AliMUONEventReconstructor package
[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$Log$
8429a5e4 18Revision 1.5 2000/07/18 16:04:06 gosset
19AliMUONEventReconstructor package:
20* a few minor modifications and more comments
21* a few corrections
22 * right sign for Z of raw clusters
23 * right loop over chambers inside station
24 * symmetrized covariance matrix for measurements (TrackChi2MCS)
25 * right sign of charge in extrapolation (ExtrapToZ)
26 * right zEndAbsorber for Branson correction below 3 degrees
27* use of TVirtualFitter instead of TMinuit for AliMUONTrack::Fit
28* no parameter for AliMUONTrack::Fit() but more fit parameters in Track object
29
956019b6 30Revision 1.4 2000/06/30 10:15:48 gosset
31Changes to EventReconstructor...:
32precision fit with multiple Coulomb scattering;
33extrapolation to vertex with Branson correction in absorber (JPC)
34
04b5ea16 35Revision 1.3 2000/06/25 13:23:28 hristov
36stdlib.h needed for non-Linux compilation
37
f6e92cf4 38Revision 1.2 2000/06/15 07:58:48 morsch
39Code from MUON-dev joined
40
a9e2aefa 41Revision 1.1.2.3 2000/06/12 10:11:34 morsch
42Dummy copy constructor and assignment operator added
43
44Revision 1.1.2.2 2000/06/09 12:58:05 gosset
45Removed comment beginnings in Log sections of .cxx files
46Suppressed most violations of coding rules
47
48Revision 1.1.2.1 2000/06/07 14:44:53 gosset
49Addition of files for track reconstruction in C++
50*/
51
52//__________________________________________________________________________
53//
54// Reconstructed track in ALICE dimuon spectrometer
55//__________________________________________________________________________
56
57#include "AliMUONTrack.h"
58
59#include <iostream.h>
60
61#include <TClonesArray.h>
04b5ea16 62#include <TMath.h>
63#include <TMatrix.h>
8429a5e4 64#include <TObjArray.h>
956019b6 65#include <TVirtualFitter.h>
a9e2aefa 66
67#include "AliMUONEventReconstructor.h"
68#include "AliMUONHitForRec.h"
69#include "AliMUONSegment.h"
70#include "AliMUONTrackHit.h"
71
f6e92cf4 72#include <stdlib.h>
73
04b5ea16 74// Functions to be minimized with Minuit
a9e2aefa 75void TrackChi2(Int_t &NParam, Double_t *Gradient, Double_t &Chi2, Double_t *Param, Int_t Flag);
04b5ea16 76void TrackChi2MCS(Int_t &NParam, Double_t *Gradient, Double_t &Chi2, Double_t *Param, Int_t Flag);
77
78Double_t MultipleScatteringAngle2(AliMUONTrackHit *TrackHit);
a9e2aefa 79
80ClassImp(AliMUONTrack) // Class implementation in ROOT context
81
956019b6 82TVirtualFitter* AliMUONTrack::fgFitter = NULL;
83
a9e2aefa 84 //__________________________________________________________________________
85AliMUONTrack::AliMUONTrack(AliMUONSegment* BegSegment, AliMUONSegment* EndSegment, AliMUONEventReconstructor* EventReconstructor)
86{
87 // Constructor from two Segment's
88 fEventReconstructor = EventReconstructor; // link back to EventReconstructor
8429a5e4 89 // memory allocation for the TObjArray of pointers to reconstructed TrackHit's
90 fTrackHitsPtr = new TObjArray(10);
a9e2aefa 91 fNTrackHits = 0;
92 AddSegment(BegSegment); // add hits from BegSegment
93 AddSegment(EndSegment); // add hits from EndSegment
94 fTrackHitsPtr->Sort(); // sort TrackHits according to increasing Z
95 SetTrackParamAtVertex(); // set track parameters at vertex
8429a5e4 96 // set fit conditions...
04b5ea16 97 fFitMCS = 0;
956019b6 98 fFitNParam = 3;
99 fFitStart = 1;
8429a5e4 100 fFitFMin = -1.0;
a9e2aefa 101 return;
102}
103
104 //__________________________________________________________________________
105AliMUONTrack::AliMUONTrack(AliMUONSegment* Segment, AliMUONHitForRec* HitForRec, AliMUONEventReconstructor* EventReconstructor)
106{
107 // Constructor from one Segment and one HitForRec
108 fEventReconstructor = EventReconstructor; // link back to EventReconstructor
8429a5e4 109 // memory allocation for the TObjArray of pointers to reconstructed TrackHit's
110 fTrackHitsPtr = new TObjArray(10);
a9e2aefa 111 fNTrackHits = 0;
112 AddSegment(Segment); // add hits from Segment
113 AddHitForRec(HitForRec); // add HitForRec
114 fTrackHitsPtr->Sort(); // sort TrackHits according to increasing Z
115 SetTrackParamAtVertex(); // set track parameters at vertex
8429a5e4 116 // set fit conditions...
