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1 | /************************************************************************** | |
2 | * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. * | |
3 | * * | |
4 | * Author: The ALICE Off-line Project. * | |
5 | * Contributors are mentioned in the code where appropriate. * | |
6 | * * | |
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 | **************************************************************************/ | |
15 | ||
16 | /* $Id$ */ | |
17 | ||
18 | //----------------------------------------------------------------------------- | |
19 | /// \class AliMUONTrackReconstructor | |
20 | /// MUON track reconstructor using the original method | |
21 | /// | |
22 | /// This class contains as data: | |
23 | /// - the parameters for the track reconstruction | |
24 | /// | |
25 | /// It contains as methods, among others: | |
26 | /// - MakeTracks to build the tracks | |
27 | //----------------------------------------------------------------------------- | |
28 | ||
29 | #include "AliMUONTrackReconstructor.h" | |
30 | ||
31 | #include "AliMUONConstants.h" | |
32 | #include "AliMUONHitForRec.h" | |
33 | #include "AliMUONTrack.h" | |
34 | #include "AliMUONTrackParam.h" | |
35 | #include "AliMUONTrackExtrap.h" | |
36 | ||
37 | #include "AliLog.h" | |
38 | ||
39 | #include <TMinuit.h> | |
40 | #include <Riostream.h> | |
41 | #include <TMath.h> | |
42 | #include <TMatrixD.h> | |
43 | ||
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); | |
46 | ||
47 | /// \cond CLASSIMP | |
48 | ClassImp(AliMUONTrackReconstructor) // Class implementation in ROOT context | |
49 | /// \endcond | |
50 | ||
51 | //************* Parameters for reconstruction | |
52 | const Double_t AliMUONTrackReconstructor::fgkBendingVertexDispersion = 10.; | |
53 | const Double_t AliMUONTrackReconstructor::fgkNonBendingVertexDispersion = 10.; | |
54 | ||
55 | ||
56 | //__________________________________________________________________________ | |
57 | AliMUONTrackReconstructor::AliMUONTrackReconstructor() | |
58 | : AliMUONVTrackReconstructor() | |
59 | { | |
60 | /// Constructor for class AliMUONTrackReconstructor | |
61 | AliInfo("*** Original tracking ***"); | |
62 | } | |
63 | ||
64 | //__________________________________________________________________________ | |
65 | AliMUONTrackReconstructor::~AliMUONTrackReconstructor() | |
66 | { | |
67 | /// Destructor | |
68 | } | |
69 | ||
70 | //__________________________________________________________________________ | |
71 | void AliMUONTrackReconstructor::MakeTrackCandidates() | |
72 | { | |
73 | /// To make track candidates (assuming linear propagation if the flag fgkMakeTrackCandidatesFast is set to kTRUE): | |
74 | /// Start with segments station(1..) 4 or 5 then follow track in station 5 or 4. | |
75 | /// Good candidates are made of at least three hitForRec's. | |
76 | /// Keep only best candidates or all of them according to the flag fgkTrackAllTracks. | |
77 | ||
78 | TClonesArray *segments; | |
79 | AliMUONTrack *track; | |
80 | Int_t iCandidate = 0; | |
81 | Bool_t hitFound; | |
82 | ||
83 | AliDebug(1,"Enter MakeTrackCandidates"); | |
84 | ||
85 | // Loop over stations(1..) 5 and 4 and make track candidates | |
86 | for (Int_t istat=4; istat>=3; istat--) { | |
87 | ||
88 | // Make segments in the station | |
89 | segments = MakeSegmentsInStation(istat); | |
90 | ||
91 | // Loop over segments | |
92 | for (Int_t iseg=0; iseg<segments->GetEntriesFast(); iseg++) | |
93 | { | |
94 | AliDebug(1,Form("Making primary candidate(1..) %d",++iCandidate)); | |
95 | ||
96 | // Transform segments to tracks and put them at the end of fRecTracksPtr | |
97 | track = new ((*fRecTracksPtr)[fRecTracksPtr->GetLast()+1]) AliMUONTrack((AliMUONObjectPair*)((*segments)[iseg])); | |
98 | fNRecTracks++; | |
99 | ||
100 | // Printout for debuging | |
101 | if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 2) || (AliLog::GetGlobalDebugLevel() >= 2)) | |
102 | { | |
103 | cout<<endl<<"Track parameter covariances at first hit with multiple Coulomb scattering effects:"<<endl; | |
104 | ((AliMUONTrackParam*) track->GetTrackParamAtHit()->First())->GetCovariances().Print(); | |
105 | } | |
106 | ||
107 | // Look for compatible hitForRec(s) in the other station | |
108 | if (fgkMakeTrackCandidatesFast) hitFound = FollowLinearTrackInStation(*track,7-istat); | |
109 | else hitFound = FollowTrackInStation(*track,7-istat); | |
110 | ||
111 | // Remove track if no hit found | |
112 | if (!hitFound) { | |
113 | fRecTracksPtr->Remove(track); | |
114 | fNRecTracks--; | |
115 | } | |
116 | ||
117 | } | |
118 | ||
119 | // delete the array of segments | |
120 | delete segments; | |
121 | } | |
122 | ||
123 | fRecTracksPtr->Compress(); // this is essential before checking tracks | |
124 | ||
125 | // Keep all different tracks or only the best ones as required | |
126 | if (fgkTrackAllTracks) RemoveIdenticalTracks(); | |
127 | else RemoveDoubleTracks(); | |
128 | ||
129 | AliDebug(1,Form("Number of good candidates = %d",fNRecTracks)); | |
130 | ||
131 | } | |
132 | ||
133 | //__________________________________________________________________________ | |
134 | void AliMUONTrackReconstructor::FollowTracks() | |
135 | { | |
136 | /// Follow tracks in stations(1..) 3, 2 and 1 | |
137 | AliDebug(1,"Enter FollowTracks"); | |
138 | ||
139 | AliMUONTrack *track, *nextTrack; | |
140 | AliMUONTrackParam *trackParam, *nextTrackParam; | |
141 | Int_t currentNRecTracks; | |
142 | Bool_t hitFound; | |
143 | ||
144 | for (Int_t station = 2; station >= 0; station--) { | |
145 | ||
146 | // Save the actual number of reconstructed track in case of | |
147 | // tracks are added or suppressed during the tracking procedure | |
