New set-up and comments for ITS. (R. Barbera)
[u/mrichter/AliRoot.git] / MUON / AliMUONTrack.cxx
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a9e2aefa 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/*
17$Log$
bbe35c23 18Revision 1.8 2001/01/08 11:01:02 gosset
19Modifications 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
26*. in track fit:
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
35
d0bfce8d 36Revision 1.7 2000/09/19 15:50:46 gosset
37TrackChi2MCS function: covariance matrix better calculated,
38taking into account missing planes...
39
eb9c9dab 40Revision 1.6 2000/07/20 12:45:27 gosset
41New "EventReconstructor..." structure,
42 hopefully more adapted to tree/streamer.
43"AliMUONEventReconstructor::RemoveDoubleTracks"
44 to keep only one track among similar ones.
45
8429a5e4 46Revision 1.5 2000/07/18 16:04:06 gosset
47AliMUONEventReconstructor package:
48* a few minor modifications and more comments
49* a few corrections
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
57
956019b6 58Revision 1.4 2000/06/30 10:15:48 gosset
59Changes to EventReconstructor...:
60precision fit with multiple Coulomb scattering;
61extrapolation to vertex with Branson correction in absorber (JPC)
62
04b5ea16 63Revision 1.3 2000/06/25 13:23:28 hristov
64stdlib.h needed for non-Linux compilation
65
f6e92cf4 66Revision 1.2 2000/06/15 07:58:48 morsch
67Code from MUON-dev joined
68
a9e2aefa 69Revision 1.1.2.3 2000/06/12 10:11:34 morsch
70Dummy copy constructor and assignment operator added
71
72Revision 1.1.2.2 2000/06/09 12:58:05 gosset
73Removed comment beginnings in Log sections of .cxx files
74Suppressed most violations of coding rules
75
76Revision 1.1.2.1 2000/06/07 14:44:53 gosset
77Addition of files for track reconstruction in C++
78*/
79
80//__________________________________________________________________________
81//
82// Reconstructed track in ALICE dimuon spectrometer
83//__________________________________________________________________________
84
85#include "AliMUONTrack.h"
86
87#include <iostream.h>
88
89#include <TClonesArray.h>
04b5ea16 90#include <TMath.h>
d0bfce8d 91#include <TMatrixD.h>
8429a5e4 92#include <TObjArray.h>
956019b6 93#include <TVirtualFitter.h>
a9e2aefa 94
95#include "AliMUONEventReconstructor.h"
96#include "AliMUONHitForRec.h"
97#include "AliMUONSegment.h"
98#include "AliMUONTrackHit.h"
99
f6e92cf4 100#include <stdlib.h>
101
04b5ea16 102// Functions to be minimized with Minuit
a9e2aefa 103void TrackChi2(Int_t &NParam, Double_t *Gradient, Double_t &Chi2, Double_t *Param, Int_t Flag);
04b5ea16 104void TrackChi2MCS(Int_t &NParam, Double_t *Gradient, Double_t &Chi2, Double_t *Param, Int_t Flag);
105
106Double_t MultipleScatteringAngle2(AliMUONTrackHit *TrackHit);
a9e2aefa 107
108ClassImp(AliMUONTrack) // Class implementation in ROOT context
109
956019b6 110TVirtualFitter* AliMUONTrack::fgFitter = NULL;
111
a9e2aefa 112 //__________________________________________________________________________
113AliMUONTrack::AliMUONTrack(AliMUONSegment* BegSegment, AliMUONSegment* EndSegment, AliMUONEventReconstructor* EventReconstructor)
114{
115 // Constructor from two Segment's
116 fEventReconstructor = EventReconstructor; // link back to EventReconstructor
8429a5e4 117 // memory allocation for the TObjArray of pointers to reconstructed TrackHit's
118 fTrackHitsPtr = new TObjArray(10);
a9e2aefa 119 fNTrackHits = 0;
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
8429a5e4 124 // set fit conditions...