04b5ea16 117 fFitMCS = 0;
956019b6 118 fFitNParam = 3;
119 fFitStart = 1;
8429a5e4 120 fFitFMin = -1.0;
a9e2aefa 121 return;
122}
123
8429a5e4 124 //__________________________________________________________________________
125AliMUONTrack::~AliMUONTrack()
126{
127 // Destructor
128 if (fTrackHitsPtr) {
129 delete fTrackHitsPtr; // delete the TObjArray of pointers to TrackHit's
130 fTrackHitsPtr = NULL;
131 }
132}
133
956019b6 134 //__________________________________________________________________________
a9e2aefa 135AliMUONTrack::AliMUONTrack (const AliMUONTrack& MUONTrack)
136{
137// Dummy copy constructor
138}
139
956019b6 140 //__________________________________________________________________________
a9e2aefa 141AliMUONTrack & AliMUONTrack::operator=(const AliMUONTrack& MUONTrack)
142{
143// Dummy assignment operator
144 return *this;
145}
146
8429a5e4 147 //__________________________________________________________________________
148void AliMUONTrack::Remove()
149{
150 // Remove current track from array of tracks,
151 // and corresponding track hits from array of track hits.
152 // Compress the TClonesArray it belongs to.
153 AliMUONTrackHit *nextTrackHit;
154 AliMUONEventReconstructor *eventRec = this->fEventReconstructor;
155 TClonesArray *trackHitsPtr = eventRec->GetRecTrackHitsPtr();
156 // Loop over all track hits of track
157 AliMUONTrackHit *trackHit = (AliMUONTrackHit*) fTrackHitsPtr->First();
158 while (trackHit) {
159 nextTrackHit = (AliMUONTrackHit*) fTrackHitsPtr->After(trackHit);
160 // Remove TrackHit from event TClonesArray.
161 // Destructor is called,
162 // hence links between HitForRec's and TrackHit's are updated
163 trackHitsPtr->Remove(trackHit);
164 trackHit = nextTrackHit;
165 }
166 // Remove the track from event TClonesArray
167 // Destructor is called,
168 // hence space for TObjArray of pointers to TrackHit's is freed
169 eventRec->GetRecTracksPtr()->Remove(this);
170 // Number of tracks decreased by 1
171 eventRec->SetNRecTracks(eventRec->GetNRecTracks() - 1);
172 // Compress event TClonesArray of Track's:
173 // this is essential to retrieve the TClonesArray afterwards
174 eventRec->GetRecTracksPtr()->Compress();
175 // Compress event TClonesArray of TrackHit's:
176 // this is probably also essential to retrieve the TClonesArray afterwards
177 trackHitsPtr->Compress();
178}
179
04b5ea16 180 //__________________________________________________________________________
181void AliMUONTrack::SetFitMCS(Int_t FitMCS)
182{
956019b6 183 // Set multiple Coulomb scattering option for track fit "fFitMCS"
04b5ea16 184 // from "FitMCS" argument: 0 without, 1 with
956019b6 185 if ((FitMCS == 0) || (FitMCS == 1)) fFitMCS = FitMCS;
04b5ea16 186 // better implementation with enum(with, without) ????
956019b6 187 else {
188 cout << "ERROR in AliMUONTrack::SetFitMCS(FitMCS)" << endl;
189 cout << "FitMCS = " << FitMCS << " is neither 0 nor 1" << endl;
190 exit(0);
191 }
192 return;
193}
194
195 //__________________________________________________________________________
196void AliMUONTrack::SetFitNParam(Int_t FitNParam)
197{
198 // Set number of parameters for track fit "fFitNParam" from "FitNParam":
199 // 3 for momentum, 5 for momentum and position
200 if ((FitNParam == 3) || (FitNParam == 5)) fFitNParam = FitNParam;
201 else {
202 cout << "ERROR in AliMUONTrack::SetFitNParam(FitNParam)" << endl;
203 cout << "FitNParam = " << FitNParam << " is neither 3 nor 5" << endl;
204 exit(0);
205 }
206 return;
207}
208
209 //__________________________________________________________________________
210void AliMUONTrack::SetFitStart(Int_t FitStart)
211{
212 // Set multiple Coulomb scattering option for track fit "fFitStart"
213 // from "FitStart" argument: 0 without, 1 with
214 if ((FitStart == 0) || (FitStart == 1)) fFitStart = FitStart;
215 // better implementation with enum(vertex, firstHit) ????
