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 extrapTrackParamAtCh;
358 AliMUONTrackParam extrapTrackParamAtCluster1;
359 AliMUONTrackParam extrapTrackParamAtCluster2;
360 AliMUONTrackParam bestTrackParamAtCluster1;
361 AliMUONTrackParam bestTrackParamAtCluster2;
363 Int_t nClusters = clusterStore.GetSize();
364 Bool_t *clusterCh1Used = new Bool_t[nClusters];
365 for (Int_t i = 0; i < nClusters; i++) clusterCh1Used[i] = kFALSE;
368 // Get track parameters according to the propagation direction
369 if (nextStation==4) extrapTrackParamAtCh = *(AliMUONTrackParam*)trackCandidate.GetTrackParamAtCluster()->Last();
370 else extrapTrackParamAtCh = *(AliMUONTrackParam*)trackCandidate.GetTrackParamAtCluster()->First();
373 AliMUONTrackExtrap::AddMCSEffect(&extrapTrackParamAtCh,AliMUONConstants::ChamberThicknessInX0(),1.);
375 // Add MCS in the missing chamber if any (only 1 chamber can be missing according to tracking criteria)
376 if (ch1 < ch2 && extrapTrackParamAtCh.GetClusterPtr()->GetChamberId() > ch2 + 1) {
377 // extrapolation to the missing chamber
378 AliMUONTrackExtrap::ExtrapToZCov(&extrapTrackParamAtCh, AliMUONConstants::DefaultChamberZ(ch2 + 1));
380 AliMUONTrackExtrap::AddMCSEffect(&extrapTrackParamAtCh,AliMUONConstants::ChamberThicknessInX0(),1.);
383 //Extrapolate trackCandidate to chamber "ch2"
384 AliMUONTrackExtrap::ExtrapToZCov(&extrapTrackParamAtCh, AliMUONConstants::DefaultChamberZ(ch2));
386 // Printout for debuging
387 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 2) || (AliLog::GetGlobalDebugLevel() >= 2)) {
388 cout<<endl<<"Track parameter covariances at first cluster extrapolated to z = "<<AliMUONConstants::DefaultChamberZ(ch2)<<":"<<endl;
389 extrapTrackParamAtCh.GetCovariances().Print();
392 // Printout for debuging
393 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
394 cout << "FollowTrackInStation: look for clusters in chamber(1..): " << ch2+1 << endl;
397 // Ask the clustering to reconstruct new clusters around the track position in the current station
398 // except for station 4 and 5 that are already entirely clusterized
399 if (AliMUONReconstructor::GetRecoParam()->CombineClusterTrackReco()) {
400 if (nextStation < 3) AskForNewClustersInStation(extrapTrackParamAtCh, clusterStore, nextStation);
403 // Create iterators to loop over clusters in both chambers
404 TIter nextInCh1(clusterStore.CreateChamberIterator(ch1,ch1));
405 TIter nextInCh2(clusterStore.CreateChamberIterator(ch2,ch2));
407 // look for candidates in chamber 2
408 while ( ( clusterCh2 = static_cast<AliMUONVCluster*>(nextInCh2()) ) ) {
410 // try to add the current cluster fast
411 if (!TryOneClusterFast(extrapTrackParamAtCh, clusterCh2)) continue;
413 // try to add the current cluster accuratly
414 chi2WithOneCluster = TryOneCluster(extrapTrackParamAtCh, clusterCh2, extrapTrackParamAtCluster2);
416 // if good chi2 then try to attach a cluster in the other chamber too
417 if (chi2WithOneCluster < maxChi2WithOneCluster) {
418 Bool_t foundSecondCluster = kFALSE;
420 // Printout for debuging
421 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
422 cout << "FollowTrackInStation: found one cluster in chamber(1..): " << ch2+1
423 << " (Chi2 = " << chi2WithOneCluster << ")" << endl;
424 cout << " look for second clusters in chamber(1..): " << ch1+1 << " ..." << endl;
427 // add MCS effect for next step
428 AliMUONTrackExtrap::AddMCSEffect(&extrapTrackParamAtCluster2,AliMUONConstants::ChamberThicknessInX0(),1.);
430 // copy new track parameters for next step
431 extrapTrackParam = extrapTrackParamAtCluster2;
433 //Extrapolate track parameters to chamber "ch1"
434 AliMUONTrackExtrap::ExtrapToZ(&extrapTrackParam, AliMUONConstants::DefaultChamberZ(ch1));