04b5ea16 125 fFitMCS = 0;
956019b6 126 fFitNParam = 3;
127 fFitStart = 1;
8429a5e4 128 fFitFMin = -1.0;
a9e2aefa 129 return;
130}
131
132 //__________________________________________________________________________
133AliMUONTrack::AliMUONTrack(AliMUONSegment* Segment, AliMUONHitForRec* HitForRec, AliMUONEventReconstructor* EventReconstructor)
134{
135 // Constructor from one Segment and one HitForRec
136 fEventReconstructor = EventReconstructor; // link back to EventReconstructor
8429a5e4 137 // memory allocation for the TObjArray of pointers to reconstructed TrackHit's
138 fTrackHitsPtr = new TObjArray(10);
a9e2aefa 139 fNTrackHits = 0;
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
8429a5e4 144 // set fit conditions...
04b5ea16 145 fFitMCS = 0;
956019b6 146 fFitNParam = 3;
147 fFitStart = 1;
8429a5e4 148 fFitFMin = -1.0;
a9e2aefa 149 return;
150}
151
8429a5e4 152 //__________________________________________________________________________
153AliMUONTrack::~AliMUONTrack()
154{
155 // Destructor
156 if (fTrackHitsPtr) {
157 delete fTrackHitsPtr; // delete the TObjArray of pointers to TrackHit's
158 fTrackHitsPtr = NULL;
159 }
160}
161
956019b6 162 //__________________________________________________________________________
a9e2aefa 163AliMUONTrack::AliMUONTrack (const AliMUONTrack& MUONTrack)
164{
165// Dummy copy constructor
166}
167
956019b6 168 //__________________________________________________________________________
a9e2aefa 169AliMUONTrack & AliMUONTrack::operator=(const AliMUONTrack& MUONTrack)
170{
171// Dummy assignment operator
172 return *this;
173}
174
8429a5e4 175 //__________________________________________________________________________
176void AliMUONTrack::Remove()
177{
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();
186 while (trackHit) {
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;
193 }
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();
206}
207
04b5ea16 208 //__________________________________________________________________________
209void AliMUONTrack::SetFitMCS(Int_t FitMCS)
210{
956019b6 211 // Set multiple Coulomb scattering option for track fit "fFitMCS"
04b5ea16 212 // from "FitMCS" argument: 0 without, 1 with
956019b6 213 if ((FitMCS == 0) || (FitMCS == 1)) fFitMCS = FitMCS;
04b5ea16 214 // better implementation with enum(with, without) ????
956019b6 215 else {
216 cout << "ERROR in AliMUONTrack::SetFitMCS(FitMCS)" << endl;
217 cout << "FitMCS = " << FitMCS << " is neither 0 nor 1" << endl;
218 exit(0);
219 }
220 return;
221}
222
223 //__________________________________________________________________________
224void AliMUONTrack::SetFitNParam(Int_t FitNParam)
225{
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;
229 else {
230 cout << "ERROR in AliMUONTrack::SetFitNParam(FitNParam)" << endl;
231 cout << "FitNParam = " << FitNParam << " is neither 3 nor 5" << endl;
232 exit(0);
233 }
234 return;
235}
236
237 //__________________________________________________________________________
238void AliMUONTrack::SetFitStart(Int_t FitStart)
239{
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) ????
