1 /**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
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 **************************************************************************/
18 ///////////////////////////////////////////////////////////////////////////////
23 // Alex Bercuci <A.Bercuci@gsi.de> //
24 // Markus Fasel <M.Fasel@gsi.de> //
26 ///////////////////////////////////////////////////////////////////////////////
29 #include <TDirectory.h>
30 #include <TLinearFitter.h>
32 #include <TClonesArray.h>
33 #include <TTreeStream.h>
34 #include <TGeoMatrix.h>
35 #include <TGeoManager.h>
38 #include "AliMathBase.h"
39 #include "AliESDEvent.h"
40 #include "AliGeomManager.h"
41 #include "AliRieman.h"
42 #include "AliTrackPointArray.h"
44 #include "AliTRDgeometry.h"
45 #include "AliTRDpadPlane.h"
46 #include "AliTRDcalibDB.h"
47 #include "AliTRDReconstructor.h"
48 #include "AliTRDCalibraFillHisto.h"
49 #include "AliTRDrecoParam.h"
51 #include "AliTRDcluster.h"
52 #include "AliTRDdigitsParam.h"
53 #include "AliTRDseedV1.h"
54 #include "AliTRDtrackV1.h"
55 #include "AliTRDtrackerV1.h"
56 #include "AliTRDtrackerDebug.h"
57 #include "AliTRDtrackingChamber.h"
58 #include "AliTRDchamberTimeBin.h"
60 ClassImp(AliTRDtrackerV1)
61 ClassImp(AliTRDtrackerV1::AliTRDLeastSquare)
62 ClassImp(AliTRDtrackerV1::AliTRDtrackFitterRieman)
64 const Float_t AliTRDtrackerV1::fgkMinClustersInTrack = 0.5; //
65 const Float_t AliTRDtrackerV1::fgkLabelFraction = 0.8; //
66 const Double_t AliTRDtrackerV1::fgkMaxChi2 = 12.0; //
67 const Double_t AliTRDtrackerV1::fgkMaxSnp = 0.95; // Maximum local sine of the azimuthal angle
68 const Double_t AliTRDtrackerV1::fgkMaxStep = 2.0; // Maximal step size in propagation
69 Double_t AliTRDtrackerV1::fgTopologicQA[kNConfigs] = {
70 0.5112, 0.5112, 0.5112, 0.0786, 0.0786,
71 0.0786, 0.0786, 0.0579, 0.0579, 0.0474,
72 0.0474, 0.0408, 0.0335, 0.0335, 0.0335
74 const Double_t AliTRDtrackerV1::fgkX0[kNPlanes] = {
75 300.2, 312.8, 325.4, 338.0, 350.6, 363.2};
76 Int_t AliTRDtrackerV1::fgNTimeBins = 0;
77 AliRieman* AliTRDtrackerV1::fgRieman = NULL;
78 TLinearFitter* AliTRDtrackerV1::fgTiltedRieman = NULL;
79 TLinearFitter* AliTRDtrackerV1::fgTiltedRiemanConstrained = NULL;
81 //____________________________________________________________________
82 AliTRDtrackerV1::AliTRDtrackerV1(AliTRDReconstructor *rec)
84 ,fkReconstructor(NULL)
94 // Default constructor.
97 SetReconstructor(rec); // initialize reconstructor
99 // initialize geometry
100 if(!AliGeomManager::GetGeometry()){
101 AliFatal("Could not get geometry.");
103 fGeom = new AliTRDgeometry();
104 fGeom->CreateClusterMatrixArray();
105 TGeoHMatrix *matrix = NULL;
106 Double_t loc[] = {0., 0., 0.};
107 Double_t glb[] = {0., 0., 0.};
108 for(Int_t ily=kNPlanes; ily--;){
110 while(!(matrix = fGeom->GetClusterMatrix(AliTRDgeometry::GetDetector(ily, 2, ism)))) ism++;
112 AliError(Form("Could not get transformation matrix for layer %d. Use default.", ily));
113 fR[ily] = fgkX0[ily];
116 matrix->LocalToMaster(loc, glb);
117 fR[ily] = glb[0]+ AliTRDgeometry::AnodePos()-.5*AliTRDgeometry::AmThick() - AliTRDgeometry::DrThick();
120 // initialize cluster containers
121 for (Int_t isector = 0; isector < AliTRDgeometry::kNsector; isector++) new(&fTrSec[isector]) AliTRDtrackingSector(fGeom, isector);
124 memset(fTrackQuality, 0, kMaxTracksStack*sizeof(Double_t));
125 memset(fSeedLayer, 0, kMaxTracksStack*sizeof(Int_t));
126 memset(fSeedTB, 0, kNSeedPlanes*sizeof(AliTRDchamberTimeBin*));
127 fTracksESD = new TClonesArray("AliESDtrack", 2*kMaxTracksStack);
128 fTracksESD->SetOwner();
131 //____________________________________________________________________
132 AliTRDtrackerV1::~AliTRDtrackerV1()
138 if(fgRieman) delete fgRieman; fgRieman = NULL;
139 if(fgTiltedRieman) delete fgTiltedRieman; fgTiltedRieman = NULL;
140 if(fgTiltedRiemanConstrained) delete fgTiltedRiemanConstrained; fgTiltedRiemanConstrained = NULL;
141 for(Int_t isl =0; isl<kNSeedPlanes; isl++) if(fSeedTB[isl]) delete fSeedTB[isl];
142 if(fTracksESD){ fTracksESD->Delete(); delete fTracksESD; }
143 if(fTracks) {fTracks->Delete(); delete fTracks;}
144 if(fTracklets) {fTracklets->Delete(); delete fTracklets;}
146 fClusters->Delete(); delete fClusters;
148 if(fGeom) delete fGeom;
151 //____________________________________________________________________
152 Int_t AliTRDtrackerV1::Clusters2Tracks(AliESDEvent *esd)
155 // Steering stand alone tracking for full TRD detector
158 // esd : The ESD event. On output it contains
159 // the ESD tracks found in TRD.
162 // Number of tracks found in the TRD detector.
164 // Detailed description
165 // 1. Launch individual SM trackers.
166 // See AliTRDtrackerV1::Clusters2TracksSM() for details.
170 AliError("Reconstruction configuration not initialized. Call first AliTRDReconstructor::SetRecoParam().");
174 //AliInfo("Start Track Finder ...");
176 for(int ism=0; ism<AliTRDgeometry::kNsector; ism++){
177 // for(int ism=1; ism<2; ism++){
178 //AliInfo(Form("Processing supermodule %i ...", ism));
179 ntracks += Clusters2TracksSM(ism, esd);
181 AliInfo(Form("Number of tracks: !TRDin[%d]", ntracks));
186 //_____________________________________________________________________________
187 Bool_t AliTRDtrackerV1::GetTrackPoint(Int_t index, AliTrackPoint &p) const
189 //AliInfo(Form("Asking for tracklet %d", index));
191 // reset position of the point before using it
192 p.SetXYZ(0., 0., 0.);
193 AliTRDseedV1 *tracklet = GetTracklet(index);
194 if (!tracklet) return kFALSE;
196 // get detector for this tracklet
197 Int_t det = tracklet->GetDetector();
198 Int_t sec = fGeom->GetSector(det);
199 Double_t alpha = (sec+.5)*AliTRDgeometry::GetAlpha(),
200 sinA = TMath::Sin(alpha),
201 cosA = TMath::Cos(alpha);
203 local[0] = tracklet->GetX();
204 local[1] = tracklet->GetY();
205 local[2] = tracklet->GetZ();
207 fGeom->RotateBack(det, local, global);
209 Double_t cov2D[3]; Float_t cov[6];
210 tracklet->GetCovAt(local[0], cov2D);
211 cov[0] = cov2D[0]*sinA*sinA;
212 cov[1] =-cov2D[0]*sinA*cosA;
213 cov[2] =-cov2D[1]*sinA;
214 cov[3] = cov2D[0]*cosA*cosA;
215 cov[4] = cov2D[1]*cosA;
217 // store the global position of the tracklet and its covariance matrix in the track point
218 p.SetXYZ(global[0],global[1],global[2], cov);
221 AliGeomManager::ELayerID iLayer = AliGeomManager::ELayerID(AliGeomManager::kTRD1+fGeom->GetLayer(det));
222 Int_t modId = fGeom->GetSector(det) * AliTRDgeometry::kNstack + fGeom->GetStack(det);
223 UShort_t volid = AliGeomManager::LayerToVolUID(iLayer, modId);
224 p.SetVolumeID(volid);
229 //____________________________________________________________________
230 TLinearFitter* AliTRDtrackerV1::GetTiltedRiemanFitter()
232 if(!fgTiltedRieman) fgTiltedRieman = new TLinearFitter(4, "hyp4");
233 return fgTiltedRieman;
236 //____________________________________________________________________
237 TLinearFitter* AliTRDtrackerV1::GetTiltedRiemanFitterConstraint()
239 if(!fgTiltedRiemanConstrained) fgTiltedRiemanConstrained = new TLinearFitter(2, "hyp2");
240 return fgTiltedRiemanConstrained;
243 //____________________________________________________________________
244 AliRieman* AliTRDtrackerV1::GetRiemanFitter()
246 if(!fgRieman) fgRieman = new AliRieman(AliTRDseedV1::kNtb * AliTRDgeometry::kNlayer);
250 //_____________________________________________________________________________
251 Int_t AliTRDtrackerV1::PropagateBack(AliESDEvent *event)
253 // Propagation of ESD tracks from TPC to TOF detectors and building of the TRD track. For building
254 // a TRD track an ESD track is used as seed. The informations obtained on the TRD track (measured points,
255 // covariance, PID, etc.) are than used to update the corresponding ESD track.
256 // Each track seed is first propagated to the geometrical limit of the TRD detector.
257 // Its prolongation is searched in the TRD and if corresponding clusters are found tracklets are
258 // constructed out of them (see AliTRDseedV1::AttachClusters()) and the track is updated.
259 // Otherwise the ESD track is left unchanged.
261 // The following steps are performed:
262 // 1. Selection of tracks based on the variance in the y-z plane.
263 // 2. Propagation to the geometrical limit of the TRD volume. If track propagation fails the AliESDtrack::kTRDStop is set.
264 // 3. Prolongation inside the fiducial volume (see AliTRDtrackerV1::FollowBackProlongation()) and marking
265 // the following status bits:
266 // - AliESDtrack::kTRDin - if the tracks enters the TRD fiducial volume
267 // - AliESDtrack::kTRDStop - if the tracks fails propagation
268 // - AliESDtrack::kTRDbackup - if the tracks fulfills chi2 conditions and qualify for refitting
269 // 4. Writting to friends, PID, MC label, quality etc. Setting status bit AliESDtrack::kTRDout.
270 // 5. Propagation to TOF. If track propagation fails the AliESDtrack::kTRDStop is set.
273 if(!fClusters || !fClusters->GetEntriesFast()){
274 AliInfo("No TRD clusters");
277 AliTRDCalibraFillHisto *calibra = AliTRDCalibraFillHisto::Instance(); // Calibration monitor
278 if (!calibra) AliInfo("Could not get Calibra instance");
279 if (!fgNTimeBins) fgNTimeBins = fkReconstructor->GetNTimeBins();
282 Int_t nFound = 0, // number of tracks found
283 nBacked = 0, // number of tracks backed up for refit
284 nSeeds = 0, // total number of ESD seeds
285 nTRDseeds= 0, // number of seeds in the TRD acceptance
286 nTPCseeds= 0; // number of TPC seeds
287 Float_t foundMin = 20.0;
289 Float_t *quality = NULL;
291 nSeeds = event->GetNumberOfTracks();
292 // Sort tracks according to quality
293 // (covariance in the yz plane)
295 quality = new Float_t[nSeeds];
296 index = new Int_t[nSeeds];
297 for (Int_t iSeed = nSeeds; iSeed--;) {
298 AliESDtrack *seed = event->GetTrack(iSeed);
299 Double_t covariance[15];
300 seed->GetExternalCovariance(covariance);
301 quality[iSeed] = covariance[0] + covariance[2];
303 TMath::Sort(nSeeds, quality, index,kFALSE);
306 // Propagate all seeds
309 for (Int_t iSeed = 0; iSeed < nSeeds; iSeed++) {
311 // Get the seeds in sorted sequence
312 AliESDtrack *seed = event->GetTrack(index[iSeed]);
313 Float_t p4 = seed->GetC(seed->GetBz());
315 // Check the seed status
316 ULong_t status = seed->GetStatus();
317 if ((status & AliESDtrack::kTPCout) == 0) continue;
318 if ((status & AliESDtrack::kTRDout) != 0) continue;
320 // Propagate to the entrance in the TRD mother volume
321 new(&track) AliTRDtrackV1(*seed);
322 if(AliTRDgeometry::GetXtrdBeg() > (fgkMaxStep + track.GetX()) && !PropagateToX(track, AliTRDgeometry::GetXtrdBeg(), fgkMaxStep)){
323 seed->UpdateTrackParams(&track, AliESDtrack::kTRDStop);
326 if(!AdjustSector(&track)){
327 seed->UpdateTrackParams(&track, AliESDtrack::kTRDStop);
330 if(TMath::Abs(track.GetSnp()) > fgkMaxSnp) {
331 seed->UpdateTrackParams(&track, AliESDtrack::kTRDStop);
337 // store track status at TRD entrance
338 seed->UpdateTrackParams(&track, AliESDtrack::kTRDbackup);
340 // prepare track and do propagation in the TRD
341 track.SetReconstructor(fkReconstructor);
342 track.SetKink(Bool_t(seed->GetKinkIndex(0)));
343 track.SetPrimary(status & AliESDtrack::kTPCin);
344 expectedClr = FollowBackProlongation(track);
345 // check if track entered the TRD fiducial volume
346 if(track.GetTrackIn()){
347 seed->UpdateTrackParams(&track, AliESDtrack::kTRDin);
350 // check if track was stopped in the TRD
352 seed->UpdateTrackParams(&track, AliESDtrack::kTRDStop);
358 // computes PID for track
360 // update calibration references using this track
361 if(calibra->GetHisto2d()) calibra->UpdateHistogramsV1(&track);
362 // save calibration object
363 if (fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) > 0) {
364 AliTRDtrackV1 *calibTrack = new AliTRDtrackV1(track);
365 calibTrack->SetOwner();
366 seed->AddCalibObject(calibTrack);
369 seed->UpdateTrackParams(&track, AliESDtrack::kTRDout);
370 track.UpdateESDtrack(seed);
373 if ((TMath::Abs(track.GetC(track.GetBz()) - p4) / TMath::Abs(p4) < 0.2) ||(track.Pt() > 0.8)) {
375 // Make backup for back propagation
376 Int_t foundClr = track.GetNumberOfClusters();
377 if (foundClr >= foundMin) {
378 track.CookLabel(1. - fgkLabelFraction);
379 //if(track.GetBackupTrack()) UseClusters(track.GetBackupTrack());
381 // Sign only gold tracks
382 if (track.GetChi2() / track.GetNumberOfClusters() < 4) {
383 //if ((seed->GetKinkIndex(0) == 0) && (track.Pt() < 1.5)) UseClusters(&track);
385 Bool_t isGold = kFALSE;
388 if (track.GetChi2() / track.GetNumberOfClusters() < 5) {
389 if (track.GetBackupTrack()) seed->UpdateTrackParams(track.GetBackupTrack(),AliESDtrack::kTRDbackup);
395 if ((!isGold) && (track.GetNCross() == 0) && (track.GetChi2() / track.GetNumberOfClusters() < 7)) {
396 //seed->UpdateTrackParams(track, AliESDtrack::kTRDbackup);
397 if (track.GetBackupTrack()) seed->UpdateTrackParams(track.GetBackupTrack(),AliESDtrack::kTRDbackup);
402 if ((!isGold) && (track.GetBackupTrack())) {
403 if ((track.GetBackupTrack()->GetNumberOfClusters() > foundMin) && ((track.GetBackupTrack()->GetChi2()/(track.GetBackupTrack()->GetNumberOfClusters()+1)) < 7)) {
404 seed->UpdateTrackParams(track.GetBackupTrack(),AliESDtrack::kTRDbackup);
412 // Propagation to the TOF
413 if(!(seed->GetStatus()&AliESDtrack::kTRDStop)) {
414 Int_t sm = track.GetSector();
415 // default value in case we have problems with the geometry.
416 Double_t xtof = 371.;
417 //Calculate radial position of the beginning of the TOF
418 //mother volume. In order to avoid mixing of the TRD
419 //and TOF modules some hard values are needed. This are:
420 //1. The path to the TOF module.
421 //2. The width of the TOF (29.05 cm)
422 //(with the help of Annalisa de Caro Mar-17-2009)
424 gGeoManager->cd(Form("/ALIC_1/B077_1/BSEGMO%d_1/BTOF%d_1", sm, sm));
425 TGeoHMatrix *m = NULL;
426 Double_t loc[]={0., 0., -.5*29.05}, glob[3];
428 if((m=gGeoManager->GetCurrentMatrix())){
429 m->LocalToMaster(loc, glob);
430 xtof = TMath::Sqrt(glob[0]*glob[0]+glob[1]*glob[1]);
433 if(xtof > (fgkMaxStep + track.GetX()) && !PropagateToX(track, xtof, fgkMaxStep)){
434 seed->UpdateTrackParams(&track, AliESDtrack::kTRDStop);
437 if(!AdjustSector(&track)){
438 seed->UpdateTrackParams(&track, AliESDtrack::kTRDStop);
441 if(TMath::Abs(track.GetSnp()) > fgkMaxSnp){
442 seed->UpdateTrackParams(&track, AliESDtrack::kTRDStop);
445 //seed->UpdateTrackParams(&track, AliESDtrack::kTRDout);
446 // TODO obsolete - delete
447 seed->SetTRDQuality(track.StatusForTOF());
449 seed->SetTRDBudget(track.GetBudget(0));
451 if(index) delete [] index;
452 if(quality) delete [] quality;
454 AliInfo(Form("Number of seeds: TPCout[%d] TRDin[%d]", nTPCseeds, nTRDseeds));
455 AliInfo(Form("Number of tracks: TRDout[%d] TRDbackup[%d]", nFound, nBacked));
457 // run stand alone tracking
458 if (fkReconstructor->IsSeeding()) Clusters2Tracks(event);
464 //____________________________________________________________________
465 Int_t AliTRDtrackerV1::RefitInward(AliESDEvent *event)
468 // Refits tracks within the TRD. The ESD event is expected to contain seeds
469 // at the outer part of the TRD.
470 // The tracks are propagated to the innermost time bin
471 // of the TRD and the ESD event is updated
472 // Origin: Thomas KUHR (Thomas.Kuhr@cern.ch)
475 Int_t nseed = 0; // contor for loaded seeds
476 Int_t found = 0; // contor for updated TRD tracks
479 if(!fClusters || !fClusters->GetEntriesFast()){
480 AliInfo("No TRD clusters");
484 for (Int_t itrack = 0; itrack < event->GetNumberOfTracks(); itrack++) {
485 AliESDtrack *seed = event->GetTrack(itrack);
486 ULong_t status = seed->GetStatus();
488 new(&track) AliTRDtrackV1(*seed);
489 if (track.GetX() < 270.0) {
490 seed->UpdateTrackParams(&track, AliESDtrack::kTRDbackup);
494 // reject tracks which failed propagation in the TRD or
495 // are produced by the TRD stand alone tracker
496 if(!(status & AliESDtrack::kTRDout)) continue;
497 if(!(status & AliESDtrack::kTRDin)) continue;
500 track.ResetCovariance(50.0);
502 // do the propagation and processing
503 Bool_t kUPDATE = kFALSE;
504 Double_t xTPC = 250.0;
505 if(FollowProlongation(track)){
506 // Update the friend track
507 if (fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) > 0){
508 TObject *o = NULL; Int_t ic = 0;
509 AliTRDtrackV1 *calibTrack = NULL;
510 while((o = seed->GetCalibObject(ic++))){
511 if(!(calibTrack = dynamic_cast<AliTRDtrackV1*>(o))) continue;
512 calibTrack->SetTrackOut(&track);
517 if (PropagateToX(track, xTPC, fgkMaxStep)) { // -with update
518 seed->UpdateTrackParams(&track, AliESDtrack::kTRDrefit);
524 // Prolongate to TPC without update
526 AliTRDtrackV1 tt(*seed);
527 if (PropagateToX(tt, xTPC, fgkMaxStep)) seed->UpdateTrackParams(&tt, AliESDtrack::kTRDbackup);
530 AliInfo(Form("Number of seeds: TRDout[%d]", nseed));
531 AliInfo(Form("Number of tracks: TRDrefit[%d]", found));
536 //____________________________________________________________________
537 Int_t AliTRDtrackerV1::FollowProlongation(AliTRDtrackV1 &t)
539 // Extrapolates the TRD track in the TPC direction.
542 // t : the TRD track which has to be extrapolated
545 // number of clusters attached to the track
547 // Detailed description
549 // Starting from current radial position of track <t> this function
550 // extrapolates the track through the 6 TRD layers. The following steps
551 // are being performed for each plane:
553 // a. get plane limits in the local x direction
554 // b. check crossing sectors
555 // c. check track inclination
556 // 2. search tracklet in the tracker list (see GetTracklet() for details)
557 // 3. evaluate material budget using the geo manager
558 // 4. propagate and update track using the tracklet information.
