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 "AliMUONHitForRec.h"
33 #include "AliMUONTrack.h"
34 #include "AliMUONTrackParam.h"
35 #include "AliMUONTrackExtrap.h"
40 #include <Riostream.h>
44 // Functions to be minimized with Minuit
45 void TrackChi2(Int_t &nParam, Double_t *gradient, Double_t &chi2, Double_t *param, Int_t flag);
48 ClassImp(AliMUONTrackReconstructor) // Class implementation in ROOT context
51 //__________________________________________________________________________
52 AliMUONTrackReconstructor::AliMUONTrackReconstructor()
53 : AliMUONVTrackReconstructor()
55 /// Constructor for class AliMUONTrackReconstructor
56 AliInfo("*** Original tracking ***");
59 //__________________________________________________________________________
60 AliMUONTrackReconstructor::~AliMUONTrackReconstructor()
65 //__________________________________________________________________________
66 void AliMUONTrackReconstructor::MakeTrackCandidates()
68 /// To make track candidates (assuming linear propagation if the flag fgkMakeTrackCandidatesFast is set to kTRUE):
69 /// Start with segments station(1..) 4 or 5 then follow track in station 5 or 4.
70 /// Good candidates are made of at least three hitForRec's.
71 /// Keep only best candidates or all of them according to the flag fgkTrackAllTracks.
73 TClonesArray *segments;
78 AliDebug(1,"Enter MakeTrackCandidates");
80 // Loop over stations(1..) 5 and 4 and make track candidates
81 for (Int_t istat=4; istat>=3; istat--) {
83 // Make segments in the station
84 segments = MakeSegmentsInStation(istat);
87 for (Int_t iseg=0; iseg<segments->GetEntriesFast(); iseg++)
89 AliDebug(1,Form("Making primary candidate(1..) %d",++iCandidate));
91 // Transform segments to tracks and put them at the end of fRecTracksPtr
92 track = new ((*fRecTracksPtr)[fRecTracksPtr->GetLast()+1]) AliMUONTrack((AliMUONObjectPair*)((*segments)[iseg]));
95 // Printout for debuging
96 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 2) || (AliLog::GetGlobalDebugLevel() >= 2))
98 cout<<endl<<"Track parameter covariances at first hit with multiple Coulomb scattering effects:"<<endl;
99 ((AliMUONTrackParam*) track->GetTrackParamAtHit()->First())->GetCovariances().Print();
102 // Look for compatible hitForRec(s) in the other station
103 if (AliMUONReconstructor::GetRecoParam()->MakeTrackCandidatesFast()) hitFound = FollowLinearTrackInStation(*track,7-istat);
104 else hitFound = FollowTrackInStation(*track,7-istat);
106 // Remove track if no hit found
108 fRecTracksPtr->Remove(track);
114 // delete the array of segments
118 fRecTracksPtr->Compress(); // this is essential before checking tracks
120 // Keep all different tracks or only the best ones as required
121 if (AliMUONReconstructor::GetRecoParam()->TrackAllTracks()) RemoveIdenticalTracks();
122 else RemoveDoubleTracks();
124 AliDebug(1,Form("Number of good candidates = %d",fNRecTracks));
128 //__________________________________________________________________________
129 void AliMUONTrackReconstructor::FollowTracks()
131 /// Follow tracks in stations(1..) 3, 2 and 1
132 AliDebug(1,"Enter FollowTracks");
134 AliMUONTrack *track, *nextTrack;
135 AliMUONTrackParam *trackParam, *nextTrackParam;
136 Int_t currentNRecTracks;
139 Double_t sigmaCut2 = AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking() *
140 AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking();
142 for (Int_t station = 2; station >= 0; station--) {
144 // Save the actual number of reconstructed track in case of
145 // tracks are added or suppressed during the tracking procedure
146 // !! Do not compress fRecTracksPtr until the end of the loop over tracks !!
147 currentNRecTracks = fNRecTracks;
149 for (Int_t iRecTrack = 0; iRecTrack <currentNRecTracks; iRecTrack++) {
150 AliDebug(1,Form("FollowTracks: track candidate(1..) %d", iRecTrack+1));
152 track = (AliMUONTrack*) fRecTracksPtr->UncheckedAt(iRecTrack);
155 // Do not take into account the multiple scattering to speed up the fit
156 // Calculate the track parameter covariance matrix
157 // If "station" is station(1..) 3 then use the vertex to better constrain the fit
159 SetVertexForFit(*track);
160 track->SetFitWithVertex(kTRUE);
161 } else track->SetFitWithVertex(kFALSE);
162 Fit(*track, kFALSE, kTRUE);
164 // Remove the track if the normalized chi2 is too high
165 if (track->GetNormalizedChi2() > sigmaCut2) {
166 fRecTracksPtr->Remove(track);
171 // save parameters from fit into smoothed parameters to complete track afterward
172 if (AliMUONReconstructor::GetRecoParam()->ComplementTracks()) {
174 if (station==2) { // save track parameters on stations 4 and 5
176 // extrapolate track parameters and covariances at each cluster
177 track->UpdateCovTrackParamAtHit();
180 trackParam = (AliMUONTrackParam*) track->GetTrackParamAtHit()->First();
182 trackParam->SetSmoothParameters(trackParam->GetParameters());
183 trackParam->SetSmoothCovariances(trackParam->GetCovariances());
184 trackParam = (AliMUONTrackParam*) track->GetTrackParamAtHit()->After(trackParam);
187 } else { // or save track parameters on last station only
189 // save parameters from fit
190 trackParam = (AliMUONTrackParam*) track->GetTrackParamAtHit()->First();
191 trackParam->SetSmoothParameters(trackParam->GetParameters());
192 trackParam->SetSmoothCovariances(trackParam->GetCovariances());
194 // save parameters extrapolated to the second chamber of the same station if it has been hit
195 nextTrackParam = (AliMUONTrackParam*) track->GetTrackParamAtHit()->After(trackParam);
196 if (nextTrackParam->GetHitForRecPtr()->GetChamberNumber() < 2*(station+2)) {
198 // reset parameters and covariances
199 nextTrackParam->SetParameters(trackParam->GetParameters());