436 // reset cluster iterator of chamber 1
440 // look for second candidates in chamber 1
441 while ( ( clusterCh1 = static_cast<AliMUONVCluster*>(nextInCh1()) ) ) {
444 // try to add the current cluster fast
445 if (!TryOneClusterFast(extrapTrackParam, clusterCh1)) continue;
447 // try to add the current cluster accuratly
448 chi2WithTwoClusters = TryTwoClusters(extrapTrackParamAtCluster2, clusterCh1, extrapTrackParamAtCluster1);
450 // if good chi2 then create a new track by adding the 2 clusters to the "trackCandidate"
451 if (chi2WithTwoClusters < maxChi2WithTwoClusters) {
452 foundSecondCluster = kTRUE;
453 foundTwoClusters = kTRUE;
455 // Printout for debuging
456 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
457 cout << "FollowTrackInStation: found second cluster in chamber(1..): " << ch1+1
458 << " (Global Chi2 = " << chi2WithTwoClusters << ")" << endl;
461 if (AliMUONReconstructor::GetRecoParam()->TrackAllTracks()) {
462 // copy trackCandidate into a new track put at the end of fRecTracksPtr and add the new clusters
463 newTrack = new ((*fRecTracksPtr)[fRecTracksPtr->GetLast()+1]) AliMUONTrack(trackCandidate);
464 UpdateTrack(*newTrack,extrapTrackParamAtCluster1,extrapTrackParamAtCluster2);
467 // Tag clusterCh1 as used
468 clusterCh1Used[iCluster1] = kTRUE;
470 // Printout for debuging
471 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
472 cout << "FollowTrackInStation: added two clusters in station(1..): " << nextStation+1 << endl;
473 if (AliLog::GetGlobalDebugLevel() >= 3) newTrack->RecursiveDump();
476 } else if (chi2WithTwoClusters < bestChi2WithTwoClusters) {
477 // keep track of the best couple of clusters
478 bestChi2WithTwoClusters = chi2WithTwoClusters;
479 bestTrackParamAtCluster1 = extrapTrackParamAtCluster1;
480 bestTrackParamAtCluster2 = extrapTrackParamAtCluster2;
487 // if no clusterCh1 found then consider to add clusterCh2 only
488 if (!foundSecondCluster) {
489 foundOneCluster = kTRUE;
491 if (AliMUONReconstructor::GetRecoParam()->TrackAllTracks()) {
492 // copy trackCandidate into a new track put at the end of fRecTracksPtr and add the new cluster
493 newTrack = new ((*fRecTracksPtr)[fRecTracksPtr->GetLast()+1]) AliMUONTrack(trackCandidate);
494 UpdateTrack(*newTrack,extrapTrackParamAtCluster2);
497 // Printout for debuging
498 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
499 cout << "FollowTrackInStation: added one cluster in chamber(1..): " << ch2+1 << endl;
500 if (AliLog::GetGlobalDebugLevel() >= 3) newTrack->RecursiveDump();
503 } else if (!foundTwoClusters && chi2WithOneCluster < bestChi2WithOneCluster) {
504 // keep track of the best single cluster except if a couple of clusters has already been found
505 bestChi2WithOneCluster = chi2WithOneCluster;
506 bestTrackParamAtCluster1 = extrapTrackParamAtCluster2;
515 // look for candidates in chamber 1 not already attached to a track
516 // if we want to keep all possible tracks or if no good couple of clusters has been found
517 if (AliMUONReconstructor::GetRecoParam()->TrackAllTracks() || !foundTwoClusters) {
519 // Printout for debuging
520 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
521 cout << "FollowTrackInStation: look for single clusters in chamber(1..): " << ch1+1 << endl;
524 // add MCS effect for next step
525 AliMUONTrackExtrap::AddMCSEffect(&extrapTrackParamAtCh,AliMUONConstants::ChamberThicknessInX0(),1.);
527 //Extrapolate trackCandidate to chamber "ch1"
528 AliMUONTrackExtrap::ExtrapToZCov(&extrapTrackParamAtCh, AliMUONConstants::DefaultChamberZ(ch1));
530 // reset cluster iterator of chamber 1
534 // look for second candidates in chamber 1