563 Int_t nClustersExpected = 0;
564 for (Int_t iplane = kNPlanes; iplane--;) {
566 AliTRDseedV1 *tracklet = GetTracklet(&t, iplane, index);
567 AliDebug(2, Form("Tracklet[%p] ly[%d] idx[%d]", (void*)tracklet, iplane, index));
568 if(!tracklet) continue;
569 if(!tracklet->IsOK()){
570 AliDebug(1, Form("Tracklet Det[%d] !OK", tracklet->GetDetector()));
573 Double_t x = tracklet->GetX();//GetX0();
574 // reject tracklets which are not considered for inward refit
575 if(x > t.GetX()+fgkMaxStep) continue;
577 // append tracklet to track
578 t.SetTracklet(tracklet, index);
580 if (x < (t.GetX()-fgkMaxStep) && !PropagateToX(t, x+fgkMaxStep, fgkMaxStep)) break;
581 if (!AdjustSector(&t)) break;
583 // Start global position
587 // End global position
588 Double_t alpha = t.GetAlpha(), y, z;
589 if (!t.GetProlongation(x,y,z)) break;
591 xyz1[0] = x * TMath::Cos(alpha) - y * TMath::Sin(alpha);
592 xyz1[1] = x * TMath::Sin(alpha) + y * TMath::Cos(alpha);
595 Double_t length = TMath::Sqrt(
596 (xyz0[0]-xyz1[0])*(xyz0[0]-xyz1[0]) +
597 (xyz0[1]-xyz1[1])*(xyz0[1]-xyz1[1]) +
598 (xyz0[2]-xyz1[2])*(xyz0[2]-xyz1[2])
601 // Get material budget
603 if(AliTracker::MeanMaterialBudget(xyz0, xyz1, param)<=0.) break;
604 Double_t xrho= param[0]*param[4];
605 Double_t xx0 = param[1]; // Get mean propagation parameters
607 // Propagate and update
608 t.PropagateTo(x, xx0, xrho);
609 if (!AdjustSector(&t)) break;
612 Double_t cov[3]; tracklet->GetCovAt(x, cov);
613 Double_t p[2] = { tracklet->GetY(), tracklet->GetZ()};
614 Double_t chi2 = ((AliExternalTrackParam)t).GetPredictedChi2(p, cov);
615 if (chi2 < 1e+10 && t.Update(p, cov, chi2)){
616 nClustersExpected += tracklet->GetN();
620 if(fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) > 1){
622 for(int iplane=0; iplane<AliTRDgeometry::kNlayer; iplane++){
623 AliTRDseedV1 *tracklet = GetTracklet(&t, iplane, index);
624 if(!tracklet) continue;
625 t.SetTracklet(tracklet, index);
628 if(fkReconstructor->IsDebugStreaming()){
629 Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
630 TTreeSRedirector &cstreamer = *fkReconstructor->GetDebugStream(AliTRDrecoParam::kTracker);
631 AliTRDtrackV1 track(t);
633 cstreamer << "FollowProlongation"
634 << "EventNumber=" << eventNumber
635 << "ncl=" << nClustersExpected
636 << "track.=" << &track
640 return nClustersExpected;
644 //_____________________________________________________________________________
645 Int_t AliTRDtrackerV1::FollowBackProlongation(AliTRDtrackV1 &t)
647 // Extrapolates/Build the TRD track in the TOF direction.
650 // t : the TRD track which has to be extrapolated
653 // number of clusters attached to the track
655 // Starting from current radial position of track <t> this function
656 // extrapolates the track through the 6 TRD layers. The following steps
657 // are being performed for each plane:
658 // 1. Propagate track to the entrance of the next chamber:
659 // - get chamber limits in the radial direction
660 // - check crossing sectors
661 // - check track inclination
662 // - check track prolongation against boundary conditions (see exclusion boundaries on AliTRDgeometry::IsOnBoundary())
663 // 2. Build tracklet (see AliTRDseed::AttachClusters() for details) for this layer if needed. If only
664 // Kalman filter is needed and tracklets are already linked to the track this step is skipped.
665 // 3. Fit tracklet using the information from the Kalman filter.
666 // 4. Propagate and update track at reference radial position of the tracklet.
667 // 5. Register tracklet with the tracker and track; update pulls monitoring.
670 // 1. During the propagation a bit map is filled detailing the status of the track in each TRD chamber. The following errors are being registered for each tracklet:
671 // - AliTRDtrackV1::kProlongation : track prolongation failed
672 // - AliTRDtrackV1::kPropagation : track prolongation failed
673 // - AliTRDtrackV1::kAdjustSector : failed during sector crossing
674 // - AliTRDtrackV1::kSnp : too large bending
675 // - AliTRDtrackV1::kTrackletInit : fail to initialize tracklet
676 // - AliTRDtrackV1::kUpdate : fail to attach clusters or fit the tracklet
677 // - AliTRDtrackV1::kUnknown : anything which is not covered before
678 // 2. By default the status of the track before first TRD update is saved.
683 // Alexandru Bercuci <A.Bercuci@gsi.de>
687 Double_t driftLength = .5*AliTRDgeometry::AmThick() + AliTRDgeometry::DrThick();
688 AliTRDtrackingChamber *chamber = NULL;
690 Int_t debugLevel = fkReconstructor->IsDebugStreaming() ? fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) : 0;
691 TTreeSRedirector *cstreamer = fkReconstructor->IsDebugStreaming() ? fkReconstructor->GetDebugStream(AliTRDrecoParam::kTracker) : 0x0;
693 Bool_t kStoreIn(kTRUE), //
694 kPropagateIn(kTRUE), //
695 kStandAlone(kFALSE), // toggle tracker awarness of stand alone seeding
696 kUseTRD(fkRecoParam->IsOverPtThreshold(t.Pt()));// use TRD measurment to update Kalman
699 AliTRDseedV1 tracklet, *ptrTracklet = NULL;
700 // Special case for stand alone tracking
701 // - store all tracklets found by seeding
702 // - start propagation from first tracklet found
703 AliTRDseedV1 *tracklets[kNPlanes];
704 memset(tracklets, 0, sizeof(AliTRDseedV1 *) * kNPlanes);
705 for(Int_t ip(kNPlanes); ip--;){
706 if(!(tracklets[ip] = t.GetTracklet(ip))) continue;
708 if(tracklets[ip]->IsOK()) startLayer=ip;
711 AliDebug(4, Form("SA[%c] Start[%d]\n"
712 " [0]idx[%d] traklet[%p]\n"
713 " [1]idx[%d] traklet[%p]\n"
714 " [2]idx[%d] traklet[%p]\n"
715 " [3]idx[%d] traklet[%p]\n"
716 " [4]idx[%d] traklet[%p]\n"
717 " [5]idx[%d] traklet[%p]"
718 , kStandAlone?'y':'n', startLayer
719 , t.GetTrackletIndex(0), (void*)tracklets[0]
720 , t.GetTrackletIndex(1), (void*)tracklets[1]
721 , t.GetTrackletIndex(2), (void*)tracklets[2]
722 , t.GetTrackletIndex(3), (void*)tracklets[3]
723 , t.GetTrackletIndex(4), (void*)tracklets[4]
724 , t.GetTrackletIndex(5), (void*)tracklets[5]));
726 // Loop through the TRD layers
727 TGeoHMatrix *matrix = NULL;
729 for (Int_t ily=startLayer, sm=-1, stk=-1, det=-1; ily < AliTRDgeometry::kNlayer; ily++) {
730 AliDebug(2, Form("Propagate to x[%d] = %7.2f", ily, fR[ily]));
732 // rough estimate of the entry point
733 if (!t.GetProlongation(fR[ily], y, z)){
735 t.SetStatus(AliTRDtrackV1::kProlongation);
736 AliDebug(4, Form("Failed Rough Prolongation to ly[%d] x[%7.2f] y[%7.2f] z[%7.2f]", ily, fR[ily], y, z));
740 // find sector / stack / detector
742 // TODO cross check with y value !
743 stk = fGeom->GetStack(z, ily);
744 det = stk>=0 ? AliTRDgeometry::GetDetector(ily, stk, sm) : -1;
745 matrix = det>=0 ? fGeom->GetClusterMatrix(det) : NULL;
746 AliDebug(3, Form("Propagate to det[%3d]", det));
748 // check if supermodule/chamber is installed
749 if( !fGeom->GetSMstatus(sm) ||
751 fGeom->IsHole(ily, stk, sm) ||
753 AliDebug(4, Form("Missing Geometry ly[%d]. Guess radial position", ily));
754 // propagate to the default radial position
755 if(fR[ily] > (fgkMaxStep + t.GetX()) && !PropagateToX(t, fR[ily], fgkMaxStep)){
757 t.SetStatus(AliTRDtrackV1::kPropagation);
758 AliDebug(4, "Failed Propagation [Missing Geometry]");
761 if(!AdjustSector(&t)){
763 t.SetStatus(AliTRDtrackV1::kAdjustSector);
764 AliDebug(4, "Failed Adjust Sector [Missing Geometry]");
767 if(TMath::Abs(t.GetSnp()) > fgkMaxSnp){
769 t.SetStatus(AliTRDtrackV1::kSnp);
770 AliDebug(4, "Failed Max Snp [Missing Geometry]");
773 t.SetStatus(AliTRDtrackV1::kGeometry, ily);
777 // retrieve rotation matrix for the current chamber
778 Double_t loc[] = {AliTRDgeometry::AnodePos()- driftLength, 0., 0.};
779 Double_t glb[] = {0., 0., 0.};
780 matrix->LocalToMaster(loc, glb);
782 // Propagate to the radial distance of the current layer
783 x = glb[0] - fgkMaxStep;
784 if(x > (fgkMaxStep + t.GetX()) && !PropagateToX(t, x, fgkMaxStep)){
786 t.SetStatus(AliTRDtrackV1::kPropagation);
787 AliDebug(4, Form("Failed Initial Propagation to x[%7.2f]", x));
790 if(!AdjustSector(&t)){
792 t.SetStatus(AliTRDtrackV1::kAdjustSector);
793 AliDebug(4, "Failed Adjust Sector Start");
796 if(TMath::Abs(t.GetSnp()) > fgkMaxSnp) {
798 t.SetStatus(AliTRDtrackV1::kSnp);
799 AliDebug(4, Form("Failed Max Snp[%f] MaxSnp[%f]", t.GetSnp(), fgkMaxSnp));
802 Bool_t doRecalculate = kFALSE;
803 if(sm != t.GetSector()){
805 doRecalculate = kTRUE;
807 if(stk != fGeom->GetStack(z, ily)){
808 stk = fGeom->GetStack(z, ily);
809 doRecalculate = kTRUE;
812 det = AliTRDgeometry::GetDetector(ily, stk, sm);
813 if(!(matrix = fGeom->GetClusterMatrix(det))){
814 t.SetStatus(AliTRDtrackV1::kGeometry, ily);
815 AliDebug(4, Form("Failed Geometry Matrix ly[%d]", ily));
818 matrix->LocalToMaster(loc, glb);
819 x = glb[0] - fgkMaxStep;
822 // check if track is well inside fiducial volume
823 if (!t.GetProlongation(x+fgkMaxStep, y, z)) {
825 t.SetStatus(AliTRDtrackV1::kProlongation);
826 AliDebug(4, Form("Failed Prolongation to x[%7.2f] y[%7.2f] z[%7.2f]", x+fgkMaxStep, y, z));
829 if(fGeom->IsOnBoundary(det, y, z, .5)){
830 t.SetStatus(AliTRDtrackV1::kBoundary, ily);
831 AliDebug(4, "Failed Track on Boundary");
834 // mark track as entering the FIDUCIAL volume of TRD
840 ptrTracklet = tracklets[ily];
841 if(!ptrTracklet){ // BUILD TRACKLET
842 AliDebug(3, Form("Building tracklet det[%d]", det));
843 // check data in supermodule
844 if(!fTrSec[sm].GetNChambers()){
845 t.SetStatus(AliTRDtrackV1::kNoClusters, ily);
846 AliDebug(4, "Failed NoClusters");
849 if(fTrSec[sm].GetX(ily) < 1.){
850 t.SetStatus(AliTRDtrackV1::kNoClusters, ily);
851 AliDebug(4, "Failed NoX");
855 // check data in chamber
856 if(!(chamber = fTrSec[sm].GetChamber(stk, ily))){
857 t.SetStatus(AliTRDtrackV1::kNoClusters, ily);
858 AliDebug(4, "Failed No Detector");
861 if(chamber->GetNClusters() < fgNTimeBins*fkRecoParam ->GetFindableClusters()){
862 t.SetStatus(AliTRDtrackV1::kNoClusters, ily);
863 AliDebug(4, "Failed Not Enough Clusters in Detector");
867 ptrTracklet = new(&tracklet) AliTRDseedV1(det);
868 ptrTracklet->SetReconstructor(fkReconstructor);
869 ptrTracklet->SetKink(t.IsKink());
870 ptrTracklet->SetPrimary(t.IsPrimary());
871 ptrTracklet->SetPadPlane(fGeom->GetPadPlane(ily, stk));
872 ptrTracklet->SetX0(glb[0]+driftLength);
873 if(!tracklet.Init(&t)){
875 t.SetStatus(AliTRDtrackV1::kTrackletInit);
876 AliDebug(4, "Failed Tracklet Init");
879 if(!tracklet.AttachClusters(chamber, kTRUE)){
880 t.SetStatus(AliTRDtrackV1::kNoAttach, ily);
882 AliTRDseedV1 trackletCp(*ptrTracklet);
883 UChar_t status(t.GetStatusTRD(ily));
884 (*cstreamer) << "FollowBackProlongation2"
885 <<"status=" << status
886 <<"tracklet.=" << &trackletCp
889 AliDebug(4, "Failed Attach Clusters");
892 AliDebug(3, Form("Number of Clusters in Tracklet: %d", tracklet.GetN()));
893 if(tracklet.GetN() < fgNTimeBins*fkRecoParam ->GetFindableClusters()){
894 t.SetStatus(AliTRDtrackV1::kNoClustersTracklet, ily);
896 AliTRDseedV1 trackletCp(*ptrTracklet);
897 UChar_t status(t.GetStatusTRD(ily));
898 (*cstreamer) << "FollowBackProlongation2"
899 <<"status=" << status
900 <<"tracklet.=" << &trackletCp
903 AliDebug(4, "Failed N Clusters Attached");
906 ptrTracklet->UpdateUsed();
907 } else AliDebug(2, Form("Use external tracklet ly[%d]", ily));
908 // propagate track to the radial position of the tracklet
911 // tilt correction options
913 // 2 : pseudo tilt correction
914 if(!ptrTracklet->Fit(2)){
915 t.SetStatus(AliTRDtrackV1::kNoFit, ily);
916 AliDebug(4, "Failed Tracklet Fit");
919 x = ptrTracklet->GetX(); //GetX0();
920 if(x > (fgkMaxStep + t.GetX()) && !PropagateToX(t, x, fgkMaxStep)) {
922 t.SetStatus(AliTRDtrackV1::kPropagation);
923 AliDebug(4, Form("Failed Propagation to Tracklet x[%7.2f]", x));
926 if(!AdjustSector(&t)) {
928 t.SetStatus(AliTRDtrackV1::kAdjustSector);
929 AliDebug(4, "Failed Adjust Sector");
932 if(TMath::Abs(t.GetSnp()) > fgkMaxSnp) {
934 t.SetStatus(AliTRDtrackV1::kSnp);
935 AliDebug(4, Form("Failed Max Snp[%f] MaxSnp[%f]", t.GetSnp(), fgkMaxSnp));
940 kPropagateIn = kFALSE;
942 Double_t cov[3]; ptrTracklet->GetCovAt(x, cov);
943 Double_t p[2] = { ptrTracklet->GetY(), ptrTracklet->GetZ()};
944 Double_t chi2 = ((AliExternalTrackParam)t).GetPredictedChi2(p, cov);
945 // update Kalman with the TRD measurement
946 if(chi2>1e+10){ // TODO
947 t.SetStatus(AliTRDtrackV1::kChi2, ily);
949 UChar_t status(t.GetStatusTRD());
950 AliTRDseedV1 trackletCp(*ptrTracklet);
951 AliTRDtrackV1 trackCp(t);
953 (*cstreamer) << "FollowBackProlongation1"
954 << "status=" << status
955 << "tracklet.=" << &trackletCp
956 << "track.=" << &trackCp
959 AliDebug(4, Form("Failed Chi2[%f]", chi2));
962 if(!t.Update(p, cov, chi2, kUseTRD)) {
964 t.SetStatus(AliTRDtrackV1::kUpdate);
966 UChar_t status(t.GetStatusTRD());
967 AliTRDseedV1 trackletCp(*ptrTracklet);
968 AliTRDtrackV1 trackCp(t);
970 (*cstreamer) << "FollowBackProlongation1"
971 << "status=" << status
972 << "tracklet.=" << &trackletCp
973 << "track.=" << &trackCp
976 AliDebug(4, Form("Failed Track Update @ y[%7.2f] z[%7.2f] s2y[%f] s2z[%f] covyz[%f]", p[0], p[1], cov[0], cov[2], cov[1]));
979 if(!kStandAlone) ptrTracklet->UseClusters();
981 AliTracker::FillResiduals(&t, p, cov, ptrTracklet->GetVolumeId());
984 // load tracklet to the tracker
985 ptrTracklet->Update(&t);
986 ptrTracklet = SetTracklet(ptrTracklet);
987 Int_t index(fTracklets->GetEntriesFast()-1);
988 t.SetTracklet(ptrTracklet, index);
989 n += ptrTracklet->GetN();
990 AliDebug(2, Form("Setting Tracklet[%d] @ Idx[%d]", ily, index));
992 // Reset material budget if 2 consecutive gold
993 // if(ilayer>0 && t.GetTracklet(ilayer-1) && ptrTracklet->GetN() + t.GetTracklet(ilayer-1)->GetN() > 20) t.SetBudget(2, 0.);
995 // Make backup of the track until is gold
997 if(!kStandAlone && (failed = t.MakeBackupTrack())) AliDebug(2, Form("Failed backup on cut[%d]", failed));
1000 //printf("clusters[%d] chi2[%f] x[%f] status[%d ", n, t.GetChi2(), t.GetX(), t.GetStatusTRD());
1001 //for(int i=0; i<6; i++) printf("%d ", t.GetStatusTRD(i)); printf("]\n");
1004 Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
1005 AliTRDtrackV1 track(t);
1007 (*cstreamer) << "FollowBackProlongation0"
1008 << "EventNumber=" << eventNumber
1010 << "track.=" << &track
1017 //_________________________________________________________________________
1018 Float_t AliTRDtrackerV1::FitRieman(AliTRDseedV1 *tracklets, Double_t *chi2, Int_t *const planes){
1020 // Fits a Riemann-circle to the given points without tilting pad correction.
1021 // The fit is performed using an instance of the class AliRieman (equations
1022 // and transformations see documentation of this class)
1023 // Afterwards all the tracklets are Updated
1025 // Parameters: - Array of tracklets (AliTRDseedV1)
1026 // - Storage for the chi2 values (beginning with direction z)
1027 // - Seeding configuration
1028 // Output: - The curvature
1030 AliRieman *fitter = AliTRDtrackerV1::GetRiemanFitter();
1032 Int_t allplanes[] = {0, 1, 2, 3, 4, 5};
1033 Int_t *ppl = &allplanes[0];
1034 Int_t maxLayers = 6;
1039 for(Int_t il = 0; il < maxLayers; il++){
1040 if(!tracklets[ppl[il]].IsOK()) continue;
1041 fitter->AddPoint(tracklets[ppl[il]].GetX0(), tracklets[ppl[il]].GetYfit(0), tracklets[ppl[il]].GetZfit(0),1,10);
1044 // Set the reference position of the fit and calculate the chi2 values
1045 memset(chi2, 0, sizeof(Double_t) * 2);
1046 for(Int_t il = 0; il < maxLayers; il++){
1047 // Reference positions
1048 tracklets[ppl[il]].Init(fitter);
1051 if((!tracklets[ppl[il]].IsOK()) && (!planes)) continue;
1052 chi2[0] += tracklets[ppl[il]].GetChi2Y();
1053 chi2[1] += tracklets[ppl[il]].GetChi2Z();
1055 return fitter->GetC();
1058 //_________________________________________________________________________
1059 void AliTRDtrackerV1::FitRieman(AliTRDcluster **seedcl, Double_t chi2[2])
1062 // Performs a Riemann helix fit using the seedclusters as spacepoints
1063 // Afterwards the chi2 values are calculated and the seeds are updated
1065 // Parameters: - The four seedclusters
1066 // - The tracklet array (AliTRDseedV1)
1067 // - The seeding configuration
1072 AliRieman *fitter = AliTRDtrackerV1::GetRiemanFitter();
1074 for(Int_t i = 0; i < 4; i++){
1075 fitter->AddPoint(seedcl[i]->GetX(), seedcl[i]->GetY(), seedcl[i]->GetZ(), 1., 10.);
1080 // Update the seed and calculated the chi2 value
1081 chi2[0] = 0; chi2[1] = 0;
1082 for(Int_t ipl = 0; ipl < kNSeedPlanes; ipl++){
1084 chi2[0] += (seedcl[ipl]->GetZ() - fitter->GetZat(seedcl[ipl]->GetX())) * (seedcl[ipl]->GetZ() - fitter->GetZat(seedcl[ipl]->GetX()));
1085 chi2[1] += (seedcl[ipl]->GetY() - fitter->GetYat(seedcl[ipl]->GetX())) * (seedcl[ipl]->GetY() - fitter->GetYat(seedcl[ipl]->GetX()));
1090 //_________________________________________________________________________
1091 Float_t AliTRDtrackerV1::FitTiltedRiemanConstraint(AliTRDseedV1 *tracklets, Double_t zVertex)
1094 // Fits a helix to the clusters. Pad tilting is considered. As constraint it is
1095 // assumed that the vertex position is set to 0.