244 else {
245 cout << "ERROR in AliMUONTrack::SetFitStart(FitStart)" << endl;
246 cout << "FitStart = " << FitStart << " is neither 0 nor 1" << endl;
247 exit(0);
248 }
04b5ea16 249 return;
250}
251
956019b6 252 //__________________________________________________________________________
a9e2aefa 253AliMUONTrackParam* AliMUONTrack::GetTrackParamAtFirstHit(void) {
254 // Get pointer to TrackParamAtFirstHit
255 return ((AliMUONTrackHit*) (fTrackHitsPtr->First()))->GetTrackParam();}
a9e2aefa 256
257 //__________________________________________________________________________
258void AliMUONTrack::RecursiveDump(void)
259{
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;
264 // Track
265 this->Dump();
266 for (Int_t trackHitIndex = 0; trackHitIndex < fNTrackHits; trackHitIndex++) {
267 trackHit = (AliMUONTrackHit*) ((*fTrackHitsPtr)[trackHitIndex]);
268 // TrackHit
269 cout << "TrackHit: " << trackHit << " (index: " << trackHitIndex << ")" << endl;
270 trackHit->Dump();
271 hitForRec = trackHit->GetHitForRecPtr();
272 // HitForRec
273 cout << "HitForRec: " << hitForRec << endl;
274 hitForRec->Dump();
275 }
276 return;
277}
278
8429a5e4 279 //__________________________________________________________________________
280Int_t AliMUONTrack::HitsInCommon(AliMUONTrack* Track)
281{
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();
289 while (trackHit1) {
290 // Loop over hits of second track
291 trackHit2 = (AliMUONTrackHit*) Track->GetTrackHitsPtr()->First();
292 while (trackHit2) {
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);
297 } // trackHit2
298 trackHit1 = (AliMUONTrackHit*) this->GetTrackHitsPtr()->After(trackHit1);
299 } // trackHit1
300 return hitsInCommon;
301}
302
a9e2aefa 303 //__________________________________________________________________________
956019b6 304void AliMUONTrack::Fit()
a9e2aefa 305{
306 // Fit the current track ("this"),
956019b6 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.
a9e2aefa 314 Double_t arg[1], benC, errorParam, invBenP, lower, nonBenC, upper, x, y;
956019b6 315 char parName[50];
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 ????
a9e2aefa 322 // how to go faster ???? choice of Minuit parameters like EDM ????
04b5ea16 323 // choice of function to be minimized according to fFitMCS
956019b6 324 if (fFitMCS == 0) fgFitter->SetFCN(TrackChi2);
325 else fgFitter->SetFCN(TrackChi2MCS);
d0bfce8d 326 arg[0] = -1;
956019b6 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
04b5ea16 333 // could be tried with no limits for the search (min=max=0) ????
956019b6 334 fgFitter->SetParameter(0, "InvBenP",
335 trackParam->GetInverseBendingMomentum(),
336 0.003, -0.4, 0.4);
337 fgFitter->SetParameter(1, "BenS",
338 trackParam->GetBendingSlope(),
339 0.001, -0.5, 0.5);
340 fgFitter->SetParameter(2, "NonBenS",
341 trackParam->GetNonBendingSlope(),
342 0.001, -0.5, 0.5);
343 if (fFitNParam == 5) {
d0bfce8d 344 // set last 2 Minuit parameters
345 // mandatory limits in Bending to avoid NaN values of parameters
956019b6 346 fgFitter->SetParameter(3, "X",
347 trackParam->GetNonBendingCoor(),
d0bfce8d 348 0.03, -500.0, 500.0);
349 // mandatory limits in non Bending to avoid NaN values of parameters
956019b6 350 fgFitter->SetParameter(4, "Y",
351 trackParam->GetBendingCoor(),
d0bfce8d 352 0.10, -500.0, 500.0);
a9e2aefa 353 }
354 // search without gradient calculation in the function
956019b6 355 fgFitter->ExecuteCommand("SET NOGRADIENT", arg, 0);
a9e2aefa 356 // minimization
956019b6 357 fgFitter->ExecuteCommand("MINIMIZE", arg, 0);
a9e2aefa 358 // exit from Minuit
956019b6 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);
a9e2aefa 367 }
368 // result of the fit into track parameters
956019b6 369 trackParam->SetInverseBendingMomentum(invBenP);
