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 //-----------------------------------------------------------------------------
19 /// \class AliMUONTrackReconstructor
20 /// MUON track reconstructor using the original method
22 /// This class contains as data:
23 /// - the parameters for the track reconstruction
25 /// It contains as methods, among others:
26 /// - MakeTracks to build the tracks
27 //-----------------------------------------------------------------------------
29 #include "AliMUONTrackReconstructor.h"
31 #include "AliMUONConstants.h"
32 #include "AliMUONVCluster.h"
33 #include "AliMUONVClusterServer.h"
34 #include "AliMUONVClusterStore.h"
35 #include "AliMUONTrack.h"
36 #include "AliMUONTrackParam.h"
37 #include "AliMUONTrackExtrap.h"
39 #include "AliMpArea.h"
44 #include <Riostream.h>
48 // Functions to be minimized with Minuit
49 void TrackChi2(Int_t &nParam, Double_t *gradient, Double_t &chi2, Double_t *param, Int_t flag);
52 ClassImp(AliMUONTrackReconstructor) // Class implementation in ROOT context
55 //__________________________________________________________________________
56 AliMUONTrackReconstructor::AliMUONTrackReconstructor(AliMUONVClusterServer& clusterServer)
57 : AliMUONVTrackReconstructor(clusterServer)
62 //__________________________________________________________________________
63 AliMUONTrackReconstructor::~AliMUONTrackReconstructor()
68 //__________________________________________________________________________
69 void AliMUONTrackReconstructor::MakeTrackCandidates(AliMUONVClusterStore& clusterStore)
71 /// To make track candidates (assuming linear propagation if the flag fgkMakeTrackCandidatesFast is set to kTRUE):
72 /// Start with segments station(1..) 4 or 5 then follow track in station 5 or 4.
73 /// Good candidates are made of at least three clusters.
74 /// Keep only best candidates or all of them according to the flag fgkTrackAllTracks.
76 TClonesArray *segments;
81 AliDebug(1,"Enter MakeTrackCandidates");
83 // Unless we're doing combined tracking, we'll clusterize all stations at once
84 Int_t firstChamber(0);
87 if (AliMUONReconstructor::GetRecoParam()->CombineClusterTrackReco()) {
88 // ... Here's the exception : ask the clustering to reconstruct
89 // clusters *only* in station 4 and 5 for combined tracking
93 for (Int_t i = firstChamber; i <= lastChamber; ++i )
95 fClusterServer.Clusterize(i, clusterStore, AliMpArea());
98 // Loop over stations(1..) 5 and 4 and make track candidates
99 for (Int_t istat=4; istat>=3; istat--) {
101 // Make segments in the station
102 segments = MakeSegmentsInStation(clusterStore,istat);
104 // Loop over segments
105 for (Int_t iseg=0; iseg<segments->GetEntriesFast(); iseg++)
107 AliDebug(1,Form("Making primary candidate(1..) %d",++iCandidate));
109 // Transform segments to tracks and put them at the end of fRecTracksPtr
110 track = new ((*fRecTracksPtr)[fRecTracksPtr->GetLast()+1]) AliMUONTrack((AliMUONObjectPair*)((*segments)[iseg]));
113 // Printout for debuging
114 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 2) || (AliLog::GetGlobalDebugLevel() >= 2)) {
115 cout<<endl<<"Track parameter covariances at first cluster:"<<endl;
116 ((AliMUONTrackParam*) track->GetTrackParamAtCluster()->First())->GetCovariances().Print();
119 // Look for compatible cluster(s) in the other station
120 if (AliMUONReconstructor::GetRecoParam()->MakeTrackCandidatesFast())
121 clusterFound = FollowLinearTrackInStation(*track, clusterStore, 7-istat);
122 else clusterFound = FollowTrackInStation(*track, clusterStore, 7-istat);
124 // Remove track if no cluster found
126 fRecTracksPtr->Remove(track);
132 // delete the array of segments
136 fRecTracksPtr->Compress(); // this is essential before checking tracks
138 // Keep all different tracks or only the best ones as required
139 if (AliMUONReconstructor::GetRecoParam()->TrackAllTracks()) RemoveIdenticalTracks();
140 else RemoveDoubleTracks();
142 AliDebug(1,Form("Number of good candidates = %d",fNRecTracks));
146 //__________________________________________________________________________
147 void AliMUONTrackReconstructor::FollowTracks(AliMUONVClusterStore& clusterStore)
149 /// Follow tracks in stations(1..) 3, 2 and 1
150 AliDebug(1,"Enter FollowTracks");
152 AliMUONTrack *track, *nextTrack;
153 AliMUONTrackParam *trackParam, *nextTrackParam;
154 Int_t currentNRecTracks;
157 Double_t sigmaCut2 = AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking() *
158 AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking();
160 for (Int_t station = 2; station >= 0; station--) {
162 // Save the actual number of reconstructed track in case of
163 // tracks are added or suppressed during the tracking procedure
164 // !! Do not compress fRecTracksPtr until the end of the loop over tracks !!