1096 // This method is very usefull for high-pt particles
1097 // Basis for the fit: (x - x0)^2 + (y - y0)^2 - R^2 = 0
1098 // x0, y0: Center of the circle
1099 // Measured y-position: ymeas = y - tan(phiT)(zc - zt)
1100 // zc: center of the pad row
1101 // Equation which has to be fitted (after transformation):
1102 // a + b * u + e * v + 2*(ymeas + tan(phiT)(z - zVertex))*t = 0
1104 // t = 1/(x^2 + y^2)
1106 // v = 2 * x * tan(phiT) * t
1107 // Parameters in the equation:
1108 // a = -1/y0, b = x0/y0, e = dz/dx
1110 // The Curvature is calculated by the following equation:
1111 // - curv = a/Sqrt(b^2 + 1) = 1/R
1112 // Parameters: - the 6 tracklets
1113 // - the Vertex constraint
1114 // Output: - the Chi2 value of the track
1119 TLinearFitter *fitter = GetTiltedRiemanFitterConstraint();
1120 fitter->StoreData(kTRUE);
1121 fitter->ClearPoints();
1122 AliTRDcluster *cl = NULL;
1124 Float_t x, y, z, w, t, error, tilt;
1127 for(Int_t ilr = 0; ilr < AliTRDgeometry::kNlayer; ilr++){
1128 if(!tracklets[ilr].IsOK()) continue;
1129 for(Int_t itb = 0; itb < AliTRDseedV1::kNclusters; itb++){
1130 if(!tracklets[ilr].IsUsable(itb)) continue;
1131 cl = tracklets[ilr].GetClusters(itb);
1132 if(!cl->IsInChamber()) continue;
1133 if(cl->GetSigmaY2()<1.e-6 || cl->GetSigmaZ2()<1.e-6){
1134 if(AliLog::GetDebugLevel("TRD", "AliTRDtrackerV1")>1) printf("D-AliTRDtrackerV1::FitTiltedRiemanConstraint: Cluster error parameterization missing. This should appear only in HLT tests.");
1140 tilt = tracklets[ilr].GetTilt();
1142 t = 1./(x * x + y * y);
1143 uvt[0] = 2. * x * t;
1144 uvt[1] = 2. * x * t * tilt ;
1145 w = 2. * (y + tilt * (z - zVertex)) * t;
1146 error = 2. * TMath::Sqrt(cl->GetSigmaY2()+tilt*tilt*cl->GetSigmaZ2()) * t;
1147 fitter->AddPoint(uvt, w, error);
1153 // Calculate curvature
1154 Double_t a = fitter->GetParameter(0);
1155 Double_t b = fitter->GetParameter(1);
1156 Double_t curvature = a/TMath::Sqrt(b*b + 1);
1158 Float_t chi2track = fitter->GetChisquare()/Double_t(nPoints);
1159 for(Int_t ip = 0; ip < AliTRDtrackerV1::kNPlanes; ip++)
1160 tracklets[ip].SetC(curvature, 1);
1162 if(AliLog::GetDebugLevel("TRD", "AliTRDtrackerV1")>3) printf("D-AliTRDtrackerV1::FitTiltedRiemanConstraint: Chi2[%f] C[%5.2e] pt[%8.3f]\n", chi2track, curvature, GetBz()*kB2C/curvature);
1164 /* if(fkReconstructor->GetRecoParam()->GetStreamLevel(AliTRDrecoParam::kTracker()) >= 5){
1165 //Linear Model on z-direction
1166 Double_t xref = CalculateReferenceX(tracklets); // Relative to the middle of the stack
1167 Double_t slope = fitter->GetParameter(2);
1168 Double_t zref = slope * xref;
1169 Float_t chi2Z = CalculateChi2Z(tracklets, zref, slope, xref);
1170 Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
1171 Int_t candidateNumber = AliTRDtrackerDebug::GetCandidateNumber();
1172 TTreeSRedirector &treeStreamer = *fkReconstructor->GetDebugStream(AliTRDReconstructor::kTracker);
1173 treeStreamer << "FitTiltedRiemanConstraint"
1174 << "EventNumber=" << eventNumber
1175 << "CandidateNumber=" << candidateNumber
1176 << "Curvature=" << curvature
1177 << "Chi2Track=" << chi2track
1178 << "Chi2Z=" << chi2Z
1185 //_________________________________________________________________________
1186 Float_t AliTRDtrackerV1::FitTiltedRieman(AliTRDseedV1 *tracklets, Bool_t sigError)
1189 // Performs a Riemann fit taking tilting pad correction into account
1190 // The equation of a Riemann circle, where the y position is substituted by the
1191 // measured y-position taking pad tilting into account, has to be transformed
1192 // into a 4-dimensional hyperplane equation
1193 // Riemann circle: (x-x0)^2 + (y-y0)^2 -R^2 = 0
1194 // Measured y-Position: ymeas = y - tan(phiT)(zc - zt)
1195 // zc: center of the pad row
1196 // zt: z-position of the track
1197 // The z-position of the track is assumed to be linear dependent on the x-position
1198 // Transformed equation: a + b * u + c * t + d * v + e * w - 2 * (ymeas + tan(phiT) * zc) * t = 0
1199 // Transformation: u = 2 * x * t
1200 // v = 2 * tan(phiT) * t
1201 // w = 2 * tan(phiT) * (x - xref) * t
1202 // t = 1 / (x^2 + ymeas^2)
1203 // Parameters: a = -1/y0
1205 // c = (R^2 -x0^2 - y0^2)/y0
1208 // If the offset respectively the slope in z-position is impossible, the parameters are fixed using
1209 // results from the simple riemann fit. Afterwards the fit is redone.
1210 // The curvature is calculated according to the formula:
1211 // curv = a/(1 + b^2 + c*a) = 1/R
1213 // Paramters: - Array of tracklets (connected to the track candidate)
1214 // - Flag selecting the error definition
1215 // Output: - Chi2 values of the track (in Parameter list)
1217 TLinearFitter *fitter = GetTiltedRiemanFitter();
1218 fitter->StoreData(kTRUE);
1219 fitter->ClearPoints();
1220 AliTRDLeastSquare zfitter;
1221 AliTRDcluster *cl = NULL;
1223 Double_t xref = CalculateReferenceX(tracklets);
1224 Double_t x, y, z, t, tilt, dx, w, we, erry, errz;
1225 Double_t uvt[4], sumPolY[5], sumPolZ[3];
1226 memset(sumPolY, 0, sizeof(Double_t) * 5);
1227 memset(sumPolZ, 0, sizeof(Double_t) * 3);
1229 // Containers for Least-square fitter
1230 for(Int_t ipl = 0; ipl < kNPlanes; ipl++){
1231 if(!tracklets[ipl].IsOK()) continue;
1232 tilt = tracklets[ipl].GetTilt();
1233 for(Int_t itb = 0; itb < AliTRDseedV1::kNclusters; itb++){
1234 if(!(cl = tracklets[ipl].GetClusters(itb))) continue;
1235 if(!cl->IsInChamber()) continue;
1236 if (!tracklets[ipl].IsUsable(itb)) continue;
1240 if(cl->GetSigmaY2()<1.e-6 || cl->GetSigmaZ2()<1.e-6){
1241 if(AliLog::GetDebugLevel("TRD", "AliTRDtrackerV1")>1) printf("D-AliTRDtrackerV1::FitTiltedRieman: Cluster error parameterization missing. This should appear only in HLT tests.");
1242 tracklets[ipl].Print("a");
1248 uvt[0] = 2. * x * t;
1250 uvt[2] = 2. * tilt * t;
1251 uvt[3] = 2. * tilt * dx * t;
1252 w = 2. * (y + tilt*z) * t;
1253 // error definition changes for the different calls
1255 we *= sigError ? TMath::Sqrt(cl->GetSigmaY2()+tilt*tilt*cl->GetSigmaZ2()) : 0.2;
1256 fitter->AddPoint(uvt, w, we);
1257 zfitter.AddPoint(&x, z, static_cast<Double_t>(TMath::Sqrt(cl->GetSigmaZ2())));
1258 // adding points for covariance matrix estimation
1259 erry = 1./(TMath::Sqrt(cl->GetSigmaY2()) + 0.1); // 0.1 is a systematic error (due to misalignment and miscalibration)
1261 errz = 1./cl->GetSigmaZ2();
1262 for(Int_t ipol = 0; ipol < 5; ipol++){
1263 sumPolY[ipol] += erry;
1266 sumPolZ[ipol] += errz;
1276 Double_t offset = fitter->GetParameter(3);
1277 Double_t slope = fitter->GetParameter(4);
1279 // Linear fitter - not possible to make boundaries
1280 // Do not accept non possible z and dzdx combinations
1281 Bool_t acceptablez = kTRUE;
1282 Double_t zref = 0.0;
1283 for (Int_t iLayer = 0; iLayer < kNPlanes; iLayer++) {
1284 if(!tracklets[iLayer].IsOK()) continue;
1285 zref = offset + slope * (tracklets[iLayer].GetX0() - xref);
1286 if (TMath::Abs(tracklets[iLayer].GetZfit(0) - zref) > tracklets[iLayer].GetPadLength() * 0.5 + 1.0)
1287 acceptablez = kFALSE;
1290 Double_t dzmf = zfitter.GetFunctionParameter(1);
1291 Double_t zmf = zfitter.GetFunctionValue(&xref);
1292 fgTiltedRieman->FixParameter(3, zmf);
1293 fgTiltedRieman->FixParameter(4, dzmf);
1295 fitter->ReleaseParameter(3);
1296 fitter->ReleaseParameter(4);
1297 offset = fitter->GetParameter(3);
1298 slope = fitter->GetParameter(4);
1301 // Calculate Curvarture
1302 Double_t a = fitter->GetParameter(0);
1303 Double_t b = fitter->GetParameter(1);
1304 Double_t c = fitter->GetParameter(2);
1305 Double_t curvature = 1.0 + b*b - c*a;
1306 if (curvature > 0.0) curvature = a / TMath::Sqrt(curvature);
1308 Double_t chi2track = fitter->GetChisquare()/Double_t(nPoints);
1310 // Prepare error calculation
1311 TMatrixD covarPolY(3,3);
1312 covarPolY(0,0) = sumPolY[0]; covarPolY(1,1) = sumPolY[2]; covarPolY(2,2) = sumPolY[4];
1313 covarPolY(0,1) = covarPolY(1,0) = sumPolY[1];
1314 covarPolY(0,2) = covarPolY(2,0) = sumPolY[2];
1315 covarPolY(2,1) = covarPolY(1,2) = sumPolY[3];
1317 TMatrixD covarPolZ(2,2);
1318 covarPolZ(0,0) = sumPolZ[0]; covarPolZ(1,1) = sumPolZ[2];
1319 covarPolZ(1,0) = covarPolZ(0,1) = sumPolZ[1];
1322 // Update the tracklets
1323 Double_t x1, dy, dz;
1325 memset(cov, 0, sizeof(Double_t) * 15);
1326 for(Int_t iLayer = 0; iLayer < AliTRDtrackerV1::kNPlanes; iLayer++) {
1328 x = tracklets[iLayer].GetX0();
1334 memset(cov, 0, sizeof(Double_t) * 3);
1335 TMatrixD transform(3,3);
1338 transform(0,2) = x*x;
1342 TMatrixD covariance(transform, TMatrixD::kMult, covarPolY);
1343 covariance *= transform.T();
1344 TMatrixD transformZ(2,2);
1345 transformZ(0,0) = transformZ(1,1) = 1;
1346 transformZ(0,1) = x;
1347 TMatrixD covarZ(transformZ, TMatrixD::kMult, covarPolZ);
1348 covarZ *= transformZ.T();
1349 // y: R^2 = (x - x0)^2 + (y - y0)^2
1350 // => y = y0 +/- Sqrt(R^2 - (x - x0)^2)
1351 // R = Sqrt() = 1/Curvature
1352 // => y = y0 +/- Sqrt(1/Curvature^2 - (x - x0)^2)
1353 Double_t res = (x * a + b); // = (x - x0)/y0
1355 res = 1.0 - c * a + b * b - res; // = (R^2 - (x - x0)^2)/y0^2
1357 res = TMath::Sqrt(res);
1358 y = (1.0 - res) / a;
1360 cov[0] = covariance(0,0);
1361 cov[2] = covarZ(0,0);
1364 // dy: R^2 = (x - x0)^2 + (y - y0)^2
1365 // => y = +/- Sqrt(R^2 - (x - x0)^2) + y0
1366 // => dy/dx = (x - x0)/Sqrt(R^2 - (x - x0)^2)
1367 // Curvature: cr = 1/R = a/Sqrt(1 + b^2 - c*a)
1368 // => dy/dx = (x - x0)/(1/(cr^2) - (x - x0)^2)
1369 Double_t x0 = -b / a;
1370 if (-c * a + b * b + 1 > 0) {
1371 if (1.0/(curvature * curvature) - (x - x0) * (x - x0) > 0.0) {
1372 Double_t yderiv = (x - x0) / TMath::Sqrt(1.0/(curvature * curvature) - (x - x0) * (x - x0));
1373 if (a < 0) yderiv *= -1.0;
1377 z = offset + slope * (x - xref);
1379 tracklets[iLayer].SetYref(0, y);
1380 tracklets[iLayer].SetYref(1, dy);
1381 tracklets[iLayer].SetZref(0, z);
1382 tracklets[iLayer].SetZref(1, dz);
1383 tracklets[iLayer].SetC(curvature);
1384 tracklets[iLayer].SetCovRef(cov);
1385 tracklets[iLayer].SetChi2(chi2track);
1387 if(AliLog::GetDebugLevel("TRD", "AliTRDtrackerV1")>3) printf("D-AliTRDtrackerV1::FitTiltedRieman: Chi2[%f] C[%5.2e] pt[%8.3f]\n", chi2track, curvature, GetBz()*kB2C/curvature);
1389 /* if(fkReconstructor->GetRecoParam()->GetStreamLevel(AliTRDrecoParam::kTracker) >=5){
1390 TTreeSRedirector &cstreamer = *fkReconstructor->GetDebugStream(AliTRDrecoParam::kTracker);
1391 Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
1392 Int_t candidateNumber = AliTRDtrackerDebug::GetCandidateNumber();
1393 Double_t chi2z = CalculateChi2Z(tracklets, offset, slope, xref);
1394 cstreamer << "FitTiltedRieman0"
1395 << "EventNumber=" << eventNumber
1396 << "CandidateNumber=" << candidateNumber
1398 << "Chi2Z=" << chi2z
1405 //____________________________________________________________________
1406 Double_t AliTRDtrackerV1::FitLine(const AliTRDtrackV1 *track, AliTRDseedV1 *tracklets, Bool_t err, Int_t np, AliTrackPoint *points)
1409 // Fit track with a staight line
1410 // Fills an AliTrackPoint array with np points
1411 // Function should be used to refit tracks when no magnetic field was on
1413 AliTRDLeastSquare yfitter, zfitter;
1414 AliTRDcluster *cl = NULL;
1416 AliTRDseedV1 work[kNPlanes], *tracklet = NULL;
1418 for(Int_t ipl = 0; ipl < kNPlanes; ipl++){
1419 if(!(tracklet = track->GetTracklet(ipl))) continue;
1420 if(!tracklet->IsOK()) continue;
1421 new(&work[ipl]) AliTRDseedV1(*tracklet);
1423 tracklets = &work[0];
1426 Double_t xref = CalculateReferenceX(tracklets);
1427 Double_t x, y, z, dx, ye, yr, tilt;
1428 for(Int_t ipl = 0; ipl < kNPlanes; ipl++){
1429 if(!tracklets[ipl].IsOK()) continue;
1430 for(Int_t itb = 0; itb < fgNTimeBins; itb++){
1431 if(!(cl = tracklets[ipl].GetClusters(itb))) continue;
1432 if (!tracklets[ipl].IsUsable(itb)) continue;
1436 zfitter.AddPoint(&dx, z, static_cast<Double_t>(TMath::Sqrt(cl->GetSigmaZ2())));
1440 Double_t z0 = zfitter.GetFunctionParameter(0);
1441 Double_t dzdx = zfitter.GetFunctionParameter(1);
1442 for(Int_t ipl = 0; ipl < kNPlanes; ipl++){
1443 if(!tracklets[ipl].IsOK()) continue;
1444 for(Int_t itb = 0; itb < fgNTimeBins; itb++){
1445 if(!(cl = tracklets[ipl].GetClusters(itb))) continue;
1446 if (!tracklets[ipl].IsUsable(itb)) continue;
1450 tilt = tracklets[ipl].GetTilt();
1452 yr = y + tilt*(z - z0 - dzdx*dx);
1453 // error definition changes for the different calls
1454 ye = tilt*TMath::Sqrt(cl->GetSigmaZ2());
1455 ye += err ? tracklets[ipl].GetSigmaY() : 0.2;
1456 yfitter.AddPoint(&dx, yr, ye);
1460 Double_t y0 = yfitter.GetFunctionParameter(0);
1461 Double_t dydx = yfitter.GetFunctionParameter(1);
1462 Double_t chi2 = 0.;//yfitter.GetChisquare()/Double_t(nPoints);
1464 //update track points array
1467 for(int ip=0; ip<np; ip++){
1468 points[ip].GetXYZ(xyz);
1469 xyz[1] = y0 + dydx * (xyz[0] - xref);
1470 xyz[2] = z0 + dzdx * (xyz[0] - xref);
1471 points[ip].SetXYZ(xyz);
1478 //_________________________________________________________________________
1479 Double_t AliTRDtrackerV1::FitRiemanTilt(const AliTRDtrackV1 *track, AliTRDseedV1 *tracklets, Bool_t sigError, Int_t np, AliTrackPoint *points)
1482 // Performs a Riemann fit taking tilting pad correction into account
1484 // Paramters: - Array of tracklets (connected to the track candidate)
1485 // - Flag selecting the error definition
1486 // Output: - Chi2 values of the track (in Parameter list)
1488 // The equations which has to be solved simultaneously are:
1490 // R^{2} = (x-x_{0})^{2} + (y^{*}-y_{0})^{2}
1491 // y^{*} = y - tg(h)(z - z_{t})
1492 // z_{t} = z_{0}+dzdx*(x-x_{r})
1494 // with (x, y, z) the coordinate of the cluster, (x_0, y_0, z_0) the coordinate of the center of the Riemann circle,
1495 // R its radius, x_r a constant refrence radial position in the middle of the TRD stack and dzdx the slope of the
1496 // track in the x-z plane. Using the following transformations
1498 // t = 1 / (x^{2} + y^{2})
1500 // v = 2 * tan(h) * t
1501 // w = 2 * tan(h) * (x - x_{r}) * t
1503 // One gets the following linear equation
1505 // a + b * u + c * t + d * v + e * w = 2 * (y + tg(h) * z) * t
1507 // where the coefficients have the following meaning
1511 // c = (R^{2} -x_{0}^{2} - y_{0}^{2})/y_{0}
1515 // The error calculation for the free term is thus
1517 // #sigma = 2 * #sqrt{#sigma^{2}_{y} + (tilt corr ...) + tg^{2}(h) * #sigma^{2}_{z}} * t
1520 // From this simple model one can compute chi^2 estimates and a rough approximation of pt from the curvature according
1523 // C = 1/R = a/(1 + b^{2} + c*a)
1527 // M.Ivanov <M.Ivanov@gsi.de>
1528 // A.Bercuci <A.Bercuci@gsi.de>
1529 // M.Fasel <M.Fasel@gsi.de>
1531 TLinearFitter *fitter = GetTiltedRiemanFitter();
1532 fitter->StoreData(kTRUE);
1533 fitter->ClearPoints();
1534 AliTRDLeastSquare zfitter;
1535 AliTRDcluster *cl = NULL;
1537 AliTRDseedV1 work[kNPlanes], *tracklet = NULL;
1539 for(Int_t ipl = 0; ipl < kNPlanes; ipl++){
1540 if(!(tracklet = track->GetTracklet(ipl))) continue;
1541 if(!tracklet->IsOK()) continue;
1542 new(&work[ipl]) AliTRDseedV1(*tracklet);
1544 tracklets = &work[0];
1547 Double_t xref = CalculateReferenceX(tracklets);
1548 if(AliLog::GetDebugLevel("TRD", "AliTRDtrackerV1")>3) printf("D-AliTRDtrackerV1::FitRiemanTilt:\nx0[(0)%6.2f (1)%6.2f (2)%6.2f (3)%6.2f (4)%6.2f (5)%6.2f] xref[%6.2f]", tracklets[0].GetX0(), tracklets[1].GetX0(), tracklets[2].GetX0(), tracklets[3].GetX0(), tracklets[4].GetX0(), tracklets[5].GetX0(), xref);
1549 Double_t x, y, z, t, tilt, dx, w, we;
1552 // Containers for Least-square fitter
1553 for(Int_t ipl = 0; ipl < kNPlanes; ipl++){
1554 if(!tracklets[ipl].IsOK()) continue;
1555 for(Int_t itb = 0; itb < AliTRDseedV1::kNclusters; itb++){
1556 if(!(cl = tracklets[ipl].GetClusters(itb))) continue;
1557 //if (!tracklets[ipl].IsUsable(itb)) continue;
1561 tilt = tracklets[ipl].GetTilt();
1565 uvt[0] = 2. * x * t;
1567 uvt[2] = 2. * tilt * t;
1568 uvt[3] = 2. * tilt * dx * t;
1569 w = 2. * (y + tilt*z) * t;
1570 // error definition changes for the different calls
1572 we *= sigError ? TMath::Sqrt(cl->GetSigmaY2()) : 0.2;
1573 fitter->AddPoint(uvt, w, we);
1574 zfitter.AddPoint(&x, z, static_cast<Double_t>(TMath::Sqrt(cl->GetSigmaZ2())));
1578 if(fitter->Eval()) return 1.E10;
1580 Double_t z0 = fitter->GetParameter(3);
1581 Double_t dzdx = fitter->GetParameter(4);
1584 // Linear fitter - not possible to make boundaries
1585 // Do not accept non possible z and dzdx combinations
1586 Bool_t accept = kTRUE;
1587 Double_t zref = 0.0;
1588 for (Int_t iLayer = 0; iLayer < kNPlanes; iLayer++) {
1589 if(!tracklets[iLayer].IsOK()) continue;
1590 zref = z0 + dzdx * (tracklets[iLayer].GetX0() - xref);
1591 if (TMath::Abs(tracklets[iLayer].GetZfit(0) - zref) > tracklets[iLayer].GetPadLength() * 0.5 + 1.0)
1596 Double_t dzmf = zfitter.GetFunctionParameter(1);
1597 Double_t zmf = zfitter.GetFunctionValue(&xref);
1598 fitter->FixParameter(3, zmf);
1599 fitter->FixParameter(4, dzmf);
1601 fitter->ReleaseParameter(3);
1602 fitter->ReleaseParameter(4);
1603 z0 = fitter->GetParameter(3); // = zmf ?
