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 Revision 1.8 2001/01/08 11:01:02 gosset
19 Modifications used for addendum to Dimuon TDR (JP Cussonneau):
20 *. MaxBendingMomentum to make both a segment and a track (default 500)
21 *. MaxChi2 per degree of freedom to make a track (default 100)
22 *. MinBendingMomentum used also to make a track
23 and not only a segment (default 3)
24 *. wider roads for track search in stations 1 to 3
25 *. extrapolation to actual Z instead of Z(chamber) in FollowTracks
27 - limits on parameters X and Y (+/-500)
28 - covariance matrices in double precision
29 - normalization of covariance matrices before inversion
30 - suppression of Minuit printouts
31 *. correction against memory leak (delete extrapHit) in FollowTracks
32 *. RMax to 10 degrees with Z(chamber) instead of fixed values;
33 RMin and Rmax cuts suppressed in NewHitForRecFromGEANT,
34 because useless with realistic geometry
36 Revision 1.7 2000/09/19 15:50:46 gosset
37 TrackChi2MCS function: covariance matrix better calculated,
38 taking into account missing planes...
40 Revision 1.6 2000/07/20 12:45:27 gosset
41 New "EventReconstructor..." structure,
42 hopefully more adapted to tree/streamer.
43 "AliMUONEventReconstructor::RemoveDoubleTracks"
44 to keep only one track among similar ones.
46 Revision 1.5 2000/07/18 16:04:06 gosset
47 AliMUONEventReconstructor package:
48 * a few minor modifications and more comments
50 * right sign for Z of raw clusters
51 * right loop over chambers inside station
52 * symmetrized covariance matrix for measurements (TrackChi2MCS)
53 * right sign of charge in extrapolation (ExtrapToZ)
54 * right zEndAbsorber for Branson correction below 3 degrees
55 * use of TVirtualFitter instead of TMinuit for AliMUONTrack::Fit
56 * no parameter for AliMUONTrack::Fit() but more fit parameters in Track object
58 Revision 1.4 2000/06/30 10:15:48 gosset
59 Changes to EventReconstructor...:
60 precision fit with multiple Coulomb scattering;
61 extrapolation to vertex with Branson correction in absorber (JPC)
63 Revision 1.3 2000/06/25 13:23:28 hristov
64 stdlib.h needed for non-Linux compilation
66 Revision 1.2 2000/06/15 07:58:48 morsch
67 Code from MUON-dev joined
69 Revision 1.1.2.3 2000/06/12 10:11:34 morsch
70 Dummy copy constructor and assignment operator added
72 Revision 1.1.2.2 2000/06/09 12:58:05 gosset
73 Removed comment beginnings in Log sections of .cxx files
74 Suppressed most violations of coding rules
76 Revision 1.1.2.1 2000/06/07 14:44:53 gosset
77 Addition of files for track reconstruction in C++
80 //__________________________________________________________________________
82 // Reconstructed track in ALICE dimuon spectrometer
83 //__________________________________________________________________________
85 #include "AliMUONTrack.h"
89 #include <TClonesArray.h>
92 #include <TObjArray.h>
93 #include <TVirtualFitter.h>
95 #include "AliMUONEventReconstructor.h"
96 #include "AliMUONHitForRec.h"
97 #include "AliMUONSegment.h"
98 #include "AliMUONTrackHit.h"
102 // Functions to be minimized with Minuit
103 void TrackChi2(Int_t &NParam, Double_t *Gradient, Double_t &Chi2, Double_t *Param, Int_t Flag);
104 void TrackChi2MCS(Int_t &NParam, Double_t *Gradient, Double_t &Chi2, Double_t *Param, Int_t Flag);
106 Double_t MultipleScatteringAngle2(AliMUONTrackHit *TrackHit);
108 ClassImp(AliMUONTrack) // Class implementation in ROOT context
110 TVirtualFitter* AliMUONTrack::fgFitter = NULL;
112 //__________________________________________________________________________
113 AliMUONTrack::AliMUONTrack(AliMUONSegment* BegSegment, AliMUONSegment* EndSegment, AliMUONEventReconstructor* EventReconstructor)
115 // Constructor from two Segment's
116 fEventReconstructor = EventReconstructor; // link back to EventReconstructor
117 // memory allocation for the TObjArray of pointers to reconstructed TrackHit's
118 fTrackHitsPtr = new TObjArray(10);
120 AddSegment(BegSegment); // add hits from BegSegment
121 AddSegment(EndSegment); // add hits from EndSegment
122 fTrackHitsPtr->Sort(); // sort TrackHits according to increasing Z
123 SetTrackParamAtVertex(); // set track parameters at vertex
124 // set fit conditions...
