Merge branch 'master' of https://git.cern.ch/reps/AliRoot
[u/mrichter/AliRoot.git] / TRD / AliTRDpidESD.cxx
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b0f03c34 1/**************************************************************************
0d83b3a5 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**************************************************************************/
b0f03c34 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. //
c8ab4518 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 : //
c8ab4518 29// Prashant Shukla <shukla@pi0.physi.uni-heidelberg.de> (orig. version) //
30// Alex Bercuci (a.bercuci@gsi.de) //
b52cb1b6 31// //
32////////////////////////////////////////////////////////////////////////////
b0f03c34 33
af885e0f 34#include "AliESDEvent.h"
b0f03c34 35#include "AliESDtrack.h"
c6011b06 36#include "AliTracker.h"
b52cb1b6 37
38#include "AliTRDpidESD.h"
39#include "AliTRDgeometry.h"
cc7cef99 40#include "AliTRDcalibDB.h"
4d6aee34 41#include "Cal/AliTRDCalPID.h"
b0f03c34 42
43ClassImp(AliTRDpidESD)
44
c8ab4518 45Bool_t AliTRDpidESD::fgCheckTrackStatus = kTRUE;
46Bool_t AliTRDpidESD::fgCheckKinkStatus = kFALSE;
47Int_t AliTRDpidESD::fgMinPlane = 0;
df34b21e 48
b52cb1b6 49//_____________________________________________________________________________
dab811d0 50AliTRDpidESD::AliTRDpidESD()
c8ab4518 51 :TObject()
4d6aee34 52 ,fTrack(NULL)
b0f03c34 53{
54 //
b52cb1b6 55 // Default constructor
b0f03c34 56 //
b52cb1b6 57
b0f03c34 58}
59
b52cb1b6 60//_____________________________________________________________________________
dab811d0 61AliTRDpidESD::AliTRDpidESD(const AliTRDpidESD &p)
c8ab4518 62 :TObject(p)
4d6aee34 63 ,fTrack(NULL)
eab5961e 64{
b0f03c34 65 //
b52cb1b6 66 // AliTRDpidESD copy constructor
b0f03c34 67 //
eab5961e 68
b52cb1b6 69 ((AliTRDpidESD &) p).Copy(*this);
70
71}
72
73//_____________________________________________________________________________
c6011b06 74AliTRDpidESD::~AliTRDpidESD()
75{
76 //
77 // Destructor
78 //
c8ab4518 79
80 if(fTrack) delete fTrack;
81
c6011b06 82}
83
84//_____________________________________________________________________________
b52cb1b6 85AliTRDpidESD &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//_____________________________________________________________________________
97void AliTRDpidESD::Copy(TObject &p) const
98{
99 //
100 // Copy function
101 //
102
c8ab4518 103 ((AliTRDpidESD &) p).fgCheckTrackStatus = fgCheckTrackStatus;
104 ((AliTRDpidESD &) p).fgCheckKinkStatus = fgCheckKinkStatus;
105 ((AliTRDpidESD &) p).fgMinPlane = fgMinPlane;
4d6aee34 106 ((AliTRDpidESD &) p).fTrack = NULL;
0d83b3a5 107
b0f03c34 108}
109
b52cb1b6 110//_____________________________________________________________________________
14a65137 111Int_t AliTRDpidESD::MakePID(AliESDEvent * const event)
b0f03c34 112{
113 //
b52cb1b6 114 // This function calculates the PID probabilities based on TRD signals
b0f03c34 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
c8ab4518 124 //
dab811d0 125
0d83b3a5 126 AliTRDcalibDB *calibration = AliTRDcalibDB::Instance();
127 if (!calibration) {
128 AliErrorGeneral("AliTRDpidESD::MakePID()"
129 ,"No access to calibration data");
130 return -1;
131 }
132
3a039a31 133// AliTRDrecoParam *rec = AliTRDReconstructor::RecoParam();
134// if (!rec) {
135// AliErrorGeneral("AliTRDpidESD::MakePID()", "No TRD reco param.");
136// return 0x0;
137// }
4ba1d6ae 138
0d83b3a5 139 // Retrieve the CDB container class with the probability distributions
140 const AliTRDCalPID *pd = calibration->GetPIDObject(AliTRDpidUtil::kLQ);
141 if (!pd) {
142 AliErrorGeneral("AliTRDpidESD::MakePID()"
143 ,"No access to AliTRDCalPID");
144 return -1;
145 }
146
147 // Loop through all ESD tracks
148 Double_t p[10];
4d6aee34 149 AliESDtrack *t = NULL;
150 Float_t dedx[AliTRDCalPID::kNSlicesLQ], dEdx;
0d83b3a5 151 Int_t timebin;
152 Float_t mom, length;
153 Int_t nPlanePID;
154 for (Int_t i=0; i<event->GetNumberOfTracks(); i++) {
155 t = event->GetTrack(i);
156
157 // Check track
158 if(!CheckTrack(t)) continue;
159
160
161 // Skip tracks which have no TRD signal at all
d8069611 162 if (t->GetTRDsignal()<1.e-5) continue;
0d83b3a5 163
164 // Loop over detector layers
165 mom = 0.;
166 length = 0.;
167 nPlanePID = 0;
168 for (Int_t iSpecies = 0; iSpecies < AliPID::kSPECIES; iSpecies++)
c8ab4518 169 p[iSpecies] = 1./AliPID::kSPECIES;
170
0d83b3a5 171 for (Int_t iLayer = 0; iLayer < AliTRDgeometry::kNlayer; iLayer++) {
172 // read data for track segment
4d6aee34 173 for(int iSlice=0; iSlice<AliTRDCalPID::kNSlicesLQ; iSlice++)
0d83b3a5 174 dedx[iSlice] = t->GetTRDslice(iLayer, iSlice);
175 dEdx = t->GetTRDslice(iLayer, -1);
176 timebin = t->GetTRDTimBin(iLayer);
177
178 // check data
179 if ((dEdx <= 0.) || (timebin <= -1.)) continue;
180
181 // retrive kinematic info for this track segment
182 if(!RecalculateTrackSegmentKine(t, iLayer, mom, length)){
183 // information is not fully reliable especialy for length
184 // estimation. To be used in the future.