1604 dzdx = fitter->GetParameter(4); // = dzmf ?
1607 // Calculate Curvature
1608 Double_t a = fitter->GetParameter(0);
1609 Double_t b = fitter->GetParameter(1);
1610 Double_t c = fitter->GetParameter(2);
1611 Double_t y0 = 1. / a;
1612 Double_t x0 = -b * y0;
1613 Double_t tmp = y0*y0 + x0*x0 - c*y0;
1614 if(tmp<=0.) return 1.E10;
1615 Double_t radius = TMath::Sqrt(tmp);
1616 Double_t curvature = 1.0 + b*b - c*a;
1617 if (curvature > 0.0) curvature = a / TMath::Sqrt(curvature);
1619 // Calculate chi2 of the fit
1620 Double_t chi2 = fitter->GetChisquare()/Double_t(nPoints);
1621 if(AliLog::GetDebugLevel("TRD", "AliTRDtrackerV1")>3) printf("D-AliTRDtrackerV1::FitRiemanTilt:x0[%6.2f] y0[%6.2f] R[%6.2f] chi2[%f]\n", x0, y0, radius, chi2);
1623 // Update the tracklets
1625 for(Int_t ip = 0; ip < kNPlanes; ip++) {
1626 x = tracklets[ip].GetX0();
1627 tmp = radius*radius-(x-x0)*(x-x0);
1628 if(tmp <= 0.) continue;
1629 tmp = TMath::Sqrt(tmp);
1631 // y: R^2 = (x - x0)^2 + (y - y0)^2
1632 // => y = y0 +/- Sqrt(R^2 - (x - x0)^2)
1633 tracklets[ip].SetYref(0, y0 - (y0>0.?1.:-1)*tmp);
1634 // => dy/dx = (x - x0)/Sqrt(R^2 - (x - x0)^2)
1635 tracklets[ip].SetYref(1, (x - x0) / tmp);
1636 tracklets[ip].SetZref(0, z0 + dzdx * (x - xref));
1637 tracklets[ip].SetZref(1, dzdx);
1638 tracklets[ip].SetC(curvature);
1639 tracklets[ip].SetChi2(chi2);
1642 //update track points array
1645 for(int ip=0; ip<np; ip++){
1646 points[ip].GetXYZ(xyz);
1647 xyz[1] = TMath::Abs(xyz[0] - x0) > radius ? 100. : y0 - (y0>0.?1.:-1.)*TMath::Sqrt((radius-(xyz[0]-x0))*(radius+(xyz[0]-x0)));
1648 xyz[2] = z0 + dzdx * (xyz[0] - xref);
1649 points[ip].SetXYZ(xyz);
1657 //____________________________________________________________________
1658 Double_t AliTRDtrackerV1::FitKalman(AliTRDtrackV1 *track, AliTRDseedV1 * const tracklets, Bool_t up, Int_t np, AliTrackPoint *points)
1660 // Kalman filter implementation for the TRD.
1661 // It returns the positions of the fit in the array "points"
1663 // Author : A.Bercuci@gsi.de
1665 // printf("Start track @ x[%f]\n", track->GetX());
1667 //prepare marker points along the track
1668 Int_t ip = np ? 0 : 1;
1670 if((up?-1:1) * (track->GetX() - points[ip].GetX()) > 0.) break;
1671 //printf("AliTRDtrackerV1::FitKalman() : Skip track marker x[%d] = %7.3f. Before track start ( %7.3f ).\n", ip, points[ip].GetX(), track->GetX());
1674 //if(points) printf("First marker point @ x[%d] = %f\n", ip, points[ip].GetX());
1677 AliTRDseedV1 tracklet, *ptrTracklet = NULL;
1679 //Loop through the TRD planes
1680 for (Int_t jplane = 0; jplane < kNPlanes; jplane++) {
1681 // GET TRACKLET OR BUILT IT
1682 Int_t iplane = up ? jplane : kNPlanes - 1 - jplane;
1684 if(!(ptrTracklet = &tracklets[iplane])) continue;
1686 if(!(ptrTracklet = track->GetTracklet(iplane))){
1687 /*AliTRDtrackerV1 *tracker = NULL;
1688 if(!(tracker = dynamic_cast<AliTRDtrackerV1*>( AliTRDrecoParam:Tracker()))) continue;
1689 ptrTracklet = new(&tracklet) AliTRDseedV1(iplane);
1690 if(!tracker->MakeTracklet(ptrTracklet, track)) */
1694 if(!ptrTracklet->IsOK()) continue;
1696 Double_t x = ptrTracklet->GetX0();
1699 //don't do anything if next marker is after next update point.
1700 if((up?-1:1) * (points[ip].GetX() - x) - fgkMaxStep < 0) break;
1701 if(((up?-1:1) * (points[ip].GetX() - track->GetX()) < 0) && !PropagateToX(*track, points[ip].GetX(), fgkMaxStep)) return -1.;
1703 Double_t xyz[3]; // should also get the covariance
1705 track->Global2LocalPosition(xyz, track->GetAlpha());
1706 points[ip].SetXYZ(xyz[0], xyz[1], xyz[2]);
1709 // printf("plane[%d] tracklet[%p] x[%f]\n", iplane, ptrTracklet, x);
1711 // Propagate closer to the next update point
1712 if(((up?-1:1) * (x - track->GetX()) + fgkMaxStep < 0) && !PropagateToX(*track, x + (up?-1:1)*fgkMaxStep, fgkMaxStep)) return -1.;
1714 if(!AdjustSector(track)) return -1;
1715 if(TMath::Abs(track->GetSnp()) > fgkMaxSnp) return -1;
1717 //load tracklet to the tracker and the track
1719 if((index = FindTracklet(ptrTracklet)) < 0){
1720 ptrTracklet = SetTracklet(&tracklet);
1721 index = fTracklets->GetEntriesFast()-1;
1723 track->SetTracklet(ptrTracklet, index);*/
1726 // register tracklet to track with tracklet creation !!
1727 // PropagateBack : loaded tracklet to the tracker and update index
1728 // RefitInward : update index
1729 // MakeTrack : loaded tracklet to the tracker and update index
1730 if(!tracklets) track->SetTracklet(ptrTracklet, -1);
1733 //Calculate the mean material budget along the path inside the chamber
1734 Double_t xyz0[3]; track->GetXYZ(xyz0);
1735 Double_t alpha = track->GetAlpha();
1736 Double_t xyz1[3], y, z;
1737 if(!track->GetProlongation(x, y, z)) return -1;
1738 xyz1[0] = x * TMath::Cos(alpha) - y * TMath::Sin(alpha);
1739 xyz1[1] = +x * TMath::Sin(alpha) + y * TMath::Cos(alpha);
1741 if(TMath::Abs(xyz0[0] - xyz1[0]) < 1e-3 && TMath::Abs(xyz0[1] - xyz1[1]) < 1e-3) continue; // check wheter we are at the same global x position
1743 if(AliTracker::MeanMaterialBudget(xyz0, xyz1, param) <=0.) break;
1744 Double_t xrho = param[0]*param[4]; // density*length
1745 Double_t xx0 = param[1]; // radiation length
1747 //Propagate the track
1748 track->PropagateTo(x, xx0, xrho);
1749 if (!AdjustSector(track)) break;
1752 Double_t cov[3]; ptrTracklet->GetCovAt(x, cov);
1753 Double_t p[2] = { ptrTracklet->GetY(), ptrTracklet->GetZ()};
1754 Double_t chi2 = ((AliExternalTrackParam*)track)->GetPredictedChi2(p, cov);
1755 if(chi2<1e+10) track->Update(p, cov, chi2);
1758 //Reset material budget if 2 consecutive gold
1759 if(iplane>0 && track->GetTracklet(iplane-1) && ptrTracklet->GetN() + track->GetTracklet(iplane-1)->GetN() > 20) track->SetBudget(2, 0.);
1760 } // end planes loop
1764 if(((up?-1:1) * (points[ip].GetX() - track->GetX()) < 0) && !PropagateToX(*track, points[ip].GetX(), fgkMaxStep)) return -1.;
1766 Double_t xyz[3]; // should also get the covariance
1768 track->Global2LocalPosition(xyz, track->GetAlpha());
1769 points[ip].SetXYZ(xyz[0], xyz[1], xyz[2]);
1773 return track->GetChi2();
1776 //_________________________________________________________________________
1777 Float_t AliTRDtrackerV1::CalculateChi2Z(AliTRDseedV1 *tracklets, Double_t offset, Double_t slope, Double_t xref)
1780 // Calculates the chi2-value of the track in z-Direction including tilting pad correction.
1781 // A linear dependence on the x-value serves as a model.
1782 // The parameters are related to the tilted Riemann fit.
1783 // Parameters: - Array of tracklets (AliTRDseedV1) related to the track candidate
1784 // - the offset for the reference x
1786 // - the reference x position
1787 // Output: - The Chi2 value of the track in z-Direction
1789 Float_t chi2Z = 0, nLayers = 0;
1790 for (Int_t iLayer = 0; iLayer < AliTRDgeometry::kNlayer; iLayer++) {
1791 if(!tracklets[iLayer].IsOK()) continue;
1792 Double_t z = offset + slope * (tracklets[iLayer].GetX0() - xref);
1793 chi2Z += TMath::Abs(tracklets[iLayer].GetZfit(0) - z);
1796 chi2Z /= TMath::Max((nLayers - 3.0),1.0);
1800 //_____________________________________________________________________________
1801 Int_t AliTRDtrackerV1::PropagateToX(AliTRDtrackV1 &t, Double_t xToGo, Double_t maxStep)
1804 // Starting from current X-position of track <t> this function
1805 // extrapolates the track up to radial position <xToGo>.
1806 // Returns 1 if track reaches the plane, and 0 otherwise
1809 const Double_t kEpsilon = 0.00001;
1811 // Current track X-position
1812 Double_t xpos = t.GetX();
1814 // Direction: inward or outward
1815 Double_t dir = (xpos < xToGo) ? 1.0 : -1.0;
1817 while (((xToGo - xpos) * dir) > kEpsilon) {
1826 // The next step size
1827 Double_t step = dir * TMath::Min(TMath::Abs(xToGo-xpos),maxStep);
1829 // Get the global position of the starting point
1832 // X-position after next step
1835 // Get local Y and Z at the X-position of the next step
1836 if(t.GetProlongation(x,y,z)<0) return 0; // No prolongation possible
1838 // The global position of the end point of this prolongation step
1839 xyz1[0] = x * TMath::Cos(t.GetAlpha()) - y * TMath::Sin(t.GetAlpha());
1840 xyz1[1] = +x * TMath::Sin(t.GetAlpha()) + y * TMath::Cos(t.GetAlpha());
1843 // Calculate the mean material budget between start and
1844 // end point of this prolongation step
1845 if(AliTracker::MeanMaterialBudget(xyz0, xyz1, param)<=0.) return 0;
1847 // Propagate the track to the X-position after the next step
1848 if (!t.PropagateTo(x, param[1], param[0]*param[4])) return 0;
1850 // Rotate the track if necessary
1853 // New track X-position
1863 //_____________________________________________________________________________
1864 Int_t AliTRDtrackerV1::ReadClusters(TClonesArray* &array, TTree *clusterTree) const
1867 // Reads AliTRDclusters from the file.
1868 // The names of the cluster tree and branches
1869 // should match the ones used in AliTRDclusterizer::WriteClusters()
1872 Int_t nsize = Int_t(clusterTree->GetTotBytes() / (sizeof(AliTRDcluster)));
1873 TObjArray *clusterArray = new TObjArray(nsize+1000);
1875 TBranch *branch = clusterTree->GetBranch("TRDcluster");
1877 AliError("Can't get the branch !");
1880 branch->SetAddress(&clusterArray);
1883 Float_t nclusters = fkRecoParam->GetNClusters();
1884 if(fkReconstructor->IsHLT()) nclusters /= AliTRDgeometry::kNsector;
1885 array = new TClonesArray("AliTRDcluster", Int_t(nclusters));
1886 array->SetOwner(kTRUE);
1889 // Loop through all entries in the tree
1890 Int_t nEntries = (Int_t) clusterTree->GetEntries();
1893 AliTRDcluster *c = NULL;
1894 for (Int_t iEntry = 0; iEntry < nEntries; iEntry++) {
1896 nbytes += clusterTree->GetEvent(iEntry);
1898 // Get the number of points in the detector
1899 Int_t nCluster = clusterArray->GetEntriesFast();
1900 for (Int_t iCluster = 0; iCluster < nCluster; iCluster++) {
1901 if(!(c = (AliTRDcluster *) clusterArray->UncheckedAt(iCluster))) continue;
1902 new((*fClusters)[ncl++]) AliTRDcluster(*c);
1903 delete (clusterArray->RemoveAt(iCluster));
1907 delete clusterArray;
1912 //_____________________________________________________________________________
1913 Int_t AliTRDtrackerV1::LoadClusters(TTree *cTree)
1916 // Fills clusters into TRD tracking sectors
1919 fkRecoParam = fkReconstructor->GetRecoParam(); // load reco param for this event
1921 if(!fkReconstructor->IsWritingClusters()){
1922 fClusters = AliTRDReconstructor::GetClusters();
1924 if (ReadClusters(fClusters, cTree)) {
1925 AliError("Problem with reading the clusters !");
1931 if(!fClusters || !fClusters->GetEntriesFast()){
1932 AliInfo("No TRD clusters");
1937 BuildTrackingContainers();
1939 //Int_t ncl = fClusters->GetEntriesFast();
1940 //AliInfo(Form("Clusters %d [%6.2f %% in the active volume]", ncl, 100.*float(nin)/ncl));
1945 //_____________________________________________________________________________
1946 Int_t AliTRDtrackerV1::LoadClusters(TClonesArray * const clusters)
1949 // Fills clusters into TRD tracking sectors
1950 // Function for use in the HLT
1952 if(!clusters || !clusters->GetEntriesFast()){
1953 AliInfo("No TRD clusters");
1957 fClusters = clusters;
1960 fkRecoParam = fkReconstructor->GetRecoParam(); // load reco param for this event
1961 BuildTrackingContainers();
1963 //Int_t ncl = fClusters->GetEntriesFast();
1964 //AliInfo(Form("Clusters %d [%6.2f %% in the active volume]", ncl, 100.*float(nin)/ncl));
1970 //____________________________________________________________________
1971 Int_t AliTRDtrackerV1::BuildTrackingContainers()
1973 // Building tracking containers for clusters
1975 Int_t nin(0), ncl(fClusters->GetEntriesFast());
1977 AliTRDcluster *c = (AliTRDcluster *) fClusters->UncheckedAt(ncl);
1978 if(c->IsInChamber()) nin++;
1979 if(fkReconstructor->IsHLT()) c->SetRPhiMethod(AliTRDcluster::kCOG);
1980 Int_t detector = c->GetDetector();
1981 Int_t sector = fGeom->GetSector(detector);
1982 Int_t stack = fGeom->GetStack(detector);
1983 Int_t layer = fGeom->GetLayer(detector);
1985 fTrSec[sector].GetChamber(stack, layer, kTRUE)->InsertCluster(c, ncl, fkReconstructor->IsHLT());
1988 for(int isector =0; isector<AliTRDgeometry::kNsector; isector++){
1989 if(!fTrSec[isector].GetNChambers()) continue;
1990 fTrSec[isector].Init(fkReconstructor);
1998 //____________________________________________________________________
1999 void AliTRDtrackerV1::UnloadClusters()
2002 // Clears the arrays of clusters and tracks. Resets sectors and timebins
2003 // If option "force" is also set the containers are also deleted. This is useful
2008 if(HasRemoveContainers()){delete fTracks; fTracks = NULL;}
2011 fTracklets->Delete();
2012 if(HasRemoveContainers()){delete fTracklets; fTracklets = NULL;}
2015 if(IsClustersOwner()) fClusters->Delete();
2017 // save clusters array in the reconstructor for further use.
2018 if(!fkReconstructor->IsWritingClusters()){
2019 AliTRDReconstructor::SetClusters(fClusters);
2020 SetClustersOwner(kFALSE);
2021 } else AliTRDReconstructor::SetClusters(NULL);
2024 for (int i = 0; i < AliTRDgeometry::kNsector; i++) fTrSec[i].Clear();
2026 // Increment the Event Number
2027 AliTRDtrackerDebug::SetEventNumber(AliTRDtrackerDebug::GetEventNumber() + 1);
2030 // //____________________________________________________________________
2031 // void AliTRDtrackerV1::UseClusters(const AliKalmanTrack *t, Int_t) const
2033 // const AliTRDtrackV1 *track = dynamic_cast<const AliTRDtrackV1*>(t);
2034 // if(!track) return;
2036 // AliTRDseedV1 *tracklet = NULL;
2037 // for(Int_t ily=AliTRDgeometry::kNlayer; ily--;){
2038 // if(!(tracklet = track->GetTracklet(ily))) continue;
2039 // AliTRDcluster *c = NULL;
2040 // for(Int_t ic=AliTRDseed::kNclusters; ic--;){
2041 // if(!(c=tracklet->GetClusters(ic))) continue;
2048 //_____________________________________________________________________________
2049 Bool_t AliTRDtrackerV1::AdjustSector(AliTRDtrackV1 *const track)
2052 // Rotates the track when necessary
2055 Double_t alpha = AliTRDgeometry::GetAlpha();
2056 Double_t y = track->GetY();
2057 Double_t ymax = track->GetX()*TMath::Tan(0.5*alpha);
2060 if (!track->Rotate( alpha)) {
2064 else if (y < -ymax) {
2065 if (!track->Rotate(-alpha)) {
2075 //____________________________________________________________________
2076 AliTRDseedV1* AliTRDtrackerV1::GetTracklet(AliTRDtrackV1 *const track, Int_t p, Int_t &idx)
2078 // Find tracklet for TRD track <track>
2087 // Detailed description
2089 idx = track->GetTrackletIndex(p);
2090 AliTRDseedV1 *tracklet = (idx<0) ? NULL : (AliTRDseedV1*)fTracklets->UncheckedAt(idx);
2095 //____________________________________________________________________
2096 AliTRDseedV1* AliTRDtrackerV1::SetTracklet(const AliTRDseedV1 * const tracklet)
2098 // Add this tracklet to the list of tracklets stored in the tracker
2101 // - tracklet : pointer to the tracklet to be added to the list
2104 // - the index of the new tracklet in the tracker tracklets list
2106 // Detailed description
2107 // Build the tracklets list if it is not yet created (late initialization)
2108 // and adds the new tracklet to the list.
2111 fTracklets = new TClonesArray("AliTRDseedV1", AliTRDgeometry::Nsector()*kMaxTracksStack);
2112 fTracklets->SetOwner(kTRUE);
2114 Int_t nentries = fTracklets->GetEntriesFast();
2115 return new ((*fTracklets)[nentries]) AliTRDseedV1(*tracklet);
2118 //____________________________________________________________________
2119 AliTRDtrackV1* AliTRDtrackerV1::SetTrack(const AliTRDtrackV1 * const track)
2121 // Add this track to the list of tracks stored in the tracker
2124 // - track : pointer to the track to be added to the list
2127 // - the pointer added
2129 // Detailed description
2130 // Build the tracks list if it is not yet created (late initialization)
2131 // and adds the new track to the list.
2134 fTracks = new TClonesArray("AliTRDtrackV1", AliTRDgeometry::Nsector()*kMaxTracksStack);
2135 fTracks->SetOwner(kTRUE);
2137 Int_t nentries = fTracks->GetEntriesFast();
2138 return new ((*fTracks)[nentries]) AliTRDtrackV1(*track);
2143 //____________________________________________________________________
2144 Int_t AliTRDtrackerV1::Clusters2TracksSM(Int_t sector, AliESDEvent *esd)
2147 // Steer tracking for one SM.
2150 // sector : Array of (SM) propagation layers containing clusters
2151 // esd : The current ESD event. On output it contains the also
2152 // the ESD (TRD) tracks found in this SM.