535 while ( ( clusterCh1 = static_cast<AliMUONVCluster*>(nextInCh1()) ) ) {
538 if (clusterCh1Used[iCluster1]) continue; // Skip cluster already used
540 // try to add the current cluster fast
541 if (!TryOneClusterFast(extrapTrackParamAtCh, clusterCh1)) continue;
543 // try to add the current cluster accuratly
544 chi2WithOneCluster = TryOneCluster(extrapTrackParamAtCh, clusterCh1, extrapTrackParamAtCluster1);
546 // if good chi2 then consider to add clusterCh1
547 // We do not try to attach a cluster in the other chamber too since it has already been done above
548 if (chi2WithOneCluster < maxChi2WithOneCluster) {
549 foundOneCluster = kTRUE;
551 // Printout for debuging
552 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
553 cout << "FollowTrackInStation: found one cluster in chamber(1..): " << ch1+1
554 << " (Chi2 = " << chi2WithOneCluster << ")" << endl;
557 if (AliMUONReconstructor::GetRecoParam()->TrackAllTracks()) {
558 // copy trackCandidate into a new track put at the end of fRecTracksPtr and add the new cluster
559 newTrack = new ((*fRecTracksPtr)[fRecTracksPtr->GetLast()+1]) AliMUONTrack(trackCandidate);
560 UpdateTrack(*newTrack,extrapTrackParamAtCluster1);
563 // Printout for debuging
564 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
565 cout << "FollowTrackInStation: added one cluster in chamber(1..): " << ch1+1 << endl;
566 if (AliLog::GetGlobalDebugLevel() >= 3) newTrack->RecursiveDump();
569 } else if (chi2WithOneCluster < bestChi2WithOneCluster) {
570 // keep track of the best single cluster except if a couple of clusters has already been found
571 bestChi2WithOneCluster = chi2WithOneCluster;
572 bestTrackParamAtCluster1 = extrapTrackParamAtCluster1;
581 // fill out the best track if required else clean up the fRecTracksPtr array
582 if (!AliMUONReconstructor::GetRecoParam()->TrackAllTracks()) {
583 if (foundTwoClusters) {
584 UpdateTrack(trackCandidate,bestTrackParamAtCluster1,bestTrackParamAtCluster2);
586 // Printout for debuging
587 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
588 cout << "FollowTrackInStation: added the two best clusters in station(1..): " << nextStation+1 << endl;
589 if (AliLog::GetGlobalDebugLevel() >= 3) newTrack->RecursiveDump();
592 } else if (foundOneCluster) {
593 UpdateTrack(trackCandidate,bestTrackParamAtCluster1);
595 // Printout for debuging
596 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
597 cout << "FollowTrackInStation: added the best cluster in chamber(1..): " << bestTrackParamAtCluster1.GetClusterPtr()->GetChamberId()+1 << endl;
598 if (AliLog::GetGlobalDebugLevel() >= 3) newTrack->RecursiveDump();
602 delete [] clusterCh1Used;
606 } else if (foundOneCluster || foundTwoClusters) {
608 // remove obsolete track
609 fRecTracksPtr->Remove(&trackCandidate);
613 delete [] clusterCh1Used;
617 delete [] clusterCh1Used;
622 //__________________________________________________________________________
623 Double_t AliMUONTrackReconstructor::TryTwoClusters(const AliMUONTrackParam &trackParamAtCluster1, AliMUONVCluster* cluster2,
624 AliMUONTrackParam &trackParamAtCluster2)
626 /// Test the compatibility between the track and the 2 clusters together (using trackParam's covariance matrix):
627 /// return the corresponding Chi2 accounting for covariances between the 2 clusters
628 /// return trackParamAtCluster1 & 2
630 // extrapolate track parameters at the z position of the second cluster (no need to extrapolate the covariances)
631 trackParamAtCluster2.SetParameters(trackParamAtCluster1.GetParameters());
632 trackParamAtCluster2.SetZ(trackParamAtCluster1.GetZ());
633 AliMUONTrackExtrap::ExtrapToZ(&trackParamAtCluster2, cluster2->GetZ());