200 nextTrackParam->SetZ(trackParam->GetZ());
201 nextTrackParam->SetCovariances(trackParam->GetCovariances());
203 // extrapolate them to the z of the corresponding cluster
204 AliMUONTrackExtrap::ExtrapToZCov(nextTrackParam, nextTrackParam->GetHitForRecPtr()->GetZ());
207 nextTrackParam->SetSmoothParameters(nextTrackParam->GetParameters());
208 nextTrackParam->SetSmoothCovariances(nextTrackParam->GetCovariances());
216 // Printout for debuging
217 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 2) || (AliLog::GetGlobalDebugLevel() >= 2)) {
218 cout<<endl<<"Track parameter covariances at first hit with multiple Coulomb scattering effects:"<<endl;
219 ((AliMUONTrackParam*) track->GetTrackParamAtHit()->First())->GetCovariances().Print();
222 // Look for compatible hitForRec in station(0..) "station"
223 hitFound = FollowTrackInStation(*track,station);
225 // Try to recover track if required
226 if (!hitFound && AliMUONReconstructor::GetRecoParam()->RecoverTracks()) hitFound = RecoverTrack(*track,station);
228 // remove track if no hit found
230 fRecTracksPtr->Remove(track);
236 // Compress fRecTracksPtr for the next step
237 fRecTracksPtr->Compress();
239 // Keep only the best tracks if required
240 if (!AliMUONReconstructor::GetRecoParam()->TrackAllTracks()) RemoveDoubleTracks();
244 // Last fit of track candidates with all station
245 // Take into account the multiple scattering and remove bad tracks
246 Int_t trackIndex = -1;
247 track = (AliMUONTrack*) fRecTracksPtr->First();
251 nextTrack = (AliMUONTrack*) fRecTracksPtr->After(track); // prepare next track
253 track->SetFitWithVertex(kFALSE); // just to be sure
254 Fit(*track, kTRUE, kTRUE);
256 // Printout for debuging
257 if (AliLog::GetGlobalDebugLevel() >= 3) {
258 cout << "FollowTracks: track candidate(0..) " << trackIndex << " after final fit" << endl;
259 track->RecursiveDump();
262 // Remove the track if the normalized chi2 is too high
263 if (track->GetNormalizedChi2() > sigmaCut2) {
264 fRecTracksPtr->Remove(track);
268 // save parameters from fit into smoothed parameters to complete track afterward
269 if (AliMUONReconstructor::GetRecoParam()->ComplementTracks()) {
271 // save parameters from fit
272 trackParam = (AliMUONTrackParam*) track->GetTrackParamAtHit()->First();
273 trackParam->SetSmoothParameters(trackParam->GetParameters());
274 trackParam->SetSmoothCovariances(trackParam->GetCovariances());
276 // save parameters extrapolated to the second chamber of the same station if it has been hit
277 nextTrackParam = (AliMUONTrackParam*) track->GetTrackParamAtHit()->After(trackParam);
278 if (nextTrackParam->GetHitForRecPtr()->GetChamberNumber() < 2) {
280 // reset parameters and covariances
281 nextTrackParam->SetParameters(trackParam->GetParameters());
282 nextTrackParam->SetZ(trackParam->GetZ());
283 nextTrackParam->SetCovariances(trackParam->GetCovariances());
285 // extrapolate them to the z of the corresponding cluster
286 AliMUONTrackExtrap::ExtrapToZCov(nextTrackParam, nextTrackParam->GetHitForRecPtr()->GetZ());
289 nextTrackParam->SetSmoothParameters(nextTrackParam->GetParameters());
290 nextTrackParam->SetSmoothCovariances(nextTrackParam->GetCovariances());
300 fRecTracksPtr->Compress();
304 //__________________________________________________________________________
305 Bool_t AliMUONTrackReconstructor::FollowTrackInStation(AliMUONTrack &trackCandidate, Int_t nextStation)
307 /// Follow trackCandidate in station(0..) nextStation and search for compatible HitForRec(s)
308 /// Keep all possibilities or only the best one(s) according to the flag fgkTrackAllTracks:
309 /// kTRUE: duplicate "trackCandidate" if there are several possibilities and add the new tracks at the end of
310 /// fRecTracksPtr to avoid conficts with other track candidates at this current stage of the tracking procedure.
311 /// Remove the obsolete "trackCandidate" at the end.
312 /// kFALSE: add only the best hit(s) to the "trackCandidate". Try to add a couple of hits in priority.
313 AliDebug(1,Form("Enter FollowTrackInStation(1..) %d", nextStation+1));
315 // Order the chamber according to the propagation direction (tracking starts with chamber 2):
316 // - nextStation == station(1...) 5 => forward propagation
317 // - nextStation < station(1...) 5 => backward propagation
319 if (nextStation==4) {
320 ch1 = 2*nextStation+1;
324 ch2 = 2*nextStation+1;
327 Double_t chi2WithOneHitForRec = 1.e10;
328 Double_t chi2WithTwoHitForRec = 1.e10;
329 Double_t maxChi2WithOneHitForRec = 2. * AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking() *
330 AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking(); // 2 because 2 quantities in chi2
331 Double_t maxChi2WithTwoHitForRec = 4. * AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking() *
332 AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking(); // 4 because 4 quantities in chi2
333 Double_t bestChi2WithOneHitForRec = maxChi2WithOneHitForRec;
334 Double_t bestChi2WithTwoHitForRec = maxChi2WithTwoHitForRec;
335 Bool_t foundOneHit = kFALSE;
336 Bool_t foundTwoHits = kFALSE;
337 AliMUONTrack *newTrack = 0x0;
338 AliMUONHitForRec *hitForRecCh1, *hitForRecCh2;
339 AliMUONTrackParam extrapTrackParam;
340 AliMUONTrackParam extrapTrackParamAtHit1;
341 AliMUONTrackParam extrapTrackParamAtHit2;
342 AliMUONTrackParam bestTrackParamAtHit1;
343 AliMUONTrackParam bestTrackParamAtHit2;
344 Bool_t *hitForRecCh1Used = new Bool_t[fNHitsForRecPerChamber[ch1]];
345 for (Int_t hit1 = 0; hit1 < fNHitsForRecPerChamber[ch1]; hit1++) hitForRecCh1Used[hit1] = kFALSE;
347 // Get track parameters
348 AliMUONTrackParam extrapTrackParamAtCh(*(AliMUONTrackParam*)trackCandidate.GetTrackParamAtHit()->First());