2155 // Number of tracks found in this TRD supermodule.
2157 // Detailed description
2159 // 1. Unpack AliTRDpropagationLayers objects for each stack.
2160 // 2. Launch stack tracking.
2161 // See AliTRDtrackerV1::Clusters2TracksStack() for details.
2162 // 3. Pack results in the ESD event.
2166 Int_t nChambers = 0;
2167 AliTRDtrackingChamber **stack = NULL, *chamber = NULL;
2168 for(int istack = 0; istack<AliTRDgeometry::kNstack; istack++){
2169 if(!(stack = fTrSec[sector].GetStack(istack))) continue;
2171 for(int ilayer=0; ilayer<AliTRDgeometry::kNlayer; ilayer++){
2172 if(!(chamber = stack[ilayer])) continue;
2173 if(chamber->GetNClusters() < fgNTimeBins * fkRecoParam->GetFindableClusters()) continue;
2175 //AliInfo(Form("sector %d stack %d layer %d clusters %d", sector, istack, ilayer, chamber->GetNClusters()));
2177 if(nChambers < 4) continue;
2178 //AliInfo(Form("Doing stack %d", istack));
2179 nTracks += Clusters2TracksStack(stack, fTracksESD);
2181 if(nTracks) AliDebug(2, Form("Number of tracks: SM_%02d[%d]", sector, nTracks));
2183 for(int itrack=0; itrack<nTracks; itrack++){
2184 AliESDtrack *esdTrack((AliESDtrack*)(fTracksESD->operator[](itrack)));
2185 Int_t id = esd->AddTrack(esdTrack);
2187 // set ESD id to stand alone TRD tracks
2188 if (fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) > 0){
2189 esdTrack=esd->GetTrack(id);
2190 TObject *o(NULL); Int_t ic(0);
2191 AliTRDtrackV1 *calibTrack(NULL);
2192 while((o = esdTrack->GetCalibObject(ic++))){
2193 if(!(calibTrack = dynamic_cast<AliTRDtrackV1*>(o))) continue;
2194 calibTrack->SetESDid(esdTrack->GetID());
2200 // Reset Track and Candidate Number
2201 AliTRDtrackerDebug::SetCandidateNumber(0);
2202 AliTRDtrackerDebug::SetTrackNumber(0);
2204 // delete ESD tracks in the array
2205 fTracksESD->Delete();
2209 //____________________________________________________________________
2210 Int_t AliTRDtrackerV1::Clusters2TracksStack(AliTRDtrackingChamber **stack, TClonesArray * const esdTrackList)
2213 // Make tracks in one TRD stack.
2216 // layer : Array of stack propagation layers containing clusters
2217 // esdTrackList : Array of ESD tracks found by the stand alone tracker.
2218 // On exit the tracks found in this stack are appended.
2221 // Number of tracks found in this stack.
2223 // Detailed description
2225 // 1. Find the 3 most useful seeding chambers. See BuildSeedingConfigs() for details.
2226 // 2. Steer AliTRDtrackerV1::MakeSeeds() for 3 seeding layer configurations.
2227 // See AliTRDtrackerV1::MakeSeeds() for more details.
2228 // 3. Arrange track candidates in decreasing order of their quality
2229 // 4. Classify tracks in 5 categories according to:
2230 // a) number of layers crossed
2232 // 5. Sign clusters by tracks in decreasing order of track quality
2233 // 6. Build AliTRDtrack out of seeding tracklets
2235 // 8. Build ESD track and register it to the output list
2238 AliTRDtrackingChamber *chamber = NULL;
2239 AliTRDtrackingChamber **ci = NULL;
2240 AliTRDseedV1 sseed[kMaxTracksStack*6]; // to be initialized
2241 Int_t pars[4]; // MakeSeeds parameters
2243 //Double_t alpha = AliTRDgeometry::GetAlpha();
2244 //Double_t shift = .5 * alpha;
2245 Int_t configs[kNConfigs];
2247 // Purge used clusters from the containers
2249 for(Int_t ic = kNPlanes; ic--; ci++){
2250 if(!(*ci)) continue;
2254 // Build initial seeding configurations
2255 Double_t quality = BuildSeedingConfigs(stack, configs);
2256 if(fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) > 10){
2257 AliInfo(Form("Plane config %d %d %d Quality %f"
2258 , configs[0], configs[1], configs[2], quality));
2262 // Initialize contors
2263 Int_t ntracks, // number of TRD track candidates
2264 ntracks1, // number of registered TRD tracks/iter
2265 ntracks2 = 0; // number of all registered TRD tracks in stack
2269 Int_t ic = 0; ci = &stack[0];
2270 while(ic<kNPlanes && !(*ci)){ic++; ci++;}
2271 if(!(*ci)) return ntracks2;
2272 Int_t istack = fGeom->GetStack((*ci)->GetDetector());
2275 // Loop over seeding configurations
2276 ntracks = 0; ntracks1 = 0;
2277 for (Int_t iconf = 0; iconf<3; iconf++) {
2278 pars[0] = configs[iconf];
2281 ntracks = MakeSeeds(stack, &sseed[6*ntracks], pars);
2282 //AliInfo(Form("Number of Tracks after iteration step %d: %d\n", iconf, ntracks));
2283 if(ntracks == kMaxTracksStack) break;
2285 AliDebug(2, Form("Candidate TRD tracks %d in iteration %d.", ntracks, fSieveSeeding));
2288 // Sort the seeds according to their quality
2289 Int_t sort[kMaxTracksStack];
2290 TMath::Sort(ntracks, fTrackQuality, sort, kTRUE);
2291 if(AliLog::GetDebugLevel("TRD", "AliTRDtrackerV1") > 2){
2292 AliDebug(3, "Track candidates classification:");
2293 for (Int_t it(0); it < ntracks; it++) {
2295 printf(" %2d idx[%d] Quality[%e]\n", it, jt, fTrackQuality[jt]);
2299 // Initialize number of tracks so far and logic switches
2300 Int_t ntracks0 = esdTrackList->GetEntriesFast();
2301 Bool_t signedTrack[kMaxTracksStack];
2302 Bool_t fakeTrack[kMaxTracksStack];
2303 for (Int_t i=0; i<ntracks; i++){
2304 signedTrack[i] = kFALSE;
2305 fakeTrack[i] = kFALSE;
2307 //AliInfo("Selecting track candidates ...");
2309 // Sieve clusters in decreasing order of track quality
2310 Int_t jSieve(0), rejectedCandidates(0);
2312 // Check track candidates
2313 rejectedCandidates=0;
2314 for (Int_t itrack = 0; itrack < ntracks; itrack++) {
2315 Int_t trackIndex = sort[itrack];
2316 if (signedTrack[trackIndex] || fakeTrack[trackIndex]) continue;
2318 // Calculate track parameters from tracklets seeds
2323 for (Int_t jLayer = 0; jLayer < kNPlanes; jLayer++) {
2324 Int_t jseed = kNPlanes*trackIndex+jLayer;
2325 sseed[jseed].UpdateUsed();
2326 if(!sseed[jseed].IsOK()) continue;
2327 // check if primary candidate
2328 if (TMath::Abs(sseed[jseed].GetYref(0) / sseed[jseed].GetX0()) < 0.158) findable++;
2329 ncl += sseed[jseed].GetN();
2330 nused += sseed[jseed].GetNUsed();
2334 // Filter duplicated tracks
2336 AliDebug(4, Form("REJECTED : %d idx[%d] quality[%e] tracklets[%d] usedClusters[%d]", itrack, trackIndex, fTrackQuality[trackIndex], nlayers, nused));
2337 fakeTrack[trackIndex] = kTRUE;
2340 if (ncl>0 && Float_t(nused)/ncl >= .25){
2341 AliDebug(4, Form("REJECTED : %d idx[%d] quality[%e] tracklets[%d] usedClusters[%d] used/ncl[%f]", itrack, trackIndex, fTrackQuality[trackIndex], nlayers, nused, Float_t(nused)/ncl));
2342 fakeTrack[trackIndex] = kTRUE;
2346 AliDebug(4, Form("Candidate[%d] Quality[%e] Tracklets[%d] Findable[%d] Ncl[%d] Nused[%d]", trackIndex, fTrackQuality[trackIndex], nlayers, findable, ncl, nused));
2349 Bool_t skip = kFALSE;
2351 case 0: // select 6 tracklets primary tracks, good quality
2352 if(nlayers > findable || nlayers < kNPlanes) {skip = kTRUE; break;}
2353 if(TMath::Log(1.E-9+fTrackQuality[trackIndex]) < -5.){skip = kTRUE; break;}
2356 case 1: // select shorter primary tracks, good quality
2357 if(findable<4){skip = kTRUE; break;}
2358 if(nlayers < findable){skip = kTRUE; break;}
2359 if(TMath::Log(1.E-9+fTrackQuality[trackIndex]) < -4.){skip = kTRUE; break;}
2362 case 2: // select 6 tracklets secondary tracks
2363 if(nlayers < kNPlanes) { skip = kTRUE; break;}
2364 if (TMath::Log(1.E-9+fTrackQuality[trackIndex]) < -6.0){skip = kTRUE; break;}
2367 case 3: // select shorter tracks, good quality
2368 if (nlayers<4){skip = kTRUE; break;}
2369 if (TMath::Log(1.E-9+fTrackQuality[trackIndex]) < -5.){skip = kTRUE; break;}
2372 case 4: // select anything with at least 4 tracklets
2373 if (nlayers<4){skip = kTRUE; break;}
2374 //if (TMath::Log(1.E-9+fTrackQuality[trackIndex]) - nused/(nlayers-3.0) < -15.0){skip = kTRUE; break;}
2378 rejectedCandidates++;
2379 AliDebug(4, Form("REJECTED : %d idx[%d] quality[%e] tracklets[%d] usedClusters[%d]", itrack, trackIndex, fTrackQuality[trackIndex], nlayers, nused));
2381 } else AliDebug(4, Form("ACCEPTED : %d idx[%d] quality[%e] tracklets[%d] usedClusters[%d]", itrack, trackIndex, fTrackQuality[trackIndex], nlayers, nused));
2383 signedTrack[trackIndex] = kTRUE;
2385 AliTRDseedV1 *lseed =&sseed[trackIndex*kNPlanes];
2386 AliTRDtrackV1 *track = MakeTrack(lseed);
2388 AliDebug(1, "Track building failed.");
2391 if(AliLog::GetDebugLevel("TRD", "AliTRDtrackerV1") > 1){
2392 Int_t ich = 0; while(!(chamber = stack[ich])) ich++;
2393 AliDebug(2, Form("Track pt=%7.2fGeV/c SM[%2d] Done.", track->Pt(), fGeom->GetSector(chamber->GetDetector())));
2397 if(fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) > 1 && fkReconstructor->IsDebugStreaming()){
2398 //AliInfo(Form("Track %d [%d] nlayers %d trackQuality = %e nused %d, yref = %3.3f", itrack, trackIndex, nlayers, fTrackQuality[trackIndex], nused, trackParams[1]));
2400 AliTRDseedV1 *dseed[6];
2401 for(Int_t iseed = AliTRDgeometry::kNlayer; iseed--;) dseed[iseed] = new AliTRDseedV1(lseed[iseed]);
2403 //Int_t eventNrInFile = esd->GetEventNumberInFile();
2404 Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
2405 Int_t trackNumber = AliTRDtrackerDebug::GetTrackNumber();
2406 Int_t candidateNumber = AliTRDtrackerDebug::GetCandidateNumber();
2407 TTreeSRedirector &cstreamer = *fkReconstructor->GetDebugStream(AliTRDrecoParam::kTracker);
2408 cstreamer << "Clusters2TracksStack"
2409 << "EventNumber=" << eventNumber
2410 << "TrackNumber=" << trackNumber
2411 << "CandidateNumber=" << candidateNumber
2412 << "Iter=" << fSieveSeeding
2413 << "Like=" << fTrackQuality[trackIndex]
2414 << "S0.=" << dseed[0]
2415 << "S1.=" << dseed[1]
2416 << "S2.=" << dseed[2]
2417 << "S3.=" << dseed[3]
2418 << "S4.=" << dseed[4]
2419 << "S5.=" << dseed[5]
2421 << "NLayers=" << nlayers
2422 << "Findable=" << findable
2423 << "NUsed=" << nused
2428 AliESDtrack *esdTrack = new ((*esdTrackList)[ntracks0++]) AliESDtrack();
2429 esdTrack->UpdateTrackParams(track, AliESDtrack::kTRDout);
2430 esdTrack->SetLabel(track->GetLabel());
2431 track->UpdateESDtrack(esdTrack);
2432 // write ESD-friends if neccessary
2433 if (fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) > 0){
2434 AliTRDtrackV1 *calibTrack = new AliTRDtrackV1(*track);
2435 calibTrack->SetOwner();
2436 esdTrack->AddCalibObject(calibTrack);
2439 AliTRDtrackerDebug::SetTrackNumber(AliTRDtrackerDebug::GetTrackNumber() + 1);
2443 } while(jSieve<5 && rejectedCandidates); // end track candidates sieve
2444 if(!ntracks1) break;
2446 // increment counters
2447 ntracks2 += ntracks1;
2449 if(fkReconstructor->IsHLT()) break;
2452 // Rebuild plane configurations and indices taking only unused clusters into account
2453 quality = BuildSeedingConfigs(stack, configs);
2454 if(quality < 1.E-7) break; //fkReconstructor->GetRecoParam() ->GetPlaneQualityThreshold()) break;
2456 for(Int_t ip = 0; ip < kNPlanes; ip++){
2457 if(!(chamber = stack[ip])) continue;
2458 chamber->Build(fGeom);//Indices(fSieveSeeding);
2461 if(fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) > 10){
2462 AliInfo(Form("Sieve level %d Plane config %d %d %d Quality %f", fSieveSeeding, configs[0], configs[1], configs[2], quality));
2464 } while(fSieveSeeding<10); // end stack clusters sieve
2468 //AliInfo(Form("Registered TRD tracks %d in stack %d.", ntracks2, pars[1]));
2473 //___________________________________________________________________
2474 Double_t AliTRDtrackerV1::BuildSeedingConfigs(AliTRDtrackingChamber **stack, Int_t *configs)
2477 // Assign probabilities to chambers according to their
2478 // capability of producing seeds.
2482 // layers : Array of stack propagation layers for all 6 chambers in one stack
2483 // configs : On exit array of configuration indexes (see GetSeedingConfig()
2484 // for details) in the decreasing order of their seeding probabilities.
2488 // Return top configuration quality
2490 // Detailed description:
2492 // To each chamber seeding configuration (see GetSeedingConfig() for
2493 // the list of all configurations) one defines 2 quality factors:
2494 // - an apriori topological quality (see GetSeedingConfig() for details) and
2495 // - a data quality based on the uniformity of the distribution of
2496 // clusters over the x range (time bins population). See CookChamberQA() for details.
2497 // The overall chamber quality is given by the product of this 2 contributions.
2500 Double_t chamberQ[kNPlanes];memset(chamberQ, 0, kNPlanes*sizeof(Double_t));
2501 AliTRDtrackingChamber *chamber = NULL;
2502 for(int iplane=0; iplane<kNPlanes; iplane++){
2503 if(!(chamber = stack[iplane])) continue;
2504 chamberQ[iplane] = (chamber = stack[iplane]) ? chamber->GetQuality() : 0.;
2507 Double_t tconfig[kNConfigs];memset(tconfig, 0, kNConfigs*sizeof(Double_t));
2508 Int_t planes[] = {0, 0, 0, 0};
2509 for(int iconf=0; iconf<kNConfigs; iconf++){
2510 GetSeedingConfig(iconf, planes);
2511 tconfig[iconf] = fgTopologicQA[iconf];
2512 for(int iplane=0; iplane<4; iplane++) tconfig[iconf] *= chamberQ[planes[iplane]];
2515 TMath::Sort((Int_t)kNConfigs, tconfig, configs, kTRUE);
2516 // AliInfo(Form("q[%d] = %f", configs[0], tconfig[configs[0]]));
2517 // AliInfo(Form("q[%d] = %f", configs[1], tconfig[configs[1]]));
2518 // AliInfo(Form("q[%d] = %f", configs[2], tconfig[configs[2]]));
2520 return tconfig[configs[0]];
2523 //____________________________________________________________________
2524 Int_t AliTRDtrackerV1::MakeSeeds(AliTRDtrackingChamber **stack, AliTRDseedV1 * const sseed, const Int_t * const ipar)
2527 // Seed tracklets and build candidate TRD tracks. The procedure is used during barrel tracking to account for tracks which are
2528 // either missed by TPC prolongation or conversions inside the TRD volume.
2529 // For stand alone tracking the procedure is used to estimate all tracks measured by TRD.
2532 // layers : Array of stack propagation layers containing clusters
2533 // sseed : Array of empty tracklet seeds. On exit they are filled.
2534 // ipar : Control parameters:
2535 // ipar[0] -> seeding chambers configuration
2536 // ipar[1] -> stack index
2537 // ipar[2] -> number of track candidates found so far
2540 // Number of tracks candidates found.
2542 // The following steps are performed:
2543 // 1. Build seeding layers by collapsing all time bins from each of the four seeding chambers along the
2544 // radial coordinate. See AliTRDtrackingChamber::GetSeedingLayer() for details. The chambers selection for seeding
2545 // is described in AliTRDtrackerV1::Clusters2TracksStack().
2546 // 2. Using the seeding clusters from the seeding layer (step 1) build combinatorics using the following algorithm:
2547 // - for each seeding cluster in the lower seeding layer find
2548 // - all seeding clusters in the upper seeding layer inside a road defined by a given phi angle. The angle
2549 // is calculated on the minimum pt of tracks from vertex accesible to the stand alone tracker.
2550 // - for each pair of two extreme seeding clusters select middle upper cluster using roads defined externally by the
2552 // - select last seeding cluster as the nearest to the linear approximation of the track described by the first three
2553 // seeding clusters.
2554 // The implementation of road calculation and cluster selection can be found in the functions AliTRDchamberTimeBin::BuildCond()
2555 // and AliTRDchamberTimeBin::GetClusters().
2556 // 3. Helix fit of the seeding clusters set. (see AliTRDtrackerFitter::FitRieman(AliTRDcluster**)). No tilt correction is
2557 // performed at this level
2558 // 4. Initialize seeding tracklets in the seeding chambers.
2559 // 5. *Filter 0* Chi2 cut on the Y and Z directions. The threshold is set externally by the reco params.
2560 // 6. Attach (true) clusters to seeding tracklets (see AliTRDseedV1::AttachClusters()) and fit tracklet (see
2561 // AliTRDseedV1::Fit()). The number of used clusters used by current seeds should not exceed ... (25).
2562 // 7. *Filter 1* Check if all 4 seeding tracklets are correctly constructed.
2563 // 8. Helix fit of the clusters from the seeding tracklets with tilt correction. Refit tracklets using the new
2564 // approximation of the track.
2565 // 9. *Filter 2* Calculate likelihood of the track. (See AliTRDtrackerV1::CookLikelihood()). The following quantities are
2566 // checked against the Riemann fit:
2567 // - position resolution in y
2568 // - angular resolution in the bending plane
2569 // - likelihood of the number of clusters attached to the tracklet
2570 // 10. Extrapolation of the helix fit to the other 2 chambers *non seeding* chambers:
2571 // - Initialization of extrapolation tracklets with the fit parameters
2572 // - Attach clusters to extrapolated tracklets
2573 // - Helix fit of tracklets
2574 // 11. Improve seeding tracklets quality by reassigning clusters based on the last parameters of the track
2575 // See AliTRDtrackerV1::ImproveSeedQuality() for details.
2576 // 12. Helix fit of all 6 seeding tracklets and chi2 calculation
2577 // 13. Hyperplane fit and track quality calculation. See AliTRDtrackerFitter::FitHyperplane() for details.
2578 // 14. Cooking labels for tracklets. Should be done only for MC
2579 // 15. Register seeds.