635 // set pointer to cluster2 into trackParamAtCluster2
636 trackParamAtCluster2.SetClusterPtr(cluster2);
638 // Set differences between track and the 2 clusters in the bending and non bending directions
639 AliMUONVCluster* cluster1 = trackParamAtCluster1.GetClusterPtr();
641 dPos(0,0) = cluster1->GetX() - trackParamAtCluster1.GetNonBendingCoor();
642 dPos(1,0) = cluster1->GetY() - trackParamAtCluster1.GetBendingCoor();
643 dPos(2,0) = cluster2->GetX() - trackParamAtCluster2.GetNonBendingCoor();
644 dPos(3,0) = cluster2->GetY() - trackParamAtCluster2.GetBendingCoor();
646 // Calculate the error matrix from the track parameter covariances at first cluster
649 if (trackParamAtCluster1.CovariancesExist()) {
650 // Save track parameters at first cluster
651 TMatrixD paramAtCluster1Save(trackParamAtCluster1.GetParameters());
653 // Save track coordinates at second cluster
654 Double_t nonBendingCoor2 = trackParamAtCluster2.GetNonBendingCoor();
655 Double_t bendingCoor2 = trackParamAtCluster2.GetBendingCoor();
657 // copy track parameters at first cluster for jacobian calculation
658 AliMUONTrackParam trackParam(trackParamAtCluster1);
660 // add MCS effect to the covariance matrix at first cluster
661 AliMUONTrackExtrap::AddMCSEffect(&trackParam,AliMUONConstants::ChamberThicknessInX0(),1.);
663 // Get the pointer to the parameter covariance matrix at first cluster
664 const TMatrixD& kParamCov = trackParam.GetCovariances();
666 // Calculate the jacobian related to the transformation between track parameters
667 // at first cluster and track coordinates at the 2 cluster z-positions
670 // first derivative at the first cluster:
671 jacob(0,0) = 1.; // dx1/dx
672 jacob(1,2) = 1.; // dy1/dy
673 // first derivative at the second cluster:
674 TMatrixD dParam(5,1);
675 for (Int_t i=0; i<5; i++) {
676 // Skip jacobian calculation for parameters with no associated error
677 if (kParamCov(i,i) == 0.) continue;
678 // Small variation of parameter i only
679 for (Int_t j=0; j<5; j++) {
681 dParam(j,0) = TMath::Sqrt(kParamCov(i,i));
682 if (j == 4) dParam(j,0) *= TMath::Sign(1.,-paramAtCluster1Save(4,0)); // variation always in the same direction
683 } else dParam(j,0) = 0.;
686 // Set new track parameters at first cluster
687 trackParam.SetParameters(paramAtCluster1Save);
688 trackParam.AddParameters(dParam);
689 trackParam.SetZ(cluster1->GetZ());
691 // Extrapolate new track parameters to the z position of the second cluster
692 AliMUONTrackExtrap::ExtrapToZ(&trackParam,cluster2->GetZ());
694 // Calculate the jacobian
695 jacob(2,i) = (trackParam.GetNonBendingCoor() - nonBendingCoor2) / dParam(i,0); // dx2/dParami
696 jacob(3,i) = (trackParam.GetBendingCoor() - bendingCoor2 ) / dParam(i,0); // dy2/dParami
699 // Calculate the error matrix
700 TMatrixD tmp(jacob,TMatrixD::kMult,kParamCov);
701 error = TMatrixD(tmp,TMatrixD::kMultTranspose,jacob);
704 // Add cluster resolution to the error matrix
705 error(0,0) += cluster1->GetErrX2();
706 error(1,1) += cluster1->GetErrY2();
707 error(2,2) += cluster2->GetErrX2();
708 error(3,3) += cluster2->GetErrY2();
710 // invert the error matrix for Chi2 calculation
711 if (error.Determinant() != 0) {
714 AliWarning(" Determinant error=0");
718 // Compute the Chi2 value
719 TMatrixD tmp2(dPos,TMatrixD::kTransposeMult,error);
720 TMatrixD result(tmp2,TMatrixD::kMult,dPos);
726 //__________________________________________________________________________
727 void AliMUONTrackReconstructor::UpdateTrack(AliMUONTrack &track, AliMUONTrackParam &trackParamAtCluster)
729 /// Add 1 cluster to the track candidate
730 /// Update chi2 of the track
732 // Compute local chi2
733 AliMUONVCluster* cluster = trackParamAtCluster.GetClusterPtr();