148 | // !! Do not compress fRecTracksPtr until the end of the loop over tracks !! | |
149 | currentNRecTracks = fNRecTracks; | |
150 | ||
151 | for (Int_t iRecTrack = 0; iRecTrack <currentNRecTracks; iRecTrack++) { | |
152 | AliDebug(1,Form("FollowTracks: track candidate(1..) %d", iRecTrack+1)); | |
153 | ||
154 | track = (AliMUONTrack*) fRecTracksPtr->UncheckedAt(iRecTrack); | |
155 | ||
156 | // Fit the track: | |
157 | // Do not take into account the multiple scattering to speed up the fit | |
158 | // Calculate the track parameter covariance matrix | |
159 | // If "station" is station(1..) 3 then use the vertex to better constrain the fit | |
160 | if (station==2) { | |
161 | SetVertexForFit(*track); | |
162 | track->SetFitWithVertex(kTRUE); | |
163 | } else track->SetFitWithVertex(kFALSE); | |
164 | Fit(*track, kFALSE, kTRUE); | |
165 | ||
166 | // Remove the track if the normalized chi2 is too high | |
167 | if (track->GetNormalizedChi2() > fgkSigmaToCutForTracking * fgkSigmaToCutForTracking) { | |
168 | fRecTracksPtr->Remove(track); | |
169 | fNRecTracks--; | |
170 | continue; | |
171 | } | |
172 | ||
173 | // save parameters from fit into smoothed parameters to complete track afterward | |
174 | if (fgkComplementTracks) { | |
175 | ||
176 | if (station==2) { // save track parameters on stations 4 and 5 | |
177 | ||
178 | // extrapolate track parameters and covariances at each cluster | |
179 | track->UpdateCovTrackParamAtHit(); | |
180 | ||
181 | // save them | |
182 | trackParam = (AliMUONTrackParam*) track->GetTrackParamAtHit()->First(); | |
183 | while (trackParam) { | |
184 | trackParam->SetSmoothParameters(trackParam->GetParameters()); | |
185 | trackParam->SetSmoothCovariances(trackParam->GetCovariances()); | |
186 | trackParam = (AliMUONTrackParam*) track->GetTrackParamAtHit()->After(trackParam); | |
187 | } | |
188 | ||
189 | } else { // or save track parameters on last station only | |
190 | ||
191 | // save parameters from fit | |
192 | trackParam = (AliMUONTrackParam*) track->GetTrackParamAtHit()->First(); | |
193 | trackParam->SetSmoothParameters(trackParam->GetParameters()); | |
194 | trackParam->SetSmoothCovariances(trackParam->GetCovariances()); | |
195 | ||
196 | // save parameters extrapolated to the second chamber of the same station if it has been hit | |
197 | nextTrackParam = (AliMUONTrackParam*) track->GetTrackParamAtHit()->After(trackParam); | |
198 | if (nextTrackParam->GetHitForRecPtr()->GetChamberNumber() < 2*(station+2)) { | |
199 | ||
200 | // reset parameters and covariances | |
201 | nextTrackParam->SetParameters(trackParam->GetParameters()); | |
202 | nextTrackParam->SetZ(trackParam->GetZ()); | |
203 | nextTrackParam->SetCovariances(trackParam->GetCovariances()); | |
204 | ||
205 | // extrapolate them to the z of the corresponding cluster | |
206 | AliMUONTrackExtrap::ExtrapToZCov(nextTrackParam, nextTrackParam->GetHitForRecPtr()->GetZ()); | |
207 | ||
208 | // save them | |
209 | nextTrackParam->SetSmoothParameters(nextTrackParam->GetParameters()); | |
210 | nextTrackParam->SetSmoothCovariances(nextTrackParam->GetCovariances()); | |
211 | ||
212 | } | |
213 | ||
214 | } | |
215 | ||
216 | } | |
217 | ||
218 | // Printout for debuging | |
219 | if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 2) || (AliLog::GetGlobalDebugLevel() >= 2)) { | |
220 | cout<<endl<<"Track parameter covariances at first hit with multiple Coulomb scattering effects:"<<endl; | |
221 | ((AliMUONTrackParam*) track->GetTrackParamAtHit()->First())->GetCovariances().Print(); | |
222 | } | |
223 | ||
224 | // Look for compatible hitForRec in station(0..) "station" | |
225 | hitFound = FollowTrackInStation(*track,station); | |
226 | ||
227 | // Try to recover track if required | |
228 | if (!hitFound && fgkRecoverTracks) hitFound = RecoverTrack(*track,station); | |
229 | ||
230 | // remove track if no hit found | |
231 | if (!hitFound) { | |
232 | fRecTracksPtr->Remove(track); | |
233 | fNRecTracks--; | |
234 | } | |
235 | ||
236 | } | |
237 | ||
238 | // Compress fRecTracksPtr for the next step | |
239 | fRecTracksPtr->Compress(); | |
240 | ||
241 | // Keep only the best tracks if required | |
242 | if (!fgkTrackAllTracks) RemoveDoubleTracks(); | |
243 | ||
244 | } | |
245 | ||
246 | // Last fit of track candidates with all station | |
247 | // Take into account the multiple scattering and remove bad tracks | |
248 | Int_t trackIndex = -1; | |
249 | track = (AliMUONTrack*) fRecTracksPtr->First(); | |
250 | while (track) { | |
251 | ||
252 | trackIndex++; | |
253 | nextTrack = (AliMUONTrack*) fRecTracksPtr->After(track); // prepare next track | |
254 | ||
255 | track->SetFitWithVertex(kFALSE); // just to be sure | |
256 | Fit(*track, kTRUE, kTRUE); | |
257 | ||
258 | // Printout for debuging | |
259 | if (AliLog::GetGlobalDebugLevel() >= 3) { | |
260 | cout << "FollowTracks: track candidate(0..) " << trackIndex << " after final fit" << endl; | |
261 | track->RecursiveDump(); | |
262 | } | |
263 | ||
264 | // Remove the track if the normalized chi2 is too high | |
265 | if (track->GetNormalizedChi2() > fgkSigmaToCutForTracking * fgkSigmaToCutForTracking) { | |
266 | fRecTracksPtr->Remove(track); | |
267 | fNRecTracks--; | |
268 | } | |
269 | ||
270 | // save parameters from fit into smoothed parameters to complete track afterward | |
271 | if (fgkComplementTracks) { | |
272 | ||
273 | // save parameters from fit | |
274 | trackParam = (AliMUONTrackParam*) track->GetTrackParamAtHit()->First(); | |
275 | trackParam->SetSmoothParameters(trackParam->GetParameters()); | |
276 | trackParam->SetSmoothCovariances(trackParam->GetCovariances()); | |
277 | ||
278 | // save parameters extrapolated to the second chamber of the same station if it has been hit | |
