | // slices. Check AliTRDCalPID and AliTRDCalPIDRefMaker for the actual |
dab811d0 | 120 | // implementation. |
121 | // | |
122 | // Author | |
123 | // Alex Bercuci (A.Bercuci@gsi.de) 2nd May 2007 | |
124 | ||
125 | AliTRDcalibDB *calibration = AliTRDcalibDB::Instance(); | |
126 | if (!calibration) { | |
127 | AliErrorGeneral("AliTRDpidESD::MakePID()" | |
128 | ,"No access to calibration data"); | |
129 | return -1; | |
130 | } | |
131 | ||
132 | // Retrieve the CDB container class with the probability distributions | |
720a0a16 | 133 | const AliTRDCalPID *pd = calibration->GetPIDLQObject(); |
dab811d0 | 134 | if (!pd) { |
135 | AliErrorGeneral("AliTRDpidESD::MakePID()" | |
720a0a16 | 136 | ,"No access to AliTRDCalPID"); |
dab811d0 | 137 | return -1; |
b52cb1b6 | 138 | } |
139 | ||
dab811d0 | 140 | // Loop through all ESD tracks |
141 | Double_t p[10]; | |
142 | AliESDtrack *t = 0x0; | |
c6011b06 | 143 | Float_t dedx[AliTRDtrack::kNslice], dEdx; |
144 | Int_t timebin; | |
145 | Float_t mom, length; | |
146 | Int_t nPlanePID; | |
dab811d0 | 147 | for (Int_t i=0; i<event->GetNumberOfTracks(); i++) { |
148 | t = event->GetTrack(i); | |
c6011b06 | 149 | |
dab811d0 | 150 | // Check track |
151 | if(!CheckTrack(t)) continue; | |
c6011b06 | 152 | |
dab811d0 | 153 | |
154 | // Skip tracks which have no TRD signal at all | |
155 | if (t->GetTRDsignal() == 0.) continue; | |
156 | ||
157 | // Loop over detector layers | |
c6011b06 | 158 | mom = 0.; |
159 | length = 0.; | |
dab811d0 | 160 | nPlanePID = 0; |
c6011b06 | 161 | for (Int_t iSpecies = 0; iSpecies < AliPID::kSPECIES; iSpecies++) p[iSpecies] = 1./AliPID::kSPECIES; |
dab811d0 | 162 | for (Int_t iPlan = 0; iPlan < AliTRDgeometry::kNplan; iPlan++) { |
163 | // read data for track segment | |
164 | for(int iSlice=0; iSlice<AliTRDtrack::kNslice; iSlice++) | |
165 | dedx[iSlice] = t->GetTRDsignals(iPlan, iSlice); | |
166 | dEdx = t->GetTRDsignals(iPlan, -1); | |
167 | timebin = t->GetTRDTimBin(iPlan); | |
168 | ||
169 | // check data | |
170 | if ((dEdx <= 0.) || (timebin <= -1.)) continue; | |
171 | ||
172 | // retrive kinematic info for this track segment | |
c8b2a461 | 173 | if(!RecalculateTrackSegmentKine(t, iPlan, mom, length)){ |
174 | // information is not fully reliable especialy for length | |
175 | // estimation. To be used in the future. | |
176 | } | |
dab811d0 | 177 | |
178 | // this track segment has fulfilled all requierments | |
179 | nPlanePID++; | |
c8b2a461 | 180 | |
dab811d0 | 181 | // Get the probabilities for the different particle species |
182 | for (Int_t iSpecies = 0; iSpecies < AliPID::kSPECIES; iSpecies++) { | |
183 | p[iSpecies] *= pd->GetProbability(iSpecies, mom, dedx, length); | |
c6011b06 | 184 | //p[iSpecies] *= pd->GetProbabilityT(iSpecies, mom, timebin); |
dab811d0 | 185 | } |
186 | } | |
c6011b06 | 187 | if(nPlanePID == 0) continue; |
188 | ||
dab811d0 | 189 | // normalize probabilities |
c6011b06 | 190 | Double_t probTotal = 0.; |
191 | for (Int_t iSpecies = 0; iSpecies < AliPID::kSPECIES; iSpecies++) probTotal += p[iSpecies]; | |
192 | if(probTotal <= 0.){ | |
c8b2a461 | 193 | AliWarningGeneral("AliTRDpidESD::MakePID()", Form("The total probability (%e) over all species <= 0 in ESD track %d. This may be caused by some error in reference data. Calculation continue but results might be corrupted.", probTotal, i)); |
c6011b06 | 194 | continue; |
195 | } | |
196 | for(Int_t iSpecies = 0; iSpecies < AliPID::kSPECIES; iSpecies++) p[iSpecies] /= probTotal; | |
dab811d0 | 197 | |