165 currentNRecTracks = fNRecTracks;
167 for (Int_t iRecTrack = 0; iRecTrack <currentNRecTracks; iRecTrack++) {
168 AliDebug(1,Form("FollowTracks: track candidate(1..) %d", iRecTrack+1));
170 track = (AliMUONTrack*) fRecTracksPtr->UncheckedAt(iRecTrack);
173 // Do not take into account the multiple scattering to speed up the fit
174 // Calculate the track parameter covariance matrix
175 // If "station" is station(1..) 3 then use the vertex to better constrain the fit
176 if (station==2) Fit(*track, kFALSE, kTRUE, kTRUE);
177 else Fit(*track, kFALSE, kFALSE, kTRUE);
179 // Remove the track if the normalized chi2 is too high
180 if (track->GetNormalizedChi2() > sigmaCut2) {
181 fRecTracksPtr->Remove(track);
186 // save parameters from fit into smoothed parameters to complete track afterward
187 if (AliMUONReconstructor::GetRecoParam()->ComplementTracks()) {
189 if (station==2) { // save track parameters on stations 4 and 5
191 // extrapolate track parameters and covariances at each cluster
192 track->UpdateCovTrackParamAtCluster();
195 trackParam = (AliMUONTrackParam*) track->GetTrackParamAtCluster()->First();
197 trackParam->SetSmoothParameters(trackParam->GetParameters());
198 trackParam->SetSmoothCovariances(trackParam->GetCovariances());
199 trackParam = (AliMUONTrackParam*) track->GetTrackParamAtCluster()->After(trackParam);
202 } else { // or save track parameters on last station only
204 // save parameters from fit
205 trackParam = (AliMUONTrackParam*) track->GetTrackParamAtCluster()->First();
206 trackParam->SetSmoothParameters(trackParam->GetParameters());
207 trackParam->SetSmoothCovariances(trackParam->GetCovariances());
209 // save parameters extrapolated to the second chamber of the same station if it has been hit
210 nextTrackParam = (AliMUONTrackParam*) track->GetTrackParamAtCluster()->After(trackParam);
211 if (nextTrackParam->GetClusterPtr()->GetChamberId() < 2*(station+2)) {
213 // reset parameters and covariances
214 nextTrackParam->SetParameters(trackParam->GetParameters());
215 nextTrackParam->SetZ(trackParam->GetZ());
216 nextTrackParam->SetCovariances(trackParam->GetCovariances());
218 // extrapolate them to the z of the corresponding cluster
219 AliMUONTrackExtrap::ExtrapToZCov(nextTrackParam, nextTrackParam->GetClusterPtr()->GetZ());
222 nextTrackParam->SetSmoothParameters(nextTrackParam->GetParameters());
223 nextTrackParam->SetSmoothCovariances(nextTrackParam->GetCovariances());
231 // Printout for debuging
232 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 2) || (AliLog::GetGlobalDebugLevel() >= 2)) {
233 cout<<endl<<"Track parameter covariances at first cluster:"<<endl;
234 ((AliMUONTrackParam*) track->GetTrackParamAtCluster()->First())->GetCovariances().Print();
237 // Look for compatible cluster(s) in station(0..) "station"
238 clusterFound = FollowTrackInStation(*track, clusterStore, station);
240 // Try to recover track if required
241 if (!clusterFound && AliMUONReconstructor::GetRecoParam()->RecoverTracks())
242 clusterFound = RecoverTrack(*track, clusterStore, station);
244 // remove track if no cluster found
246 fRecTracksPtr->Remove(track);
252 // Compress fRecTracksPtr for the next step
253 fRecTracksPtr->Compress();
255 // Keep only the best tracks if required
256 if (!AliMUONReconstructor::GetRecoParam()->TrackAllTracks()) RemoveDoubleTracks();
260 // Last fit of track candidates with all stations
261 // Take into account the multiple scattering and remove bad tracks
262 Int_t trackIndex = -1;
263 track = (AliMUONTrack*) fRecTracksPtr->First();
267 nextTrack = (AliMUONTrack*) fRecTracksPtr->After(track); // prepare next track
269 Fit(*track, kTRUE, kFALSE, kTRUE);
271 // Printout for debuging
272 if (AliLog::GetGlobalDebugLevel() >= 3) {
273 cout << "FollowTracks: track candidate(0..) " << trackIndex << " after final fit" << endl;
274 track->RecursiveDump();
277 // Remove the track if the normalized chi2 is too high
278 if (track->GetNormalizedChi2() > sigmaCut2) {
279 fRecTracksPtr->Remove(track);
285 // save parameters from fit into smoothed parameters to complete track afterward
286 if (AliMUONReconstructor::GetRecoParam()->ComplementTracks()) {
288 // save parameters from fit
289 trackParam = (AliMUONTrackParam*) track->GetTrackParamAtCluster()->First();
290 trackParam->SetSmoothParameters(trackParam->GetParameters());
291 trackParam->SetSmoothCovariances(trackParam->GetCovariances());
293 // save parameters extrapolated to the second chamber of the same station if it has been hit
294 nextTrackParam = (AliMUONTrackParam*) track->GetTrackParamAtCluster()->After(trackParam);
295 if (nextTrackParam->GetClusterPtr()->GetChamberId() < 2) {
297 // reset parameters and covariances
298 nextTrackParam->SetParameters(trackParam->GetParameters());
299 nextTrackParam->SetZ(trackParam->GetZ());
300 nextTrackParam->SetCovariances(trackParam->GetCovariances());
302 // extrapolate them to the z of the corresponding cluster
303 AliMUONTrackExtrap::ExtrapToZCov(nextTrackParam, nextTrackParam->GetClusterPtr()->GetZ());
306 nextTrackParam->SetSmoothParameters(nextTrackParam->GetParameters());
307 nextTrackParam->SetSmoothCovariances(nextTrackParam->GetCovariances());
317 fRecTracksPtr->Compress();
321 //__________________________________________________________________________
322 Bool_t AliMUONTrackReconstructor::FollowTrackInStation(AliMUONTrack &trackCandidate, AliMUONVClusterStore& clusterStore, Int_t nextStation)
324 /// Follow trackCandidate in station(0..) nextStation and search for compatible cluster(s)
325 /// Keep all possibilities or only the best one(s) according to the flag fgkTrackAllTracks:
326 /// kTRUE: duplicate "trackCandidate" if there are several possibilities and add the new tracks at the end of
327 /// fRecTracksPtr to avoid conficts with other track candidates at this current stage of the tracking procedure.
328 /// Remove the obsolete "trackCandidate" at the end.
329 /// kFALSE: add only the best cluster(s) to the "trackCandidate". Try to add a couple of clusters in priority.