279 | nextTrackParam = (AliMUONTrackParam*) track->GetTrackParamAtHit()->After(trackParam); | |
280 | if (nextTrackParam->GetHitForRecPtr()->GetChamberNumber() < 2) { | |
281 | ||
282 | // reset parameters and covariances | |
283 | nextTrackParam->SetParameters(trackParam->GetParameters()); | |
284 | nextTrackParam->SetZ(trackParam->GetZ()); | |
285 | nextTrackParam->SetCovariances(trackParam->GetCovariances()); | |
286 | ||
287 | // extrapolate them to the z of the corresponding cluster | |
288 | AliMUONTrackExtrap::ExtrapToZCov(nextTrackParam, nextTrackParam->GetHitForRecPtr()->GetZ()); | |
289 | ||
290 | // save them | |
291 | nextTrackParam->SetSmoothParameters(nextTrackParam->GetParameters()); | |
292 | nextTrackParam->SetSmoothCovariances(nextTrackParam->GetCovariances()); | |
293 | ||
294 | } | |
295 | ||
296 | } | |
297 | ||
298 | track = nextTrack; | |
299 | ||
300 | } | |
301 | ||
302 | fRecTracksPtr->Compress(); | |
303 | ||
304 | } | |
305 | ||
306 | //__________________________________________________________________________ | |
307 | Bool_t AliMUONTrackReconstructor::FollowTrackInStation(AliMUONTrack &trackCandidate, Int_t nextStation) | |
308 | { | |
309 | /// Follow trackCandidate in station(0..) nextStation and search for compatible HitForRec(s) | |
310 | /// Keep all possibilities or only the best one(s) according to the flag fgkTrackAllTracks: | |
311 | /// kTRUE: duplicate "trackCandidate" if there are several possibilities and add the new tracks at the end of | |
312 | /// fRecTracksPtr to avoid conficts with other track candidates at this current stage of the tracking procedure. | |
313 | /// Remove the obsolete "trackCandidate" at the end. | |
314 | /// kFALSE: add only the best hit(s) to the "trackCandidate". Try to add a couple of hits in priority. | |
315 | AliDebug(1,Form("Enter FollowTrackInStation(1..) %d", nextStation+1)); | |
316 | ||
317 | // Order the chamber according to the propagation direction (tracking starts with chamber 2): | |
318 | // - nextStation == station(1...) 5 => forward propagation | |
319 | // - nextStation < station(1...) 5 => backward propagation | |
320 | Int_t ch1, ch2; | |
321 | if (nextStation==4) { | |
322 | ch1 = 2*nextStation+1; | |
323 | ch2 = 2*nextStation; | |
324 | } else { | |
325 | ch1 = 2*nextStation; | |
326 | ch2 = 2*nextStation+1; | |
327 | } | |
328 | ||
329 | Double_t chi2WithOneHitForRec = 1.e10; | |
330 | Double_t chi2WithTwoHitForRec = 1.e10; | |
331 | Double_t maxChi2WithOneHitForRec = 2. * fgkSigmaToCutForTracking * fgkSigmaToCutForTracking; // 2 because 2 quantities in chi2 | |
332 | Double_t maxChi2WithTwoHitForRec = 4. * fgkSigmaToCutForTracking * fgkSigmaToCutForTracking; // 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; | |
346 | ||
347 | // Get track parameters | |
348 | AliMUONTrackParam extrapTrackParamAtCh(*(AliMUONTrackParam*)trackCandidate.GetTrackParamAtHit()->First()); | |
349 | ||
350 | // Add MCS effect | |
351 | AliMUONTrackExtrap::AddMCSEffect(&extrapTrackParamAtCh,AliMUONConstants::ChamberThicknessInX0(),1.); | |
352 | ||
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)); | |
357 | // add MCS effect | |
358 | AliMUONTrackExtrap::AddMCSEffect(&extrapTrackParamAtCh,AliMUONConstants::ChamberThicknessInX0(),1.); | |
359 | } | |
360 | ||
361 | //Extrapolate trackCandidate to chamber "ch2" | |
362 | AliMUONTrackExtrap::ExtrapToZCov(&extrapTrackParamAtCh, AliMUONConstants::DefaultChamberZ(ch2)); | |
363 | ||
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(); | |
368 | } | |
369 | ||
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; | |
373 | } | |
374 | ||
375 | // look for candidates in chamber 2 | |
376 | for (Int_t hit2 = 0; hit2 < fNHitsForRecPerChamber[ch2]; hit2++) { | |
377 | ||
378 | hitForRecCh2 = (AliMUONHitForRec*) fHitsForRecPtr->UncheckedAt(fIndexOfFirstHitForRecPerChamber[ch2]+hit2); | |
379 | ||
380 | // try to add the current hit fast | |
381 | if (!TryOneHitForRecFast(extrapTrackParamAtCh, hitForRecCh2)) continue; | |
382 | ||
383 | // try to add the current hit accuratly | |
384 | chi2WithOneHitForRec = TryOneHitForRec(extrapTrackParamAtCh, hitForRecCh2, extrapTrackParamAtHit2); | |
385 | ||
386 | // if good chi2 then try to attach a hitForRec in the other chamber too | |
387 | if (chi2WithOneHitForRec < maxChi2WithOneHitForRec) { | |
388 | Bool_t foundSecondHit = kFALSE; | |
389 | ||
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; | |
395 | } | |
396 | ||
397 | // add MCS effect for next step | |
398 | AliMUONTrackExtrap::AddMCSEffect(&extrapTrackParamAtHit2,AliMUONConstants::ChamberThicknessInX0(),1.); | |
399 | ||
400 | // copy new track parameters for next step | |
401 | extrapTrackParam = extrapTrackParamAtHit2; | |
402 | ||
403 | //Extrapolate track parameters to chamber "ch1" | |
404 | AliMUONTrackExtrap::ExtrapToZ(&extrapTrackParam, AliMUONConstants::DefaultChamberZ(ch1)); | |
405 | ||
406 | for (Int_t hit1 = 0; hit1 < fNHitsForRecPerChamber[ch1]; hit1++) { | |
407 | ||
408 | hitForRecCh1 = (AliMUONHitForRec*) fHitsForRecPtr->UncheckedAt(fIndexOfFirstHitForRecPerChamber[ch1]+hit1); | |
409 | ||
410 | // try to add the current hit fast | |
411 | if (!TryOneHitForRecFast(extrapTrackParam, hitForRecCh1)) continue; | |
412 | ||
413 | // try to add the current hit accuratly | |
414 | chi2WithTwoHitForRec = TryTwoHitForRec(extrapTrackParamAtHit2, hitForRecCh1, extrapTrackParamAtHit1); | |
415 | ||
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; | |
420 | ||
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; | |
425 | } | |
426 | ||
427 | if (fgkTrackAllTracks) { | |
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); | |
431 | fNRecTracks++; | |
432 | ||