351 AliMUONTrackExtrap::AddMCSEffect(&extrapTrackParamAtCh,AliMUONConstants::ChamberThicknessInX0(),1.);
353 // Add MCS in the missing chamber if any (only 1 chamber can be missing according to tracking criteria)
354 if (ch1 < ch2 && extrapTrackParamAtCh.GetHitForRecPtr()->GetChamberNumber() > ch2 + 1) {
355 // extrapolation to the missing chamber
356 AliMUONTrackExtrap::ExtrapToZCov(&extrapTrackParamAtCh, AliMUONConstants::DefaultChamberZ(ch2 + 1));
358 AliMUONTrackExtrap::AddMCSEffect(&extrapTrackParamAtCh,AliMUONConstants::ChamberThicknessInX0(),1.);
361 //Extrapolate trackCandidate to chamber "ch2"
362 AliMUONTrackExtrap::ExtrapToZCov(&extrapTrackParamAtCh, AliMUONConstants::DefaultChamberZ(ch2));
364 // Printout for debuging
365 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 2) || (AliLog::GetGlobalDebugLevel() >= 2)) {
366 cout<<endl<<"Track parameter covariances at first hit extrapolated to z = "<<AliMUONConstants::DefaultChamberZ(ch2)<<":"<<endl;
367 extrapTrackParamAtCh.GetCovariances().Print();
370 // Printout for debuging
371 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
372 cout << "FollowTrackInStation: look for hits in chamber(1..): " << ch2+1 << endl;
375 // look for candidates in chamber 2
376 for (Int_t hit2 = 0; hit2 < fNHitsForRecPerChamber[ch2]; hit2++) {
378 hitForRecCh2 = (AliMUONHitForRec*) fHitsForRecPtr->UncheckedAt(fIndexOfFirstHitForRecPerChamber[ch2]+hit2);
380 // try to add the current hit fast
381 if (!TryOneHitForRecFast(extrapTrackParamAtCh, hitForRecCh2)) continue;
383 // try to add the current hit accuratly
384 chi2WithOneHitForRec = TryOneHitForRec(extrapTrackParamAtCh, hitForRecCh2, extrapTrackParamAtHit2);
386 // if good chi2 then try to attach a hitForRec in the other chamber too
387 if (chi2WithOneHitForRec < maxChi2WithOneHitForRec) {
388 Bool_t foundSecondHit = kFALSE;
390 // Printout for debuging
391 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
392 cout << "FollowTrackInStation: found one hit in chamber(1..): " << ch2+1
393 << " (Chi2 = " << chi2WithOneHitForRec << ")" << endl;
394 cout << " look for second hits in chamber(1..): " << ch1+1 << " ..." << endl;
397 // add MCS effect for next step
398 AliMUONTrackExtrap::AddMCSEffect(&extrapTrackParamAtHit2,AliMUONConstants::ChamberThicknessInX0(),1.);
400 // copy new track parameters for next step
401 extrapTrackParam = extrapTrackParamAtHit2;
403 //Extrapolate track parameters to chamber "ch1"
404 AliMUONTrackExtrap::ExtrapToZ(&extrapTrackParam, AliMUONConstants::DefaultChamberZ(ch1));
406 for (Int_t hit1 = 0; hit1 < fNHitsForRecPerChamber[ch1]; hit1++) {
408 hitForRecCh1 = (AliMUONHitForRec*) fHitsForRecPtr->UncheckedAt(fIndexOfFirstHitForRecPerChamber[ch1]+hit1);
410 // try to add the current hit fast
411 if (!TryOneHitForRecFast(extrapTrackParam, hitForRecCh1)) continue;
413 // try to add the current hit accuratly
414 chi2WithTwoHitForRec = TryTwoHitForRec(extrapTrackParamAtHit2, hitForRecCh1, extrapTrackParamAtHit1);
416 // if good chi2 then create a new track by adding the 2 hitForRec to the "trackCandidate"
417 if (chi2WithTwoHitForRec < maxChi2WithTwoHitForRec) {
418 foundSecondHit = kTRUE;
419 foundTwoHits = kTRUE;
421 // Printout for debuging
422 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
423 cout << "FollowTrackInStation: found second hit in chamber(1..): " << ch1+1
424 << " (Global Chi2 = " << chi2WithTwoHitForRec << ")" << endl;
427 if (AliMUONReconstructor::GetRecoParam()->TrackAllTracks()) {
428 // copy trackCandidate into a new track put at the end of fRecTracksPtr and add the new hitForRec's
429 newTrack = new ((*fRecTracksPtr)[fRecTracksPtr->GetLast()+1]) AliMUONTrack(trackCandidate);
430 UpdateTrack(*newTrack,extrapTrackParamAtHit1,extrapTrackParamAtHit2);
433 // Tag hitForRecCh1 as used
434 hitForRecCh1Used[hit1] = kTRUE;
436 // Printout for debuging
437 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
438 cout << "FollowTrackInStation: added two hits in station(1..): " << nextStation+1 << endl;
439 if (AliLog::GetGlobalDebugLevel() >= 3) newTrack->RecursiveDump();
442 } else if (chi2WithTwoHitForRec < bestChi2WithTwoHitForRec) {
443 // keep track of the best couple of hits
444 bestChi2WithTwoHitForRec = chi2WithTwoHitForRec;
445 bestTrackParamAtHit1 = extrapTrackParamAtHit1;
446 bestTrackParamAtHit2 = extrapTrackParamAtHit2;
453 // if no hitForRecCh1 found then consider to add hitForRecCh2 only
454 if (!foundSecondHit) {
457 if (AliMUONReconstructor::GetRecoParam()->TrackAllTracks()) {
458 // copy trackCandidate into a new track put at the end of fRecTracksPtr and add the new hitForRec's
459 newTrack = new ((*fRecTracksPtr)[fRecTracksPtr->GetLast()+1]) AliMUONTrack(trackCandidate);
460 UpdateTrack(*newTrack,extrapTrackParamAtHit2);
463 // Printout for debuging
464 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
465 cout << "FollowTrackInStation: added one hit in chamber(1..): " << ch2+1 << endl;
466 if (AliLog::GetGlobalDebugLevel() >= 3) newTrack->RecursiveDump();
469 } else if (!foundTwoHits && chi2WithOneHitForRec < bestChi2WithOneHitForRec) {
470 // keep track of the best single hitForRec except if a couple of hits has already been found
471 bestChi2WithOneHitForRec = chi2WithOneHitForRec;
472 bestTrackParamAtHit1 = extrapTrackParamAtHit2;
481 // look for candidates in chamber 1 not already attached to a track
482 // if we want to keep all possible tracks or if no good couple of hitForRec has been found
483 if (AliMUONReconstructor::GetRecoParam()->TrackAllTracks() || !foundTwoHits) {
485 // Printout for debuging
486 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
487 cout << "FollowTrackInStation: look for single hits in chamber(1..): " << ch1+1 << endl;