330 AliDebug(1,Form("Enter FollowTrackInStation(1..) %d", nextStation+1));
332 // Order the chamber according to the propagation direction (tracking starts with chamber 2):
333 // - nextStation == station(1...) 5 => forward propagation
334 // - nextStation < station(1...) 5 => backward propagation
336 if (nextStation==4) {
337 ch1 = 2*nextStation+1;
341 ch2 = 2*nextStation+1;
344 Double_t chi2WithOneCluster = 1.e10;
345 Double_t chi2WithTwoClusters = 1.e10;
346 Double_t maxChi2WithOneCluster = 2. * AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking() *
347 AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking(); // 2 because 2 quantities in chi2
348 Double_t maxChi2WithTwoClusters = 4. * AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking() *
349 AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking(); // 4 because 4 quantities in chi2
350 Double_t bestChi2WithOneCluster = maxChi2WithOneCluster;
351 Double_t bestChi2WithTwoClusters = maxChi2WithTwoClusters;
352 Bool_t foundOneCluster = kFALSE;
353 Bool_t foundTwoClusters = kFALSE;
354 AliMUONTrack *newTrack = 0x0;
355 AliMUONVCluster *clusterCh1, *clusterCh2;
356 AliMUONTrackParam extrapTrackParam;
357 AliMUONTrackParam extrapTrackParamAtCluster1;
358 AliMUONTrackParam extrapTrackParamAtCluster2;
359 AliMUONTrackParam bestTrackParamAtCluster1;
360 AliMUONTrackParam bestTrackParamAtCluster2;
362 Int_t nClusters = clusterStore.GetSize();
363 Bool_t *clusterCh1Used = new Bool_t[nClusters];
364 for (Int_t i = 0; i < nClusters; i++) clusterCh1Used[i] = kFALSE;
367 // Get track parameters
368 AliMUONTrackParam extrapTrackParamAtCh(*(AliMUONTrackParam*)trackCandidate.GetTrackParamAtCluster()->First());
371 AliMUONTrackExtrap::AddMCSEffect(&extrapTrackParamAtCh,AliMUONConstants::ChamberThicknessInX0(),1.);
373 // Add MCS in the missing chamber if any (only 1 chamber can be missing according to tracking criteria)
374 if (ch1 < ch2 && extrapTrackParamAtCh.GetClusterPtr()->GetChamberId() > ch2 + 1) {
375 // extrapolation to the missing chamber
376 AliMUONTrackExtrap::ExtrapToZCov(&extrapTrackParamAtCh, AliMUONConstants::DefaultChamberZ(ch2 + 1));
378 AliMUONTrackExtrap::AddMCSEffect(&extrapTrackParamAtCh,AliMUONConstants::ChamberThicknessInX0(),1.);
381 //Extrapolate trackCandidate to chamber "ch2"
382 AliMUONTrackExtrap::ExtrapToZCov(&extrapTrackParamAtCh, AliMUONConstants::DefaultChamberZ(ch2));
384 // Printout for debuging
385 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 2) || (AliLog::GetGlobalDebugLevel() >= 2)) {
386 cout<<endl<<"Track parameter covariances at first cluster extrapolated to z = "<<AliMUONConstants::DefaultChamberZ(ch2)<<":"<<endl;
387 extrapTrackParamAtCh.GetCovariances().Print();
390 // Printout for debuging
391 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
392 cout << "FollowTrackInStation: look for clusters in chamber(1..): " << ch2+1 << endl;
395 // Ask the clustering to reconstruct new clusters around the track position in the current station
396 // except for station 4 and 5 that are already entirely clusterized
397 if (AliMUONReconstructor::GetRecoParam()->CombineClusterTrackReco()) {
398 if (nextStation < 3) AskForNewClustersInStation(extrapTrackParamAtCh, clusterStore, nextStation);
401 // Create iterators to loop over clusters in both chambers
402 TIter nextInCh1(clusterStore.CreateChamberIterator(ch1,ch1));
403 TIter nextInCh2(clusterStore.CreateChamberIterator(ch2,ch2));
405 // look for candidates in chamber 2
406 while ( ( clusterCh2 = static_cast<AliMUONVCluster*>(nextInCh2()) ) ) {
408 // try to add the current cluster fast
409 if (!TryOneClusterFast(extrapTrackParamAtCh, clusterCh2)) continue;
411 // try to add the current cluster accuratly
412 chi2WithOneCluster = TryOneCluster(extrapTrackParamAtCh, clusterCh2, extrapTrackParamAtCluster2);
414 // if good chi2 then try to attach a cluster in the other chamber too
415 if (chi2WithOneCluster < maxChi2WithOneCluster) {
416 Bool_t foundSecondCluster = kFALSE;
418 // Printout for debuging
419 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
420 cout << "FollowTrackInStation: found one cluster in chamber(1..): " << ch2+1
421 << " (Chi2 = " << chi2WithOneCluster << ")" << endl;
422 cout << " look for second clusters in chamber(1..): " << ch1+1 << " ..." << endl;
425 // add MCS effect for next step
426 AliMUONTrackExtrap::AddMCSEffect(&extrapTrackParamAtCluster2,AliMUONConstants::ChamberThicknessInX0(),1.);
428 // copy new track parameters for next step
429 extrapTrackParam = extrapTrackParamAtCluster2;
431 //Extrapolate track parameters to chamber "ch1"
432 AliMUONTrackExtrap::ExtrapToZ(&extrapTrackParam, AliMUONConstants::DefaultChamberZ(ch1));
434 // reset cluster iterator of chamber 1
438 // look for second candidates in chamber 1
439 while ( ( clusterCh1 = static_cast<AliMUONVCluster*>(nextInCh1()) ) ) {
442 // try to add the current cluster fast
443 if (!TryOneClusterFast(extrapTrackParam, clusterCh1)) continue;
445 // try to add the current cluster accuratly
446 chi2WithTwoClusters = TryTwoClusters(extrapTrackParamAtCluster2, clusterCh1, extrapTrackParamAtCluster1);
448 // if good chi2 then create a new track by adding the 2 clusters to the "trackCandidate"
449 if (chi2WithTwoClusters < maxChi2WithTwoClusters) {
450 foundSecondCluster = kTRUE;
451 foundTwoClusters = kTRUE;
453 // Printout for debuging
454 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
455 cout << "FollowTrackInStation: found second cluster in chamber(1..): " << ch1+1
456 << " (Global Chi2 = " << chi2WithTwoClusters << ")" << endl;
459 if (AliMUONReconstructor::GetRecoParam()->TrackAllTracks()) {
460 // copy trackCandidate into a new track put at the end of fRecTracksPtr and add the new clusters
461 newTrack = new ((*fRecTracksPtr)[fRecTracksPtr->GetLast()+1]) AliMUONTrack(trackCandidate);