433 | // Tag hitForRecCh1 as used | |
434 | hitForRecCh1Used[hit1] = kTRUE; | |
435 | ||
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(); | |
440 | } | |
441 | ||
442 | } else if (chi2WithTwoHitForRec < bestChi2WithTwoHitForRec) { | |
443 | // keep track of the best couple of hits | |
444 | bestChi2WithTwoHitForRec = chi2WithTwoHitForRec; | |
445 | bestTrackParamAtHit1 = extrapTrackParamAtHit1; | |
446 | bestTrackParamAtHit2 = extrapTrackParamAtHit2; | |
447 | } | |
448 | ||
449 | } | |
450 | ||
451 | } | |
452 | ||
453 | // if no hitForRecCh1 found then consider to add hitForRecCh2 only | |
454 | if (!foundSecondHit) { | |
455 | foundOneHit = kTRUE; | |
456 | ||
457 | if (fgkTrackAllTracks) { | |
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); | |
461 | fNRecTracks++; | |
462 | ||
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(); | |
467 | } | |
468 | ||
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; | |
473 | } | |
474 | ||
475 | } | |
476 | ||
477 | } | |
478 | ||
479 | } | |
480 | ||
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 (fgkTrackAllTracks || !foundTwoHits) { | |
484 | ||
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; | |
488 | } | |
489 | ||
490 | // add MCS effect for next step | |
491 | AliMUONTrackExtrap::AddMCSEffect(&extrapTrackParamAtCh,AliMUONConstants::ChamberThicknessInX0(),1.); | |
492 | ||
493 | //Extrapolate trackCandidate to chamber "ch1" | |
494 | AliMUONTrackExtrap::ExtrapToZCov(&extrapTrackParamAtCh, AliMUONConstants::DefaultChamberZ(ch1)); | |
495 | ||
496 | for (Int_t hit1 = 0; hit1 < fNHitsForRecPerChamber[ch1]; hit1++) { | |
497 | ||
498 | hitForRecCh1 = (AliMUONHitForRec*) fHitsForRecPtr->UncheckedAt(fIndexOfFirstHitForRecPerChamber[ch1]+hit1); | |
499 | ||
500 | if (hitForRecCh1Used[hit1]) continue; // Skip hitForRec already used | |
501 | ||
502 | // try to add the current hit fast | |
503 | if (!TryOneHitForRecFast(extrapTrackParamAtCh, hitForRecCh1)) continue; | |
504 | ||
505 | // try to add the current hit accuratly | |
506 | chi2WithOneHitForRec = TryOneHitForRec(extrapTrackParamAtCh, hitForRecCh1, extrapTrackParamAtHit1); | |
507 | ||
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) { | |
511 | foundOneHit = kTRUE; | |
512 | ||
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; | |
517 | } | |
518 | ||
519 | if (fgkTrackAllTracks) { | |
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); | |
523 | fNRecTracks++; | |
524 | ||
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(); | |
529 | } | |
530 | ||
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; | |
535 | } | |
536 | ||
537 | } | |
538 | ||
539 | } | |
540 | ||
541 | } | |
542 | ||
543 | // fill out the best track if required else clean up the fRecTracksPtr array | |
544 | if (!fgkTrackAllTracks) { | |
545 | if (foundTwoHits) { | |
546 | UpdateTrack(trackCandidate,bestTrackParamAtHit1,bestTrackParamAtHit2); | |
547 | ||
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(); | |
552 | } | |
553 | ||
554 | } else if (foundOneHit) { | |
555 | UpdateTrack(trackCandidate,bestTrackParamAtHit1); | |
556 | ||
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(); | |
561 | } | |
562 | ||
563 | } else { | |
564 | delete [] hitForRecCh1Used; | |
565 | return kFALSE; | |
566 | } | |
567 | ||
568 | } else if (foundOneHit || foundTwoHits) { | |
569 | ||
570 | // remove obsolete track | |
571 | fRecTracksPtr->Remove(&trackCandidate); | |
572 | fNRecTracks--; | |
573 | ||
574 | } else { | |
575 | delete [] hitForRecCh1Used; | |
576 | return kFALSE; | |
577 | } | |
578 | ||
579 | delete [] hitForRecCh1Used; | |
580 | return kTRUE; | |
581 | ||
582 | } | |
583 | ||
584 | //__________________________________________________________________________ | |
585 | Double_t AliMUONTrackReconstructor::TryTwoHitForRec(const AliMUONTrackParam &trackParamAtHit1, AliMUONHitForRec* hitForRec2, | |
586 | AliMUONTrackParam &trackParamAtHit2) | |
587 | { | |
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 | |
591 | ||
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()); | |
596 | ||
597 | // set pointer to hit2 into trackParamAtHit2 | |
598 | trackParamAtHit2.SetHitForRecPtr(hitForRec2); | |
599 | ||
600 | // Set differences between track and the 2 hitForRec in the bending and non bending directions | |
601 | AliMUONHitForRec* hitForRec1 = trackParamAtHit1.GetHitForRecPtr(); | |
602 | TMatrixD dPos(4,1); | |
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(); | |
607 | ||
608 | // Calculate the error matrix from the track parameter covariances at first hitForRec | |
609 | TMatrixD error(4,4); | |
610 | error.Zero(); | |
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(); | |
616 | ||
617 | // Save track coordinates at second hitForRec | |
618 | Double_t nonBendingCoor2 = trackParamAtHit2.GetNonBendingCoor(); | |
619 | Double_t bendingCoor2 = trackParamAtHit2.GetBendingCoor(); | |
620 | ||
621 | // add MCS effect at first hitForRec | |
622 | AliMUONTrackExtrap::AddMCSEffect(&trackParamAtHit1Save,AliMUONConstants::ChamberThicknessInX0(),1.); | |
623 | ||
624 | // Get the pointer to the parameter covariance matrix at first hitForRec | |
625 | const TMatrixD& kParamCov = trackParamAtHit1Save.GetCovariances(); | |
626 | ||
627 | // Calculate the jacobian related to the transformation between track parameters | |
628 | // at first hitForRec and track coordinates at the 2 hitForRec z-position | |
629 | TMatrixD jacob(4,5); | |
630 | jacob.Zero(); | |
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++) { | |
641 | if (j==i) { | |
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.; | |
645 | } | |
646 | ||
647 | // Set new track parameters at first hitForRec | |