2582 // Marian Ivanov <M.Ivanov@gsi.de>
2583 // Alexandru Bercuci <A.Bercuci@gsi.de>
2584 // Markus Fasel <M.Fasel@gsi.de>
2586 AliTRDtrackingChamber *chamber = NULL;
2587 AliTRDcluster *c[kNSeedPlanes] = {NULL, NULL, NULL, NULL}; // initilize seeding clusters
2588 AliTRDseedV1 *cseed = &sseed[0]; // initialize tracklets for first track
2589 Int_t ncl, mcl; // working variable for looping over clusters
2590 Int_t index[AliTRDchamberTimeBin::kMaxClustersLayer], jndex[AliTRDchamberTimeBin::kMaxClustersLayer];
2592 // chi2[0] = tracklet chi2 on the Z direction
2593 // chi2[1] = tracklet chi2 on the R direction
2596 // this should be data member of AliTRDtrack TODO
2597 Double_t seedQuality[kMaxTracksStack];
2599 // unpack control parameters
2600 Int_t config = ipar[0];
2601 Int_t ntracks = ipar[1];
2602 Int_t istack = ipar[2];
2603 Int_t planes[kNSeedPlanes]; GetSeedingConfig(config, planes);
2604 Int_t planesExt[kNPlanes-kNSeedPlanes]; GetExtrapolationConfig(config, planesExt);
2607 // Init chambers geometry
2608 Double_t hL[kNPlanes]; // Tilting angle
2609 Float_t padlength[kNPlanes]; // pad lenghts
2610 Float_t padwidth[kNPlanes]; // pad widths
2611 AliTRDpadPlane *pp = NULL;
2612 for(int iplane=0; iplane<kNPlanes; iplane++){
2613 pp = fGeom->GetPadPlane(iplane, istack);
2614 hL[iplane] = TMath::Tan(TMath::DegToRad()*pp->GetTiltingAngle());
2615 padlength[iplane] = pp->GetLengthIPad();
2616 padwidth[iplane] = pp->GetWidthIPad();
2619 // Init anode wire position for chambers
2620 Double_t x0[kNPlanes], // anode wire position
2621 driftLength = .5*AliTRDgeometry::AmThick() - AliTRDgeometry::DrThick(); // drift length
2622 TGeoHMatrix *matrix = NULL;
2623 Double_t loc[] = {AliTRDgeometry::AnodePos(), 0., 0.};
2624 Double_t glb[] = {0., 0., 0.};
2625 AliTRDtrackingChamber **cIter = &stack[0];
2626 for(int iLayer=0; iLayer<kNPlanes; iLayer++,cIter++){
2627 if(!(*cIter)) continue;
2628 if(!(matrix = fGeom->GetClusterMatrix((*cIter)->GetDetector()))){
2630 x0[iLayer] = fgkX0[iLayer];
2632 matrix->LocalToMaster(loc, glb);
2633 x0[iLayer] = glb[0];
2636 AliDebug(2, Form("Making seeds Stack[%d] Config[%d] Tracks[%d]...", istack, config, ntracks));
2638 // Build seeding layers
2641 for(int isl=0; isl<kNSeedPlanes; isl++){
2642 if(!(chamber = stack[planes[isl]])) continue;
2643 if(!chamber->GetSeedingLayer(fSeedTB[isl], fGeom, fkReconstructor)) continue;
2646 if(nlayers < kNSeedPlanes) return ntracks;
2649 // Start finding seeds
2650 Double_t cond0[4], cond1[4], cond2[4];
2652 while((c[3] = (*fSeedTB[3])[icl++])){
2654 fSeedTB[0]->BuildCond(c[3], cond0, 0);
2655 fSeedTB[0]->GetClusters(cond0, index, ncl);
2656 //printf("Found c[3] candidates 0 %d\n", ncl);
2659 c[0] = (*fSeedTB[0])[index[jcl++]];
2661 Double_t dx = c[3]->GetX() - c[0]->GetX();
2662 Double_t dzdx = (c[3]->GetZ() - c[0]->GetZ())/dx;
2663 Double_t dydx = (c[3]->GetY() - c[0]->GetY())/dx;
2664 fSeedTB[1]->BuildCond(c[0], cond1, 1, dzdx, dydx);
2665 fSeedTB[1]->GetClusters(cond1, jndex, mcl);
2666 //printf("Found c[0] candidates 1 %d\n", mcl);
2670 c[1] = (*fSeedTB[1])[jndex[kcl++]];
2672 fSeedTB[2]->BuildCond(c[1], cond2, 2, dzdx, dydx);
2673 c[2] = fSeedTB[2]->GetNearestCluster(cond2);
2674 //printf("Found c[1] candidate 2 %p\n", c[2]);
2677 AliDebug(3, Form("Seeding clusters\n 0[%6.3f %6.3f %6.3f]\n 1[%6.3f %6.3f %6.3f]\n 2[%6.3f %6.3f %6.3f]\n 3[%6.3f %6.3f %6.3f].",
2678 c[0]->GetX(), c[0]->GetY(), c[0]->GetZ(),
2679 c[1]->GetX(), c[1]->GetY(), c[1]->GetZ(),
2680 c[2]->GetX(), c[2]->GetY(), c[2]->GetZ(),
2681 c[3]->GetX(), c[3]->GetY(), c[3]->GetZ()));
2683 for (Int_t il = 0; il < kNPlanes; il++) cseed[il].Reset();
2687 AliTRDseedV1 *tseed = &cseed[0];
2689 for(int iLayer=0; iLayer<kNPlanes; iLayer++, tseed++, cIter++){
2690 Int_t det = (*cIter) ? (*cIter)->GetDetector() : -1;
2691 tseed->SetDetector(det);
2692 tseed->SetTilt(hL[iLayer]);
2693 tseed->SetPadLength(padlength[iLayer]);
2694 tseed->SetPadWidth(padwidth[iLayer]);
2695 tseed->SetReconstructor(fkReconstructor);
2696 tseed->SetX0(det<0 ? fR[iLayer]+driftLength : x0[iLayer]);
2697 tseed->Init(GetRiemanFitter());
2698 tseed->SetStandAlone(kTRUE);
2701 Bool_t isFake = kFALSE;
2702 if(fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) >= 2 && fkReconstructor->IsDebugStreaming()){
2703 if (c[0]->GetLabel(0) != c[3]->GetLabel(0)) isFake = kTRUE;
2704 if (c[1]->GetLabel(0) != c[3]->GetLabel(0)) isFake = kTRUE;
2705 if (c[2]->GetLabel(0) != c[3]->GetLabel(0)) isFake = kTRUE;
2708 for(Int_t l = 0; l < kNSeedPlanes; l++) xpos[l] = fSeedTB[l]->GetX();
2710 for(int il=0; il<4; il++) yref[il] = cseed[planes[il]].GetYref(0);
2711 Int_t ll = c[3]->GetLabel(0);
2712 Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
2713 Int_t candidateNumber = AliTRDtrackerDebug::GetCandidateNumber();
2714 AliRieman *rim = GetRiemanFitter();
2715 TTreeSRedirector &cs0 = *fkReconstructor->GetDebugStream(AliTRDrecoParam::kTracker);
2717 <<"EventNumber=" << eventNumber
2718 <<"CandidateNumber=" << candidateNumber
2719 <<"isFake=" << isFake
2720 <<"config=" << config
2722 <<"chi2z=" << chi2[0]
2723 <<"chi2y=" << chi2[1]
2724 <<"Y2exp=" << cond2[0]
2725 <<"Z2exp=" << cond2[1]
2726 <<"X0=" << xpos[0] //layer[sLayer]->GetX()
2727 <<"X1=" << xpos[1] //layer[sLayer + 1]->GetX()
2728 <<"X2=" << xpos[2] //layer[sLayer + 2]->GetX()
2729 <<"X3=" << xpos[3] //layer[sLayer + 3]->GetX()
2730 <<"yref0=" << yref[0]
2731 <<"yref1=" << yref[1]
2732 <<"yref2=" << yref[2]
2733 <<"yref3=" << yref[3]
2738 <<"Seed0.=" << &cseed[planes[0]]
2739 <<"Seed1.=" << &cseed[planes[1]]
2740 <<"Seed2.=" << &cseed[planes[2]]
2741 <<"Seed3.=" << &cseed[planes[3]]
2742 <<"RiemanFitter.=" << rim
2745 if(chi2[0] > fkRecoParam->GetChi2Z()/*7./(3. - sLayer)*//*iter*/){
2746 AliDebug(3, Form("Filter on chi2Z [%f].", chi2[0]));
2747 AliTRDtrackerDebug::SetCandidateNumber(AliTRDtrackerDebug::GetCandidateNumber() + 1);
2750 if(chi2[1] > fkRecoParam->GetChi2Y()/*1./(3. - sLayer)*//*iter*/){
2751 AliDebug(3, Form("Filter on chi2Y [%f].", chi2[1]));
2752 AliTRDtrackerDebug::SetCandidateNumber(AliTRDtrackerDebug::GetCandidateNumber() + 1);
2755 //AliInfo("Passed chi2 filter.");
2757 // try attaching clusters to tracklets
2759 AliTRDcluster *cl = NULL;
2760 for(int iLayer=0; iLayer<kNSeedPlanes; iLayer++){
2761 Int_t jLayer = planes[iLayer];
2762 Int_t nNotInChamber = 0;
2763 if(!cseed[jLayer].AttachClusters(stack[jLayer], kTRUE)) continue;
2764 if(/*fkReconstructor->IsHLT()*/kFALSE){
2765 cseed[jLayer].UpdateUsed();
2766 if(!cseed[jLayer].IsOK()) continue;
2768 cseed[jLayer].Fit();
2769 cseed[jLayer].UpdateUsed();
2770 cseed[jLayer].ResetClusterIter();
2771 while((cl = cseed[jLayer].NextCluster())){
2772 if(!cl->IsInChamber()) nNotInChamber++;
2774 //printf("clusters[%d], used[%d], not in chamber[%d]\n", cseed[jLayer].GetN(), cseed[jLayer].GetNUsed(), nNotInChamber);
2775 if(cseed[jLayer].GetN() - (cseed[jLayer].GetNUsed() + nNotInChamber) < 5) continue; // checking for Cluster which are not in chamber is a much stronger restriction on real data
2780 if(mlayers < kNSeedPlanes){
2781 AliDebug(2, Form("Found only %d tracklets out of %d. Skip.", mlayers, kNSeedPlanes));
2782 AliTRDtrackerDebug::SetCandidateNumber(AliTRDtrackerDebug::GetCandidateNumber() + 1);
2786 // temporary exit door for the HLT
2787 if(fkReconstructor->IsHLT()){
2788 // attach clusters to extrapolation chambers
2789 for(int iLayer=0; iLayer<kNPlanes-kNSeedPlanes; iLayer++){
2790 Int_t jLayer = planesExt[iLayer];
2791 if(!(chamber = stack[jLayer])) continue;
2792 if(!cseed[jLayer].AttachClusters(chamber, kTRUE)) continue;
2793 cseed[jLayer].Fit();
2795 FitTiltedRiemanConstraint(&cseed[0], GetZ());
2796 fTrackQuality[ntracks] = 1.; // dummy value
2798 if(ntracks == kMaxTracksStack) return ntracks;
2804 // Update Seeds and calculate Likelihood
2805 // fit tracklets and cook likelihood
2806 Double_t chi2Vals[4];
2807 chi2Vals[0] = FitTiltedRieman(&cseed[0], kTRUE);
2808 for(int iLayer=0; iLayer<kNSeedPlanes; iLayer++){
2809 Int_t jLayer = planes[iLayer];
2810 cseed[jLayer].Fit(1);
2812 Double_t like = CookLikelihood(&cseed[0], planes); // to be checked
2814 if (TMath::Log(1.E-9 + like) < fkRecoParam->GetTrackLikelihood()){
2815 AliDebug(3, Form("Filter on likelihood %f[%e].", TMath::Log(1.E-9 + like), like));
2816 AliTRDtrackerDebug::SetCandidateNumber(AliTRDtrackerDebug::GetCandidateNumber() + 1);
2819 //AliInfo(Form("Passed likelihood %f[%e].", TMath::Log(1.E-9 + like), like));
2821 // book preliminary results
2822 seedQuality[ntracks] = like;
2823 fSeedLayer[ntracks] = config;/*sLayer;*/
2825 // attach clusters to the extrapolation seeds
2827 for(int iLayer=0; iLayer<kNPlanes-kNSeedPlanes; iLayer++){
2828 Int_t jLayer = planesExt[iLayer];
2829 if(!(chamber = stack[jLayer])) continue;
2831 // fit extrapolated seed
2832 if ((jLayer == 0) && !(cseed[1].IsOK())) continue;
2833 if ((jLayer == 5) && !(cseed[4].IsOK())) continue;
2834 AliTRDseedV1 pseed = cseed[jLayer];
2835 if(!pseed.AttachClusters(chamber, kTRUE)) continue;
2837 cseed[jLayer] = pseed;
2838 chi2Vals[0] = FitTiltedRieman(cseed, kTRUE);
2839 cseed[jLayer].Fit(1);
2843 // AliInfo("Extrapolation done.");
2844 // Debug Stream containing all the 6 tracklets
2845 if(fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) >= 2 && fkReconstructor->IsDebugStreaming()){
2846 TTreeSRedirector &cstreamer = *fkReconstructor->GetDebugStream(AliTRDrecoParam::kTracker);
2847 TLinearFitter *tiltedRieman = GetTiltedRiemanFitter();
2848 Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
2849 Int_t candidateNumber = AliTRDtrackerDebug::GetCandidateNumber();
2850 cstreamer << "MakeSeeds1"
2851 << "EventNumber=" << eventNumber
2852 << "CandidateNumber=" << candidateNumber
2853 << "S0.=" << &cseed[0]
2854 << "S1.=" << &cseed[1]
2855 << "S2.=" << &cseed[2]
2856 << "S3.=" << &cseed[3]
2857 << "S4.=" << &cseed[4]
2858 << "S5.=" << &cseed[5]
2859 << "FitterT.=" << tiltedRieman
2863 if(fkRecoParam->HasImproveTracklets()){
2864 if(!ImproveSeedQuality(stack, cseed, chi2Vals[0])){
2865 AliTRDtrackerDebug::SetCandidateNumber(AliTRDtrackerDebug::GetCandidateNumber() + 1);
2866 AliDebug(3, "ImproveSeedQuality() failed.");
2870 // do track fitting with vertex constraint
2871 if(fkRecoParam->IsVertexConstrained()) chi2Vals[1] = FitTiltedRiemanConstraint(&cseed[0], GetZ());
2872 else chi2Vals[1] = -1.;
2873 chi2Vals[2] = GetChi2Z(&cseed[0]);
2874 chi2Vals[3] = GetChi2Phi(&cseed[0]);
2876 // calculate track quality
2877 fTrackQuality[ntracks] = CalculateTrackLikelihood(&chi2Vals[0]);
2879 if(fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) >= 2 && fkReconstructor->IsDebugStreaming()){
2880 TTreeSRedirector &cstreamer = *fkReconstructor->GetDebugStream(AliTRDrecoParam::kTracker);
2881 Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
2882 Int_t candidateNumber = AliTRDtrackerDebug::GetCandidateNumber();
2883 TLinearFitter *fitterTC = GetTiltedRiemanFitterConstraint();
2884 TLinearFitter *fitterT = GetTiltedRiemanFitter();
2886 for(Int_t iseed = 0; iseed < kNPlanes; iseed++){
2887 ncls += cseed[iseed].IsOK() ? cseed[iseed].GetN2() : 0;
2889 cstreamer << "MakeSeeds2"
2890 << "EventNumber=" << eventNumber
2891 << "CandidateNumber=" << candidateNumber
2892 << "Chi2TR=" << chi2Vals[0]
2893 << "Chi2TC=" << chi2Vals[1]
2894 << "Nlayers=" << mlayers
2895 << "NClusters=" << ncls
2897 << "S0.=" << &cseed[0]
2898 << "S1.=" << &cseed[1]
2899 << "S2.=" << &cseed[2]
2900 << "S3.=" << &cseed[3]
2901 << "S4.=" << &cseed[4]
2902 << "S5.=" << &cseed[5]
2903 << "FitterT.=" << fitterT
2904 << "FitterTC.=" << fitterTC
2907 if(AliLog::GetDebugLevel("TRD", "AliTRDtrackerV1")){
2908 Double_t pt[]={0., 0.};
2909 for(Int_t il(0); il<kNPlanes; il++){
2910 if(!cseed[il].IsOK()) continue;
2911 pt[0] = GetBz()*kB2C/cseed[il].GetC();
2912 pt[1] = GetBz()*kB2C/cseed[il].GetC(1);
2915 AliDebug(2, Form("Candidate[%2d] pt[%7.3f %7.3f] Q[%e]\n"
2916 " [0] x[%6.2f] n[%2d] nu[%d] OK[%c]\n"
2917 " [1] x[%6.2f] n[%2d] nu[%d] OK[%c]\n"
2918 " [2] x[%6.2f] n[%2d] nu[%d] OK[%c]\n"
2919 " [3] x[%6.2f] n[%2d] nu[%d] OK[%c]\n"
2920 " [4] x[%6.2f] n[%2d] nu[%d] OK[%c]\n"
2921 " [5] x[%6.2f] n[%2d] nu[%d] OK[%c]"
2922 , ntracks, pt[0], pt[1], fTrackQuality[ntracks]
2923 ,cseed[0].GetX(), cseed[0].GetN(), cseed[0].GetNUsed(), cseed[0].IsOK()?'y':'n'
2924 ,cseed[1].GetX(), cseed[1].GetN(), cseed[1].GetNUsed(), cseed[1].IsOK()?'y':'n'
2925 ,cseed[2].GetX(), cseed[2].GetN(), cseed[2].GetNUsed(), cseed[2].IsOK()?'y':'n'
2926 ,cseed[3].GetX(), cseed[3].GetN(), cseed[3].GetNUsed(), cseed[3].IsOK()?'y':'n'
2927 ,cseed[4].GetX(), cseed[4].GetN(), cseed[4].GetNUsed(), cseed[4].IsOK()?'y':'n'
2928 ,cseed[5].GetX(), cseed[5].GetN(), cseed[5].GetNUsed(), cseed[5].IsOK()?'y':'n'));
2931 AliTRDtrackerDebug::SetCandidateNumber(AliTRDtrackerDebug::GetCandidateNumber() + 1);
2932 if(ntracks == kMaxTracksStack){
2933 AliWarning(Form("Number of seeds reached maximum allowed (%d) in stack.", kMaxTracksStack));
2944 //_____________________________________________________________________________
2945 AliTRDtrackV1* AliTRDtrackerV1::MakeTrack(AliTRDseedV1 * const tracklet)
2948 // Build a TRD track out of tracklet candidates
2951 // seeds : array of tracklets
2952 // params : array of track parameters as they are estimated by stand alone tracker. 7 elements.
2953 // [0] - radial position of the track at reference point
2954 // [1] - y position of the fit at [0]
2955 // [2] - z position of the fit at [0]
2956 // [3] - snp of the first tracklet
2957 // [4] - tgl of the first tracklet
2958 // [5] - curvature of the Riemann fit - 1/pt
2959 // [6] - sector rotation angle
2964 // Initialize the TRD track based on the parameters of the fit and a parametric covariance matrix
2965 // (diagonal with constant variance terms TODO - correct parameterization)
2967 // In case of HLT just register the tracklets in the tracker and return values of the Riemann fit. For the
2968 // offline case perform a full Kalman filter on the already found tracklets (see AliTRDtrackerV1::FollowBackProlongation()
2969 // for details). Do also MC label calculation and PID if propagation successfully.