490 // add MCS effect for next step
491 AliMUONTrackExtrap::AddMCSEffect(&extrapTrackParamAtCh,AliMUONConstants::ChamberThicknessInX0(),1.);
493 //Extrapolate trackCandidate to chamber "ch1"
494 AliMUONTrackExtrap::ExtrapToZCov(&extrapTrackParamAtCh, AliMUONConstants::DefaultChamberZ(ch1));
496 for (Int_t hit1 = 0; hit1 < fNHitsForRecPerChamber[ch1]; hit1++) {
498 hitForRecCh1 = (AliMUONHitForRec*) fHitsForRecPtr->UncheckedAt(fIndexOfFirstHitForRecPerChamber[ch1]+hit1);
500 if (hitForRecCh1Used[hit1]) continue; // Skip hitForRec already used
502 // try to add the current hit fast
503 if (!TryOneHitForRecFast(extrapTrackParamAtCh, hitForRecCh1)) continue;
505 // try to add the current hit accuratly
506 chi2WithOneHitForRec = TryOneHitForRec(extrapTrackParamAtCh, hitForRecCh1, extrapTrackParamAtHit1);
508 // if good chi2 then consider to add hitForRecCh1
509 // We do not try to attach a hitForRec in the other chamber too since it has already been done above
510 if (chi2WithOneHitForRec < maxChi2WithOneHitForRec) {
513 // Printout for debuging
514 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
515 cout << "FollowTrackInStation: found one hit in chamber(1..): " << ch1+1
516 << " (Chi2 = " << chi2WithOneHitForRec << ")" << endl;
519 if (AliMUONReconstructor::GetRecoParam()->TrackAllTracks()) {
520 // copy trackCandidate into a new track put at the end of fRecTracksPtr and add the new hitForRec's
521 newTrack = new ((*fRecTracksPtr)[fRecTracksPtr->GetLast()+1]) AliMUONTrack(trackCandidate);
522 UpdateTrack(*newTrack,extrapTrackParamAtHit1);
525 // Printout for debuging
526 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
527 cout << "FollowTrackInStation: added one hit in chamber(1..): " << ch1+1 << endl;
528 if (AliLog::GetGlobalDebugLevel() >= 3) newTrack->RecursiveDump();
531 } else if (chi2WithOneHitForRec < bestChi2WithOneHitForRec) {
532 // keep track of the best single hitForRec except if a couple of hits has already been found
533 bestChi2WithOneHitForRec = chi2WithOneHitForRec;
534 bestTrackParamAtHit1 = extrapTrackParamAtHit1;
543 // fill out the best track if required else clean up the fRecTracksPtr array
544 if (!AliMUONReconstructor::GetRecoParam()->TrackAllTracks()) {
546 UpdateTrack(trackCandidate,bestTrackParamAtHit1,bestTrackParamAtHit2);
548 // Printout for debuging
549 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
550 cout << "FollowTrackInStation: added the two best hits in station(1..): " << nextStation+1 << endl;
551 if (AliLog::GetGlobalDebugLevel() >= 3) newTrack->RecursiveDump();
554 } else if (foundOneHit) {
555 UpdateTrack(trackCandidate,bestTrackParamAtHit1);
557 // Printout for debuging
558 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
559 cout << "FollowTrackInStation: added the best hit in chamber(1..): " << bestTrackParamAtHit1.GetHitForRecPtr()->GetChamberNumber()+1 << endl;
560 if (AliLog::GetGlobalDebugLevel() >= 3) newTrack->RecursiveDump();
564 delete [] hitForRecCh1Used;
568 } else if (foundOneHit || foundTwoHits) {
570 // remove obsolete track
571 fRecTracksPtr->Remove(&trackCandidate);
575 delete [] hitForRecCh1Used;
579 delete [] hitForRecCh1Used;
584 //__________________________________________________________________________
585 Double_t AliMUONTrackReconstructor::TryTwoHitForRec(const AliMUONTrackParam &trackParamAtHit1, AliMUONHitForRec* hitForRec2,
586 AliMUONTrackParam &trackParamAtHit2)
588 /// Test the compatibility between the track and the 2 hitForRec together (using trackParam's covariance matrix):
589 /// return the corresponding Chi2 accounting for covariances between the 2 hitForRec
590 /// return trackParamAtHit1 & 2
592 // extrapolate track parameters at the z position of the second hit
593 trackParamAtHit2.SetParameters(trackParamAtHit1.GetParameters());
594 trackParamAtHit2.SetZ(trackParamAtHit1.GetZ());
595 AliMUONTrackExtrap::ExtrapToZ(&trackParamAtHit2, hitForRec2->GetZ());
597 // set pointer to hit2 into trackParamAtHit2
598 trackParamAtHit2.SetHitForRecPtr(hitForRec2);
600 // Set differences between track and the 2 hitForRec in the bending and non bending directions
601 AliMUONHitForRec* hitForRec1 = trackParamAtHit1.GetHitForRecPtr();
603 dPos(0,0) = hitForRec1->GetNonBendingCoor() - trackParamAtHit1.GetNonBendingCoor();
604 dPos(1,0) = hitForRec1->GetBendingCoor() - trackParamAtHit1.GetBendingCoor();
605 dPos(2,0) = hitForRec2->GetNonBendingCoor() - trackParamAtHit2.GetNonBendingCoor();
606 dPos(3,0) = hitForRec2->GetBendingCoor() - trackParamAtHit2.GetBendingCoor();
608 // Calculate the error matrix from the track parameter covariances at first hitForRec
611 if (trackParamAtHit1.CovariancesExist()) {
612 // Save track parameters at first hitForRec
613 AliMUONTrackParam trackParamAtHit1Save(trackParamAtHit1);
614 TMatrixD paramAtHit1Save(trackParamAtHit1Save.GetParameters());
615 Double_t z1 = trackParamAtHit1Save.GetZ();
617 // Save track coordinates at second hitForRec
618 Double_t nonBendingCoor2 = trackParamAtHit2.GetNonBendingCoor();
619 Double_t bendingCoor2 = trackParamAtHit2.GetBendingCoor();
621 // add MCS effect at first hitForRec
622 AliMUONTrackExtrap::AddMCSEffect(&trackParamAtHit1Save,AliMUONConstants::ChamberThicknessInX0(),1.);
624 // Get the pointer to the parameter covariance matrix at first hitForRec
625 const TMatrixD& kParamCov = trackParamAtHit1Save.GetCovariances();
627 // Calculate the jacobian related to the transformation between track parameters
628 // at first hitForRec and track coordinates at the 2 hitForRec z-position
631 // first derivative at the first hitForRec:
632 jacob(0,0) = 1.; // dx1/dx
633 jacob(1,2) = 1.; // dy1/dy
634 // first derivative at the second hitForRec:
635 TMatrixD dParam(5,1);