462 UpdateTrack(*newTrack,extrapTrackParamAtCluster1,extrapTrackParamAtCluster2);
465 // Tag clusterCh1 as used
466 clusterCh1Used[iCluster1] = kTRUE;
468 // Printout for debuging
469 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
470 cout << "FollowTrackInStation: added two clusters in station(1..): " << nextStation+1 << endl;
471 if (AliLog::GetGlobalDebugLevel() >= 3) newTrack->RecursiveDump();
474 } else if (chi2WithTwoClusters < bestChi2WithTwoClusters) {
475 // keep track of the best couple of clusters
476 bestChi2WithTwoClusters = chi2WithTwoClusters;
477 bestTrackParamAtCluster1 = extrapTrackParamAtCluster1;
478 bestTrackParamAtCluster2 = extrapTrackParamAtCluster2;
485 // if no clusterCh1 found then consider to add clusterCh2 only
486 if (!foundSecondCluster) {
487 foundOneCluster = kTRUE;
489 if (AliMUONReconstructor::GetRecoParam()->TrackAllTracks()) {
490 // copy trackCandidate into a new track put at the end of fRecTracksPtr and add the new cluster
491 newTrack = new ((*fRecTracksPtr)[fRecTracksPtr->GetLast()+1]) AliMUONTrack(trackCandidate);
492 UpdateTrack(*newTrack,extrapTrackParamAtCluster2);
495 // Printout for debuging
496 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
497 cout << "FollowTrackInStation: added one cluster in chamber(1..): " << ch2+1 << endl;
498 if (AliLog::GetGlobalDebugLevel() >= 3) newTrack->RecursiveDump();
501 } else if (!foundTwoClusters && chi2WithOneCluster < bestChi2WithOneCluster) {
502 // keep track of the best single cluster except if a couple of clusters has already been found
503 bestChi2WithOneCluster = chi2WithOneCluster;
504 bestTrackParamAtCluster1 = extrapTrackParamAtCluster2;
513 // look for candidates in chamber 1 not already attached to a track
514 // if we want to keep all possible tracks or if no good couple of clusters has been found
515 if (AliMUONReconstructor::GetRecoParam()->TrackAllTracks() || !foundTwoClusters) {
517 // Printout for debuging
518 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
519 cout << "FollowTrackInStation: look for single clusters in chamber(1..): " << ch1+1 << endl;
522 // add MCS effect for next step
523 AliMUONTrackExtrap::AddMCSEffect(&extrapTrackParamAtCh,AliMUONConstants::ChamberThicknessInX0(),1.);
525 //Extrapolate trackCandidate to chamber "ch1"
526 AliMUONTrackExtrap::ExtrapToZCov(&extrapTrackParamAtCh, AliMUONConstants::DefaultChamberZ(ch1));
528 // reset cluster iterator of chamber 1
532 // look for second candidates in chamber 1
533 while ( ( clusterCh1 = static_cast<AliMUONVCluster*>(nextInCh1()) ) ) {
536 if (clusterCh1Used[iCluster1]) continue; // Skip cluster already used
538 // try to add the current cluster fast
539 if (!TryOneClusterFast(extrapTrackParamAtCh, clusterCh1)) continue;
541 // try to add the current cluster accuratly
542 chi2WithOneCluster = TryOneCluster(extrapTrackParamAtCh, clusterCh1, extrapTrackParamAtCluster1);
544 // if good chi2 then consider to add clusterCh1
545 // We do not try to attach a cluster in the other chamber too since it has already been done above
546 if (chi2WithOneCluster < maxChi2WithOneCluster) {
547 foundOneCluster = kTRUE;
549 // Printout for debuging
550 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
551 cout << "FollowTrackInStation: found one cluster in chamber(1..): " << ch1+1
552 << " (Chi2 = " << chi2WithOneCluster << ")" << endl;
555 if (AliMUONReconstructor::GetRecoParam()->TrackAllTracks()) {
556 // copy trackCandidate into a new track put at the end of fRecTracksPtr and add the new cluster
557 newTrack = new ((*fRecTracksPtr)[fRecTracksPtr->GetLast()+1]) AliMUONTrack(trackCandidate);
558 UpdateTrack(*newTrack,extrapTrackParamAtCluster1);
561 // Printout for debuging
562 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
563 cout << "FollowTrackInStation: added one cluster in chamber(1..): " << ch1+1 << endl;
564 if (AliLog::GetGlobalDebugLevel() >= 3) newTrack->RecursiveDump();
567 } else if (chi2WithOneCluster < bestChi2WithOneCluster) {
568 // keep track of the best single cluster except if a couple of clusters has already been found
569 bestChi2WithOneCluster = chi2WithOneCluster;
570 bestTrackParamAtCluster1 = extrapTrackParamAtCluster1;
579 // fill out the best track if required else clean up the fRecTracksPtr array
580 if (!AliMUONReconstructor::GetRecoParam()->TrackAllTracks()) {
581 if (foundTwoClusters) {
582 UpdateTrack(trackCandidate,bestTrackParamAtCluster1,bestTrackParamAtCluster2);
584 // Printout for debuging
585 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
586 cout << "FollowTrackInStation: added the two best clusters in station(1..): " << nextStation+1 << endl;
587 if (AliLog::GetGlobalDebugLevel() >= 3) newTrack->RecursiveDump();
590 } else if (foundOneCluster) {
591 UpdateTrack(trackCandidate,bestTrackParamAtCluster1);
593 // Printout for debuging
594 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
595 cout << "FollowTrackInStation: added the best cluster in chamber(1..): " << bestTrackParamAtCluster1.GetClusterPtr()->GetChamberId()+1 << endl;
596 if (AliLog::GetGlobalDebugLevel() >= 3) newTrack->RecursiveDump();
600 delete [] clusterCh1Used;
604 } else if (foundOneCluster || foundTwoClusters) {
606 // remove obsolete track
607 fRecTracksPtr->Remove(&trackCandidate);
611 delete [] clusterCh1Used;
615 delete [] clusterCh1Used;
620 //__________________________________________________________________________
621 Double_t AliMUONTrackReconstructor::TryTwoClusters(const AliMUONTrackParam &trackParamAtCluster1, AliMUONVCluster* cluster2,
622 AliMUONTrackParam &trackParamAtCluster2)
624 /// Test the compatibility between the track and the 2 clusters together (using trackParam's covariance matrix):
625 /// return the corresponding Chi2 accounting for covariances between the 2 clusters