734 Double_t deltaX = trackParamAtCluster.GetNonBendingCoor() - cluster->GetX();
735 Double_t deltaY = trackParamAtCluster.GetBendingCoor() - cluster->GetY();
736 Double_t localChi2 = deltaX*deltaX / cluster->GetErrX2() +
737 deltaY*deltaY / cluster->GetErrY2();
739 // Flag cluster as being not removable
740 trackParamAtCluster.SetRemovable(kFALSE);
741 trackParamAtCluster.SetLocalChi2(0.); // --> Local chi2 not used
743 // Update the chi2 of the new track
744 track.SetGlobalChi2(track.GetGlobalChi2() + localChi2);
746 // Update TrackParamAtCluster
747 track.AddTrackParamAtCluster(trackParamAtCluster,*cluster);
751 //__________________________________________________________________________
752 void AliMUONTrackReconstructor::UpdateTrack(AliMUONTrack &track, AliMUONTrackParam &trackParamAtCluster1, AliMUONTrackParam &trackParamAtCluster2)
754 /// Add 2 clusters to the track candidate
755 /// Update track and local chi2
757 // Update local chi2 at first cluster
758 AliMUONVCluster* cluster1 = trackParamAtCluster1.GetClusterPtr();
759 Double_t deltaX = trackParamAtCluster1.GetNonBendingCoor() - cluster1->GetX();
760 Double_t deltaY = trackParamAtCluster1.GetBendingCoor() - cluster1->GetY();
761 Double_t localChi2AtCluster1 = deltaX*deltaX / cluster1->GetErrX2() +
762 deltaY*deltaY / cluster1->GetErrY2();
763 trackParamAtCluster1.SetLocalChi2(localChi2AtCluster1);
765 // Flag first cluster as being removable
766 trackParamAtCluster1.SetRemovable(kTRUE);
768 // Update local chi2 at second cluster
769 AliMUONVCluster* cluster2 = trackParamAtCluster2.GetClusterPtr();
770 deltaX = trackParamAtCluster2.GetNonBendingCoor() - cluster2->GetX();
771 deltaY = trackParamAtCluster2.GetBendingCoor() - cluster2->GetY();
772 Double_t localChi2AtCluster2 = deltaX*deltaX / cluster2->GetErrX2() +
773 deltaY*deltaY / cluster2->GetErrY2();
774 trackParamAtCluster2.SetLocalChi2(localChi2AtCluster2);
776 // Flag first cluster as being removable
777 trackParamAtCluster2.SetRemovable(kTRUE);
779 // Update the chi2 of the new track
780 track.SetGlobalChi2(track.GetGlobalChi2() + localChi2AtCluster1 + localChi2AtCluster2);
782 // Update TrackParamAtCluster
783 track.AddTrackParamAtCluster(trackParamAtCluster1,*cluster1);
784 track.AddTrackParamAtCluster(trackParamAtCluster2,*cluster2);
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".
866 AliDebug(1,"Enter Fit");
868 Double_t benC, errorParam, invBenP, nonBenC, x, y;
869 AliMUONTrackParam *trackParam;
870 Double_t arg[1], fedm, errdef, globalChi2;
872 Int_t status, covStatus;
874 // Instantiate gMinuit if not already done
875 if (!gMinuit) gMinuit = new TMinuit(6);
876 // Clear MINUIT parameters
878 // Give the fitted track to MINUIT
879 gMinuit->SetObjectFit(&track);
880 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 2) || (AliLog::GetGlobalDebugLevel() >= 2)) {
881 // Define print level
883 gMinuit->mnexcm("SET PRI", arg, 1, status);
884 // Print covariance matrix
885 gMinuit->mnexcm("SHO COV", arg, 0, status);
888 gMinuit->mnexcm("SET PRI", arg, 1, status);
891 gMinuit->mnexcm("SET NOW", arg, 0, status);
894 //gMinuit->mnexcm("SET STR", arg, 1, status);
896 // set flag w/wo multiple scattering according to "includeMCS"
897 track.FitWithMCS(includeMCS);
899 // compute cluster weights only once
900 if (!track.ComputeClusterWeights()) {
901 AliWarning("cannot take into account the multiple scattering effects");
902 track.FitWithMCS(kFALSE);
906 track.FitWithVertex(fitWithVertex);
907 if (fitWithVertex) SetVertexErrXY2ForFit(track);
909 // Set fitting function
910 gMinuit->SetFCN(TrackChi2);
912 // Set fitted parameters (!! The order is very important for the covariance matrix !!)
