more methods use the correction framework
[u/mrichter/AliRoot.git] / TRD / AliTRDpidESD.cxx
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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. *
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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 *
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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. //
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
b52cb1b6 34#include "AliLog.h"
af885e0f 35#include "AliESDEvent.h"
b0f03c34 36#include "AliESDtrack.h"
c6011b06 37#include "AliTracker.h"
c8ab4518 38#include "AliRun.h"
b52cb1b6 39
4ba1d6ae 40#include "AliTRDReconstructor.h"
b52cb1b6 41#include "AliTRDpidESD.h"
42#include "AliTRDgeometry.h"
cc7cef99 43#include "AliTRDcalibDB.h"
dab811d0 44#include "AliTRDtrack.h"
720a0a16 45#include "Cal/AliTRDCalPID.h"
b0f03c34 46
47ClassImp(AliTRDpidESD)
48
c8ab4518 49Bool_t AliTRDpidESD::fgCheckTrackStatus = kTRUE;
50Bool_t AliTRDpidESD::fgCheckKinkStatus = kFALSE;
51Int_t AliTRDpidESD::fgMinPlane = 0;
df34b21e 52
b52cb1b6 53//_____________________________________________________________________________
dab811d0 54AliTRDpidESD::AliTRDpidESD()
c8ab4518 55 :TObject()
56 ,fTrack(0x0)
b0f03c34 57{
58 //
b52cb1b6 59 // Default constructor
b0f03c34 60 //
b52cb1b6 61
b0f03c34 62}
63
b52cb1b6 64//_____________________________________________________________________________
dab811d0 65AliTRDpidESD::AliTRDpidESD(const AliTRDpidESD &p)
c8ab4518 66 :TObject(p)
67 ,fTrack(0x0)
eab5961e 68{
b0f03c34 69 //
b52cb1b6 70 // AliTRDpidESD copy constructor
b0f03c34 71 //
eab5961e 72
b52cb1b6 73 ((AliTRDpidESD &) p).Copy(*this);
74
75}
76
77//_____________________________________________________________________________
c6011b06 78AliTRDpidESD::~AliTRDpidESD()
79{
80 //
81 // Destructor
82 //
c8ab4518 83
84 if(fTrack) delete fTrack;
85
c6011b06 86}
87
88//_____________________________________________________________________________
b52cb1b6 89AliTRDpidESD &AliTRDpidESD::operator=(const AliTRDpidESD &p)
90{
91 //
92 // Assignment operator
93 //
94
95 if (this != &p) ((AliTRDpidESD &) p).Copy(*this);
96 return *this;
97
98}
99
100//_____________________________________________________________________________
101void AliTRDpidESD::Copy(TObject &p) const
102{
103 //
104 // Copy function
105 //
106
c8ab4518 107 ((AliTRDpidESD &) p).fgCheckTrackStatus = fgCheckTrackStatus;
108 ((AliTRDpidESD &) p).fgCheckKinkStatus = fgCheckKinkStatus;
109 ((AliTRDpidESD &) p).fgMinPlane = fgMinPlane;
c6011b06 110 ((AliTRDpidESD &) p).fTrack = 0x0;
111
b0f03c34 112}
113
b52cb1b6 114//_____________________________________________________________________________
af885e0f 115Int_t AliTRDpidESD::MakePID(AliESDEvent *event)
b0f03c34 116{
117 //
b52cb1b6 118 // This function calculates the PID probabilities based on TRD signals
b0f03c34 119 //
dab811d0 120 // The method produces probabilities based on the charge
121 // and the position of the maximum time bin in each layer.
122 // The dE/dx information can be used as global charge or 2 to 3
720a0a16 123 // slices. Check AliTRDCalPID and AliTRDCalPIDRefMaker for the actual
dab811d0 124 // implementation.