648 | trackParamAtHit1Save.SetParameters(paramAtHit1Save); | |
649 | trackParamAtHit1Save.AddParameters(dParam); | |
650 | trackParamAtHit1Save.SetZ(z1); | |
651 | ||
652 | // Extrapolate new track parameters to the z position of the second hitForRec | |
653 | AliMUONTrackExtrap::ExtrapToZ(&trackParamAtHit1Save,hitForRec2->GetZ()); | |
654 | ||
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 | |
658 | } | |
659 | ||
660 | // Calculate the error matrix | |
661 | TMatrixD tmp(jacob,TMatrixD::kMult,kParamCov); | |
662 | error = TMatrixD(tmp,TMatrixD::kMultTranspose,jacob); | |
663 | } | |
664 | ||
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(); | |
670 | ||
671 | // invert the error matrix for Chi2 calculation | |
672 | if (error.Determinant() != 0) { | |
673 | error.Invert(); | |
674 | } else { | |
675 | AliWarning(" Determinant error=0"); | |
676 | return 1.e10; | |
677 | } | |
678 | ||
679 | // Compute the Chi2 value | |
680 | TMatrixD tmp2(dPos,TMatrixD::kTransposeMult,error); | |
681 | TMatrixD result(tmp2,TMatrixD::kMult,dPos); | |
682 | ||
683 | return result(0,0); | |
684 | ||
685 | } | |
686 | ||
687 | //__________________________________________________________________________ | |
688 | void AliMUONTrackReconstructor::UpdateTrack(AliMUONTrack &track, AliMUONTrackParam &trackParamAtHit) | |
689 | { | |
690 | /// Add 1 hit to the track candidate | |
691 | /// Update chi2 of the track | |
692 | ||
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(); | |
699 | ||
700 | // Flag hit as being not removable | |
701 | trackParamAtHit.SetRemovable(kFALSE); | |
702 | trackParamAtHit.SetLocalChi2(0.); // --> Local chi2 not used | |
703 | ||
704 | // Update the chi2 of the new track | |
705 | track.SetFitFMin(track.GetFitFMin() + localChi2); | |
706 | ||
707 | // Update TrackParamAtHit | |
708 | track.AddTrackParamAtHit(&trackParamAtHit,trackParamAtHit.GetHitForRecPtr()); | |
709 | track.GetTrackParamAtHit()->Sort(); | |
710 | ||
711 | } | |
712 | ||
713 | //__________________________________________________________________________ | |
714 | void AliMUONTrackReconstructor::UpdateTrack(AliMUONTrack &track, AliMUONTrackParam &trackParamAtHit1, AliMUONTrackParam &trackParamAtHit2) | |
715 | { | |
716 | /// Add 2 hits to the track candidate | |
717 | /// Update track and local chi2 | |
718 | ||
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); | |
726 | ||
727 | // Flag first hit as being removable | |
728 | trackParamAtHit1.SetRemovable(kTRUE); | |
729 | ||
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); | |
737 | ||
738 | // Flag first hit as being removable | |
739 | trackParamAtHit2.SetRemovable(kTRUE); | |
740 | ||
741 | // Update the chi2 of the new track | |
742 | track.SetFitFMin(track.GetFitFMin() + localChi2AtHit1 + localChi2AtHit2); | |
743 | ||
744 | // Update TrackParamAtHit | |
745 | track.AddTrackParamAtHit(&trackParamAtHit1,trackParamAtHit1.GetHitForRecPtr()); | |
746 | track.AddTrackParamAtHit(&trackParamAtHit2,trackParamAtHit2.GetHitForRecPtr()); | |
747 | track.GetTrackParamAtHit()->Sort(); | |
748 | ||
749 | } | |
750 | ||
751 | //__________________________________________________________________________ | |
752 | Bool_t AliMUONTrackReconstructor::RecoverTrack(AliMUONTrack &trackCandidate, Int_t nextStation) | |
753 | { | |
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"); | |
758 | ||
759 | // Do not try to recover track until we have attached hit(s) on station(1..) 3 | |
760 | if (nextStation > 1) return kFALSE; | |
761 | ||
762 | Int_t worstHitNumber = -1; | |
763 | Double_t localChi2, worstLocalChi2 = 0.; | |
764 | ||
765 | // Look for the hit to remove | |
766 | for (Int_t hitNumber = 0; hitNumber < 2; hitNumber++) { | |
767 | AliMUONTrackParam *trackParamAtHit = (AliMUONTrackParam*)trackCandidate.GetTrackParamAtHit()->UncheckedAt(hitNumber); | |
768 | ||
769 | // check if current hit is removable | |
770 | if (!trackParamAtHit->IsRemovable()) return kFALSE; | |
771 | ||
772 | // Pick up hit with the worst chi2 | |
773 | localChi2 = trackParamAtHit->GetLocalChi2(); | |
774 | if (localChi2 > worstLocalChi2) { | |
775 | worstLocalChi2 = localChi2; | |
776 | worstHitNumber = hitNumber; | |
777 | } | |
778 | } | |
779 | ||
780 | // Reset best hit as being NOT removable | |
781 | ((AliMUONTrackParam*)trackCandidate.GetTrackParamAtHit()->UncheckedAt((worstHitNumber+1)%2))->SetRemovable(kFALSE); | |
782 | ||
783 | // Remove the worst hit | |
784 | trackCandidate.RemoveTrackParamAtHit((AliMUONTrackParam*)trackCandidate.GetTrackParamAtHit()->UncheckedAt(worstHitNumber)); | |
785 | ||
786 | // Re-fit the track: | |
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); | |
791 | ||
792 | // Look for new hit(s) in next station | |
793 | return FollowTrackInStation(trackCandidate,nextStation); | |
794 | ||
795 | } | |
796 | ||
797 | //__________________________________________________________________________ | |
798 | void AliMUONTrackReconstructor::SetVertexForFit(AliMUONTrack &trackCandidate) | |
799 | { | |
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"); | |
806 | ||
807 | Double_t nonBendingReso2 = fgkNonBendingVertexDispersion * fgkNonBendingVertexDispersion; | |
808 | Double_t bendingReso2 = fgkBendingVertexDispersion * fgkBendingVertexDispersion; | |
809 | // add multiple scattering effets | |
810 | AliMUONTrackParam paramAtVertex(*((AliMUONTrackParam*)(trackCandidate.GetTrackParamAtHit()->First()))); | |
811 | paramAtVertex.DeleteCovariances(); // to be sure to account only for multiple scattering | |
812 | AliMUONTrackExtrap::ExtrapToVertexUncorrected(¶mAtVertex,0.); | |
813 | const TMatrixD& kParamCov = paramAtVertex.GetCovariances(); | |
814 | nonBendingReso2 += kParamCov(0,0); | |