132 //__________________________________________________________________________
133 AliMUONTrack::AliMUONTrack(AliMUONSegment* Segment, AliMUONHitForRec* HitForRec, AliMUONEventReconstructor* EventReconstructor)
135 // Constructor from one Segment and one HitForRec
136 fEventReconstructor = EventReconstructor; // link back to EventReconstructor
137 // memory allocation for the TObjArray of pointers to reconstructed TrackHit's
138 fTrackHitsPtr = new TObjArray(10);
140 AddSegment(Segment); // add hits from Segment
141 AddHitForRec(HitForRec); // add HitForRec
142 fTrackHitsPtr->Sort(); // sort TrackHits according to increasing Z
143 SetTrackParamAtVertex(); // set track parameters at vertex
144 // set fit conditions...
152 //__________________________________________________________________________
153 AliMUONTrack::~AliMUONTrack()
157 delete fTrackHitsPtr; // delete the TObjArray of pointers to TrackHit's
158 fTrackHitsPtr = NULL;
162 //__________________________________________________________________________
163 AliMUONTrack::AliMUONTrack (const AliMUONTrack& MUONTrack)
165 // Dummy copy constructor
168 //__________________________________________________________________________
169 AliMUONTrack & AliMUONTrack::operator=(const AliMUONTrack& MUONTrack)
171 // Dummy assignment operator
175 //__________________________________________________________________________
176 void AliMUONTrack::Remove()
178 // Remove current track from array of tracks,
179 // and corresponding track hits from array of track hits.
180 // Compress the TClonesArray it belongs to.
181 AliMUONTrackHit *nextTrackHit;
182 AliMUONEventReconstructor *eventRec = this->fEventReconstructor;
183 TClonesArray *trackHitsPtr = eventRec->GetRecTrackHitsPtr();
184 // Loop over all track hits of track
185 AliMUONTrackHit *trackHit = (AliMUONTrackHit*) fTrackHitsPtr->First();
187 nextTrackHit = (AliMUONTrackHit*) fTrackHitsPtr->After(trackHit);
188 // Remove TrackHit from event TClonesArray.
189 // Destructor is called,
190 // hence links between HitForRec's and TrackHit's are updated
191 trackHitsPtr->Remove(trackHit);
192 trackHit = nextTrackHit;
194 // Remove the track from event TClonesArray
195 // Destructor is called,
196 // hence space for TObjArray of pointers to TrackHit's is freed
197 eventRec->GetRecTracksPtr()->Remove(this);
198 // Number of tracks decreased by 1
199 eventRec->SetNRecTracks(eventRec->GetNRecTracks() - 1);
200 // Compress event TClonesArray of Track's:
201 // this is essential to retrieve the TClonesArray afterwards
202 eventRec->GetRecTracksPtr()->Compress();
203 // Compress event TClonesArray of TrackHit's:
204 // this is probably also essential to retrieve the TClonesArray afterwards
205 trackHitsPtr->Compress();
208 //__________________________________________________________________________
209 void AliMUONTrack::SetFitMCS(Int_t FitMCS)
211 // Set multiple Coulomb scattering option for track fit "fFitMCS"
212 // from "FitMCS" argument: 0 without, 1 with
213 if ((FitMCS == 0) || (FitMCS == 1)) fFitMCS = FitMCS;
214 // better implementation with enum(with, without) ????