626 /// return trackParamAtCluster1 & 2
628 // extrapolate track parameters at the z position of the second cluster (no need to extrapolate the covariances)
629 trackParamAtCluster2.SetParameters(trackParamAtCluster1.GetParameters());
630 trackParamAtCluster2.SetZ(trackParamAtCluster1.GetZ());
631 AliMUONTrackExtrap::ExtrapToZ(&trackParamAtCluster2, cluster2->GetZ());
633 // set pointer to cluster2 into trackParamAtCluster2
634 trackParamAtCluster2.SetClusterPtr(cluster2);
636 // Set differences between track and the 2 clusters in the bending and non bending directions
637 AliMUONVCluster* cluster1 = trackParamAtCluster1.GetClusterPtr();
639 dPos(0,0) = cluster1->GetX() - trackParamAtCluster1.GetNonBendingCoor();
640 dPos(1,0) = cluster1->GetY() - trackParamAtCluster1.GetBendingCoor();
641 dPos(2,0) = cluster2->GetX() - trackParamAtCluster2.GetNonBendingCoor();
642 dPos(3,0) = cluster2->GetY() - trackParamAtCluster2.GetBendingCoor();
644 // Calculate the error matrix from the track parameter covariances at first cluster
647 if (trackParamAtCluster1.CovariancesExist()) {
648 // Save track parameters at first cluster
649 TMatrixD paramAtCluster1Save(trackParamAtCluster1.GetParameters());
651 // Save track coordinates at second cluster
652 Double_t nonBendingCoor2 = trackParamAtCluster2.GetNonBendingCoor();
653 Double_t bendingCoor2 = trackParamAtCluster2.GetBendingCoor();
655 // copy track parameters at first cluster for jacobian calculation
656 AliMUONTrackParam trackParam(trackParamAtCluster1);
658 // add MCS effect to the covariance matrix at first cluster
659 AliMUONTrackExtrap::AddMCSEffect(&trackParam,AliMUONConstants::ChamberThicknessInX0(),1.);
661 // Get the pointer to the parameter covariance matrix at first cluster
662 const TMatrixD& kParamCov = trackParam.GetCovariances();
664 // Calculate the jacobian related to the transformation between track parameters
665 // at first cluster and track coordinates at the 2 cluster z-positions
668 // first derivative at the first cluster:
669 jacob(0,0) = 1.; // dx1/dx
670 jacob(1,2) = 1.; // dy1/dy
671 // first derivative at the second cluster:
672 TMatrixD dParam(5,1);
673 for (Int_t i=0; i<5; i++) {
674 // Skip jacobian calculation for parameters with no associated error
675 if (kParamCov(i,i) == 0.) continue;
676 // Small variation of parameter i only
677 for (Int_t j=0; j<5; j++) {
679 dParam(j,0) = TMath::Sqrt(kParamCov(i,i));
680 if (j == 4) dParam(j,0) *= TMath::Sign(1.,-paramAtCluster1Save(4,0)); // variation always in the same direction
681 } else dParam(j,0) = 0.;
684 // Set new track parameters at first cluster
685 trackParam.SetParameters(paramAtCluster1Save);
686 trackParam.AddParameters(dParam);
687 trackParam.SetZ(cluster1->GetZ());
689 // Extrapolate new track parameters to the z position of the second cluster
690 AliMUONTrackExtrap::ExtrapToZ(&trackParam,cluster2->GetZ());
692 // Calculate the jacobian
693 jacob(2,i) = (trackParam.GetNonBendingCoor() - nonBendingCoor2) / dParam(i,0); // dx2/dParami
694 jacob(3,i) = (trackParam.GetBendingCoor() - bendingCoor2 ) / dParam(i,0); // dy2/dParami
697 // Calculate the error matrix
698 TMatrixD tmp(jacob,TMatrixD::kMult,kParamCov);
699 error = TMatrixD(tmp,TMatrixD::kMultTranspose,jacob);
702 // Add cluster resolution to the error matrix
703 error(0,0) += cluster1->GetErrX2();
704 error(1,1) += cluster1->GetErrY2();
705 error(2,2) += cluster2->GetErrX2();
706 error(3,3) += cluster2->GetErrY2();
708 // invert the error matrix for Chi2 calculation
709 if (error.Determinant() != 0) {
712 AliWarning(" Determinant error=0");
716 // Compute the Chi2 value
717 TMatrixD tmp2(dPos,TMatrixD::kTransposeMult,error);
718 TMatrixD result(tmp2,TMatrixD::kMult,dPos);
724 //__________________________________________________________________________
725 void AliMUONTrackReconstructor::UpdateTrack(AliMUONTrack &track, AliMUONTrackParam &trackParamAtCluster)
727 /// Add 1 cluster to the track candidate
728 /// Update chi2 of the track
730 // Compute local chi2
731 AliMUONVCluster* cluster = trackParamAtCluster.GetClusterPtr();
732 Double_t deltaX = trackParamAtCluster.GetNonBendingCoor() - cluster->GetX();
733 Double_t deltaY = trackParamAtCluster.GetBendingCoor() - cluster->GetY();
734 Double_t localChi2 = deltaX*deltaX / cluster->GetErrX2() +
735 deltaY*deltaY / cluster->GetErrY2();
737 // Flag cluster as being not removable
738 trackParamAtCluster.SetRemovable(kFALSE);
739 trackParamAtCluster.SetLocalChi2(0.); // --> Local chi2 not used
741 // Update the chi2 of the new track
742 track.SetGlobalChi2(track.GetGlobalChi2() + localChi2);
744 // Update TrackParamAtCluster
745 track.AddTrackParamAtCluster(trackParamAtCluster,*cluster);
746 track.GetTrackParamAtCluster()->Sort();
750 //__________________________________________________________________________
751 void AliMUONTrackReconstructor::UpdateTrack(AliMUONTrack &track, AliMUONTrackParam &trackParamAtCluster1, AliMUONTrackParam &trackParamAtCluster2)
753 /// Add 2 clusters to the track candidate
754 /// Update track and local chi2
756 // Update local chi2 at first cluster
757 AliMUONVCluster* cluster1 = trackParamAtCluster1.GetClusterPtr();
758 Double_t deltaX = trackParamAtCluster1.GetNonBendingCoor() - cluster1->GetX();
759 Double_t deltaY = trackParamAtCluster1.GetBendingCoor() - cluster1->GetY();
760 Double_t localChi2AtCluster1 = deltaX*deltaX / cluster1->GetErrX2() +
761 deltaY*deltaY / cluster1->GetErrY2();
762 trackParamAtCluster1.SetLocalChi2(localChi2AtCluster1);
764 // Flag first cluster as being removable
765 trackParamAtCluster1.SetRemovable(kTRUE);
767 // Update local chi2 at second cluster
768 AliMUONVCluster* cluster2 = trackParamAtCluster2.GetClusterPtr();
769 deltaX = trackParamAtCluster2.GetNonBendingCoor() - cluster2->GetX();
770 deltaY = trackParamAtCluster2.GetBendingCoor() - cluster2->GetY();