815 | bendingReso2 += kParamCov(2,2); | |
816 | // Set the vertex | |
817 | AliMUONHitForRec vertex; // Coordinates set to (0.,0.,0.) by default | |
818 | vertex.SetNonBendingReso2(nonBendingReso2); | |
819 | vertex.SetBendingReso2(bendingReso2); | |
820 | trackCandidate.SetVertex(&vertex); | |
821 | } | |
822 | ||
823 | //__________________________________________________________________________ | |
824 | void AliMUONTrackReconstructor::Fit(AliMUONTrack &track, Bool_t includeMCS, Bool_t calcCov) | |
825 | { | |
826 | /// Fit the track "track" w/wo multiple Coulomb scattering according to "includeMCS". | |
827 | ||
828 | Double_t benC, errorParam, invBenP, nonBenC, x, y; | |
829 | AliMUONTrackParam *trackParam; | |
830 | Double_t arg[1], fedm, errdef, fitFMin; | |
831 | Int_t npari, nparx; | |
832 | Int_t status, covStatus; | |
833 | ||
834 | // Instantiate gMinuit if not already done | |
835 | if (!gMinuit) gMinuit = new TMinuit(6); | |
836 | // Clear MINUIT parameters | |
837 | gMinuit->mncler(); | |
838 | // Give the fitted track to MINUIT | |
839 | gMinuit->SetObjectFit(&track); | |
840 | if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 2) || (AliLog::GetGlobalDebugLevel() >= 2)) { | |
841 | // Define print level | |
842 | arg[0] = 1; | |
843 | gMinuit->mnexcm("SET PRI", arg, 1, status); | |
844 | // Print covariance matrix | |
845 | gMinuit->mnexcm("SHO COV", arg, 0, status); | |
846 | } else { | |
847 | arg[0] = -1; | |
848 | gMinuit->mnexcm("SET PRI", arg, 1, status); | |
849 | } | |
850 | // No warnings | |
851 | gMinuit->mnexcm("SET NOW", arg, 0, status); | |
852 | // Define strategy | |
853 | //arg[0] = 2; | |
854 | //gMinuit->mnexcm("SET STR", arg, 1, status); | |
855 | ||
856 | // set flag w/wo multiple scattering according to "includeMCS" | |
857 | track.SetFitWithMCS(includeMCS); | |
858 | if (includeMCS) { | |
859 | // compute hit weights only once | |
860 | if (!track.ComputeHitWeights()) { | |
861 | AliWarning("cannot take into account the multiple scattering effects"); | |
862 | track.SetFitWithMCS(kFALSE); | |
863 | } | |
864 | } | |
865 | ||
866 | // Set fitting function | |
867 | gMinuit->SetFCN(TrackChi2); | |
868 | ||
869 | // Set fitted parameters (!! The order is very important for the covariance matrix !!) | |
870 | trackParam = (AliMUONTrackParam*) (track.GetTrackParamAtHit()->First()); | |
871 | // could be tried with no limits for the search (min=max=0) ???? | |
872 | // mandatory limits in non Bending to avoid NaN values of parameters | |
873 | gMinuit->mnparm(0, "X", trackParam->GetNonBendingCoor(), 0.03, -500.0, 500.0, status); | |
874 | gMinuit->mnparm(1, "NonBenS", trackParam->GetNonBendingSlope(), 0.001, -0.5, 0.5, status); | |
875 | // mandatory limits in Bending to avoid NaN values of parameters | |
876 | gMinuit->mnparm(2, "Y", trackParam->GetBendingCoor(), 0.10, -500.0, 500.0, status); | |
877 | gMinuit->mnparm(3, "BenS", trackParam->GetBendingSlope(), 0.001, -0.5, 0.5, status); | |
878 | gMinuit->mnparm(4, "InvBenP", trackParam->GetInverseBendingMomentum(), 0.003, -0.4, 0.4, status); | |
879 | ||
880 | // minimization | |
881 | gMinuit->mnexcm("MIGRAD", arg, 0, status); | |
882 | ||
883 | // Calculate the covariance matrix more accurately if required | |
884 | if (calcCov) gMinuit->mnexcm("HESSE", arg, 0, status); | |
885 | ||
886 | // get results into "invBenP", "benC", "nonBenC" ("x", "y") | |
887 | gMinuit->GetParameter(0, x, errorParam); | |
888 | trackParam->SetNonBendingCoor(x); | |
889 | gMinuit->GetParameter(1, nonBenC, errorParam); | |
890 | trackParam->SetNonBendingSlope(nonBenC); | |
891 | gMinuit->GetParameter(2, y, errorParam); | |
892 | trackParam->SetBendingCoor(y); | |
893 | gMinuit->GetParameter(3, benC, errorParam); | |
894 | trackParam->SetBendingSlope(benC); | |
895 | gMinuit->GetParameter(4, invBenP, errorParam); | |
896 | trackParam->SetInverseBendingMomentum(invBenP); | |
897 | ||
898 | // global result of the fit | |
899 | gMinuit->mnstat(fitFMin, fedm, errdef, npari, nparx, covStatus); | |
900 | track.SetFitFMin(fitFMin); | |
901 | ||
902 | // Get the covariance matrix if required | |
903 | if (calcCov) { | |
904 | // Covariance matrix according to HESSE status | |
905 | // If problem then keep only the diagonal terms (variances) | |
906 | Double_t matrix[5][5]; | |
907 | gMinuit->mnemat(&matrix[0][0],5); | |
908 | if (covStatus == 3) trackParam->SetCovariances(matrix); | |
909 | else trackParam->SetVariances(matrix); | |
910 | } else trackParam->DeleteCovariances(); | |
911 | ||
912 | } | |
913 | ||
914 | //__________________________________________________________________________ | |
915 | void TrackChi2(Int_t & /*nParam*/, Double_t * /*gradient*/, Double_t &chi2, Double_t *param, Int_t /*flag*/) | |
916 | { | |
917 | /// Return the "Chi2" to be minimized with Minuit for track fitting. | |
918 | /// Assumes that the track hits are sorted according to increasing Z. | |
919 | /// Track parameters at each TrackHit are updated accordingly. | |
920 | /// Vertex is used according to the flag "trackBeingFitted->GetFitWithVertex()". | |
921 | /// Multiple Coulomb scattering is taken into account according to the flag "trackBeingFitted->GetFitWithMCS()". | |
922 | ||
923 | AliMUONTrack *trackBeingFitted = (AliMUONTrack*) gMinuit->GetObjectFit(); | |
924 | AliMUONTrackParam* trackParamAtHit = (AliMUONTrackParam*) trackBeingFitted->GetTrackParamAtHit()->First(); | |
925 | Double_t dX, dY; | |
926 | chi2 = 0.; // initialize chi2 | |
927 | ||
928 | // update track parameters | |
929 | trackParamAtHit->SetNonBendingCoor(param[0]); | |
930 | trackParamAtHit->SetNonBendingSlope(param[1]); | |
931 | trackParamAtHit->SetBendingCoor(param[2]); | |
932 | trackParamAtHit->SetBendingSlope(param[3]); | |