636 for (Int_t i=0; i<5; i++) {
637 // Skip jacobian calculation for parameters with no associated error
638 if (kParamCov(i,i) == 0.) continue;
639 // Small variation of parameter i only
640 for (Int_t j=0; j<5; j++) {
642 dParam(j,0) = TMath::Sqrt(kParamCov(i,i));
643 if (j == 4) dParam(j,0) *= TMath::Sign(1.,-paramAtHit1Save(4,0)); // variation always in the same direction
644 } else dParam(j,0) = 0.;
647 // Set new track parameters at first hitForRec
648 trackParamAtHit1Save.SetParameters(paramAtHit1Save);
649 trackParamAtHit1Save.AddParameters(dParam);
650 trackParamAtHit1Save.SetZ(z1);
652 // Extrapolate new track parameters to the z position of the second hitForRec
653 AliMUONTrackExtrap::ExtrapToZ(&trackParamAtHit1Save,hitForRec2->GetZ());
655 // Calculate the jacobian
656 jacob(2,i) = (trackParamAtHit1Save.GetNonBendingCoor() - nonBendingCoor2) / dParam(i,0); // dx2/dParami
657 jacob(3,i) = (trackParamAtHit1Save.GetBendingCoor() - bendingCoor2 ) / dParam(i,0); // dy2/dParami
660 // Calculate the error matrix
661 TMatrixD tmp(jacob,TMatrixD::kMult,kParamCov);
662 error = TMatrixD(tmp,TMatrixD::kMultTranspose,jacob);
665 // Add hitForRec resolution to the error matrix
666 error(0,0) += hitForRec1->GetNonBendingReso2();
667 error(1,1) += hitForRec1->GetBendingReso2();
668 error(2,2) += hitForRec2->GetNonBendingReso2();
669 error(3,3) += hitForRec2->GetBendingReso2();
671 // invert the error matrix for Chi2 calculation
672 if (error.Determinant() != 0) {
675 AliWarning(" Determinant error=0");
679 // Compute the Chi2 value
680 TMatrixD tmp2(dPos,TMatrixD::kTransposeMult,error);
681 TMatrixD result(tmp2,TMatrixD::kMult,dPos);
687 //__________________________________________________________________________
688 void AliMUONTrackReconstructor::UpdateTrack(AliMUONTrack &track, AliMUONTrackParam &trackParamAtHit)
690 /// Add 1 hit to the track candidate
691 /// Update chi2 of the track
693 // Compute local chi2
694 AliMUONHitForRec* hit = trackParamAtHit.GetHitForRecPtr();
695 Double_t deltaX = trackParamAtHit.GetNonBendingCoor() - hit->GetNonBendingCoor();
696 Double_t deltaY = trackParamAtHit.GetBendingCoor() - hit->GetBendingCoor();
697 Double_t localChi2 = deltaX*deltaX / hit->GetNonBendingReso2() +
698 deltaY*deltaY / hit->GetBendingReso2();
700 // Flag hit as being not removable
701 trackParamAtHit.SetRemovable(kFALSE);
702 trackParamAtHit.SetLocalChi2(0.); // --> Local chi2 not used
704 // Update the chi2 of the new track
705 track.SetFitFMin(track.GetFitFMin() + localChi2);
707 // Update TrackParamAtHit
708 track.AddTrackParamAtHit(&trackParamAtHit,trackParamAtHit.GetHitForRecPtr());
709 track.GetTrackParamAtHit()->Sort();
713 //__________________________________________________________________________
714 void AliMUONTrackReconstructor::UpdateTrack(AliMUONTrack &track, AliMUONTrackParam &trackParamAtHit1, AliMUONTrackParam &trackParamAtHit2)
716 /// Add 2 hits to the track candidate
717 /// Update track and local chi2
719 // Update local chi2 at first hit
720 AliMUONHitForRec* hit1 = trackParamAtHit1.GetHitForRecPtr();
721 Double_t deltaX = trackParamAtHit1.GetNonBendingCoor() - hit1->GetNonBendingCoor();
722 Double_t deltaY = trackParamAtHit1.GetBendingCoor() - hit1->GetBendingCoor();
723 Double_t localChi2AtHit1 = deltaX*deltaX / hit1->GetNonBendingReso2() +
724 deltaY*deltaY / hit1->GetBendingReso2();
725 trackParamAtHit1.SetLocalChi2(localChi2AtHit1);
727 // Flag first hit as being removable
728 trackParamAtHit1.SetRemovable(kTRUE);
730 // Update local chi2 at second hit
731 AliMUONHitForRec* hit2 = trackParamAtHit2.GetHitForRecPtr();
732 deltaX = trackParamAtHit2.GetNonBendingCoor() - hit2->GetNonBendingCoor();
733 deltaY = trackParamAtHit2.GetBendingCoor() - hit2->GetBendingCoor();
734 Double_t localChi2AtHit2 = deltaX*deltaX / hit2->GetNonBendingReso2() +
735 deltaY*deltaY / hit2->GetBendingReso2();
736 trackParamAtHit2.SetLocalChi2(localChi2AtHit2);
738 // Flag first hit as being removable
739 trackParamAtHit2.SetRemovable(kTRUE);
741 // Update the chi2 of the new track
742 track.SetFitFMin(track.GetFitFMin() + localChi2AtHit1 + localChi2AtHit2);
744 // Update TrackParamAtHit
745 track.AddTrackParamAtHit(&trackParamAtHit1,trackParamAtHit1.GetHitForRecPtr());
746 track.AddTrackParamAtHit(&trackParamAtHit2,trackParamAtHit2.GetHitForRecPtr());
747 track.GetTrackParamAtHit()->Sort();
751 //__________________________________________________________________________
752 Bool_t AliMUONTrackReconstructor::RecoverTrack(AliMUONTrack &trackCandidate, Int_t nextStation)
754 /// Try to recover the track candidate in the next station
755 /// by removing the worst of the two hits attached in the current station
756 /// Return kTRUE if recovering succeeds
757 AliDebug(1,"Enter RecoverTrack");
759 // Do not try to recover track until we have attached hit(s) on station(1..) 3
760 if (nextStation > 1) return kFALSE;
762 Int_t worstHitNumber = -1;
763 Double_t localChi2, worstLocalChi2 = 0.;
765 // Look for the hit to remove
766 for (Int_t hitNumber = 0; hitNumber < 2; hitNumber++) {
767 AliMUONTrackParam *trackParamAtHit = (AliMUONTrackParam*)trackCandidate.GetTrackParamAtHit()->UncheckedAt(hitNumber);
769 // check if current hit is removable
770 if (!trackParamAtHit->IsRemovable()) return kFALSE;
772 // Pick up hit with the worst chi2
773 localChi2 = trackParamAtHit->GetLocalChi2();
774 if (localChi2 > worstLocalChi2) {
775 worstLocalChi2 = localChi2;
776 worstHitNumber = hitNumber;
780 // Reset best hit as being NOT removable
781 ((AliMUONTrackParam*)trackCandidate.GetTrackParamAtHit()->UncheckedAt((worstHitNumber+1)%2))->SetRemovable(kFALSE);
783 // Remove the worst hit