370 trackParam->SetBendingSlope(benC);
371 trackParam->SetNonBendingSlope(nonBenC);
372 if (fFitNParam == 5) {
373 trackParam->SetNonBendingCoor(x);
374 trackParam->SetBendingCoor(y);
a9e2aefa 375 }
8429a5e4 376 // global result of the fit
377 Double_t fedm, errdef;
378 Int_t npari, nparx;
379 fgFitter->GetStats(fFitFMin, fedm, errdef, npari, nparx);
a9e2aefa 380}
381
382 //__________________________________________________________________________
383void AliMUONTrack::AddSegment(AliMUONSegment* Segment)
384{
8429a5e4 385 // Add Segment to the track
a9e2aefa 386 AddHitForRec(Segment->GetHitForRec1()); // 1st hit
387 AddHitForRec(Segment->GetHitForRec2()); // 2nd hit
388}
389
390 //__________________________________________________________________________
391void AliMUONTrack::AddHitForRec(AliMUONHitForRec* HitForRec)
392{
8429a5e4 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();
398 // event
399 AliMUONTrackHit* trackHit =
400 new ((*recTrackHitsPtr)[eventTrackHits]) AliMUONTrackHit(HitForRec);
401 this->fEventReconstructor->SetNRecTrackHits(eventTrackHits + 1);
402 // track
403 fTrackHitsPtr->Add(trackHit);
a9e2aefa 404 fNTrackHits++;
405}
406
407 //__________________________________________________________________________
408void AliMUONTrack::SetTrackParamAtHit(Int_t indexHit, AliMUONTrackParam *TrackParam)
409{
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);
414}
415
416 //__________________________________________________________________________
417void AliMUONTrack::SetTrackParamAtVertex()
418{
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);
438 // impact parameter
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
446 trackParam->
447 SetBendingSlope(bendingSlope +
448 impactParam / fEventReconstructor->GetSimpleBPosition());
449 // non bending slope
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);
457}
458
459 //__________________________________________________________________________
460void TrackChi2(Int_t &NParam, Double_t *Gradient, Double_t &Chi2, Double_t *Param, Int_t Flag)
461{
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.
04b5ea16 467 // Multiple Coulomb scattering is not taken into account
956019b6 468 AliMUONTrack *trackBeingFitted;
a9e2aefa 469 AliMUONTrackHit* hit;
470 AliMUONTrackParam param1;
471 Int_t hitNumber;
472 Double_t zHit;
473 Chi2 = 0.0; // initialize Chi2
474 // copy of track parameters to be fitted
956019b6 475 trackBeingFitted = (AliMUONTrack*) AliMUONTrack::Fitter()->GetObjectFit();
476 if (trackBeingFitted->GetFitStart() == 0)
477 param1 = *(trackBeingFitted->GetTrackParamAtVertex());
478 else param1 = *(trackBeingFitted->GetTrackParamAtFirstHit());
a9e2aefa 479 // Minuit parameters to be fitted into this copy
480 param1.SetInverseBendingMomentum(Param[0]);
481 param1.SetBendingSlope(Param[1]);
482 param1.SetNonBendingSlope(Param[2]);
483 if (NParam == 5) {
484 param1.SetNonBendingCoor(Param[3]);
485 param1.SetBendingCoor(Param[4]);
486 }
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 (&param1)->ExtrapToZ(zHit); // extrapolation
494 hit->SetTrackParam(&param1);
495 // Increment Chi2
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 ????
499 Double_t dX =
500 hit->GetHitForRecPtr()->GetNonBendingCoor() - (&param1)->GetNonBendingCoor();
501 Double_t dY =
502 hit->GetHitForRecPtr()->GetBendingCoor() - (&param1)->GetBendingCoor();
503 Chi2 =
504 Chi2 +
505 dX * dX / hit->GetHitForRecPtr()->GetNonBendingReso2() +
506 dY * dY / hit->GetHitForRecPtr()->GetBendingReso2();
507 }
508}
04b5ea16 509
510 //__________________________________________________________________________
511void TrackChi2MCS(Int_t &NParam, Double_t *Gradient, Double_t &Chi2, Double_t *Param, Int_t Flag)
512{
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.