185 }
186
187 // this track segment has fulfilled all requierments
188 nPlanePID++;
189
190 // Get the probabilities for the different particle species
191 for (Int_t iSpecies = 0; iSpecies < AliPID::kSPECIES; iSpecies++) {
192 p[iSpecies] *= pd->GetProbability(iSpecies, mom, dedx, length, iLayer);
193 //p[iSpecies] *= pd->GetProbabilityT(iSpecies, mom, timebin);
194 }
195 }
196 if(nPlanePID == 0) continue;
197
198 // normalize probabilities
199 Double_t probTotal = 0.;
200 for (Int_t iSpecies = 0; iSpecies < AliPID::kSPECIES; iSpecies++) probTotal += p[iSpecies];
201 if(probTotal <= 0.){
202 AliWarning(Form("The total probability (%e) over all species <= 0 in ESD track %d."
203 , probTotal, i));
204 AliWarning("This may be caused by some error in reference data.");
205 AliWarning("Calculation continues but results might be corrupted.");
206 continue;
207 }
208 for(Int_t iSpecies = 0; iSpecies < AliPID::kSPECIES; iSpecies++) p[iSpecies] /= probTotal;
209
210 // book PID to the track
211 t->SetTRDpid(p);
ed15ef4f 212 t->SetTRDntracklets(nPlanePID<<3);
0d83b3a5 213 }
214
215 return 0;
c8ab4518 216
dab811d0 217}
b52cb1b6 218
dab811d0 219//_____________________________________________________________________________
14a65137 220Bool_t AliTRDpidESD::CheckTrack(AliESDtrack * const t)
dab811d0 221{
222 //
223 // Check if track is eligible for PID calculations
224 //
0d83b3a5 225
226 // Check the ESD track status
227 if (fgCheckTrackStatus) {
228 if (((t->GetStatus() & AliESDtrack::kTRDout ) == 0) &&
229 ((t->GetStatus() & AliESDtrack::kTRDrefit) == 0)) return kFALSE;
230 }
b52cb1b6 231
0d83b3a5 232 // Check for ESD kink tracks
233 if (fgCheckKinkStatus && (t->GetKinkIndex(0) != 0)) return kFALSE;
b52cb1b6 234
0d83b3a5 235 return kTRUE;
c8ab4518 236
dab811d0 237}
b52cb1b6 238
dab811d0 239//_____________________________________________________________________________
14a65137 240Bool_t AliTRDpidESD::RecalculateTrackSegmentKine(AliESDtrack * const esd
0d83b3a5 241 , Int_t layer
242 , Float_t &mom
243 , Float_t &length)
dab811d0 244{
245 //
246 // Retrive momentum "mom" and track "length" in TRD chamber from plane
247 // "plan" according to information stored in AliESDtrack "t".
c6011b06 248 //
249 // Origin
250 // Alex Bercuci (A.Bercuci@gsi.de)
c8ab4518 251 //
dab811d0 252
0d83b3a5 253 const Float_t kAmHalfWidth = AliTRDgeometry::AmThick() / 2.;
f162af62 254 const Float_t kDrWidth = AliTRDgeometry::DrThick();
0d83b3a5 255 const Float_t kTime0 = AliTRDgeometry::GetTime0(layer);
256
257 // set initial length value to chamber height
258 length = 2 * kAmHalfWidth + kDrWidth;
259
260 // retrive track's outer param
261 const AliExternalTrackParam *op = esd->GetOuterParam();
262 if(!op){
263 mom = esd->GetP();
264 return kFALSE;
265 }
266
4d6aee34 267 AliExternalTrackParam *param = NULL;
0d83b3a5 268 if(!fTrack){
269 fTrack = new AliExternalTrackParam(*op);
270 param = fTrack;
271 } else param = new(fTrack) AliExternalTrackParam(*op);
272
273 // retrive the magnetic field
274 Double_t xyz0[3];
275 op->GetXYZ(xyz0);
276 Float_t field = AliTracker::GetBz(xyz0); // Bz in kG at point xyz0
277 Double_t s, t;
278
279 // propagate to chamber entrance
280 if(!param->PropagateTo(kTime0-kAmHalfWidth-kDrWidth, field)){
281 mom = op->GetP();
282 s = op->GetSnp();
283 t = op->GetTgl();
bfd20868 284 if (s < 1.) length /= TMath::Sqrt((1.-s)*(1.+s) / (1. + t*t));
0d83b3a5 285 return kFALSE;
286 }
287 mom = param->GetP();
288 s = param->GetSnp();
289 t = param->GetTgl();
bfd20868 290 if (s < 1.) length /= TMath::Sqrt((1.-s)*(1.+s) / (1. + t*t));
0d83b3a5 291
292 // check if track is crossing tracking sector by propagating to chamber exit- maybe is too much :)
293 Double_t alpha = param->GetAlpha();
294 if(!param->PropagateTo(kTime0+kAmHalfWidth, field)) return kFALSE;
295
296 // mark track segments which are crossing SM boundaries along chamber
297 if(TMath::Abs(alpha-param->GetAlpha())>.01) return kFALSE;
298
299 return kTRUE;
dab811d0 300
c8ab4518 301}