784 trackCandidate.RemoveTrackParamAtHit((AliMUONTrackParam*)trackCandidate.GetTrackParamAtHit()->UncheckedAt(worstHitNumber));
787 // Do not take into account the multiple scattering to speed up the fit
788 // Calculate the track parameter covariance matrix
789 trackCandidate.SetFitWithVertex(kFALSE); // To be sure
790 Fit(trackCandidate, kFALSE, kTRUE);
792 // Look for new hit(s) in next station
793 return FollowTrackInStation(trackCandidate,nextStation);
797 //__________________________________________________________________________
798 void AliMUONTrackReconstructor::SetVertexForFit(AliMUONTrack &trackCandidate)
800 /// Add the vertex as a measured hit to constrain the fit of the "trackCandidate"
801 /// Compute the vertex resolution from natural vertex dispersion and
802 /// multiple scattering effets according to trackCandidate path in absorber
803 /// It is necessary to account for multiple scattering effects here instead of during the fit of
804 /// the "trackCandidate" to do not influence the result by changing track resolution at vertex
805 AliDebug(1,"Enter SetVertexForFit");
807 Double_t nonBendingReso2 = AliMUONReconstructor::GetRecoParam()->GetNonBendingVertexDispersion() *
808 AliMUONReconstructor::GetRecoParam()->GetNonBendingVertexDispersion();
809 Double_t bendingReso2 = AliMUONReconstructor::GetRecoParam()->GetBendingVertexDispersion() *
810 AliMUONReconstructor::GetRecoParam()->GetBendingVertexDispersion();
811 // add multiple scattering effets
812 AliMUONTrackParam paramAtVertex(*((AliMUONTrackParam*)(trackCandidate.GetTrackParamAtHit()->First())));
813 paramAtVertex.DeleteCovariances(); // to be sure to account only for multiple scattering
814 AliMUONTrackExtrap::ExtrapToVertexUncorrected(¶mAtVertex,0.);
815 const TMatrixD& kParamCov = paramAtVertex.GetCovariances();
816 nonBendingReso2 += kParamCov(0,0);
817 bendingReso2 += kParamCov(2,2);
819 AliMUONHitForRec vertex; // Coordinates set to (0.,0.,0.) by default
820 vertex.SetNonBendingReso2(nonBendingReso2);
821 vertex.SetBendingReso2(bendingReso2);
822 trackCandidate.SetVertex(&vertex);
825 //__________________________________________________________________________
826 void AliMUONTrackReconstructor::Fit(AliMUONTrack &track, Bool_t includeMCS, Bool_t calcCov)
828 /// Fit the track "track" w/wo multiple Coulomb scattering according to "includeMCS".
830 Double_t benC, errorParam, invBenP, nonBenC, x, y;
831 AliMUONTrackParam *trackParam;
832 Double_t arg[1], fedm, errdef, fitFMin;
834 Int_t status, covStatus;
836 // Instantiate gMinuit if not already done
837 if (!gMinuit) gMinuit = new TMinuit(6);
838 // Clear MINUIT parameters
840 // Give the fitted track to MINUIT
841 gMinuit->SetObjectFit(&track);
842 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 2) || (AliLog::GetGlobalDebugLevel() >= 2)) {
843 // Define print level
845 gMinuit->mnexcm("SET PRI", arg, 1, status);
846 // Print covariance matrix
847 gMinuit->mnexcm("SHO COV", arg, 0, status);
850 gMinuit->mnexcm("SET PRI", arg, 1, status);
853 gMinuit->mnexcm("SET NOW", arg, 0, status);
856 //gMinuit->mnexcm("SET STR", arg, 1, status);
858 // set flag w/wo multiple scattering according to "includeMCS"
859 track.SetFitWithMCS(includeMCS);
861 // compute hit weights only once
862 if (!track.ComputeHitWeights()) {
863 AliWarning("cannot take into account the multiple scattering effects");
864 track.SetFitWithMCS(kFALSE);
868 // Set fitting function
869 gMinuit->SetFCN(TrackChi2);
871 // Set fitted parameters (!! The order is very important for the covariance matrix !!)
872 trackParam = (AliMUONTrackParam*) (track.GetTrackParamAtHit()->First());
873 // could be tried with no limits for the search (min=max=0) ????
874 // mandatory limits in non Bending to avoid NaN values of parameters
875 gMinuit->mnparm(0, "X", trackParam->GetNonBendingCoor(), 0.03, -500.0, 500.0, status);
876 gMinuit->mnparm(1, "NonBenS", trackParam->GetNonBendingSlope(), 0.001, -0.5, 0.5, status);
877 // mandatory limits in Bending to avoid NaN values of parameters
878 gMinuit->mnparm(2, "Y", trackParam->GetBendingCoor(), 0.10, -500.0, 500.0, status);
879 gMinuit->mnparm(3, "BenS", trackParam->GetBendingSlope(), 0.001, -0.5, 0.5, status);
880 gMinuit->mnparm(4, "InvBenP", trackParam->GetInverseBendingMomentum(), 0.003, -0.4, 0.4, status);
883 gMinuit->mnexcm("MIGRAD", arg, 0, status);
885 // Calculate the covariance matrix more accurately if required
886 if (calcCov) gMinuit->mnexcm("HESSE", arg, 0, status);
888 // get results into "invBenP", "benC", "nonBenC" ("x", "y")
889 gMinuit->GetParameter(0, x, errorParam);
890 trackParam->SetNonBendingCoor(x);
891 gMinuit->GetParameter(1, nonBenC, errorParam);
892 trackParam->SetNonBendingSlope(nonBenC);
893 gMinuit->GetParameter(2, y, errorParam);
894 trackParam->SetBendingCoor(y);
895 gMinuit->GetParameter(3, benC, errorParam);
896 trackParam->SetBendingSlope(benC);
897 gMinuit->GetParameter(4, invBenP, errorParam);
898 trackParam->SetInverseBendingMomentum(invBenP);
900 // global result of the fit
901 gMinuit->mnstat(fitFMin, fedm, errdef, npari, nparx, covStatus);
902 track.SetFitFMin(fitFMin);
904 // Get the covariance matrix if required
906 // Covariance matrix according to HESSE status
907 // If problem then keep only the diagonal terms (variances)
908 Double_t matrix[5][5];
909 gMinuit->mnemat(&matrix[0][0],5);
910 if (covStatus == 3) trackParam->SetCovariances(matrix);
911 else trackParam->SetVariances(matrix);
912 } else trackParam->DeleteCovariances();
916 //__________________________________________________________________________
917 void TrackChi2(Int_t & /*nParam*/, Double_t * /*gradient*/, Double_t &chi2, Double_t *param, Int_t /*flag*/)
919 /// Return the "Chi2" to be minimized with Minuit for track fitting.