216 cout << "ERROR in AliMUONTrack::SetFitMCS(FitMCS)" << endl;
217 cout << "FitMCS = " << FitMCS << " is neither 0 nor 1" << endl;
223 //__________________________________________________________________________
224 void AliMUONTrack::SetFitNParam(Int_t FitNParam)
226 // Set number of parameters for track fit "fFitNParam" from "FitNParam":
227 // 3 for momentum, 5 for momentum and position
228 if ((FitNParam == 3) || (FitNParam == 5)) fFitNParam = FitNParam;
230 cout << "ERROR in AliMUONTrack::SetFitNParam(FitNParam)" << endl;
231 cout << "FitNParam = " << FitNParam << " is neither 3 nor 5" << endl;
237 //__________________________________________________________________________
238 void AliMUONTrack::SetFitStart(Int_t FitStart)
240 // Set multiple Coulomb scattering option for track fit "fFitStart"
241 // from "FitStart" argument: 0 without, 1 with
242 if ((FitStart == 0) || (FitStart == 1)) fFitStart = FitStart;
243 // better implementation with enum(vertex, firstHit) ????
245 cout << "ERROR in AliMUONTrack::SetFitStart(FitStart)" << endl;
246 cout << "FitStart = " << FitStart << " is neither 0 nor 1" << endl;
252 //__________________________________________________________________________
253 AliMUONTrackParam* AliMUONTrack::GetTrackParamAtFirstHit(void) {
254 // Get pointer to TrackParamAtFirstHit
255 return ((AliMUONTrackHit*) (fTrackHitsPtr->First()))->GetTrackParam();}
257 //__________________________________________________________________________
258 void AliMUONTrack::RecursiveDump(void)
260 // Recursive dump of AliMUONTrack, i.e. with dump of TrackHit's and HitForRec's
261 AliMUONTrackHit *trackHit;
262 AliMUONHitForRec *hitForRec;
263 cout << "Recursive dump of Track: " << this << endl;
266 for (Int_t trackHitIndex = 0; trackHitIndex < fNTrackHits; trackHitIndex++) {
267 trackHit = (AliMUONTrackHit*) ((*fTrackHitsPtr)[trackHitIndex]);
269 cout << "TrackHit: " << trackHit << " (index: " << trackHitIndex << ")" << endl;
271 hitForRec = trackHit->GetHitForRecPtr();
273 cout << "HitForRec: " << hitForRec << endl;
279 //__________________________________________________________________________
280 Int_t AliMUONTrack::HitsInCommon(AliMUONTrack* Track)
282 // Returns the number of hits in common
283 // between the current track ("this")
284 // and the track pointed to by "Track".
285 Int_t hitsInCommon = 0;
286 AliMUONTrackHit *trackHit1, *trackHit2;
287 // Loop over hits of first track
288 trackHit1 = (AliMUONTrackHit*) this->GetTrackHitsPtr()->First();
290 // Loop over hits of second track
291 trackHit2 = (AliMUONTrackHit*) Track->GetTrackHitsPtr()->First();
293 // Increment "hitsInCommon" if both TrackHits point to the same HitForRec
294 if ( (trackHit1->GetHitForRecPtr()) ==
295 (trackHit2->GetHitForRecPtr()) ) hitsInCommon++;
296 trackHit2 = (AliMUONTrackHit*) Track->GetTrackHitsPtr()->After(trackHit2);
298 trackHit1 = (AliMUONTrackHit*) this->GetTrackHitsPtr()->After(trackHit1);
303 //__________________________________________________________________________
304 void AliMUONTrack::Fit()
306 // Fit the current track ("this"),
307 // with or without multiple Coulomb scattering according to "fFitMCS",
308 // with the number of parameters given by "fFitNParam"
309 // (3 if one keeps X and Y fixed in "TrackParam", 5 if one lets them vary),
310 // starting, according to "fFitStart",
311 // with track parameters at vertex or at the first TrackHit.
312 // "fFitMCS", "fFitNParam" and "fFitStart" have to be set before
313 // by calling the corresponding Set methods.
314 Double_t arg[1], benC, errorParam, invBenP, lower, nonBenC, upper, x, y;
316 AliMUONTrackParam *trackParam;
317 // Check if Minuit is initialized...
318 fgFitter = TVirtualFitter::Fitter(this); // add 3 or 5 for the maximum number of parameters ???
319 fgFitter->Clear(); // necessary ???? probably yes
320 // how to reset the printout number at every fit ????
321 // is there any risk to leave it like that ????
322 // how to go faster ???? choice of Minuit parameters like EDM ????