125 //
126 // Author
127 // Alex Bercuci (A.Bercuci@gsi.de) 2nd May 2007
c8ab4518 128 //
dab811d0 129
130 AliTRDcalibDB *calibration = AliTRDcalibDB::Instance();
131 if (!calibration) {
132 AliErrorGeneral("AliTRDpidESD::MakePID()"
133 ,"No access to calibration data");
134 return -1;
135 }
136
7e88424f 137 const AliTRDrecoParam *rec = AliTRDReconstructor::GetRecoParam();
4ba1d6ae 138 if (!rec) {
139 AliErrorGeneral("AliTRDpidESD::MakePID()", "No TRD reco param.");
140 return 0x0;
141 }
142
dab811d0 143 // Retrieve the CDB container class with the probability distributions
4ba1d6ae 144 const AliTRDCalPID *pd = calibration->GetPIDObject(rec->GetPIDMethod());
dab811d0 145 if (!pd) {
146 AliErrorGeneral("AliTRDpidESD::MakePID()"
720a0a16 147 ,"No access to AliTRDCalPID");
dab811d0 148 return -1;
b52cb1b6 149 }
150
dab811d0 151 // Loop through all ESD tracks
152 Double_t p[10];
153 AliESDtrack *t = 0x0;
c6011b06 154 Float_t dedx[AliTRDtrack::kNslice], dEdx;
155 Int_t timebin;
156 Float_t mom, length;
157 Int_t nPlanePID;
dab811d0 158 for (Int_t i=0; i<event->GetNumberOfTracks(); i++) {
159 t = event->GetTrack(i);
c6011b06 160
dab811d0 161 // Check track
162 if(!CheckTrack(t)) continue;
c6011b06 163
dab811d0 164
165 // Skip tracks which have no TRD signal at all
166 if (t->GetTRDsignal() == 0.) continue;
167
168 // Loop over detector layers
c6011b06 169 mom = 0.;
170 length = 0.;
dab811d0 171 nPlanePID = 0;
c8ab4518 172 for (Int_t iSpecies = 0; iSpecies < AliPID::kSPECIES; iSpecies++)
173 p[iSpecies] = 1./AliPID::kSPECIES;
174
053767a4 175 for (Int_t iLayer = 0; iLayer < AliTRDgeometry::kNlayer; iLayer++) {
dab811d0 176 // read data for track segment
177 for(int iSlice=0; iSlice<AliTRDtrack::kNslice; iSlice++)
053767a4 178 dedx[iSlice] = t->GetTRDslice(iLayer, iSlice);
179 dEdx = t->GetTRDslice(iLayer, -1);
180 timebin = t->GetTRDTimBin(iLayer);
dab811d0 181
182 // check data
183 if ((dEdx <= 0.) || (timebin <= -1.)) continue;
184
185 // retrive kinematic info for this track segment
053767a4 186 if(!RecalculateTrackSegmentKine(t, iLayer, mom, length)){
c8b2a461 187 // information is not fully reliable especialy for length
188 // estimation. To be used in the future.
189 }
dab811d0 190
191 // this track segment has fulfilled all requierments
192 nPlanePID++;
c8b2a461 193
dab811d0 194 // Get the probabilities for the different particle species
195 for (Int_t iSpecies = 0; iSpecies < AliPID::kSPECIES; iSpecies++) {
053767a4 196 p[iSpecies] *= pd->GetProbability(iSpecies, mom, dedx, length, iLayer);
c6011b06 197 //p[iSpecies] *= pd->GetProbabilityT(iSpecies, mom, timebin);
dab811d0 198 }
199 }
c6011b06 200 if(nPlanePID == 0) continue;
201
dab811d0 202 // normalize probabilities
c6011b06 203 Double_t probTotal = 0.;
204 for (Int_t iSpecies = 0; iSpecies < AliPID::kSPECIES; iSpecies++) probTotal += p[iSpecies];
205 if(probTotal <= 0.){
c8ab4518 206 AliWarning(Form("The total probability (%e) over all species <= 0 in ESD track %d."