771 Double_t localChi2AtCluster2 = deltaX*deltaX / cluster2->GetErrX2() +
772 deltaY*deltaY / cluster2->GetErrY2();
773 trackParamAtCluster2.SetLocalChi2(localChi2AtCluster2);
775 // Flag first cluster as being removable
776 trackParamAtCluster2.SetRemovable(kTRUE);
778 // Update the chi2 of the new track
779 track.SetGlobalChi2(track.GetGlobalChi2() + localChi2AtCluster1 + localChi2AtCluster2);
781 // Update TrackParamAtCluster
782 track.AddTrackParamAtCluster(trackParamAtCluster1,*cluster1);
783 track.AddTrackParamAtCluster(trackParamAtCluster2,*cluster2);
784 track.GetTrackParamAtCluster()->Sort();
788 //__________________________________________________________________________
789 Bool_t AliMUONTrackReconstructor::RecoverTrack(AliMUONTrack &trackCandidate, AliMUONVClusterStore& clusterStore, Int_t nextStation)
791 /// Try to recover the track candidate in the next station
792 /// by removing the worst of the two clusters attached in the current station
793 /// Return kTRUE if recovering succeeds
794 AliDebug(1,"Enter RecoverTrack");
796 // Do not try to recover track until we have attached cluster(s) on station(1..) 3
797 if (nextStation > 1) return kFALSE;
799 Int_t worstClusterNumber = -1;
800 Double_t localChi2, worstLocalChi2 = 0.;
802 // Look for the cluster to remove
803 for (Int_t clusterNumber = 0; clusterNumber < 2; clusterNumber++) {
804 AliMUONTrackParam *trackParamAtCluster = (AliMUONTrackParam*)trackCandidate.GetTrackParamAtCluster()->UncheckedAt(clusterNumber);
806 // check if current cluster is removable
807 if (!trackParamAtCluster->IsRemovable()) return kFALSE;
809 // Pick up cluster with the worst chi2
810 localChi2 = trackParamAtCluster->GetLocalChi2();
811 if (localChi2 > worstLocalChi2) {
812 worstLocalChi2 = localChi2;
813 worstClusterNumber = clusterNumber;
817 // Reset best cluster as being NOT removable
818 ((AliMUONTrackParam*)trackCandidate.GetTrackParamAtCluster()->UncheckedAt((worstClusterNumber+1)%2))->SetRemovable(kFALSE);
820 // Remove the worst cluster
821 trackCandidate.RemoveTrackParamAtCluster((AliMUONTrackParam*)trackCandidate.GetTrackParamAtCluster()->UncheckedAt(worstClusterNumber));
824 // Do not take into account the multiple scattering to speed up the fit
825 // Calculate the track parameter covariance matrix
826 Fit(trackCandidate, kFALSE, kFALSE, kTRUE);
828 // Look for new cluster(s) in next station
829 return FollowTrackInStation(trackCandidate,clusterStore,nextStation);
833 //__________________________________________________________________________
834 void AliMUONTrackReconstructor::SetVertexErrXY2ForFit(AliMUONTrack &trackCandidate)
836 /// Compute the vertex resolution square from natural vertex dispersion and
837 /// multiple scattering effets according to trackCandidate path in absorber
838 /// It is necessary to account for multiple scattering effects here instead of during the fit of
839 /// the "trackCandidate" to do not influence the result by changing track resolution at vertex
840 AliDebug(1,"Enter SetVertexForFit");
842 Double_t nonBendingReso2 = AliMUONReconstructor::GetRecoParam()->GetNonBendingVertexDispersion() *
843 AliMUONReconstructor::GetRecoParam()->GetNonBendingVertexDispersion();
844 Double_t bendingReso2 = AliMUONReconstructor::GetRecoParam()->GetBendingVertexDispersion() *
845 AliMUONReconstructor::GetRecoParam()->GetBendingVertexDispersion();
847 // add multiple scattering effets
848 AliMUONTrackParam paramAtVertex(*((AliMUONTrackParam*)(trackCandidate.GetTrackParamAtCluster()->First())));
849 paramAtVertex.DeleteCovariances(); // to be sure to account only for multiple scattering
850 AliMUONTrackExtrap::ExtrapToVertexUncorrected(¶mAtVertex,0.);
851 const TMatrixD& kParamCov = paramAtVertex.GetCovariances();
852 nonBendingReso2 += kParamCov(0,0);
853 bendingReso2 += kParamCov(2,2);
855 // Set the vertex resolution square
856 trackCandidate.SetVertexErrXY2(nonBendingReso2,bendingReso2);
859 //__________________________________________________________________________
860 void AliMUONTrackReconstructor::Fit(AliMUONTrack &track, Bool_t includeMCS, Bool_t fitWithVertex, Bool_t calcCov)
863 /// w/wo multiple Coulomb scattering according to "includeMCS".
864 /// w/wo constraining the vertex according to "fitWithVertex".
865 /// calculating or not the covariance matrix according to "calcCov".
867 Double_t benC, errorParam, invBenP, nonBenC, x, y;
868 AliMUONTrackParam *trackParam;
869 Double_t arg[1], fedm, errdef, globalChi2;
871 Int_t status, covStatus;
873 // Instantiate gMinuit if not already done
874 if (!gMinuit) gMinuit = new TMinuit(6);
875 // Clear MINUIT parameters
877 // Give the fitted track to MINUIT
878 gMinuit->SetObjectFit(&track);
879 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 2) || (AliLog::GetGlobalDebugLevel() >= 2)) {
880 // Define print level
882 gMinuit->mnexcm("SET PRI", arg, 1, status);
883 // Print covariance matrix
884 gMinuit->mnexcm("SHO COV", arg, 0, status);
887 gMinuit->mnexcm("SET PRI", arg, 1, status);
890 gMinuit->mnexcm("SET NOW", arg, 0, status);
893 //gMinuit->mnexcm("SET STR", arg, 1, status);
895 // set flag w/wo multiple scattering according to "includeMCS"
896 track.FitWithMCS(includeMCS);
898 // compute cluster weights only once
899 if (!track.ComputeClusterWeights()) {
900 AliWarning("cannot take into account the multiple scattering effects");
901 track.FitWithMCS(kFALSE);
905 track.FitWithVertex(fitWithVertex);
906 if (fitWithVertex) SetVertexErrXY2ForFit(track);
908 // Set fitting function
909 gMinuit->SetFCN(TrackChi2);
911 // Set fitted parameters (!! The order is very important for the covariance matrix !!)
912 trackParam = (AliMUONTrackParam*) (track.GetTrackParamAtCluster()->First());
913 // could be tried with no limits for the search (min=max=0) ????