913 trackParam = (AliMUONTrackParam*) (track.GetTrackParamAtCluster()->First());
914 // could be tried with no limits for the search (min=max=0) ????
915 // mandatory limits in non Bending to avoid NaN values of parameters
916 gMinuit->mnparm(0, "X", trackParam->GetNonBendingCoor(), 0.03, -500.0, 500.0, status);
917 gMinuit->mnparm(1, "NonBenS", trackParam->GetNonBendingSlope(), 0.001, -0.5, 0.5, status);
918 // mandatory limits in Bending to avoid NaN values of parameters
919 gMinuit->mnparm(2, "Y", trackParam->GetBendingCoor(), 0.10, -500.0, 500.0, status);
920 gMinuit->mnparm(3, "BenS", trackParam->GetBendingSlope(), 0.001, -0.5, 0.5, status);
921 gMinuit->mnparm(4, "InvBenP", trackParam->GetInverseBendingMomentum(), 0.003, -0.5, 0.5, status);
924 gMinuit->mnexcm("MIGRAD", arg, 0, status);
926 // Calculate the covariance matrix more accurately if required
927 if (calcCov) gMinuit->mnexcm("HESSE", arg, 0, status);
929 // get results into "invBenP", "benC", "nonBenC" ("x", "y")
930 gMinuit->GetParameter(0, x, errorParam);
931 trackParam->SetNonBendingCoor(x);
932 gMinuit->GetParameter(1, nonBenC, errorParam);
933 trackParam->SetNonBendingSlope(nonBenC);
934 gMinuit->GetParameter(2, y, errorParam);
935 trackParam->SetBendingCoor(y);
936 gMinuit->GetParameter(3, benC, errorParam);
937 trackParam->SetBendingSlope(benC);
938 gMinuit->GetParameter(4, invBenP, errorParam);
939 trackParam->SetInverseBendingMomentum(invBenP);
941 // global result of the fit
942 gMinuit->mnstat(globalChi2, fedm, errdef, npari, nparx, covStatus);
943 track.SetGlobalChi2(globalChi2);
945 // Get the covariance matrix if required
947 // Covariance matrix according to HESSE status
948 // If problem then keep only the diagonal terms (variances)
949 Double_t matrix[5][5];
950 gMinuit->mnemat(&matrix[0][0],5);
951 if (covStatus == 3) trackParam->SetCovariances(matrix);
952 else trackParam->SetVariances(matrix);
953 } else trackParam->DeleteCovariances();
957 //__________________________________________________________________________
958 void TrackChi2(Int_t & /*nParam*/, Double_t * /*gradient*/, Double_t &chi2, Double_t *param, Int_t /*flag*/)
960 /// Return the "Chi2" to be minimized with Minuit for track fitting.
961 /// Assumes that the trackParamAtCluster are sorted according to increasing Z.
962 /// Track parameters at each cluster are updated accordingly.
963 /// Vertex is used according to the flag "trackBeingFitted->GetFitWithVertex()".
964 /// Multiple Coulomb scattering is taken into account according to the flag "trackBeingFitted->GetFitWithMCS()".