323 // choice of function to be minimized according to fFitMCS
324 if (fFitMCS == 0) fgFitter->SetFCN(TrackChi2);
325 else fgFitter->SetFCN(TrackChi2MCS);
327 fgFitter->ExecuteCommand("SET PRINT", arg, 1); // More printing !!!!
328 // Parameters according to "fFitStart"
329 // (should be a function to be used at every place where needed ????)
330 if (fFitStart == 0) trackParam = &fTrackParamAtVertex;
331 else trackParam = this->GetTrackParamAtFirstHit();
332 // set first 3 Minuit parameters
333 // could be tried with no limits for the search (min=max=0) ????
334 fgFitter->SetParameter(0, "InvBenP",
335 trackParam->GetInverseBendingMomentum(),
337 fgFitter->SetParameter(1, "BenS",
338 trackParam->GetBendingSlope(),
340 fgFitter->SetParameter(2, "NonBenS",
341 trackParam->GetNonBendingSlope(),
343 if (fFitNParam == 5) {
344 // set last 2 Minuit parameters
345 // mandatory limits in Bending to avoid NaN values of parameters
346 fgFitter->SetParameter(3, "X",
347 trackParam->GetNonBendingCoor(),
348 0.03, -500.0, 500.0);
349 // mandatory limits in non Bending to avoid NaN values of parameters
350 fgFitter->SetParameter(4, "Y",
351 trackParam->GetBendingCoor(),
352 0.10, -500.0, 500.0);
354 // search without gradient calculation in the function
355 fgFitter->ExecuteCommand("SET NOGRADIENT", arg, 0);
357 fgFitter->ExecuteCommand("MINIMIZE", arg, 0);
359 fgFitter->ExecuteCommand("EXIT", arg, 0); // necessary ????
360 // get results into "invBenP", "benC", "nonBenC" ("x", "y")
361 fgFitter->GetParameter(0, parName, invBenP, errorParam, lower, upper);
362 fgFitter->GetParameter(1, parName, benC, errorParam, lower, upper);
363 fgFitter->GetParameter(2, parName, nonBenC, errorParam, lower, upper);
364 if (fFitNParam == 5) {
365 fgFitter->GetParameter(3, parName, x, errorParam, lower, upper);
366 fgFitter->GetParameter(4, parName, y, errorParam, lower, upper);
368 // result of the fit into track parameters
369 trackParam->SetInverseBendingMomentum(invBenP);
370 trackParam->SetBendingSlope(benC);
371 trackParam->SetNonBendingSlope(nonBenC);
372 if (fFitNParam == 5) {
373 trackParam->SetNonBendingCoor(x);
374 trackParam->SetBendingCoor(y);
376 // global result of the fit
377 Double_t fedm, errdef;
379 fgFitter->GetStats(fFitFMin, fedm, errdef, npari, nparx);
382 //__________________________________________________________________________
383 void AliMUONTrack::AddSegment(AliMUONSegment* Segment)
385 // Add Segment to the track
386 AddHitForRec(Segment->GetHitForRec1()); // 1st hit
387 AddHitForRec(Segment->GetHitForRec2()); // 2nd hit
390 //__________________________________________________________________________
391 void AliMUONTrack::AddHitForRec(AliMUONHitForRec* HitForRec)
393 // Add HitForRec to the track:
394 // actual TrackHit into TClonesArray of TrackHit's for the event;
395 // pointer to actual TrackHit in TObjArray of pointers to TrackHit's for the track
396 TClonesArray *recTrackHitsPtr = this->fEventReconstructor->GetRecTrackHitsPtr();
397 Int_t eventTrackHits = this->fEventReconstructor->GetNRecTrackHits();
399 AliMUONTrackHit* trackHit =
400 new ((*recTrackHitsPtr)[eventTrackHits]) AliMUONTrackHit(HitForRec);
401 this->fEventReconstructor->SetNRecTrackHits(eventTrackHits + 1);
403 fTrackHitsPtr->Add(trackHit);
407 //__________________________________________________________________________
408 void AliMUONTrack::SetTrackParamAtHit(Int_t indexHit, AliMUONTrackParam *TrackParam)
410 // Set track parameters at TrackHit with index "indexHit"
411 // from the track parameters pointed to by "TrackParam".