933 | trackParamAtHit->SetInverseBendingMomentum(param[4]); | |
934 | trackBeingFitted->UpdateTrackParamAtHit(); | |
935 | ||
936 | // Take the vertex into account in the fit if required | |
937 | if (trackBeingFitted->GetFitWithVertex()) { | |
938 | AliMUONTrackParam paramAtVertex(*trackParamAtHit); | |
939 | AliMUONTrackExtrap::ExtrapToZ(¶mAtVertex, 0.); | |
940 | AliMUONHitForRec *vertex = trackBeingFitted->GetVertex(); | |
941 | if (!vertex) { | |
942 | cout<<"Error in TrackChi2: Want to use the vertex in tracking but it has not been created!!"<<endl; | |
943 | exit(-1); | |
944 | } | |
945 | dX = vertex->GetNonBendingCoor() - paramAtVertex.GetNonBendingCoor(); | |
946 | dY = vertex->GetBendingCoor() - paramAtVertex.GetBendingCoor(); | |
947 | chi2 += dX * dX / vertex->GetNonBendingReso2() + dY * dY / vertex->GetBendingReso2(); | |
948 | } | |
949 | ||
950 | // compute chi2 w/wo multiple scattering | |
951 | chi2 += trackBeingFitted->ComputeGlobalChi2(trackBeingFitted->GetFitWithMCS()); | |
952 | ||
953 | } | |
954 | ||
955 | //__________________________________________________________________________ | |
956 | void AliMUONTrackReconstructor::ComplementTracks() | |
957 | { | |
958 | /// Complete tracks by adding missing clusters (if there is an overlap between | |
959 | /// two detection elements, the track may have two clusters in the same chamber) | |
960 | /// Re-fit track parameters and covariances | |
961 | AliDebug(1,"Enter ComplementTracks"); | |
962 | ||
963 | Int_t chamberId, detElemId; | |
964 | Double_t chi2OfHitForRec, bestChi2OfHitForRec; | |
965 | Bool_t foundOneHit, trackModified; | |
966 | AliMUONHitForRec* hitForRec; | |
967 | AliMUONTrackParam* trackParam, *nextTrackParam; | |
968 | AliMUONTrackParam copyOfTrackParam; | |
969 | AliMUONTrackParam trackParamAtHit; | |
970 | AliMUONTrackParam bestTrackParamAtHit; | |
971 | ||
972 | // Remove double track to complete only "good" tracks | |
973 | RemoveDoubleTracks(); | |
974 | ||
975 | AliMUONTrack *track = (AliMUONTrack*) fRecTracksPtr->First(); | |
976 | while (track) { | |
977 | trackModified = kFALSE; | |
978 | ||
979 | trackParam = (AliMUONTrackParam*)track->GetTrackParamAtHit()->First(); | |
980 | while (trackParam) { | |
981 | foundOneHit = kFALSE; | |
982 | bestChi2OfHitForRec = 2. * fgkSigmaToCutForTracking * fgkSigmaToCutForTracking; // 2 because 2 quantities in chi2 | |
983 | ||
984 | // prepare nextTrackParam before adding new cluster because of the sorting | |
985 | nextTrackParam = (AliMUONTrackParam*)track->GetTrackParamAtHit()->After(trackParam); | |
986 | ||
987 | chamberId = trackParam->GetHitForRecPtr()->GetChamberNumber(); | |
988 | detElemId = trackParam->GetHitForRecPtr()->GetDetElemId(); | |
989 | ||
990 | // recover track parameters from local fit and put them into a copy of trackParam | |
991 | copyOfTrackParam.SetZ(trackParam->GetZ()); | |
992 | copyOfTrackParam.SetParameters(trackParam->GetSmoothParameters()); | |
993 | copyOfTrackParam.SetCovariances(trackParam->GetSmoothCovariances()); | |
994 | ||
995 | // look for one second candidate in the same chamber | |
996 | for (Int_t hit = 0; hit < fNHitsForRecPerChamber[chamberId]; hit++) { | |
997 | ||
998 | hitForRec = (AliMUONHitForRec*) fHitsForRecPtr->UncheckedAt(fIndexOfFirstHitForRecPerChamber[chamberId]+hit); | |
999 | ||
1000 | // look for a cluster in another detection element | |
1001 | if (hitForRec->GetDetElemId() == detElemId) continue; | |
1002 | ||
1003 | // try to add the current hit fast | |
1004 | if (!TryOneHitForRecFast(copyOfTrackParam, hitForRec)) continue; | |
1005 | ||
1006 | // try to add the current hit accurately | |
1007 | chi2OfHitForRec = TryOneHitForRec(copyOfTrackParam, hitForRec, trackParamAtHit); | |
1008 | ||
1009 | // if better chi2 then prepare to add this cluster to the track | |
1010 | if (chi2OfHitForRec < bestChi2OfHitForRec) { | |
1011 | bestChi2OfHitForRec = chi2OfHitForRec; | |
1012 | bestTrackParamAtHit = trackParamAtHit; | |
1013 | foundOneHit = kTRUE; | |
1014 | } | |
1015 | ||
1016 | } | |
1017 | ||
1018 | // add new cluster if any | |
1019 | if (foundOneHit) { | |
1020 | UpdateTrack(*track,bestTrackParamAtHit); | |
1021 | bestTrackParamAtHit.SetAloneInChamber(kFALSE); | |
1022 | trackParam->SetAloneInChamber(kFALSE); | |
1023 | trackModified = kTRUE; | |
1024 | } | |
1025 | ||
1026 | trackParam = nextTrackParam; | |
1027 | } | |
1028 | ||
1029 | // re-fit track parameters if needed | |
1030 | if (trackModified) Fit(*track, kTRUE, kTRUE); | |
1031 | ||
1032 | track = (AliMUONTrack*) fRecTracksPtr->After(track); | |
1033 | } | |
1034 | ||
1035 | } | |
1036 | ||
1037 | //__________________________________________________________________________ | |
1038 | void AliMUONTrackReconstructor::ImproveTracks() | |
1039 | { | |
1040 | /// Improve tracks by removing clusters with local chi2 highter than the defined cut | |
1041 | /// Recompute track parameters and covariances at the remaining clusters | |
1042 | AliDebug(1,"Enter ImproveTracks"); | |
1043 | ||
1044 | Double_t localChi2, worstLocalChi2; | |
1045 | Int_t worstChamber, previousChamber; | |
1046 | AliMUONTrack *track, *nextTrack; | |
1047 | AliMUONTrackParam *trackParamAtHit, *worstTrackParamAtHit, *previousTrackParam, *nextTrackParam; | |
1048 | ||
1049 | // Remove double track to improve only "good" tracks | |
1050 | RemoveDoubleTracks(); | |
1051 | ||
1052 | track = (AliMUONTrack*) fRecTracksPtr->First(); | |
1053 | while (track) { | |
1054 | ||
1055 | // prepare next track in case the actual track is suppressed | |
1056 | nextTrack = (AliMUONTrack*) fRecTracksPtr->After(track); | |
1057 | ||
1058 | while (!track->IsImproved()) { | |
1059 | ||
1060 | // Update track parameters and covariances | |