2972 Double_t alpha = AliTRDgeometry::GetAlpha();
2973 Double_t shift = AliTRDgeometry::GetAlpha()/2.0;
2975 // find first good tracklet
2976 Int_t idx(0); while(idx<kNPlanes && !tracklet[idx].IsOK()) idx++;
2977 if(idx>2){ AliDebug(1, Form("Found suspect track start @ layer idx[%d]\n"
2978 " %c[0] x0[%f] n[%d] nu[%d] OK[%c]\n"
2979 " %c[1] x0[%f] n[%d] nu[%d] OK[%c]\n"
2980 " %c[2] x0[%f] n[%d] nu[%d] OK[%c]\n"
2981 " %c[3] x0[%f] n[%d] nu[%d] OK[%c]\n"
2982 " %c[4] x0[%f] n[%d] nu[%d] OK[%c]\n"
2983 " %c[5] x0[%f] n[%d] nu[%d] OK[%c]"
2985 ,idx==0?'*':' ', tracklet[0].GetX0(), tracklet[0].GetN(), tracklet[0].GetNUsed(), tracklet[0].IsOK()?'y':'n'
2986 ,idx==1?'*':' ', tracklet[1].GetX0(), tracklet[1].GetN(), tracklet[1].GetNUsed(), tracklet[1].IsOK()?'y':'n'
2987 ,idx==2?'*':' ', tracklet[2].GetX0(), tracklet[2].GetN(), tracklet[2].GetNUsed(), tracklet[2].IsOK()?'y':'n'
2988 ,idx==3?'*':' ', tracklet[3].GetX0(), tracklet[3].GetN(), tracklet[3].GetNUsed(), tracklet[3].IsOK()?'y':'n'
2989 ,idx==4?'*':' ', tracklet[4].GetX0(), tracklet[4].GetN(), tracklet[4].GetNUsed(), tracklet[4].IsOK()?'y':'n'
2990 ,idx==5?'*':' ', tracklet[5].GetX0(), tracklet[5].GetN(), tracklet[5].GetNUsed(), tracklet[5].IsOK()?'y':'n'));
2995 Double_t x(tracklet[idx].GetX0() - dx);
2996 // Build track parameters
2997 Double_t params[] = {
2998 tracklet[idx].GetYref(0) - dx*tracklet[idx].GetYref(1) // y
2999 ,tracklet[idx].GetZref(0) - dx*tracklet[idx].GetZref(1) // z
3000 ,TMath::Sin(TMath::ATan(tracklet[idx].GetYref(1))) // snp
3001 ,tracklet[idx].GetZref(1) / TMath::Sqrt(1. + tracklet[idx].GetYref(1) * tracklet[idx].GetYref(1)) // tgl
3002 ,tracklet[idx].GetC(fkReconstructor->IsHLT()?1:0) // curvature -> 1/pt
3004 Int_t sector(fGeom->GetSector(tracklet[idx].GetDetector()));
3007 c[ 0] = 0.2; // s^2_y
3008 c[ 1] = 0.0; c[ 2] = 2.0; // s^2_z
3009 c[ 3] = 0.0; c[ 4] = 0.0; c[ 5] = 0.02; // s^2_snp
3010 c[ 6] = 0.0; c[ 7] = 0.0; c[ 8] = 0.0; c[ 9] = 0.1; // s^2_tgl
3011 c[10] = 0.0; c[11] = 0.0; c[12] = 0.0; c[13] = 0.0; c[14] = params[4]*params[4]*0.01; // s^2_1/pt
3013 AliTRDtrackV1 track(tracklet, params, c, x, sector*alpha+shift);
3015 AliTRDseedV1 *ptrTracklet = NULL;
3017 // skip Kalman filter for HLT
3018 if(/*fkReconstructor->IsHLT()*/kFALSE){
3019 for (Int_t jLayer = 0; jLayer < AliTRDgeometry::kNlayer; jLayer++) {
3020 track.UnsetTracklet(jLayer);
3021 ptrTracklet = &tracklet[jLayer];
3022 if(!ptrTracklet->IsOK()) continue;
3023 if(TMath::Abs(ptrTracklet->GetYref(1) - ptrTracklet->GetYfit(1)) >= .2) continue; // check this condition with Marian
3024 ptrTracklet = SetTracklet(ptrTracklet);
3025 ptrTracklet->UseClusters();
3026 track.SetTracklet(ptrTracklet, fTracklets->GetEntriesFast()-1);
3028 AliTRDtrackV1 *ptrTrack = SetTrack(&track);
3029 ptrTrack->CookPID();
3030 ptrTrack->CookLabel(.9);
3031 ptrTrack->SetReconstructor(fkReconstructor);
3035 // prevent the error message in AliTracker::MeanMaterialBudget: "start point out of geometry"
3036 if(TMath::Abs(track.GetX()) + TMath::Abs(track.GetY()) + TMath::Abs(track.GetZ()) > 10000) return NULL;
3038 track.ResetCovariance(1);
3039 Int_t nc = TMath::Abs(FollowBackProlongation(track));
3040 if(fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) > 5 && fkReconstructor->IsDebugStreaming()){
3041 Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
3042 Int_t candidateNumber = AliTRDtrackerDebug::GetCandidateNumber();
3043 Double_t p[5]; // Track Params for the Debug Stream
3044 track.GetExternalParameters(x, p);
3045 TTreeSRedirector &cs = *fkReconstructor->GetDebugStream(AliTRDrecoParam::kTracker);
3047 << "EventNumber=" << eventNumber
3048 << "CandidateNumber=" << candidateNumber
3056 << "Yin=" << params[0]
3057 << "Zin=" << params[1]
3058 << "snpin=" << params[2]
3059 << "tndin=" << params[3]
3060 << "crvin=" << params[4]
3061 << "track.=" << &track
3065 UnsetTrackletsTrack(&track);
3068 AliTRDtrackV1 *ptrTrack = SetTrack(&track);
3069 ptrTrack->SetReconstructor(fkReconstructor);
3070 ptrTrack->CookLabel(.9);
3071 for(Int_t il(kNPlanes); il--;){
3072 if(!(ptrTracklet = ptrTrack->GetTracklet(il))) continue;
3073 ptrTracklet->UseClusters();
3076 // computes PID for track
3077 ptrTrack->CookPID();
3078 // update calibration references using this track
3079 AliTRDCalibraFillHisto *calibra = AliTRDCalibraFillHisto::Instance();
3081 AliInfo("Could not get Calibra instance\n");
3082 if(calibra->GetHisto2d()) calibra->UpdateHistogramsV1(ptrTrack);
3088 //____________________________________________________________________
3089 Bool_t AliTRDtrackerV1::ImproveSeedQuality(AliTRDtrackingChamber **stack, AliTRDseedV1 *cseed, Double_t &chi2)
3092 // Sort tracklets according to "quality" and try to "improve" the first 4 worst
3095 // layers : Array of propagation layers for a stack/supermodule
3096 // cseed : Array of 6 seeding tracklets which has to be improved
3099 // cssed : Improved seeds
3101 // Detailed description
3103 // Iterative procedure in which new clusters are searched for each
3104 // tracklet seed such that the seed quality (see AliTRDseed::GetQuality())
3105 // can be maximized. If some optimization is found the old seeds are replaced.
3110 // make a local working copy
3111 AliTRDtrackingChamber *chamber = NULL;
3112 AliTRDseedV1 bseed[AliTRDgeometry::kNlayer];
3114 Float_t quality(1.e3),
3115 lQuality[] = {1.e3, 1.e3, 1.e3, 1.e3, 1.e3, 1.e3};
3117 for(Int_t jLayer=AliTRDgeometry::kNlayer; jLayer--;){
3118 bseed[jLayer] = cseed[jLayer];
3119 if(!bseed[jLayer].IsOK()) continue;
3121 lQuality[jLayer] = bseed[jLayer].GetQuality(kTRUE);
3122 quality += lQuality[jLayer];
3125 AliDebug(2, Form("Start N[%d] Q[%f] chi2[%f]", rLayers, quality, chi2));
3127 for (Int_t iter = 0; iter < 4; iter++) {
3128 // Try better cluster set
3129 Int_t nLayers(0); Float_t qualitynew(0.);
3131 TMath::Sort(Int_t(AliTRDgeometry::kNlayer), lQuality, indexes, kFALSE);
3132 for(Int_t jLayer=AliTRDgeometry::kNlayer; jLayer--;) {
3133 Int_t bLayer = indexes[jLayer];
3134 bseed[bLayer].Reset("c");
3135 if(!(chamber = stack[bLayer])) continue;
3136 if(!bseed[bLayer].AttachClusters(chamber, kTRUE)) continue;
3137 bseed[bLayer].Fit(1);
3138 if(!bseed[bLayer].IsOK()) continue;
3140 lQuality[jLayer] = bseed[jLayer].GetQuality(kTRUE);
3141 qualitynew += lQuality[jLayer];
3143 if(rLayers > nLayers){
3144 AliDebug(1, Form("Lost %d tracklets while improving.", rLayers-nLayers));
3145 return iter>0?kTRUE:kFALSE;
3146 } else rLayers=nLayers;
3147 qualitynew /= rLayers;
3149 if(qualitynew > quality){
3150 AliDebug(4, Form("Quality[%f] worsen in iter[%d] to ref[%f].", qualitynew, iter, quality));
3151 return iter>0?kTRUE:kFALSE;
3152 } else quality = qualitynew;
3154 // try improve track parameters
3155 Float_t chi2new = FitTiltedRieman(bseed, kTRUE);
3157 AliDebug(4, Form("Chi2[%f] worsen in iter[%d] to ref[%f].", chi2new, iter, chi2));
3158 return iter>0?kTRUE:kFALSE;
3159 } else chi2 = chi2new;
3161 // store better tracklets
3162 for(Int_t jLayer=AliTRDgeometry::kNlayer; jLayer--;) cseed[jLayer]=bseed[jLayer];
3163 AliDebug(2, Form("Iter[%d] Q[%f] chi2[%f]", iter, quality, chi2));
3166 if(fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) >= 7 && fkReconstructor->IsDebugStreaming()){
3167 Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
3168 Int_t candidateNumber = AliTRDtrackerDebug::GetCandidateNumber();
3169 TLinearFitter *tiltedRieman = GetTiltedRiemanFitter();
3170 TTreeSRedirector &cstreamer = *fkReconstructor->GetDebugStream(AliTRDrecoParam::kTracker);
3171 cstreamer << "ImproveSeedQuality"
3172 << "EventNumber=" << eventNumber
3173 << "CandidateNumber=" << candidateNumber
3174 << "Iteration=" << iter
3175 << "S0.=" << &cseed[0]
3176 << "S1.=" << &cseed[1]
3177 << "S2.=" << &cseed[2]
3178 << "S3.=" << &cseed[3]
3179 << "S4.=" << &cseed[4]
3180 << "S5.=" << &cseed[5]
3181 << "FitterT.=" << tiltedRieman
3186 // we are sure that at least 4 tracklets are OK !
3190 //_________________________________________________________________________
3191 Double_t AliTRDtrackerV1::CalculateTrackLikelihood(Double_t *chi2){
3193 // Calculates the Track Likelihood value. This parameter serves as main quality criterion for
3194 // the track selection
3195 // The likelihood value containes:
3196 // - The chi2 values from the both fitters and the chi2 values in z-direction from a linear fit
3197 // - The Sum of the Parameter |slope_ref - slope_fit|/Sigma of the tracklets
3198 // For all Parameters an exponential dependency is used
3200 // Parameters: - Array of tracklets (AliTRDseedV1) related to the track candidate
3201 // - Array of chi2 values:
3202 // * Non-Constrained Tilted Riemann fit
3203 // * Vertex-Constrained Tilted Riemann fit
3204 // * z-Direction from Linear fit
3205 // Output: - The calculated track likelihood
3210 // Non-constrained Tilted Riemann
3211 Double_t likeChi2TR = TMath::Exp(-chi2[0] * 0.0078);
3212 // Constrained Tilted Riemann
3213 Double_t likeChi2TC(1.);
3215 likeChi2TC = TMath::Exp(-chi2[1] * 0.677);
3216 Double_t r = likeChi2TC/likeChi2TR;
3217 if(r>1.e2){;} // -> a primary track use TC
3218 else if(r<1.e2) // -> a secondary track use TR
3220 else{;} // -> test not conclusive
3222 // Chi2 only on Z direction
3223 Double_t likeChi2Z = TMath::Exp(-chi2[2] * 0.14);
3224 // Chi2 angular resolution
3225 Double_t likeChi2Phi= TMath::Exp(-chi2[3] * 3.23);
3227 Double_t trackLikelihood = likeChi2Z * likeChi2TR * likeChi2TC * likeChi2Phi;
3229 AliDebug(2, Form("Likelihood [%e]\n"
3230 " Rieman : chi2[%f] likelihood[%6.2e]\n"
3231 " Vertex : chi2[%f] likelihood[%6.2e]\n"
3232 " Z : chi2[%f] likelihood[%6.2e]\n"
3233 " Phi : chi2[%f] likelihood[%6.2e]"
3235 , chi2[0], likeChi2TR
3236 , chi2[1], likeChi2TC
3237 , chi2[2], likeChi2Z
3238 , chi2[3], likeChi2Phi
3241 if(fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) >= 2 && fkReconstructor->IsDebugStreaming()){
3242 Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
3243 Int_t candidateNumber = AliTRDtrackerDebug::GetCandidateNumber();
3244 TTreeSRedirector &cstreamer = *fkReconstructor->GetDebugStream(AliTRDrecoParam::kTracker);
3245 cstreamer << "CalculateTrackLikelihood0"
3246 << "EventNumber=" << eventNumber
3247 << "CandidateNumber=" << candidateNumber
3248 << "LikeChi2Z=" << likeChi2Z
3249 << "LikeChi2TR=" << likeChi2TR
3250 << "LikeChi2TC=" << likeChi2TC
3251 << "LikeChi2Phi=" << likeChi2Phi
3252 << "TrackLikelihood=" << trackLikelihood
3256 return trackLikelihood;
3259 //____________________________________________________________________
3260 Double_t AliTRDtrackerV1::CookLikelihood(AliTRDseedV1 *cseed, Int_t planes[4])
3263 // Calculate the probability of this track candidate.
3266 // cseeds : array of candidate tracklets
3267 // planes : array of seeding planes (see seeding configuration)
3268 // chi2 : chi2 values (on the Z and Y direction) from the rieman fit of the track.
3273 // Detailed description
3275 // The track quality is estimated based on the following 4 criteria:
3276 // 1. precision of the rieman fit on the Y direction (likea)
3277 // 2. chi2 on the Y direction (likechi2y)
3278 // 3. chi2 on the Z direction (likechi2z)
3279 // 4. number of attached clusters compared to a reference value
3280 // (see AliTRDrecoParam::fkFindable) (likeN)
3282 // The distributions for each type of probabilities are given below as of
3283 // (date). They have to be checked to assure consistency of estimation.
3286 // ratio of the total number of clusters/track which are expected to be found by the tracker.
3287 Double_t chi2y = GetChi2Y(&cseed[0]);
3288 Double_t chi2z = GetChi2Z(&cseed[0]);
3290 Float_t nclusters = 0.;
3291 Double_t sumda = 0.;
3292 for(UChar_t ilayer = 0; ilayer < 4; ilayer++){
3293 Int_t jlayer = planes[ilayer];
3294 nclusters += cseed[jlayer].GetN2();
3295 sumda += TMath::Abs(cseed[jlayer].GetYfit(1) - cseed[jlayer].GetYref(1));
3299 Double_t likea = TMath::Exp(-sumda * fkRecoParam->GetPhiSlope());
3300 Double_t likechi2y = 0.0000000001;
3301 if (fkReconstructor->IsCosmic() || chi2y < fkRecoParam->GetChi2YCut()) likechi2y += TMath::Exp(-TMath::Sqrt(chi2y) * fkRecoParam->GetChi2YSlope());
3302 Double_t likechi2z = TMath::Exp(-chi2z * fkRecoParam->GetChi2ZSlope());
3303 Double_t likeN = TMath::Exp(-(fkRecoParam->GetNMeanClusters() - nclusters) / fkRecoParam->GetNSigmaClusters());
3304 Double_t like = likea * likechi2y * likechi2z * likeN;
3306 if(fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) >= 2 && fkReconstructor->IsDebugStreaming()){
3307 Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
3308 Int_t candidateNumber = AliTRDtrackerDebug::GetCandidateNumber();
3309 Int_t nTracklets = 0; Float_t meanNcls = 0;
3310 for(Int_t iseed=0; iseed < kNPlanes; iseed++){
3311 if(!cseed[iseed].IsOK()) continue;
3313 meanNcls += cseed[iseed].GetN2();
3315 if(nTracklets) meanNcls /= nTracklets;
3316 // The Debug Stream contains the seed
3317 TTreeSRedirector &cstreamer = *fkReconstructor->GetDebugStream(AliTRDrecoParam::kTracker);
3318 cstreamer << "CookLikelihood"
3319 << "EventNumber=" << eventNumber
3320 << "CandidateNumber=" << candidateNumber
3321 << "tracklet0.=" << &cseed[0]
3322 << "tracklet1.=" << &cseed[1]
3323 << "tracklet2.=" << &cseed[2]
3324 << "tracklet3.=" << &cseed[3]
3325 << "tracklet4.=" << &cseed[4]
3326 << "tracklet5.=" << &cseed[5]
3327 << "sumda=" << sumda
3328 << "chi2y=" << chi2y
3329 << "chi2z=" << chi2z
3330 << "likea=" << likea
3331 << "likechi2y=" << likechi2y
3332 << "likechi2z=" << likechi2z
3333 << "nclusters=" << nclusters
3334 << "likeN=" << likeN
3336 << "meanncls=" << meanNcls
3343 //____________________________________________________________________
3344 void AliTRDtrackerV1::GetSeedingConfig(Int_t iconfig, Int_t planes[4])
3347 // Map seeding configurations to detector planes.
3350 // iconfig : configuration index
3351 // planes : member planes of this configuration. On input empty.
3354 // planes : contains the planes which are defining the configuration
3356 // Detailed description
3358 // Here is the list of seeding planes configurations together with
3359 // their topological classification:
3377 // The topologic quality is modeled as follows:
3378 // 1. The general model is define by the equation:
3379 // p(conf) = exp(-conf/2)
3380 // 2. According to the topologic classification, configurations from the same
3381 // class are assigned the agerage value over the model values.
3382 // 3. Quality values are normalized.
3384 // The topologic quality distribution as function of configuration is given below:
3386 // <img src="gif/topologicQA.gif">
3391 case 0: // 5432 TQ 0
3397 case 1: // 4321 TQ 0
3403 case 2: // 3210 TQ 0
3409 case 3: // 5321 TQ 1
3415 case 4: // 4210 TQ 1
3421 case 5: // 5431 TQ 1
3427 case 6: // 4320 TQ 1
3433 case 7: // 5430 TQ 2
3439 case 8: // 5210 TQ 2
3445 case 9: // 5421 TQ 3
3451 case 10: // 4310 TQ 3
3457 case 11: // 5410 TQ 4
3463 case 12: // 5420 TQ 5
3469 case 13: // 5320 TQ 5
3475 case 14: // 5310 TQ 5
3484 //____________________________________________________________________
3485 void AliTRDtrackerV1::GetExtrapolationConfig(Int_t iconfig, Int_t planes[2])
3488 // Returns the extrapolation planes for a seeding configuration.
3491 // iconfig : configuration index
3492 // planes : planes which are not in this configuration. On input empty.