412 AliMUONTrackHit* trackHit = (AliMUONTrackHit*) ((*fTrackHitsPtr)[indexHit]);
413 trackHit->SetTrackParam(TrackParam);
416 //__________________________________________________________________________
417 void AliMUONTrack::SetTrackParamAtVertex()
419 // Set track parameters at vertex.
420 // TrackHit's are assumed to be only in stations(1..) 4 and 5,
421 // and sorted according to increasing Z..
422 // Parameters are calculated from information in HitForRec's
423 // of first and last TrackHit's.
424 AliMUONTrackParam *trackParam =
425 &fTrackParamAtVertex; // pointer to track parameters
426 // Pointer to HitForRec of first TrackHit
427 AliMUONHitForRec *firstHit =
428 ((AliMUONTrackHit*) (fTrackHitsPtr->First()))->GetHitForRecPtr();
429 // Pointer to HitForRec of last TrackHit
430 AliMUONHitForRec *lastHit =
431 ((AliMUONTrackHit*) (fTrackHitsPtr->Last()))->GetHitForRecPtr();
432 // Z difference between first and last hits
433 Double_t deltaZ = firstHit->GetZ() - lastHit->GetZ();
434 // bending slope in stations(1..) 4 and 5
435 Double_t bendingSlope =
436 (firstHit->GetBendingCoor() - lastHit->GetBendingCoor()) / deltaZ;
437 trackParam->SetBendingSlope(bendingSlope);
439 Double_t impactParam =
440 firstHit->GetBendingCoor() - bendingSlope * firstHit->GetZ(); // same if from firstHit and lastHit ????
441 // signed bending momentum
442 Double_t signedBendingMomentum =
443 fEventReconstructor->GetBendingMomentumFromImpactParam(impactParam);
444 trackParam->SetInverseBendingMomentum(1.0 / signedBendingMomentum);
445 // bending slope at vertex
447 SetBendingSlope(bendingSlope +
448 impactParam / fEventReconstructor->GetSimpleBPosition());
450 Double_t nonBendingSlope =
451 (firstHit->GetNonBendingCoor() - lastHit->GetNonBendingCoor()) / deltaZ;
452 trackParam->SetNonBendingSlope(nonBendingSlope);
453 // vertex coordinates at (0,0,0)
454 trackParam->SetZ(0.0);
455 trackParam->SetBendingCoor(0.0);
456 trackParam->SetNonBendingCoor(0.0);
459 //__________________________________________________________________________
460 void TrackChi2(Int_t &NParam, Double_t *Gradient, Double_t &Chi2, Double_t *Param, Int_t Flag)
462 // Return the "Chi2" to be minimized with Minuit for track fitting,
463 // with "NParam" parameters
464 // and their current values in array pointed to by "Param".
465 // Assumes that the track hits are sorted according to increasing Z.
466 // Track parameters at each TrackHit are updated accordingly.
467 // Multiple Coulomb scattering is not taken into account
468 AliMUONTrack *trackBeingFitted;
469 AliMUONTrackHit* hit;
470 AliMUONTrackParam param1;
473 Chi2 = 0.0; // initialize Chi2
474 // copy of track parameters to be fitted
475 trackBeingFitted = (AliMUONTrack*) AliMUONTrack::Fitter()->GetObjectFit();
476 if (trackBeingFitted->GetFitStart() == 0)
477 param1 = *(trackBeingFitted->GetTrackParamAtVertex());
478 else param1 = *(trackBeingFitted->GetTrackParamAtFirstHit());
479 // Minuit parameters to be fitted into this copy
480 param1.SetInverseBendingMomentum(Param[0]);
481 param1.SetBendingSlope(Param[1]);
482 param1.SetNonBendingSlope(Param[2]);
484 param1.SetNonBendingCoor(Param[3]);
485 param1.SetBendingCoor(Param[4]);
487 // Follow track through all planes of track hits
488 for (hitNumber = 0; hitNumber < trackBeingFitted->GetNTrackHits(); hitNumber++) {
489 hit = (AliMUONTrackHit*) (*(trackBeingFitted->GetTrackHitsPtr()))[hitNumber];
490 zHit = hit->GetHitForRecPtr()->GetZ();
491 // do something special if 2 hits with same Z ????