207 , probTotal, i));
208 AliWarning("This may be caused by some error in reference data.");
209 AliWarning("Calculation continues but results might be corrupted.");
c6011b06 210 continue;
211 }
212 for(Int_t iSpecies = 0; iSpecies < AliPID::kSPECIES; iSpecies++) p[iSpecies] /= probTotal;
dab811d0 213
214 // book PID to the track
215 t->SetTRDpid(p);
c6011b06 216 t->SetTRDpidQuality(nPlanePID);
dab811d0 217 }
218
219 return 0;
c8ab4518 220
dab811d0 221}
b52cb1b6 222
dab811d0 223//_____________________________________________________________________________
224Bool_t AliTRDpidESD::CheckTrack(AliESDtrack *t)
225{
226 //
227 // Check if track is eligible for PID calculations
228 //
229
230 // Check the ESD track status
c8ab4518 231 if (fgCheckTrackStatus) {
dab811d0 232 if (((t->GetStatus() & AliESDtrack::kTRDout ) == 0) &&
233 ((t->GetStatus() & AliESDtrack::kTRDrefit) == 0)) return kFALSE;
234 }
b52cb1b6 235
dab811d0 236 // Check for ESD kink tracks
c8ab4518 237 if (fgCheckKinkStatus && (t->GetKinkIndex(0) != 0)) return kFALSE;
b52cb1b6 238
dab811d0 239 return kTRUE;
c8ab4518 240
dab811d0 241}
b52cb1b6 242
dab811d0 243//_____________________________________________________________________________
c8ab4518 244Bool_t AliTRDpidESD::RecalculateTrackSegmentKine(AliESDtrack *esd
053767a4 245 , Int_t layer
c8ab4518 246 , Float_t &mom
247 , Float_t &length)
dab811d0 248{
249 //
250 // Retrive momentum "mom" and track "length" in TRD chamber from plane
251 // "plan" according to information stored in AliESDtrack "t".
c6011b06 252 //
253 // Origin
254 // Alex Bercuci (A.Bercuci@gsi.de)
c8ab4518 255 //
dab811d0 256
dab811d0 257 const Float_t kAmHalfWidth = AliTRDgeometry::AmThick() / 2.;
f162af62 258 const Float_t kDrWidth = AliTRDgeometry::DrThick();
053767a4 259 const Float_t kTime0 = AliTRDgeometry::GetTime0(layer);
dab811d0 260
c6011b06 261 // set initial length value to chamber height
262 length = 2 * kAmHalfWidth + kDrWidth;
dab811d0 263
c6011b06 264 // retrive track's outer param
265 const AliExternalTrackParam *op = esd->GetOuterParam();
266 if(!op){
267 mom = esd->GetP();
dab811d0 268 return kFALSE;
269 }
dab811d0 270
c6011b06 271 AliExternalTrackParam *param = 0x0;
272 if(!fTrack){
273 fTrack = new AliExternalTrackParam(*op);
274 param = fTrack;
c8b2a461 275 } else param = new(fTrack) AliExternalTrackParam(*op);
276
c6011b06 277 // retrive the magnetic field
278 Double_t xyz0[3];
279 op->GetXYZ(xyz0);
280 Float_t field = AliTracker::GetBz(xyz0); // Bz in kG at point xyz0
c8b2a461 281 Double_t s, t;
282
c6011b06 283 // propagate to chamber entrance
284 if(!param->PropagateTo(kTime0-kAmHalfWidth-kDrWidth, field)){
c8b2a461 285 mom = op->GetP();
286 s = op->GetSnp();
287 t = op->GetTgl();
01d8ed58 288 if (s < 1.) length /= TMath::Sqrt((1. - s*s) / (1. + t*t));
c6011b06 289 return kFALSE;
290 }
291 mom = param->GetP();
c8b2a461 292 s = param->GetSnp();
293 t = param->GetTgl();
01d8ed58 294 if (s < 1.) length /= TMath::Sqrt((1. - s*s) / (1. + t*t));
c6011b06 295
296 // check if track is crossing tracking sector by propagating to chamber exit- maybe is too much :)
297 Double_t alpha = param->GetAlpha();
298 if(!param->PropagateTo(kTime0+kAmHalfWidth, field)) return kFALSE;
299
300 // mark track segments which are crossing SM boundaries along chamber
301 if(TMath::Abs(alpha-param->GetAlpha())>.01) return kFALSE;
302
dab811d0 303 return kTRUE;
dab811d0 304
c8ab4518 305}