920 /// Assumes that the track hits are sorted according to increasing Z.
921 /// Track parameters at each TrackHit are updated accordingly.
922 /// Vertex is used according to the flag "trackBeingFitted->GetFitWithVertex()".
923 /// Multiple Coulomb scattering is taken into account according to the flag "trackBeingFitted->GetFitWithMCS()".
925 AliMUONTrack *trackBeingFitted = (AliMUONTrack*) gMinuit->GetObjectFit();
926 AliMUONTrackParam* trackParamAtHit = (AliMUONTrackParam*) trackBeingFitted->GetTrackParamAtHit()->First();
928 chi2 = 0.; // initialize chi2
930 // update track parameters
931 trackParamAtHit->SetNonBendingCoor(param[0]);
932 trackParamAtHit->SetNonBendingSlope(param[1]);
933 trackParamAtHit->SetBendingCoor(param[2]);
934 trackParamAtHit->SetBendingSlope(param[3]);
935 trackParamAtHit->SetInverseBendingMomentum(param[4]);
936 trackBeingFitted->UpdateTrackParamAtHit();
938 // Take the vertex into account in the fit if required
939 if (trackBeingFitted->GetFitWithVertex()) {
940 AliMUONTrackParam paramAtVertex(*trackParamAtHit);
941 AliMUONTrackExtrap::ExtrapToZ(¶mAtVertex, 0.);
942 AliMUONHitForRec *vertex = trackBeingFitted->GetVertex();
944 cout<<"Error in TrackChi2: Want to use the vertex in tracking but it has not been created!!"<<endl;
947 dX = vertex->GetNonBendingCoor() - paramAtVertex.GetNonBendingCoor();
948 dY = vertex->GetBendingCoor() - paramAtVertex.GetBendingCoor();
949 chi2 += dX * dX / vertex->GetNonBendingReso2() + dY * dY / vertex->GetBendingReso2();
952 // compute chi2 w/wo multiple scattering
953 chi2 += trackBeingFitted->ComputeGlobalChi2(trackBeingFitted->GetFitWithMCS());
957 //__________________________________________________________________________
958 void AliMUONTrackReconstructor::ComplementTracks()
960 /// Complete tracks by adding missing clusters (if there is an overlap between
961 /// two detection elements, the track may have two clusters in the same chamber)
962 /// Re-fit track parameters and covariances
963 AliDebug(1,"Enter ComplementTracks");
965 Int_t chamberId, detElemId;
966 Double_t chi2OfHitForRec, bestChi2OfHitForRec;
967 Bool_t foundOneHit, trackModified;
968 AliMUONHitForRec* hitForRec;
969 AliMUONTrackParam* trackParam, *nextTrackParam;
970 AliMUONTrackParam copyOfTrackParam;
971 AliMUONTrackParam trackParamAtHit;
972 AliMUONTrackParam bestTrackParamAtHit;
973 Double_t sigmaCut2 = AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking() *
974 AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking();
976 // Remove double track to complete only "good" tracks
977 RemoveDoubleTracks();
979 AliMUONTrack *track = (AliMUONTrack*) fRecTracksPtr->First();
981 trackModified = kFALSE;
983 trackParam = (AliMUONTrackParam*)track->GetTrackParamAtHit()->First();
985 foundOneHit = kFALSE;
986 bestChi2OfHitForRec = 2. * sigmaCut2; // 2 because 2 quantities in chi2
988 // prepare nextTrackParam before adding new cluster because of the sorting
989 nextTrackParam = (AliMUONTrackParam*)track->GetTrackParamAtHit()->After(trackParam);
991 chamberId = trackParam->GetHitForRecPtr()->GetChamberNumber();
992 detElemId = trackParam->GetHitForRecPtr()->GetDetElemId();
994 // recover track parameters from local fit and put them into a copy of trackParam
995 copyOfTrackParam.SetZ(trackParam->GetZ());
996 copyOfTrackParam.SetParameters(trackParam->GetSmoothParameters());
997 copyOfTrackParam.SetCovariances(trackParam->GetSmoothCovariances());
999 // look for one second candidate in the same chamber
1000 for (Int_t hit = 0; hit < fNHitsForRecPerChamber[chamberId]; hit++) {
1002 hitForRec = (AliMUONHitForRec*) fHitsForRecPtr->UncheckedAt(fIndexOfFirstHitForRecPerChamber[chamberId]+hit);
1004 // look for a cluster in another detection element
1005 if (hitForRec->GetDetElemId() == detElemId) continue;
1007 // try to add the current hit fast
1008 if (!TryOneHitForRecFast(copyOfTrackParam, hitForRec)) continue;
1010 // try to add the current hit accurately
1011 chi2OfHitForRec = TryOneHitForRec(copyOfTrackParam, hitForRec, trackParamAtHit);
1013 // if better chi2 then prepare to add this cluster to the track
1014 if (chi2OfHitForRec < bestChi2OfHitForRec) {
1015 bestChi2OfHitForRec = chi2OfHitForRec;
1016 bestTrackParamAtHit = trackParamAtHit;
1017 foundOneHit = kTRUE;
1022 // add new cluster if any
1024 UpdateTrack(*track,bestTrackParamAtHit);
1025 bestTrackParamAtHit.SetAloneInChamber(kFALSE);
1026 trackParam->SetAloneInChamber(kFALSE);
1027 trackModified = kTRUE;
1030 trackParam = nextTrackParam;
1033 // re-fit track parameters if needed
1034 if (trackModified) Fit(*track, kTRUE, kTRUE);
1036 track = (AliMUONTrack*) fRecTracksPtr->After(track);
1041 //__________________________________________________________________________
1042 void AliMUONTrackReconstructor::ImproveTracks()
1044 /// Improve tracks by removing clusters with local chi2 highter than the defined cut
1045 /// Recompute track parameters and covariances at the remaining clusters
1046 AliDebug(1,"Enter ImproveTracks");
1048 Double_t localChi2, worstLocalChi2;
1049 Int_t worstChamber, previousChamber;