492 // security against infinite loop ????
493 (¶m1)->ExtrapToZ(zHit); // extrapolation
494 hit->SetTrackParam(¶m1);
496 // done hit per hit, with hit resolution,
497 // and not with point and angle like in "reco_muon.F" !!!!
498 // Needs to add multiple scattering contribution ????
500 hit->GetHitForRecPtr()->GetNonBendingCoor() - (¶m1)->GetNonBendingCoor();
502 hit->GetHitForRecPtr()->GetBendingCoor() - (¶m1)->GetBendingCoor();
505 dX * dX / hit->GetHitForRecPtr()->GetNonBendingReso2() +
506 dY * dY / hit->GetHitForRecPtr()->GetBendingReso2();
510 //__________________________________________________________________________
511 void TrackChi2MCS(Int_t &NParam, Double_t *Gradient, Double_t &Chi2, Double_t *Param, Int_t Flag)
513 // Return the "Chi2" to be minimized with Minuit for track fitting,
514 // with "NParam" parameters
515 // and their current values in array pointed to by "Param".
516 // Assumes that the track hits are sorted according to increasing Z.
517 // Track parameters at each TrackHit are updated accordingly.
518 // Multiple Coulomb scattering is taken into account with covariance matrix.
519 AliMUONTrack *trackBeingFitted;
520 AliMUONTrackParam param1;
521 Chi2 = 0.0; // initialize Chi2
522 // copy of track parameters to be fitted
523 trackBeingFitted = (AliMUONTrack*) AliMUONTrack::Fitter()->GetObjectFit();
524 if (trackBeingFitted->GetFitStart() == 0)
525 param1 = *(trackBeingFitted->GetTrackParamAtVertex());
526 else param1 = *(trackBeingFitted->GetTrackParamAtFirstHit());
527 // Minuit parameters to be fitted into this copy
528 param1.SetInverseBendingMomentum(Param[0]);
529 param1.SetBendingSlope(Param[1]);
530 param1.SetNonBendingSlope(Param[2]);
532 param1.SetNonBendingCoor(Param[3]);
533 param1.SetBendingCoor(Param[4]);
536 AliMUONTrackHit *hit;
537 Bool_t goodDeterminant;
538 Int_t chCurrent, chPrev = 0, hitNumber, hitNumber1, hitNumber2, hitNumber3;
539 Double_t z, z1, z2, z3;
540 AliMUONTrackHit *hit1, *hit2, *hit3;
541 Double_t hbc1, hbc2, pbc1, pbc2;
542 Double_t hnbc1, hnbc2, pnbc1, pnbc2;
543 Int_t numberOfHit = trackBeingFitted->GetNTrackHits();
544 TMatrixD *covBending = new TMatrixD(numberOfHit, numberOfHit);
545 TMatrixD *covNonBending = new TMatrixD(numberOfHit, numberOfHit);
546 Double_t *msa2 = new Double_t[numberOfHit];
548 // Predicted coordinates and multiple scattering angles are first calculated
549 for (hitNumber = 0; hitNumber < numberOfHit; hitNumber++) {
550 hit = (AliMUONTrackHit*) (*(trackBeingFitted->GetTrackHitsPtr()))[hitNumber];
551 z = hit->GetHitForRecPtr()->GetZ();
552 // do something special if 2 hits with same Z ????
553 // security against infinite loop ????