198 | // book PID to the track | |
199 | t->SetTRDpid(p); | |
c6011b06 | 200 | t->SetTRDpidQuality(nPlanePID); |
dab811d0 | 201 | } |
202 | ||
203 | return 0; | |
204 | } | |
b52cb1b6 | 205 | |
dab811d0 | 206 | //_____________________________________________________________________________ |
207 | Bool_t AliTRDpidESD::CheckTrack(AliESDtrack *t) | |
208 | { | |
209 | // | |
210 | // Check if track is eligible for PID calculations | |
211 | // | |
212 | ||
213 | // Check the ESD track status | |
214 | if (fCheckTrackStatus) { | |
215 | if (((t->GetStatus() & AliESDtrack::kTRDout ) == 0) && | |
216 | ((t->GetStatus() & AliESDtrack::kTRDrefit) == 0)) return kFALSE; | |
217 | } | |
b52cb1b6 | 218 | |
dab811d0 | 219 | // Check for ESD kink tracks |
220 | if (fCheckKinkStatus && (t->GetKinkIndex(0) != 0)) return kFALSE; | |
b52cb1b6 | 221 | |
dab811d0 | 222 | return kTRUE; |
223 | } | |
b52cb1b6 | 224 | |
dab811d0 | 225 | //_____________________________________________________________________________ |
c6011b06 | 226 | Bool_t AliTRDpidESD::RecalculateTrackSegmentKine(AliESDtrack *esd, Int_t plan, Float_t &mom, Float_t &length) |
dab811d0 | 227 | { |
228 | // | |
229 | // Retrive momentum "mom" and track "length" in TRD chamber from plane | |
230 | // "plan" according to information stored in AliESDtrack "t". | |
c6011b06 | 231 | // |
232 | // Origin | |
233 | // Alex Bercuci (A.Bercuci@gsi.de) | |
dab811d0 | 234 | |
dab811d0 | 235 | const Float_t kAmHalfWidth = AliTRDgeometry::AmThick() / 2.; |
f162af62 | 236 | const Float_t kDrWidth = AliTRDgeometry::DrThick(); |
c6011b06 | 237 | const Float_t kTime0 = AliTRDgeometry::GetTime0(plan); |
dab811d0 | 238 | |
c6011b06 | 239 | // set initial length value to chamber height |
240 | length = 2 * kAmHalfWidth + kDrWidth; | |
dab811d0 | 241 | |
c6011b06 | 242 | // retrive track's outer param |
243 | const AliExternalTrackParam *op = esd->GetOuterParam(); | |
244 | if(!op){ | |
245 | mom = esd->GetP(); | |
dab811d0 | 246 | return kFALSE; |
247 | } | |
dab811d0 | 248 | |
c6011b06 | 249 | AliExternalTrackParam *param = 0x0; |
250 | if(!fTrack){ | |
251 | fTrack = new AliExternalTrackParam(*op); | |
252 | param = fTrack; | |
c8b2a461 | 253 | } else param = new(fTrack) AliExternalTrackParam(*op); |
254 | ||
c6011b06 | 255 | // retrive the magnetic field |
256 | Double_t xyz0[3]; | |
257 | op->GetXYZ(xyz0); | |
258 | Float_t field = AliTracker::GetBz(xyz0); // Bz in kG at point xyz0 | |
c8b2a461 | 259 | Double_t s, t; |
260 | ||
c6011b06 | 261 | // propagate to chamber entrance |
262 | if(!param->PropagateTo(kTime0-kAmHalfWidth-kDrWidth, field)){ | |
c8b2a461 | 263 | mom = op->GetP(); |
264 | s = op->GetSnp(); | |
265 | t = op->GetTgl(); | |
01d8ed58 | 266 | if (s < 1.) length /= TMath::Sqrt((1. - s*s) / (1. + t*t)); |
c6011b06 | 267 | return kFALSE; |
268 | } | |
269 | mom = param->GetP(); | |
c8b2a461 | 270 | s = param->GetSnp(); |
271 | t = param->GetTgl(); | |
01d8ed58 | 272 | if (s < 1.) length /= TMath::Sqrt((1. - s*s) / (1. + t*t)); |
c6011b06 | 273 | |
274 | // check if track is crossing tracking sector by propagating to chamber exit- maybe is too much :) | |
275 | Double_t alpha = param->GetAlpha(); | |
276 | if(!param->PropagateTo(kTime0+kAmHalfWidth, field)) return kFALSE; | |
277 | ||
278 | // mark track segments which are crossing SM boundaries along chamber | |
279 | if(TMath::Abs(alpha-param->GetAlpha())>.01) return kFALSE; | |
280 | ||
dab811d0 | 281 | return kTRUE; |
b0f03c34 | 282 | } |
dab811d0 | 283 |