3495 // planes : contains the planes which are not in the configuration
3497 // Detailed description
3501 case 0: // 5432 TQ 0
3505 case 1: // 4321 TQ 0
3509 case 2: // 3210 TQ 0
3513 case 3: // 5321 TQ 1
3517 case 4: // 4210 TQ 1
3521 case 5: // 5431 TQ 1
3525 case 6: // 4320 TQ 1
3529 case 7: // 5430 TQ 2
3533 case 8: // 5210 TQ 2
3537 case 9: // 5421 TQ 3
3541 case 10: // 4310 TQ 3
3545 case 11: // 5410 TQ 4
3549 case 12: // 5420 TQ 5
3553 case 13: // 5320 TQ 5
3557 case 14: // 5310 TQ 5
3564 //____________________________________________________________________
3565 AliCluster* AliTRDtrackerV1::GetCluster(Int_t idx) const
3567 if(!fClusters) return NULL;
3568 Int_t ncls = fClusters->GetEntriesFast();
3569 return idx >= 0 && idx < ncls ? (AliCluster*)fClusters->UncheckedAt(idx) : NULL;
3572 //____________________________________________________________________
3573 AliTRDseedV1* AliTRDtrackerV1::GetTracklet(Int_t idx) const
3575 if(!fTracklets) return NULL;
3576 Int_t ntrklt = fTracklets->GetEntriesFast();
3577 return idx >= 0 && idx < ntrklt ? (AliTRDseedV1*)fTracklets->UncheckedAt(idx) : NULL;
3580 //____________________________________________________________________
3581 AliKalmanTrack* AliTRDtrackerV1::GetTrack(Int_t idx) const
3583 if(!fTracks) return NULL;
3584 Int_t ntrk = fTracks->GetEntriesFast();
3585 return idx >= 0 && idx < ntrk ? (AliKalmanTrack*)fTracks->UncheckedAt(idx) : NULL;
3590 // //_____________________________________________________________________________
3591 // Int_t AliTRDtrackerV1::Freq(Int_t n, const Int_t *inlist
3592 // , Int_t *outlist, Bool_t down)
3595 // // Sort eleements according occurancy
3596 // // The size of output array has is 2*n
3603 // Int_t *sindexS = new Int_t[n]; // Temporary array for sorting
3604 // Int_t *sindexF = new Int_t[2*n];
3605 // for (Int_t i = 0; i < n; i++) {
3609 // TMath::Sort(n,inlist,sindexS,down);
3611 // Int_t last = inlist[sindexS[0]];
3612 // Int_t val = last;
3614 // sindexF[0+n] = last;
3615 // Int_t countPos = 0;
3617 // // Find frequency
3618 // for (Int_t i = 1; i < n; i++) {
3619 // val = inlist[sindexS[i]];
3620 // if (last == val) {
3621 // sindexF[countPos]++;
3625 // sindexF[countPos+n] = val;
3626 // sindexF[countPos]++;
3630 // if (last == val) {
3634 // // Sort according frequency
3635 // TMath::Sort(countPos,sindexF,sindexS,kTRUE);
3637 // for (Int_t i = 0; i < countPos; i++) {
3638 // outlist[2*i ] = sindexF[sindexS[i]+n];
3639 // outlist[2*i+1] = sindexF[sindexS[i]];
3642 // delete [] sindexS;
3643 // delete [] sindexF;
3650 //____________________________________________________________________
3651 void AliTRDtrackerV1::ResetSeedTB()
3653 // reset buffer for seeding time bin layers. If the time bin
3654 // layers are not allocated this function allocates them
3656 for(Int_t isl=0; isl<kNSeedPlanes; isl++){
3657 if(!fSeedTB[isl]) fSeedTB[isl] = new AliTRDchamberTimeBin();
3658 else fSeedTB[isl]->Clear();
3663 //_____________________________________________________________________________
3664 Float_t AliTRDtrackerV1::GetChi2Y(const AliTRDseedV1 * const tracklets) const
3666 // Calculates normalized chi2 in y-direction
3667 // chi2 = Sum chi2 / n_tracklets
3669 Double_t chi2 = 0.; Int_t n = 0;
3670 for(Int_t ipl = kNPlanes; ipl--;){
3671 if(!tracklets[ipl].IsOK()) continue;
3672 chi2 += tracklets[ipl].GetChi2Y();
3675 return n ? chi2/n : 0.;
3678 //_____________________________________________________________________________
3679 Float_t AliTRDtrackerV1::GetChi2Z(const AliTRDseedV1 *const tracklets) const
3681 // Calculates normalized chi2 in z-direction
3682 // chi2 = Sum chi2 / n_tracklets
3684 Double_t chi2 = 0; Int_t n = 0;
3685 for(Int_t ipl = kNPlanes; ipl--;){
3686 if(!tracklets[ipl].IsOK()) continue;
3687 chi2 += tracklets[ipl].GetChi2Z();
3690 return n ? chi2/n : 0.;
3693 //_____________________________________________________________________________
3694 Float_t AliTRDtrackerV1::GetChi2Phi(const AliTRDseedV1 *const tracklets) const
3696 // Calculates normalized chi2 for angular resolution
3697 // chi2 = Sum chi2 / n_tracklets
3699 Double_t chi2 = 0; Int_t n = 0;
3700 for (Int_t iLayer = 0; iLayer < kNPlanes; iLayer++) {
3701 if(!tracklets[iLayer].IsOK()) continue;
3702 chi2 += tracklets[iLayer].GetChi2Phi();
3705 return n ? chi2/n: 0.;
3708 //____________________________________________________________________
3709 Float_t AliTRDtrackerV1::CalculateReferenceX(const AliTRDseedV1 *const tracklets){
3711 // Calculates the reference x-position for the tilted Rieman fit defined as middle
3712 // of the stack (middle between layers 2 and 3). For the calculation all the tracklets
3713 // are taken into account
3715 // Parameters: - Array of tracklets(AliTRDseedV1)
3717 // Output: - The reference x-position(Float_t)
3718 // Only kept for compatibility with the old code
3720 Int_t nDistances = 0;
3721 Float_t meanDistance = 0.;
3722 Int_t startIndex = 5;
3723 for(Int_t il =5; il > 0; il--){
3724 if(tracklets[il].IsOK() && tracklets[il -1].IsOK()){
3725 Float_t xdiff = tracklets[il].GetX0() - tracklets[il -1].GetX0();
3726 meanDistance += xdiff;
3729 if(tracklets[il].IsOK()) startIndex = il;
3731 if(tracklets[0].IsOK()) startIndex = 0;
3733 // We should normally never get here
3734 Float_t xpos[2]; memset(xpos, 0, sizeof(Float_t) * 2);
3735 Int_t iok = 0, idiff = 0;
3736 // This attempt is worse and should be avoided:
3737 // check for two chambers which are OK and repeat this without taking the mean value
3738 // Strategy avoids a division by 0;
3739 for(Int_t il = 5; il >= 0; il--){
3740 if(tracklets[il].IsOK()){
3741 xpos[iok] = tracklets[il].GetX0();
3745 if(iok) idiff++; // to get the right difference;
3749 meanDistance = (xpos[0] - xpos[1])/idiff;
3752 // we have do not even have 2 layers which are OK? The we do not need to fit at all
3757 meanDistance /= nDistances;
3759 return tracklets[startIndex].GetX0() + (2.5 - startIndex) * meanDistance - 0.5 * (AliTRDgeometry::AmThick() + AliTRDgeometry::DrThick());
3762 //_____________________________________________________________________________
3763 Double_t AliTRDtrackerV1::FitTiltedRiemanV1(AliTRDseedV1 *const tracklets){
3765 // Track Fitter Function using the new class implementation of
3768 AliTRDtrackFitterRieman fitter;
3769 fitter.SetRiemanFitter(GetTiltedRiemanFitter());
3771 for(Int_t il = 0; il < AliTRDgeometry::kNlayer; il++) fitter.SetTracklet(il, &tracklets[il]);
3772 Double_t chi2 = fitter.Eval();
3773 // Update the tracklets
3774 Double_t cov[15]; Double_t x0;
3775 memset(cov, 0, sizeof(Double_t) * 15);
3776 for(Int_t il = 0; il < AliTRDgeometry::kNlayer; il++){
3777 x0 = tracklets[il].GetX0();
3778 tracklets[il].SetYref(0, fitter.GetYat(x0));
3779 tracklets[il].SetZref(0, fitter.GetZat(x0));
3780 tracklets[il].SetYref(1, fitter.GetDyDxAt(x0));
3781 tracklets[il].SetZref(1, fitter.GetDzDx());
3782 tracklets[il].SetC(fitter.GetCurvature());
3783 fitter.GetCovAt(x0, cov);
3784 tracklets[il].SetCovRef(cov);
3785 tracklets[il].SetChi2(chi2);
3790 //____________________________________________________________________
3791 void AliTRDtrackerV1::UnsetTrackletsTrack(const AliTRDtrackV1 * const track)
3794 for(Int_t il(0); il<kNPlanes; il++){
3795 if((idx = track->GetTrackletIndex(il)) < 0) continue;
3796 delete (fTracklets->RemoveAt(idx));
3801 ///////////////////////////////////////////////////////
3803 // Resources of class AliTRDLeastSquare //
3805 ///////////////////////////////////////////////////////
3807 //_____________________________________________________________________________
3808 AliTRDtrackerV1::AliTRDLeastSquare::AliTRDLeastSquare(){
3810 // Constructor of the nested class AliTRDtrackFitterLeastSquare
3812 // Fast solving linear regresion in 2D
3814 // The data members have the following meaning
3825 // fCovarianceMatrix[0] : s2a
3826 // fCovarianceMatrix[1] : s2b
3827 // fCovarianceMatrix[2] : cov(ab)
3829 memset(fParams, 0, sizeof(Double_t) * 2);
3830 memset(fSums, 0, sizeof(Double_t) * 6);
3831 memset(fCovarianceMatrix, 0, sizeof(Double_t) * 3);
3835 //_____________________________________________________________________________
3836 void AliTRDtrackerV1::AliTRDLeastSquare::AddPoint(const Double_t *const x, Double_t y, Double_t sigmaY){
3838 // Adding Point to the fitter
3841 Double_t weight = 1/(sigmaY > 1e-9 ? sigmaY : 1e-9);
3843 const Double_t &xpt = *x;
3844 // printf("Adding point x = %f, y = %f, sigma = %f\n", xpt, y, sigmaY);
3846 fSums[1] += weight * xpt;
3847 fSums[2] += weight * y;
3848 fSums[3] += weight * xpt * y;
3849 fSums[4] += weight * xpt * xpt;
3850 fSums[5] += weight * y * y;
3853 //_____________________________________________________________________________
3854 void AliTRDtrackerV1::AliTRDLeastSquare::RemovePoint(const Double_t *const x, Double_t y, Double_t sigmaY){
3856 // Remove Point from the sample
3859 Double_t weight = 1/(sigmaY > 1e-9 ? sigmaY : 1e-9);
3861 const Double_t &xpt = *x;
3863 fSums[1] -= weight * xpt;
3864 fSums[2] -= weight * y;
3865 fSums[3] -= weight * xpt * y;
3866 fSums[4] -= weight * xpt * xpt;
3867 fSums[5] -= weight * y * y;
3870 //_____________________________________________________________________________
3871 Bool_t AliTRDtrackerV1::AliTRDLeastSquare::Eval(){
3873 // Evaluation of the fit:
3874 // Calculation of the parameters
3875 // Calculation of the covariance matrix
3878 Double_t det = fSums[0] * fSums[4] - fSums[1] *fSums[1];
3879 if(det==0) return kFALSE;
3881 // for(Int_t isum = 0; isum < 5; isum++)
3882 // printf("fSums[%d] = %f\n", isum, fSums[isum]);
3883 // printf("denominator = %f\n", denominator);
3884 fParams[0] = (fSums[2] * fSums[4] - fSums[1] * fSums[3])/det;
3885 fParams[1] = (fSums[0] * fSums[3] - fSums[1] * fSums[2])/det;
3886 // printf("fParams[0] = %f, fParams[1] = %f\n", fParams[0], fParams[1]);
3888 // Covariance matrix
3889 Double_t den = fSums[0]*fSums[4] - fSums[1]*fSums[1];
3890 fCovarianceMatrix[0] = fSums[4] / den;
3891 fCovarianceMatrix[1] = fSums[0] / den;
3892 fCovarianceMatrix[2] = -fSums[1] / den;
3893 /* fCovarianceMatrix[0] = fSums[4] / fSums[0] - fSums[1] * fSums[1] / (fSums[0] * fSums[0]);
3894 fCovarianceMatrix[1] = fSums[5] / fSums[0] - fSums[2] * fSums[2] / (fSums[0] * fSums[0]);
3895 fCovarianceMatrix[2] = fSums[3] / fSums[0] - fSums[1] * fSums[2] / (fSums[0] * fSums[0]);*/
3902 //_____________________________________________________________________________
3903 Double_t AliTRDtrackerV1::AliTRDLeastSquare::GetFunctionValue(const Double_t *const xpos) const {
3905 // Returns the Function value of the fitted function at a given x-position
3907 return fParams[0] + fParams[1] * (*xpos);
3910 //_____________________________________________________________________________
3911 void AliTRDtrackerV1::AliTRDLeastSquare::GetCovarianceMatrix(Double_t *storage) const {
3913 // Copies the values of the covariance matrix into the storage
3915 memcpy(storage, fCovarianceMatrix, sizeof(Double_t) * 3);
3918 //_____________________________________________________________________________
3919 void AliTRDtrackerV1::AliTRDLeastSquare::Reset(){
3923 memset(fParams, 0, sizeof(Double_t) * 2);
3924 memset(fCovarianceMatrix, 0, sizeof(Double_t) * 3);
3925 memset(fSums, 0, sizeof(Double_t) * 6);
3928 ///////////////////////////////////////////////////////
3930 // Resources of class AliTRDtrackFitterRieman //
3932 ///////////////////////////////////////////////////////
3934 //_____________________________________________________________________________
3935 AliTRDtrackerV1::AliTRDtrackFitterRieman::AliTRDtrackFitterRieman():
3941 fSysClusterError(0.)
3944 // Default constructor
3946 fZfitter = new AliTRDLeastSquare;
3947 fCovarPolY = new TMatrixD(3,3);
3948 fCovarPolZ = new TMatrixD(2,2);
3949 memset(fTracklets, 0, sizeof(AliTRDseedV1 *) * 6);
3950 memset(fParameters, 0, sizeof(Double_t) * 5);
3951 memset(fSumPolY, 0, sizeof(Double_t) * 5);
3952 memset(fSumPolZ, 0, sizeof(Double_t) * 2);
3955 //_____________________________________________________________________________
3956 AliTRDtrackerV1::AliTRDtrackFitterRieman::~AliTRDtrackFitterRieman(){
3960 if(fZfitter) delete fZfitter;
3961 if(fCovarPolY) delete fCovarPolY;
3962 if(fCovarPolZ) delete fCovarPolZ;
3965 //_____________________________________________________________________________
3966 void AliTRDtrackerV1::AliTRDtrackFitterRieman::Reset(){
3971 fTrackFitter->StoreData(kTRUE);
3972 fTrackFitter->ClearPoints();
3978 memset(fTracklets, 0, sizeof(AliTRDseedV1 *) * AliTRDgeometry::kNlayer);
3979 memset(fParameters, 0, sizeof(Double_t) * 5);
3980 memset(fSumPolY, 0, sizeof(Double_t) * 5);
3981 memset(fSumPolZ, 0, sizeof(Double_t) * 2);
3982 for(Int_t irow = 0; irow < fCovarPolY->GetNrows(); irow++)
3983 for(Int_t icol = 0; icol < fCovarPolY->GetNcols(); icol++){
3984 (*fCovarPolY)(irow, icol) = 0.;
3985 if(irow < 2 && icol < 2)
3986 (*fCovarPolZ)(irow, icol) = 0.;
3990 //_____________________________________________________________________________
3991 void AliTRDtrackerV1::AliTRDtrackFitterRieman::SetTracklet(Int_t itr, AliTRDseedV1 *tracklet){
3993 // Add tracklet into the fitter
3995 if(itr >= AliTRDgeometry::kNlayer) return;
3996 fTracklets[itr] = tracklet;
3999 //_____________________________________________________________________________
4000 Double_t AliTRDtrackerV1::AliTRDtrackFitterRieman::Eval(){
4003 // 1. Apply linear transformation and store points in the fitter
4004 // 2. Evaluate the fit
4005 // 3. Check if the result of the fit in z-direction is reasonable
4007 // 3a. Fix the parameters 3 and 4 with the results of a simple least
4009 // 3b. Redo the fit with the fixed parameters
4010 // 4. Store fit results (parameters and errors)
4015 fXref = CalculateReferenceX();
4016 for(Int_t il = 0; il < AliTRDgeometry::kNlayer; il++) UpdateFitters(fTracklets[il]);
4017 if(!fTrackFitter->GetNpoints()) return 1e10;
4019 fTrackFitter->Eval();
4021 fParameters[3] = fTrackFitter->GetParameter(3);
4022 fParameters[4] = fTrackFitter->GetParameter(4);
4023 if(!CheckAcceptable(fParameters[3], fParameters[4])) {
4024 fTrackFitter->FixParameter(3, fZfitter->GetFunctionValue(&fXref));
4025 fTrackFitter->FixParameter(4, fZfitter->GetFunctionParameter(1));
4026 fTrackFitter->Eval();
4027 fTrackFitter->ReleaseParameter(3);
4028 fTrackFitter->ReleaseParameter(4);
4029 fParameters[3] = fTrackFitter->GetParameter(3);
4030 fParameters[4] = fTrackFitter->GetParameter(4);
4032 // Update the Fit Parameters and the errors
4033 fParameters[0] = fTrackFitter->GetParameter(0);
4034 fParameters[1] = fTrackFitter->GetParameter(1);
4035 fParameters[2] = fTrackFitter->GetParameter(2);
4037 // Prepare Covariance estimation
4038 (*fCovarPolY)(0,0) = fSumPolY[0]; (*fCovarPolY)(1,1) = fSumPolY[2]; (*fCovarPolY)(2,2) = fSumPolY[4];
4039 (*fCovarPolY)(1,0) = (*fCovarPolY)(0,1) = fSumPolY[1];
4040 (*fCovarPolY)(2,0) = (*fCovarPolY)(0,2) = fSumPolY[2];
4041 (*fCovarPolY)(2,1) = (*fCovarPolY)(1,2) = fSumPolY[3];
4042 fCovarPolY->Invert();
4043 (*fCovarPolZ)(0,0) = fSumPolZ[0]; (*fCovarPolZ)(1,1) = fSumPolZ[2];
4044 (*fCovarPolZ)(1,0) = (*fCovarPolZ)(0,1) = fSumPolZ[1];
4045 fCovarPolZ->Invert();
4046 return fTrackFitter->GetChisquare() / fTrackFitter->GetNpoints();
4049 //_____________________________________________________________________________
4050 void AliTRDtrackerV1::AliTRDtrackFitterRieman::UpdateFitters(AliTRDseedV1 * const tracklet){
4052 // Does the transformations and updates the fitters
4053 // The following transformation is applied
4055 AliTRDcluster *cl = NULL;
4056 Double_t x, y, z, dx, t, w, we, yerr, zerr;
4058 if(!tracklet || !tracklet->IsOK()) return;
4059 Double_t tilt = tracklet->GetTilt();
4060 for(Int_t itb = 0; itb < AliTRDseedV1::kNclusters; itb++){
4061 if(!(cl = tracklet->GetClusters(itb))) continue;
4062 if(!cl->IsInChamber()) continue;
4063 if (!tracklet->IsUsable(itb)) continue;
4070 uvt[0] = 2. * x * t;
4072 uvt[2] = 2. * tilt * t;
4073 uvt[3] = 2. * tilt * dx * t;
4074 w = 2. * (y + tilt*z) * t;
4075 // error definition changes for the different calls
4077 we *= TMath::Sqrt(cl->GetSigmaY2()+tilt*tilt*cl->GetSigmaZ2());
4078 // Update sums for error calculation
4079 yerr = 1./(TMath::Sqrt(cl->GetSigmaY2()) + fSysClusterError);
4081 zerr = 1./cl->GetSigmaZ2();
4082 for(Int_t ipol = 0; ipol < 5; ipol++){
4083 fSumPolY[ipol] += yerr;
4086 fSumPolZ[ipol] += zerr;
4090 fTrackFitter->AddPoint(uvt, w, we);
4091 fZfitter->AddPoint(&x, z, static_cast<Double_t>(TMath::Sqrt(cl->GetSigmaZ2())));
4095 //_____________________________________________________________________________
4096 Bool_t AliTRDtrackerV1::AliTRDtrackFitterRieman::CheckAcceptable(Double_t offset, Double_t slope){
4098 // Check whether z-results are acceptable
4099 // Definition: Distance between tracklet fit and track fit has to be
4100 // less then half a padlength
4101 // Point of comparision is at the anode wire
4103 Bool_t acceptablez = kTRUE;
4104 Double_t zref = 0.0;
4105 for (Int_t iLayer = 0; iLayer < kNPlanes; iLayer++) {
4106 if(!fTracklets[iLayer]->IsOK()) continue;
4107 zref = offset + slope * (fTracklets[iLayer]->GetX0() - fXref);
4108 if (TMath::Abs(fTracklets[iLayer]->GetZfit(0) - zref) > fTracklets[iLayer]->GetPadLength() * 0.5 + 1.0)
4109 acceptablez = kFALSE;
4114 //_____________________________________________________________________________
4115 Double_t AliTRDtrackerV1::AliTRDtrackFitterRieman::GetYat(Double_t x) const {
4117 // Calculate y position out of the track parameters
4118 // y: R^2 = (x - x0)^2 + (y - y0)^2
4119 // => y = y0 +/- Sqrt(R^2 - (x - x0)^2)
4120 // R = Sqrt() = 1/Curvature
4121 // => y = y0 +/- Sqrt(1/Curvature^2 - (x - x0)^2)
4124 Double_t disc = (x * fParameters[0] + fParameters[1]);
4125 disc = 1 - fParameters[0]*fParameters[2] + fParameters[1]*fParameters[1] - disc*disc;
4127 disc = TMath::Sqrt(disc);
4128 y = (1.0 - disc) / fParameters[0];
4133 //_____________________________________________________________________________
4134 Double_t AliTRDtrackerV1::AliTRDtrackFitterRieman::GetZat(Double_t x) const {
4136 // Return z position for a given x position
4137 // Simple linear function
4139 return fParameters[3] + fParameters[4] * (x - fXref);
4142 //_____________________________________________________________________________
4143 Double_t AliTRDtrackerV1::AliTRDtrackFitterRieman::GetDyDxAt(Double_t x) const {
4145 // Calculate dydx at a given radial position out of the track parameters
4146 // dy: R^2 = (x - x0)^2 + (y - y0)^2
4147 // => y = +/- Sqrt(R^2 - (x - x0)^2) + y0
4148 // => dy/dx = (x - x0)/Sqrt(R^2 - (x - x0)^2)
4149 // Curvature: cr = 1/R = a/Sqrt(1 + b^2 - c*a)
4150 // => dy/dx = (x - x0)/(1/(cr^2) - (x - x0)^2)
4152 Double_t x0 = -fParameters[1] / fParameters[0];
4153 Double_t curvature = GetCurvature();
4155 if (-fParameters[2] * fParameters[0] + fParameters[1] * fParameters[1] + 1 > 0) {
4156 if (1.0/(curvature * curvature) - (x - x0) * (x - x0) > 0.0) {
4157 Double_t yderiv = (x - x0) / TMath::Sqrt(1.0/(curvature * curvature) - (x - x0) * (x - x0));
4158 if (fParameters[0] < 0) yderiv *= -1.0;
4165 //_____________________________________________________________________________
4166 Double_t AliTRDtrackerV1::AliTRDtrackFitterRieman::GetCurvature() const {
4168 // Calculate track curvature
4171 Double_t curvature = 1.0 + fParameters[1]*fParameters[1] - fParameters[2]*fParameters[0];
4172 if (curvature > 0.0)
4173 curvature = fParameters[0] / TMath::Sqrt(curvature);
4177 //_____________________________________________________________________________
4178 void AliTRDtrackerV1::AliTRDtrackFitterRieman::GetCovAt(Double_t x, Double_t *cov) const {
4180 // Error Definition according to gauss error propagation
4182 TMatrixD transform(3,3);
4183 transform(0,0) = transform(1,1) = transform(2,2) = 1;
4184 transform(0,1) = transform(1,2) = x;
4185 transform(0,2) = x*x;
4186 TMatrixD covariance(transform, TMatrixD::kMult, *fCovarPolY);
4187 covariance *= transform.T();
4188 cov[0] = covariance(0,0);
4189 TMatrixD transformZ(2,2);
4190 transformZ(0,0) = transformZ(1,1) = 1;
4191 transformZ(0,1) = x;
4192 TMatrixD covarZ(transformZ, TMatrixD::kMult, *fCovarPolZ);
4193 covarZ *= transformZ.T();
4194 cov[1] = covarZ(0,0);
4198 //____________________________________________________________________
4199 Double_t AliTRDtrackerV1::AliTRDtrackFitterRieman::CalculateReferenceX(){
4201 // Calculates the reference x-position for the tilted Rieman fit defined as middle
4202 // of the stack (middle between layers 2 and 3). For the calculation all the tracklets
4203 // are taken into account
4205 // Parameters: - Array of tracklets(AliTRDseedV1)
4207 // Output: - The reference x-position(Float_t)
4209 Int_t nDistances = 0;
4210 Float_t meanDistance = 0.;
4211 Int_t startIndex = 5;
4212 for(Int_t il =5; il > 0; il--){
4213 if(fTracklets[il]->IsOK() && fTracklets[il -1]->IsOK()){
4214 Float_t xdiff = fTracklets[il]->GetX0() - fTracklets[il -1]->GetX0();
4215 meanDistance += xdiff;
4218 if(fTracklets[il]->IsOK()) startIndex = il;
4220 if(fTracklets[0]->IsOK()) startIndex = 0;
4222 // We should normally never get here
4223 Float_t xpos[2]; memset(xpos, 0, sizeof(Float_t) * 2);
4224 Int_t iok = 0, idiff = 0;
4225 // This attempt is worse and should be avoided:
4226 // check for two chambers which are OK and repeat this without taking the mean value
4227 // Strategy avoids a division by 0;
4228 for(Int_t il = 5; il >= 0; il--){
4229 if(fTracklets[il]->IsOK()){
4230 xpos[iok] = fTracklets[il]->GetX0();
4234 if(iok) idiff++; // to get the right difference;
4238 meanDistance = (xpos[0] - xpos[1])/idiff;
4241 // we have do not even have 2 layers which are OK? The we do not need to fit at all
4246 meanDistance /= nDistances;
4248 return fTracklets[startIndex]->GetX0() + (2.5 - startIndex) * meanDistance - 0.5 * (AliTRDgeometry::AmThick() + AliTRDgeometry::DrThick());