914 // mandatory limits in non Bending to avoid NaN values of parameters
915 gMinuit->mnparm(0, "X", trackParam->GetNonBendingCoor(), 0.03, -500.0, 500.0, status);
916 gMinuit->mnparm(1, "NonBenS", trackParam->GetNonBendingSlope(), 0.001, -0.5, 0.5, status);
917 // mandatory limits in Bending to avoid NaN values of parameters
918 gMinuit->mnparm(2, "Y", trackParam->GetBendingCoor(), 0.10, -500.0, 500.0, status);
919 gMinuit->mnparm(3, "BenS", trackParam->GetBendingSlope(), 0.001, -0.5, 0.5, status);
920 gMinuit->mnparm(4, "InvBenP", trackParam->GetInverseBendingMomentum(), 0.003, -0.4, 0.4, status);
923 gMinuit->mnexcm("MIGRAD", arg, 0, status);
925 // Calculate the covariance matrix more accurately if required
926 if (calcCov) gMinuit->mnexcm("HESSE", arg, 0, status);
928 // get results into "invBenP", "benC", "nonBenC" ("x", "y")
929 gMinuit->GetParameter(0, x, errorParam);
930 trackParam->SetNonBendingCoor(x);
931 gMinuit->GetParameter(1, nonBenC, errorParam);
932 trackParam->SetNonBendingSlope(nonBenC);
933 gMinuit->GetParameter(2, y, errorParam);
934 trackParam->SetBendingCoor(y);
935 gMinuit->GetParameter(3, benC, errorParam);
936 trackParam->SetBendingSlope(benC);
937 gMinuit->GetParameter(4, invBenP, errorParam);
938 trackParam->SetInverseBendingMomentum(invBenP);
940 // global result of the fit
941 gMinuit->mnstat(globalChi2, fedm, errdef, npari, nparx, covStatus);
942 track.SetGlobalChi2(globalChi2);
944 // Get the covariance matrix if required
946 // Covariance matrix according to HESSE status
947 // If problem then keep only the diagonal terms (variances)
948 Double_t matrix[5][5];
949 gMinuit->mnemat(&matrix[0][0],5);
950 if (covStatus == 3) trackParam->SetCovariances(matrix);
951 else trackParam->SetVariances(matrix);
952 } else trackParam->DeleteCovariances();
956 //__________________________________________________________________________
957 void TrackChi2(Int_t & /*nParam*/, Double_t * /*gradient*/, Double_t &chi2, Double_t *param, Int_t /*flag*/)
959 /// Return the "Chi2" to be minimized with Minuit for track fitting.
960 /// Assumes that the trackParamAtCluster are sorted according to increasing Z.
961 /// Track parameters at each cluster are updated accordingly.
962 /// Vertex is used according to the flag "trackBeingFitted->GetFitWithVertex()".
963 /// Multiple Coulomb scattering is taken into account according to the flag "trackBeingFitted->GetFitWithMCS()".
965 AliMUONTrack *trackBeingFitted = (AliMUONTrack*) gMinuit->GetObjectFit();
966 AliMUONTrackParam* trackParamAtCluster = (AliMUONTrackParam*) trackBeingFitted->GetTrackParamAtCluster()->First();
968 chi2 = 0.; // initialize chi2
970 // update track parameters
971 trackParamAtCluster->SetNonBendingCoor(param[0]);
972 trackParamAtCluster->SetNonBendingSlope(param[1]);
973 trackParamAtCluster->SetBendingCoor(param[2]);
974 trackParamAtCluster->SetBendingSlope(param[3]);
975 trackParamAtCluster->SetInverseBendingMomentum(param[4]);
976 trackBeingFitted->UpdateTrackParamAtCluster();
978 // Take the vertex into account in the fit if required
979 if (trackBeingFitted->FitWithVertex()) {
980 Double_t nonBendingReso2,bendingReso2;
981 trackBeingFitted->GetVertexErrXY2(nonBendingReso2,bendingReso2);
982 if (nonBendingReso2 == 0. || bendingReso2 == 0.) chi2 += 1.e10;
984 AliMUONTrackParam paramAtVertex(*trackParamAtCluster);
985 AliMUONTrackExtrap::ExtrapToZ(¶mAtVertex, 0.); // vextex position = (0,0,0)
986 dX = paramAtVertex.GetNonBendingCoor();
987 dY = paramAtVertex.GetBendingCoor();
988 chi2 += dX * dX / nonBendingReso2 + dY * dY / bendingReso2;
992 // compute chi2 w/wo multiple scattering
993 chi2 += trackBeingFitted->ComputeGlobalChi2(trackBeingFitted->FitWithMCS());
997 //__________________________________________________________________________
998 void AliMUONTrackReconstructor::ComplementTracks(const AliMUONVClusterStore& clusterStore)
1000 /// Complete tracks by adding missing clusters (if there is an overlap between
1001 /// two detection elements, the track may have two clusters in the same chamber)
1002 /// Re-fit track parameters and covariances
1003 AliDebug(1,"Enter ComplementTracks");
1005 Int_t chamberId, detElemId;
1006 Double_t chi2OfCluster, bestChi2OfCluster;
1007 Double_t sigmaCut2 = AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking() *
1008 AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking();
1009 Bool_t foundOneCluster, trackModified;
1010 AliMUONVCluster* cluster;
1011 AliMUONTrackParam *trackParam, *nextTrackParam, copyOfTrackParam, trackParamAtCluster, bestTrackParamAtCluster;
1013 // Remove double track to complete only "good" tracks
1014 RemoveDoubleTracks();
1016 AliMUONTrack *track = (AliMUONTrack*) fRecTracksPtr->First();
1018 trackModified = kFALSE;
1020 trackParam = (AliMUONTrackParam*)track->GetTrackParamAtCluster()->First();
1021 while (trackParam) {
1022 foundOneCluster = kFALSE;
1023 bestChi2OfCluster = 2. * sigmaCut2; // 2 because 2 quantities in chi2
1024 chamberId = trackParam->GetClusterPtr()->GetChamberId();
1025 detElemId = trackParam->GetClusterPtr()->GetDetElemId();
1027 // prepare nextTrackParam before adding new cluster because of the sorting
1028 nextTrackParam = (AliMUONTrackParam*)track->GetTrackParamAtCluster()->After(trackParam);
1030 // recover track parameters from local fit and put them into a copy of trackParam
1031 copyOfTrackParam.SetZ(trackParam->GetZ());
1032 copyOfTrackParam.SetParameters(trackParam->GetSmoothParameters());
1033 copyOfTrackParam.SetCovariances(trackParam->GetSmoothCovariances());
1035 // Create iterators to loop over clusters in current chamber
1036 TIter nextInCh(clusterStore.CreateChamberIterator(chamberId,chamberId));
1038 // look for one second candidate in the same chamber
1039 while ( ( cluster = static_cast<AliMUONVCluster*>(nextInCh()) ) ) {
1041 // look for a cluster in another detection element
1042 if (cluster->GetDetElemId() == detElemId) continue;
1044 // try to add the current cluster fast
1045 if (!TryOneClusterFast(copyOfTrackParam, cluster)) continue;