1061 | track->UpdateCovTrackParamAtHit(); | |
1062 | ||
1063 | // Compute local chi2 of each hits | |
1064 | track->ComputeLocalChi2(kTRUE); | |
1065 | ||
1066 | // Look for the hit to remove | |
1067 | worstTrackParamAtHit = NULL; | |
1068 | worstLocalChi2 = 0.; | |
1069 | trackParamAtHit = (AliMUONTrackParam*) track->GetTrackParamAtHit()->First(); | |
1070 | while (trackParamAtHit) { | |
1071 | ||
1072 | // Pick up hit with the worst chi2 | |
1073 | localChi2 = trackParamAtHit->GetLocalChi2(); | |
1074 | if (localChi2 > worstLocalChi2) { | |
1075 | worstLocalChi2 = localChi2; | |
1076 | worstTrackParamAtHit = trackParamAtHit; | |
1077 | } | |
1078 | ||
1079 | trackParamAtHit = (AliMUONTrackParam*) track->GetTrackParamAtHit()->After(trackParamAtHit); | |
1080 | } | |
1081 | ||
1082 | // Check if bad hit found | |
1083 | if (!worstTrackParamAtHit) { | |
1084 | track->SetImproved(kTRUE); | |
1085 | break; | |
1086 | } | |
1087 | ||
1088 | // Check whether the worst chi2 is under requirement or not | |
1089 | if (worstLocalChi2 < 2. * fgkSigmaToCutForImprovement * fgkSigmaToCutForImprovement) { // 2 because 2 quantities in chi2 | |
1090 | track->SetImproved(kTRUE); | |
1091 | break; | |
1092 | } | |
1093 | ||
1094 | // if the worst hit is not removable then remove the entire track | |
1095 | if (!worstTrackParamAtHit->IsRemovable() && worstTrackParamAtHit->IsAloneInChamber()) { | |
1096 | fRecTracksPtr->Remove(track); | |
1097 | fNRecTracks--; | |
1098 | break; | |
1099 | } | |
1100 | ||
1101 | // Reset the second hit in the same station as being not removable | |
1102 | // or reset the second hit in the same chamber as being alone | |
1103 | worstChamber = worstTrackParamAtHit->GetHitForRecPtr()->GetChamberNumber(); | |
1104 | previousTrackParam = (AliMUONTrackParam*) track->GetTrackParamAtHit()->Before(worstTrackParamAtHit); | |
1105 | nextTrackParam = (AliMUONTrackParam*) track->GetTrackParamAtHit()->After(worstTrackParamAtHit); | |
1106 | if (worstTrackParamAtHit->IsAloneInChamber()) { // Worst hit removable and alone in chamber | |
1107 | ||
1108 | if (worstChamber%2 == 0) { // Modify flags in next chamber | |
1109 | ||
1110 | nextTrackParam->SetRemovable(kFALSE); | |
1111 | if (!nextTrackParam->IsAloneInChamber()) // Make sure both hits in second chamber are not removable anymore | |
1112 | ((AliMUONTrackParam*) track->GetTrackParamAtHit()->After(nextTrackParam))->SetRemovable(kFALSE); | |
1113 | ||
1114 | } else { // Modify flags in previous chamber | |
1115 | ||
1116 | previousTrackParam->SetRemovable(kFALSE); | |
1117 | if (!previousTrackParam->IsAloneInChamber()) // Make sure both hits in second chamber are not removable anymore | |
1118 | ((AliMUONTrackParam*) track->GetTrackParamAtHit()->Before(previousTrackParam))->SetRemovable(kFALSE); | |
1119 | ||
1120 | } | |
1121 | ||
1122 | } else { // Worst hit not alone in its chamber | |
1123 | ||
1124 | if (previousTrackParam) previousChamber = previousTrackParam->GetHitForRecPtr()->GetChamberNumber(); | |
1125 | else previousChamber = -1; | |
1126 | ||
1127 | if (previousChamber == worstChamber) { // the second hit on the same chamber is the previous one | |
1128 | ||
1129 | previousTrackParam->SetAloneInChamber(kTRUE); | |
1130 | // transfert the removability to the second hit | |
1131 | if (worstTrackParamAtHit->IsRemovable()) previousTrackParam->SetRemovable(kTRUE); | |
1132 | ||
1133 | } else { // the second hit on the same chamber is the next one | |
1134 | ||
1135 | nextTrackParam->SetAloneInChamber(kTRUE); | |
1136 | // transfert the removability to the second hit | |
1137 | if (worstTrackParamAtHit->IsRemovable()) nextTrackParam->SetRemovable(kTRUE); | |
1138 | ||
1139 | } | |
1140 | ||
1141 | } | |
1142 | ||
1143 | // Remove the worst hit | |
1144 | track->RemoveTrackParamAtHit(worstTrackParamAtHit); | |
1145 | ||
1146 | // Re-fit the track: | |
1147 | // Take into account the multiple scattering | |
1148 | // Calculate the track parameter covariance matrix | |
1149 | Fit(*track, kTRUE, kTRUE); | |
1150 | ||
1151 | // Printout for debuging | |
1152 | if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructor") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) { | |
1153 | cout << "ImproveTracks: track " << fRecTracksPtr->IndexOf(track)+1 << " improved " << endl; | |
1154 | } | |
1155 | ||
1156 | } | |
1157 | ||
1158 | track = nextTrack; | |
1159 | } | |
1160 | ||
1161 | // compress the array in case of some tracks have been removed | |
1162 | fRecTracksPtr->Compress(); | |
1163 | ||
1164 | } | |
1165 | ||
1166 | //__________________________________________________________________________ | |
1167 | void AliMUONTrackReconstructor::Finalize() | |
1168 | { | |
1169 | /// Fill AliMUONTrack's fHitForRecAtHit array | |
1170 | /// Recompute track parameters and covariances at each attached cluster from those at the first one | |
1171 | ||
1172 | AliMUONTrack *track; | |
1173 | AliMUONTrackParam *trackParamAtHit; | |
1174 | ||
1175 | track = (AliMUONTrack*) fRecTracksPtr->First(); | |
1176 | while (track) { | |
1177 | ||
1178 | // update track parameters if not already done | |
1179 | if (!track->IsImproved()) track->UpdateCovTrackParamAtHit(); | |
1180 | ||
1181 | trackParamAtHit = (AliMUONTrackParam*) (track->GetTrackParamAtHit()->First()); | |
1182 | while (trackParamAtHit) { | |
1183 | ||
1184 | // update array of track hit | |
1185 | track->AddHitForRecAtHit(trackParamAtHit->GetHitForRecPtr()); | |
1186 | ||
1187 | trackParamAtHit = (AliMUONTrackParam*) (track->GetTrackParamAtHit()->After(trackParamAtHit)); | |
1188 | } | |
1189 | ||
1190 | track = (AliMUONTrack*) fRecTracksPtr->After(track); | |
1191 | ||
1192 | } | |
1193 | ||
1194 | } | |
1195 | ||
1196 |