1050 AliMUONTrack *track, *nextTrack;
1051 AliMUONTrackParam *trackParamAtHit, *worstTrackParamAtHit, *previousTrackParam, *nextTrackParam;
1052 Double_t sigmaCut2 = AliMUONReconstructor::GetRecoParam()->GetSigmaCutForImprovement() *
1053 AliMUONReconstructor::GetRecoParam()->GetSigmaCutForImprovement();
1055 // Remove double track to improve only "good" tracks
1056 RemoveDoubleTracks();
1058 track = (AliMUONTrack*) fRecTracksPtr->First();
1061 // prepare next track in case the actual track is suppressed
1062 nextTrack = (AliMUONTrack*) fRecTracksPtr->After(track);
1064 while (!track->IsImproved()) {
1066 // Update track parameters and covariances
1067 track->UpdateCovTrackParamAtHit();
1069 // Compute local chi2 of each hits
1070 track->ComputeLocalChi2(kTRUE);
1072 // Look for the hit to remove
1073 worstTrackParamAtHit = NULL;
1074 worstLocalChi2 = 0.;
1075 trackParamAtHit = (AliMUONTrackParam*) track->GetTrackParamAtHit()->First();
1076 while (trackParamAtHit) {
1078 // Pick up hit with the worst chi2
1079 localChi2 = trackParamAtHit->GetLocalChi2();
1080 if (localChi2 > worstLocalChi2) {
1081 worstLocalChi2 = localChi2;
1082 worstTrackParamAtHit = trackParamAtHit;
1085 trackParamAtHit = (AliMUONTrackParam*) track->GetTrackParamAtHit()->After(trackParamAtHit);
1088 // Check if bad hit found
1089 if (!worstTrackParamAtHit) {
1090 track->SetImproved(kTRUE);
1094 // Check whether the worst chi2 is under requirement or not
1095 if (worstLocalChi2 < 2. * sigmaCut2) { // 2 because 2 quantities in chi2
1096 track->SetImproved(kTRUE);
1100 // if the worst hit is not removable then remove the entire track
1101 if (!worstTrackParamAtHit->IsRemovable() && worstTrackParamAtHit->IsAloneInChamber()) {
1102 fRecTracksPtr->Remove(track);
1107 // Reset the second hit in the same station as being not removable
1108 // or reset the second hit in the same chamber as being alone
1109 worstChamber = worstTrackParamAtHit->GetHitForRecPtr()->GetChamberNumber();
1110 previousTrackParam = (AliMUONTrackParam*) track->GetTrackParamAtHit()->Before(worstTrackParamAtHit);
1111 nextTrackParam = (AliMUONTrackParam*) track->GetTrackParamAtHit()->After(worstTrackParamAtHit);
1112 if (worstTrackParamAtHit->IsAloneInChamber()) { // Worst hit removable and alone in chamber
1114 if (worstChamber%2 == 0) { // Modify flags in next chamber
1116 nextTrackParam->SetRemovable(kFALSE);
1117 if (!nextTrackParam->IsAloneInChamber()) // Make sure both hits in second chamber are not removable anymore
1118 ((AliMUONTrackParam*) track->GetTrackParamAtHit()->After(nextTrackParam))->SetRemovable(kFALSE);
1120 } else { // Modify flags in previous chamber
1122 previousTrackParam->SetRemovable(kFALSE);
1123 if (!previousTrackParam->IsAloneInChamber()) // Make sure both hits in second chamber are not removable anymore
1124 ((AliMUONTrackParam*) track->GetTrackParamAtHit()->Before(previousTrackParam))->SetRemovable(kFALSE);
1128 } else { // Worst hit not alone in its chamber
1130 if (previousTrackParam) previousChamber = previousTrackParam->GetHitForRecPtr()->GetChamberNumber();
1131 else previousChamber = -1;
1133 if (previousChamber == worstChamber) { // the second hit on the same chamber is the previous one
1135 previousTrackParam->SetAloneInChamber(kTRUE);
1136 // transfert the removability to the second hit
1137 if (worstTrackParamAtHit->IsRemovable()) previousTrackParam->SetRemovable(kTRUE);
1139 } else { // the second hit on the same chamber is the next one
1141 nextTrackParam->SetAloneInChamber(kTRUE);
1142 // transfert the removability to the second hit
1143 if (worstTrackParamAtHit->IsRemovable()) nextTrackParam->SetRemovable(kTRUE);
1149 // Remove the worst hit
1150 track->RemoveTrackParamAtHit(worstTrackParamAtHit);
1152 // Re-fit the track:
1153 // Take into account the multiple scattering
1154 // Calculate the track parameter covariance matrix
1155 Fit(*track, kTRUE, kTRUE);
1157 // Printout for debuging
1158 if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
1159 cout << "ImproveTracks: track " << fRecTracksPtr->IndexOf(track)+1 << " improved " << endl;
1167 // compress the array in case of some tracks have been removed
1168 fRecTracksPtr->Compress();
1172 //__________________________________________________________________________
1173 void AliMUONTrackReconstructor::Finalize()
1175 /// Fill AliMUONTrack's fHitForRecAtHit array
1176 /// Recompute track parameters and covariances at each attached cluster from those at the first one
1178 AliMUONTrack *track;
1179 AliMUONTrackParam *trackParamAtHit;
1181 track = (AliMUONTrack*) fRecTracksPtr->First();
1184 // update track parameters if not already done
1185 if (!track->IsImproved()) track->UpdateCovTrackParamAtHit();
1187 trackParamAtHit = (AliMUONTrackParam*) (track->GetTrackParamAtHit()->First());
1188 while (trackParamAtHit) {
1190 // update array of track hit
1191 track->AddHitForRecAtHit(trackParamAtHit->GetHitForRecPtr());
1193 trackParamAtHit = (AliMUONTrackParam*) (track->GetTrackParamAtHit()->After(trackParamAtHit));
1196 track = (AliMUONTrack*) fRecTracksPtr->After(track);