554 (¶m1)->ExtrapToZ(z); // extrapolation
555 hit->SetTrackParam(¶m1);
556 // square of multiple scattering angle at current hit, with one chamber
557 msa2[hitNumber] = MultipleScatteringAngle2(hit);
558 // correction for eventual missing hits or multiple hits in a chamber,
559 // according to the number of chambers
560 // between the current hit and the previous one
561 chCurrent = hit->GetHitForRecPtr()->GetChamberNumber();
562 if (hitNumber > 0) msa2[hitNumber] = msa2[hitNumber] * (chCurrent - chPrev);
566 // Calculates the covariance matrix
567 for (hitNumber1 = 0; hitNumber1 < numberOfHit; hitNumber1++) {
568 hit1 = (AliMUONTrackHit*) (*(trackBeingFitted->GetTrackHitsPtr()))[hitNumber1];
569 z1 = hit1->GetHitForRecPtr()->GetZ();
570 for (hitNumber2 = hitNumber1; hitNumber2 < numberOfHit; hitNumber2++) {
571 hit2 = (AliMUONTrackHit*) (*(trackBeingFitted->GetTrackHitsPtr()))[hitNumber2];
572 z2 = hit2->GetHitForRecPtr()->GetZ();
573 // initialization to 0 (diagonal plus upper triangular part)
574 (*covBending)(hitNumber2, hitNumber1) = 0.0;
575 // contribution from multiple scattering in bending plane:
576 // loop over upstream hits
577 for (hitNumber3 = 0; hitNumber3 < hitNumber1; hitNumber3++) {
578 hit3 = (AliMUONTrackHit*)
579 (*(trackBeingFitted->GetTrackHitsPtr()))[hitNumber3];
580 z3 = hit3->GetHitForRecPtr()->GetZ();
581 (*covBending)(hitNumber2, hitNumber1) =
582 (*covBending)(hitNumber2, hitNumber1) +
583 ((z1 - z3) * (z2 - z3) * msa2[hitNumber3]);
585 // equal contribution from multiple scattering in non bending plane
586 (*covNonBending)(hitNumber2, hitNumber1) =
587 (*covBending)(hitNumber2, hitNumber1);
588 if (hitNumber1 == hitNumber2) {
589 // Diagonal elements: add contribution from position measurements
591 (*covBending)(hitNumber2, hitNumber1) =
592 (*covBending)(hitNumber2, hitNumber1) +
593 hit1->GetHitForRecPtr()->GetBendingReso2();
594 // and in non bending plane
595 (*covNonBending)(hitNumber2, hitNumber1) =
596 (*covNonBending)(hitNumber2, hitNumber1) +
597 hit1->GetHitForRecPtr()->GetNonBendingReso2();
600 // Non diagonal elements: symmetrization
602 (*covBending)(hitNumber1, hitNumber2) =
603 (*covBending)(hitNumber2, hitNumber1);
604 // and non bending plane
605 (*covNonBending)(hitNumber1, hitNumber2) =
606 (*covNonBending)(hitNumber2, hitNumber1);
608 } // for (hitNumber2 = hitNumber1;...
609 } // for (hitNumber1 = 0;...
610 // Normalization of covariance matrices
611 Double_t normCovBending2 = covBending->E2Norm();
612 Double_t normCovNonBending2 = covNonBending->E2Norm();
613 (*covBending) *= 1/normCovBending2;
614 (*covNonBending) *= 1/normCovNonBending2;
615 // if (covBending->Determinant() < 1.e-33) {
616 // printf(" *** covBending *** \n");
617 // covBending->Print();
618 // printf(" *** covNonBending *** \n");
619 // covNonBending->Print();
620 // cout << " number of hits " << numberOfHit << endl;
621 // cout << "Momentum = " << 1/Param[0] <<endl;
622 // cout << "normCovBending = " << normCovBending2 << endl;
623 // cout << "normCovNonBending = " << normCovNonBending2 << endl;
627 // Inverts covariance matrix
628 goodDeterminant = kTRUE;
629 // check whether the Invert method returns flag if matrix cannot be inverted,
630 // and do not calculate the Determinant in that case !!!!
631 if (covBending->Determinant() != 0) {
632 covBending->Invert();
634 goodDeterminant = kFALSE;
635 cout << "Warning in ChiMCS Determinant Bending=0: " << endl;
637 if (covNonBending->Determinant() != 0) {
638 covNonBending->Invert();
640 goodDeterminant = kFALSE;
641 cout << "Warning in ChiMCS Determinant non Bending=0: " << endl;
644 // It would be worth trying to calculate the inverse of the covariance matrix
645 // only once per fit, since it cannot change much in principle,
646 // and it would save a lot of computing time !!!!