966 AliMUONTrack *trackBeingFitted = (AliMUONTrack*) gMinuit->GetObjectFit();
967 AliMUONTrackParam* trackParamAtCluster = (AliMUONTrackParam*) trackBeingFitted->GetTrackParamAtCluster()->First();
969 chi2 = 0.; // initialize chi2
971 // update track parameters
972 trackParamAtCluster->SetNonBendingCoor(param[0]);
973 trackParamAtCluster->SetNonBendingSlope(param[1]);
974 trackParamAtCluster->SetBendingCoor(param[2]);
975 trackParamAtCluster->SetBendingSlope(param[3]);
976 trackParamAtCluster->SetInverseBendingMomentum(param[4]);
977 trackBeingFitted->UpdateTrackParamAtCluster();
979 // Take the vertex into account in the fit if required
980 if (trackBeingFitted->FitWithVertex()) {
981 Double_t nonBendingReso2,bendingReso2;
982 trackBeingFitted->GetVertexErrXY2(nonBendingReso2,bendingReso2);
983 if (nonBendingReso2 == 0. || bendingReso2 == 0.) chi2 += 1.e10;
985 AliMUONTrackParam paramAtVertex(*trackParamAtCluster);
986 AliMUONTrackExtrap::ExtrapToZ(¶mAtVertex, 0.); // vextex position = (0,0,0)
987 dX = paramAtVertex.GetNonBendingCoor();
988 dY = paramAtVertex.GetBendingCoor();
989 chi2 += dX * dX / nonBendingReso2 + dY * dY / bendingReso2;
993 // compute chi2 w/wo multiple scattering
994 chi2 += trackBeingFitted->ComputeGlobalChi2(trackBeingFitted->FitWithMCS());
998 //__________________________________________________________________________
999 void AliMUONTrackReconstructor::ComplementTracks(const AliMUONVClusterStore& clusterStore)
1001 /// Complete tracks by adding missing clusters (if there is an overlap between
1002 /// two detection elements, the track may have two clusters in the same chamber)
1003 /// Re-fit track parameters and covariances
1004 AliDebug(1,"Enter ComplementTracks");
1006 Int_t chamberId, detElemId;
1007 Double_t chi2OfCluster, bestChi2OfCluster;
1008 Double_t sigmaCut2 = AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking() *
1009 AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking();
1010 Bool_t foundOneCluster, trackModified;
1011 AliMUONVCluster* cluster;
1012 AliMUONTrackParam *trackParam, *nextTrackParam, copyOfTrackParam, trackParamAtCluster, bestTrackParamAtCluster;
1014 // Remove double track to complete only "good" tracks
1015 RemoveDoubleTracks();
1017 AliMUONTrack *track = (AliMUONTrack*) fRecTracksPtr->First();
1019 trackModified = kFALSE;
1021 trackParam = (AliMUONTrackParam*)track->GetTrackParamAtCluster()->First();
1022 while (trackParam) {
1023 foundOneCluster = kFALSE;
1024 bestChi2OfCluster = 2. * sigmaCut2; // 2 because 2 quantities in chi2
1025 chamberId = trackParam->GetClusterPtr()->GetChamberId();
1026 detElemId = trackParam->GetClusterPtr()->GetDetElemId();
1028 // prepare nextTrackParam before adding new cluster because of the sorting
1029 nextTrackParam = (AliMUONTrackParam*)track->GetTrackParamAtCluster()->After(trackParam);
1031 // recover track parameters from local fit and put them into a copy of trackParam
1032 copyOfTrackParam.SetZ(trackParam->GetZ());
1033 copyOfTrackParam.SetParameters(trackParam->GetSmoothParameters());
1034 copyOfTrackParam.SetCovariances(trackParam->GetSmoothCovariances());
1036 // Create iterators to loop over clusters in current chamber
1037 TIter nextInCh(clusterStore.CreateChamberIterator(chamberId,chamberId));
1039 // look for one second candidate in the same chamber
1040 while ( ( cluster = static_cast<AliMUONVCluster*>(nextInCh()) ) ) {
1042 // look for a cluster in another detection element
1043 if (cluster->GetDetElemId() == detElemId) continue;
1045 // try to add the current cluster fast
1046 if (!TryOneClusterFast(copyOfTrackParam, cluster)) continue;
1048 // try to add the current cluster accurately
1049 chi2OfCluster = TryOneCluster(copyOfTrackParam, cluster, trackParamAtCluster);
1051 // if better chi2 then prepare to add this cluster to the track
1052 if (chi2OfCluster < bestChi2OfCluster) {
1053 bestChi2OfCluster = chi2OfCluster;
1054 bestTrackParamAtCluster = trackParamAtCluster;
1055 foundOneCluster = kTRUE;
1060 // add new cluster if any
1061 if (foundOneCluster) {
1062 trackParam->SetRemovable(kTRUE);
1063 bestTrackParamAtCluster.SetRemovable(kTRUE);
1064 track->AddTrackParamAtCluster(bestTrackParamAtCluster,*(bestTrackParamAtCluster.GetClusterPtr()));