1047 // try to add the current cluster accurately
1048 chi2OfCluster = TryOneCluster(copyOfTrackParam, cluster, trackParamAtCluster);
1050 // if better chi2 then prepare to add this cluster to the track
1051 if (chi2OfCluster < bestChi2OfCluster) {
1052 bestChi2OfCluster = chi2OfCluster;
1053 bestTrackParamAtCluster = trackParamAtCluster;
1054 foundOneCluster = kTRUE;
1059 // add new cluster if any
1060 if (foundOneCluster) {
1061 UpdateTrack(*track,bestTrackParamAtCluster);
1062 bestTrackParamAtCluster.SetAloneInChamber(kFALSE);
1063 trackParam->SetAloneInChamber(kFALSE);
1064 trackModified = kTRUE;
1067 trackParam = nextTrackParam;
1070 // re-fit track parameters if needed
1071 if (trackModified) Fit(*track, kTRUE, kFALSE, kTRUE);
1073 track = (AliMUONTrack*) fRecTracksPtr->After(track);
1078 //__________________________________________________________________________
1079 void AliMUONTrackReconstructor::ImproveTracks()
1081 /// Improve tracks by removing clusters with local chi2 highter than the defined cut
1082 /// Recompute track parameters and covariances at the remaining clusters
1083 AliDebug(1,"Enter ImproveTracks");
1085 Double_t localChi2, worstLocalChi2;
1086 Int_t worstChamber, previousChamber;
1087 AliMUONTrack *track, *nextTrack;
1088 AliMUONTrackParam *trackParamAtCluster, *worstTrackParamAtCluster, *previousTrackParam, *nextTrackParam;
1089 Double_t sigmaCut2 = AliMUONReconstructor::GetRecoParam()->GetSigmaCutForImprovement() *
1090 AliMUONReconstructor::GetRecoParam()->GetSigmaCutForImprovement();
1092 // Remove double track to improve only "good" tracks
1093 RemoveDoubleTracks();
1095 track = (AliMUONTrack*) fRecTracksPtr->First();
1098 // prepare next track in case the actual track is suppressed
1099 nextTrack = (AliMUONTrack*) fRecTracksPtr->After(track);
1101 while (!track->IsImproved()) {
1103 // Update track parameters and covariances
1104 track->UpdateCovTrackParamAtCluster();
1106 // Compute local chi2 of each clusters
1107 track->ComputeLocalChi2(kTRUE);
1109 // Look for the cluster to remove
1110 worstTrackParamAtCluster = NULL;
1111 worstLocalChi2 = 0.;
1112 trackParamAtCluster = (AliMUONTrackParam*) track->GetTrackParamAtCluster()->First();
1113 while (trackParamAtCluster) {
1115 // Pick up cluster with the worst chi2
1116 localChi2 = trackParamAtCluster->GetLocalChi2();
1117 if (localChi2 > worstLocalChi2) {
1118 worstLocalChi2 = localChi2;
1119 worstTrackParamAtCluster = trackParamAtCluster;
1122 trackParamAtCluster = (AliMUONTrackParam*) track->GetTrackParamAtCluster()->After(trackParamAtCluster);
1125 // Check if bad cluster found
1126 if (!worstTrackParamAtCluster) {
1127 track->SetImproved(kTRUE);
1131 // Check whether the worst chi2 is under requirement or not
1132 if (worstLocalChi2 < 2. * sigmaCut2) { // 2 because 2 quantities in chi2
1133 track->SetImproved(kTRUE);
1137 // if the worst cluster is not removable then remove the entire track
1138 if (!worstTrackParamAtCluster->IsRemovable() && worstTrackParamAtCluster->IsAloneInChamber()) {
1139 fRecTracksPtr->Remove(track);
1144 // Reset the second cluster in the same station as being not removable
1145 // or reset the second cluster in the same chamber as being alone
1146 worstChamber = worstTrackParamAtCluster->GetClusterPtr()->GetChamberId();
1147 previousTrackParam = (AliMUONTrackParam*) track->GetTrackParamAtCluster()->Before(worstTrackParamAtCluster);
1148 nextTrackParam = (AliMUONTrackParam*) track->GetTrackParamAtCluster()->After(worstTrackParamAtCluster);
1149 if (worstTrackParamAtCluster->IsAloneInChamber()) { // Worst cluster removable and alone in chamber
1151 if (worstChamber%2 == 0) { // Modify flags in next chamber
1153 nextTrackParam->SetRemovable(kFALSE);
1154 if (!nextTrackParam->IsAloneInChamber()) // Make sure both clusters in second chamber are not removable anymore
1155 ((AliMUONTrackParam*) track->GetTrackParamAtCluster()->After(nextTrackParam))->SetRemovable(kFALSE);
1157 } else { // Modify flags in previous chamber
1159 previousTrackParam->SetRemovable(kFALSE);
1160 if (!previousTrackParam->IsAloneInChamber()) // Make sure both clusters in second chamber are not removable anymore
1161 ((AliMUONTrackParam*) track->GetTrackParamAtCluster()->Before(previousTrackParam))->SetRemovable(kFALSE);
1165 } else { // Worst cluster not alone in its chamber
1167 if (previousTrackParam) previousChamber = previousTrackParam->GetClusterPtr()->GetChamberId();
1168 else previousChamber = -1;
1170 if (previousChamber == worstChamber) { // the second cluster on the same chamber is the previous one
1172 previousTrackParam->SetAloneInChamber(kTRUE);
1173 // transfert the removability to the second cluster
1174 if (worstTrackParamAtCluster->IsRemovable()) previousTrackParam->SetRemovable(kTRUE);
1176 } else { // the second cluster on the same chamber is the next one
1178 nextTrackParam->SetAloneInChamber(kTRUE);
1179 // transfert the removability to the second cluster
1180 if (worstTrackParamAtCluster->IsRemovable()) nextTrackParam->SetRemovable(kTRUE);
1186 // Remove the worst cluster
1187 track->RemoveTrackParamAtCluster(worstTrackParamAtCluster);
1189 // Re-fit the track:
1190 // Take into account the multiple scattering
1191 // Calculate the track parameter covariance matrix
1192 Fit(*track, kTRUE, kFALSE, kTRUE);
1194 // Printout for debuging
1195 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
1196 cout << "ImproveTracks: track " << fRecTracksPtr->IndexOf(track)+1 << " improved " << endl;
1204 // compress the array in case of some tracks have been removed
1205 fRecTracksPtr->Compress();
1209 //__________________________________________________________________________
1210 void AliMUONTrackReconstructor::Finalize()
1212 /// Recompute track parameters and covariances at each attached cluster from those at the first one
1214 AliMUONTrack *track;
1216 track = (AliMUONTrack*) fRecTracksPtr->First();
1219 // update track parameters if not already done
1220 if (!track->IsImproved()) track->UpdateCovTrackParamAtCluster();
1222 track = (AliMUONTrack*) fRecTracksPtr->After(track);