649 if (goodDeterminant) {
650 // with Multiple Scattering if inversion correct
651 // Inverse matrices without normalization
652 (*covBending) *= 1/normCovBending2;
653 (*covNonBending) *= 1/normCovNonBending2;
654 for (hitNumber1 = 0; hitNumber1 < numberOfHit ; hitNumber1++) {
655 hit1 = (AliMUONTrackHit*) (*(trackBeingFitted->GetTrackHitsPtr()))[hitNumber1];
656 hbc1 = hit1->GetHitForRecPtr()->GetBendingCoor();
657 pbc1 = hit1->GetTrackParam()->GetBendingCoor();
658 hnbc1 = hit1->GetHitForRecPtr()->GetNonBendingCoor();
659 pnbc1 = hit1->GetTrackParam()->GetNonBendingCoor();
660 for (hitNumber2 = 0; hitNumber2 < numberOfHit; hitNumber2++) {
661 hit2 = (AliMUONTrackHit*)
662 (*(trackBeingFitted->GetTrackHitsPtr()))[hitNumber2];
663 hbc2 = hit2->GetHitForRecPtr()->GetBendingCoor();
664 pbc2 = hit2->GetTrackParam()->GetBendingCoor();
665 hnbc2 = hit2->GetHitForRecPtr()->GetNonBendingCoor();
666 pnbc2 = hit2->GetTrackParam()->GetNonBendingCoor();
668 ((*covBending)(hitNumber2, hitNumber1) *
669 (hbc1 - pbc1) * (hbc2 - pbc2)) +
670 ((*covNonBending)(hitNumber2, hitNumber1) *
671 (hnbc1 - pnbc1) * (hnbc2 - pnbc2));
675 // without Multiple Scattering if inversion impossible
676 for (hitNumber1 = 0; hitNumber1 < numberOfHit ; hitNumber1++) {
677 hit1 = (AliMUONTrackHit*) (*(trackBeingFitted->GetTrackHitsPtr()))[hitNumber1];
678 hbc1 = hit1->GetHitForRecPtr()->GetBendingCoor();
679 pbc1 = hit1->GetTrackParam()->GetBendingCoor();
680 hnbc1 = hit1->GetHitForRecPtr()->GetNonBendingCoor();
681 pnbc1 = hit1->GetTrackParam()->GetNonBendingCoor();
683 ((hbc1 - pbc1) * (hbc1 - pbc1) /
684 hit1->GetHitForRecPtr()->GetBendingReso2()) +
685 ((hnbc1 - pnbc1) * (hnbc1 - pnbc1) /
686 hit1->GetHitForRecPtr()->GetNonBendingReso2());
691 delete covNonBending;
695 Double_t MultipleScatteringAngle2(AliMUONTrackHit *TrackHit)
697 // Returns square of multiple Coulomb scattering angle
698 // at TrackHit pointed to by "TrackHit"
699 Double_t slopeBending, slopeNonBending, radiationLength, inverseBendingMomentum2, inverseTotalMomentum2;
700 Double_t varMultipleScatteringAngle;
701 AliMUONTrack *trackBeingFitted = (AliMUONTrack*) AliMUONTrack::Fitter()->GetObjectFit();
702 AliMUONTrackParam *param = TrackHit->GetTrackParam();
703 // Better implementation in AliMUONTrack class ????
704 slopeBending = param->GetBendingSlope();
705 slopeNonBending = param->GetNonBendingSlope();
706 // thickness in radiation length for the current track,
707 // taking local angle into account
709 trackBeingFitted->GetEventReconstructor()->GetChamberThicknessInX0() *
711 slopeBending * slopeBending + slopeNonBending * slopeNonBending);
712 inverseBendingMomentum2 =
713 param->GetInverseBendingMomentum() * param->GetInverseBendingMomentum();
714 inverseTotalMomentum2 =
715 inverseBendingMomentum2 * (1.0 + slopeBending * slopeBending) /
716 (1.0 + slopeBending *slopeBending + slopeNonBending * slopeNonBending);
717 varMultipleScatteringAngle = 0.0136 * (1.0 + 0.038 * TMath::Log(radiationLength));
718 // The velocity is assumed to be 1 !!!!
719 varMultipleScatteringAngle = inverseTotalMomentum2 * radiationLength *
720 varMultipleScatteringAngle * varMultipleScatteringAngle;
721 return varMultipleScatteringAngle;