1065 trackModified = kTRUE;
1068 trackParam = nextTrackParam;
1071 // re-fit track parameters if needed
1072 if (trackModified) Fit(*track, kTRUE, kFALSE, kTRUE);
1074 track = (AliMUONTrack*) fRecTracksPtr->After(track);
1079 //__________________________________________________________________________
1080 void AliMUONTrackReconstructor::ImproveTrack(AliMUONTrack &track)
1082 /// Improve the given track by removing clusters with local chi2 highter than the defined cut
1083 /// Recompute track parameters and covariances at the remaining clusters
1084 AliDebug(1,"Enter ImproveTrack");
1086 Double_t localChi2, worstLocalChi2;
1087 AliMUONTrackParam *trackParamAtCluster, *worstTrackParamAtCluster;
1088 Double_t sigmaCut2 = AliMUONReconstructor::GetRecoParam()->GetSigmaCutForImprovement() *
1089 AliMUONReconstructor::GetRecoParam()->GetSigmaCutForImprovement();
1091 while (!track.IsImproved()) {
1093 // identify removable clusters
1094 track.TagRemovableClusters();
1096 // Update track parameters and covariances
1097 track.UpdateCovTrackParamAtCluster();
1099 // Compute local chi2 of each clusters
1100 track.ComputeLocalChi2(kTRUE);
1102 // Look for the cluster to remove
1103 worstTrackParamAtCluster = NULL;
1104 worstLocalChi2 = 0.;
1105 trackParamAtCluster = (AliMUONTrackParam*) track.GetTrackParamAtCluster()->First();
1106 while (trackParamAtCluster) {
1108 // Pick up cluster with the worst chi2
1109 localChi2 = trackParamAtCluster->GetLocalChi2();
1110 if (localChi2 > worstLocalChi2) {
1111 worstLocalChi2 = localChi2;
1112 worstTrackParamAtCluster = trackParamAtCluster;
1115 trackParamAtCluster = (AliMUONTrackParam*) track.GetTrackParamAtCluster()->After(trackParamAtCluster);
1118 // Check if worst cluster found
1119 if (!worstTrackParamAtCluster) {
1120 AliWarning("Bad local chi2 values?");
1124 // Check whether the worst chi2 is under requirement or not
1125 if (worstLocalChi2 < 2. * sigmaCut2) { // 2 because 2 quantities in chi2
1126 track.SetImproved(kTRUE);
1130 // if the worst cluster is not removable then stop improvement
1131 if (!worstTrackParamAtCluster->IsRemovable()) break;
1133 // Remove the worst cluster
1134 track.RemoveTrackParamAtCluster(worstTrackParamAtCluster);
1136 // Re-fit the track:
1137 // Take into account the multiple scattering
1138 // Calculate the track parameter covariance matrix
1139 Fit(track, kTRUE, kFALSE, kTRUE);
1141 // Printout for debuging
1142 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
1143 cout << "ImproveTracks: track " << fRecTracksPtr->IndexOf(&track)+1 << " improved " << endl;
1150 //__________________________________________________________________________
1151 void AliMUONTrackReconstructor::FinalizeTrack(AliMUONTrack &track)
1153 /// Recompute track parameters and covariances at each attached cluster
1154 /// from those at the first one, if not already done
1155 AliDebug(1,"Enter FinalizeTrack");
1156 if (!track.IsImproved()) track.UpdateCovTrackParamAtCluster();
1159 //__________________________________________________________________________
1160 Bool_t AliMUONTrackReconstructor::RefitTrack(AliMUONTrack &track)
1162 /// re-fit the given track
1164 // check validity of the track
1165 if (!track.IsValid()) {
1166 AliWarning("the track does not contain enough clusters --> unable to refit");
1170 // reset the seed (i.e. parameters at first cluster) before fitting
1171 AliMUONTrackParam* firstTrackParam = (AliMUONTrackParam*) track.GetTrackParamAtCluster()->First();
1172 if (firstTrackParam->GetInverseBendingMomentum() == 0.) {
1173 AliWarning("track parameters at first chamber are not initialized --> unable to refit");
1177 // compute track parameters at each cluster from parameters at the first one
1178 // necessary to compute multiple scattering effect during refitting
1179 track.UpdateTrackParamAtCluster();
1181 // Re-fit the track:
1182 // Take into account the multiple scattering
1183 // Calculate the track parameter covariance matrix
1184 Fit(track, kTRUE, kFALSE, kTRUE);
1186 // Improve the reconstructed tracks if required
1187 if (AliMUONReconstructor::GetRecoParam()->ImproveTracks()) ImproveTrack(track);
1189 // Fill AliMUONTrack data members
1190 FinalizeTrack(track);