956019b6 519 AliMUONTrack *trackBeingFitted;
04b5ea16 520 AliMUONTrackParam param1;
521 Chi2 = 0.0; // initialize Chi2
522 // copy of track parameters to be fitted
956019b6 523 trackBeingFitted = (AliMUONTrack*) AliMUONTrack::Fitter()->GetObjectFit();
524 if (trackBeingFitted->GetFitStart() == 0)
525 param1 = *(trackBeingFitted->GetTrackParamAtVertex());
526 else param1 = *(trackBeingFitted->GetTrackParamAtFirstHit());
04b5ea16 527 // Minuit parameters to be fitted into this copy
528 param1.SetInverseBendingMomentum(Param[0]);
529 param1.SetBendingSlope(Param[1]);
530 param1.SetNonBendingSlope(Param[2]);
531 if (NParam == 5) {
532 param1.SetNonBendingCoor(Param[3]);
533 param1.SetBendingCoor(Param[4]);
534 }
535
956019b6 536 AliMUONTrackHit *hit;
537 Bool_t goodDeterminant;
bbe35c23 538 Int_t chCurrent, chPrev = 0, hitNumber, hitNumber1, hitNumber2, hitNumber3;
eb9c9dab 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();
d0bfce8d 544 TMatrixD *covBending = new TMatrixD(numberOfHit, numberOfHit);
545 TMatrixD *covNonBending = new TMatrixD(numberOfHit, numberOfHit);
eb9c9dab 546 Double_t *msa2 = new Double_t[numberOfHit];
04b5ea16 547
548 // Predicted coordinates and multiple scattering angles are first calculated
549 for (hitNumber = 0; hitNumber < numberOfHit; hitNumber++) {
550 hit = (AliMUONTrackHit*) (*(trackBeingFitted->GetTrackHitsPtr()))[hitNumber];
eb9c9dab 551 z = hit->GetHitForRecPtr()->GetZ();
04b5ea16 552 // do something special if 2 hits with same Z ????
553 // security against infinite loop ????
eb9c9dab 554 (&param1)->ExtrapToZ(z); // extrapolation
04b5ea16 555 hit->SetTrackParam(&param1);
eb9c9dab 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);
563 chPrev = chCurrent;
04b5ea16 564 }
565
566 // Calculates the covariance matrix
eb9c9dab 567 for (hitNumber1 = 0; hitNumber1 < numberOfHit; hitNumber1++) {
568 hit1 = (AliMUONTrackHit*) (*(trackBeingFitted->GetTrackHitsPtr()))[hitNumber1];
569 z1 = hit1->GetHitForRecPtr()->GetZ();
04b5ea16 570 for (hitNumber2 = hitNumber1; hitNumber2 < numberOfHit; hitNumber2++) {
eb9c9dab 571 hit2 = (AliMUONTrackHit*) (*(trackBeingFitted->GetTrackHitsPtr()))[hitNumber2];
572 z2 = hit2->GetHitForRecPtr()->GetZ();
956019b6 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++) {
eb9c9dab 578 hit3 = (AliMUONTrackHit*)
579 (*(trackBeingFitted->GetTrackHitsPtr()))[hitNumber3];
580 z3 = hit3->GetHitForRecPtr()->GetZ();
04b5ea16 581 (*covBending)(hitNumber2, hitNumber1) =
582 (*covBending)(hitNumber2, hitNumber1) +
eb9c9dab 583 ((z1 - z3) * (z2 - z3) * msa2[hitNumber3]);
956019b6 584 }
585 // equal contribution from multiple scattering in non bending plane
04b5ea16 586 (*covNonBending)(hitNumber2, hitNumber1) =
587 (*covBending)(hitNumber2, hitNumber1);
956019b6 588 if (hitNumber1 == hitNumber2) {
589 // Diagonal elements: add contribution from position measurements
590 // in bending plane
591 (*covBending)(hitNumber2, hitNumber1) =
eb9c9dab 592 (*covBending)(hitNumber2, hitNumber1) +
593 hit1->GetHitForRecPtr()->GetBendingReso2();
956019b6 594 // and in non bending plane
04b5ea16 595 (*covNonBending)(hitNumber2, hitNumber1) =
eb9c9dab 596 (*covNonBending)(hitNumber2, hitNumber1) +
597 hit1->GetHitForRecPtr()->GetNonBendingReso2();
956019b6 598 }
599 else {
600 // Non diagonal elements: symmetrization
601 // for bending plane
602 (*covBending)(hitNumber1, hitNumber2) =
603 (*covBending)(hitNumber2, hitNumber1);
604 // and non bending plane
605 (*covNonBending)(hitNumber1, hitNumber2) =
606 (*covNonBending)(hitNumber2, hitNumber1);
607 }
608 } // for (hitNumber2 = hitNumber1;...
609 } // for (hitNumber1 = 0;...
d0bfce8d 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;
624// exit(0);
625
626// }
04b5ea16 627 // Inverts covariance matrix
956019b6 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 !!!!
04b5ea16 631 if (covBending->Determinant() != 0) {
632 covBending->Invert();
633 } else {
956019b6 634 goodDeterminant = kFALSE;
04b5ea16 635 cout << "Warning in ChiMCS Determinant Bending=0: " << endl;
636 }
956019b6 637 if (covNonBending->Determinant() != 0) {
04b5ea16 638 covNonBending->Invert();
639 } else {
956019b6 640 goodDeterminant = kFALSE;
04b5ea16 641 cout << "Warning in ChiMCS Determinant non Bending=0: " << endl;
642 }
956019b6 643
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 !!!!
04b5ea16 647
648 // Calculates Chi2
eb9c9dab 649 if (goodDeterminant) {
650 // with Multiple Scattering if inversion correct
d0bfce8d 651 // Inverse matrices without normalization
652 (*covBending) *= 1/normCovBending2;
653 (*covNonBending) *= 1/normCovNonBending2;
eb9c9dab 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();
04b5ea16 667 Chi2 = Chi2 +
eb9c9dab 668 ((*covBending)(hitNumber2, hitNumber1) *
669 (hbc1 - pbc1) * (hbc2 - pbc2)) +
04b5ea16 670 ((*covNonBending)(hitNumber2, hitNumber1) *
eb9c9dab 671 (hnbc1 - pnbc1) * (hnbc2 - pnbc2));
04b5ea16 672 }
673 }
eb9c9dab 674 } else {
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();
682 Chi2 = Chi2 +
683 ((hbc1 - pbc1) * (hbc1 - pbc1) /
684 hit1->GetHitForRecPtr()->GetBendingReso2()) +
685 ((hnbc1 - pnbc1) * (hnbc1 - pnbc1) /
686 hit1->GetHitForRecPtr()->GetNonBendingReso2());
04b5ea16 687 }
688 }
689
690 delete covBending;
691 delete covNonBending;
eb9c9dab 692 delete [] msa2;
04b5ea16 693}
694
695Double_t MultipleScatteringAngle2(AliMUONTrackHit *TrackHit)
696{
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;
956019b6 701 AliMUONTrack *trackBeingFitted = (AliMUONTrack*) AliMUONTrack::Fitter()->GetObjectFit();
04b5ea16 702 AliMUONTrackParam *param = TrackHit->GetTrackParam();
956019b6 703 // Better implementation in AliMUONTrack class ????
04b5ea16 704 slopeBending = param->GetBendingSlope();
705 slopeNonBending = param->GetNonBendingSlope();
706 // thickness in radiation length for the current track,
707 // taking local angle into account
708 radiationLength =
709 trackBeingFitted->GetEventReconstructor()->GetChamberThicknessInX0() *
710 TMath::Sqrt(1.0 +
711 slopeBending * slopeBending + slopeNonBending * slopeNonBending);
712 inverseBendingMomentum2 =
713 param->GetInverseBendingMomentum() * param->GetInverseBendingMomentum();
714 inverseTotalMomentum2 =
956019b6 715 inverseBendingMomentum2 * (1.0 + slopeBending * slopeBending) /
04b5ea16 716 (1.0 + slopeBending *slopeBending + slopeNonBending * slopeNonBending);
717 varMultipleScatteringAngle = 0.0136 * (1.0 + 0.038 * TMath::Log(radiationLength));
956019b6 718 // The velocity is assumed to be 1 !!!!
04b5ea16 719 varMultipleScatteringAngle = inverseTotalMomentum2 * radiationLength *
720 varMultipleScatteringAngle * varMultipleScatteringAngle;
721 return varMultipleScatteringAngle;
722}