216 else {
217 cout << "ERROR in AliMUONTrack::SetFitStart(FitStart)" << endl;
218 cout << "FitStart = " << FitStart << " is neither 0 nor 1" << endl;
219 exit(0);
220 }
04b5ea16 221 return;
222}
223
956019b6 224 //__________________________________________________________________________
a9e2aefa 225AliMUONTrackParam* AliMUONTrack::GetTrackParamAtFirstHit(void) {
226 // Get pointer to TrackParamAtFirstHit
227 return ((AliMUONTrackHit*) (fTrackHitsPtr->First()))->GetTrackParam();}
a9e2aefa 228
229 //__________________________________________________________________________
230void AliMUONTrack::RecursiveDump(void)
231{
232 // Recursive dump of AliMUONTrack, i.e. with dump of TrackHit's and HitForRec's
233 AliMUONTrackHit *trackHit;
234 AliMUONHitForRec *hitForRec;
235 cout << "Recursive dump of Track: " << this << endl;
236 // Track
237 this->Dump();
238 for (Int_t trackHitIndex = 0; trackHitIndex < fNTrackHits; trackHitIndex++) {
239 trackHit = (AliMUONTrackHit*) ((*fTrackHitsPtr)[trackHitIndex]);
240 // TrackHit
241 cout << "TrackHit: " << trackHit << " (index: " << trackHitIndex << ")" << endl;
242 trackHit->Dump();
243 hitForRec = trackHit->GetHitForRecPtr();
244 // HitForRec
245 cout << "HitForRec: " << hitForRec << endl;
246 hitForRec->Dump();
247 }
248 return;
249}
250
8429a5e4 251 //__________________________________________________________________________
252Int_t AliMUONTrack::HitsInCommon(AliMUONTrack* Track)
253{
254 // Returns the number of hits in common
255 // between the current track ("this")
256 // and the track pointed to by "Track".
257 Int_t hitsInCommon = 0;
258 AliMUONTrackHit *trackHit1, *trackHit2;
259 // Loop over hits of first track
260 trackHit1 = (AliMUONTrackHit*) this->GetTrackHitsPtr()->First();
261 while (trackHit1) {
262 // Loop over hits of second track
263 trackHit2 = (AliMUONTrackHit*) Track->GetTrackHitsPtr()->First();
264 while (trackHit2) {
265 // Increment "hitsInCommon" if both TrackHits point to the same HitForRec
266 if ( (trackHit1->GetHitForRecPtr()) ==
267 (trackHit2->GetHitForRecPtr()) ) hitsInCommon++;
268 trackHit2 = (AliMUONTrackHit*) Track->GetTrackHitsPtr()->After(trackHit2);
269 } // trackHit2
270 trackHit1 = (AliMUONTrackHit*) this->GetTrackHitsPtr()->After(trackHit1);
271 } // trackHit1
272 return hitsInCommon;
273}
274
a9e2aefa 275 //__________________________________________________________________________
956019b6 276void AliMUONTrack::Fit()
a9e2aefa 277{
278 // Fit the current track ("this"),
956019b6 279 // with or without multiple Coulomb scattering according to "fFitMCS",
280 // with the number of parameters given by "fFitNParam"
281 // (3 if one keeps X and Y fixed in "TrackParam", 5 if one lets them vary),
282 // starting, according to "fFitStart",
283 // with track parameters at vertex or at the first TrackHit.
284 // "fFitMCS", "fFitNParam" and "fFitStart" have to be set before
285 // by calling the corresponding Set methods.
a9e2aefa 286 Double_t arg[1], benC, errorParam, invBenP, lower, nonBenC, upper, x, y;
956019b6 287 char parName[50];
288 AliMUONTrackParam *trackParam;
289 // Check if Minuit is initialized...
290 fgFitter = TVirtualFitter::Fitter(this); // add 3 or 5 for the maximum number of parameters ???
291 fgFitter->Clear(); // necessary ???? probably yes
292 // how to reset the printout number at every fit ????
293 // is there any risk to leave it like that ????
a9e2aefa 294 // how to go faster ???? choice of Minuit parameters like EDM ????
04b5ea16 295 // choice of function to be minimized according to fFitMCS
956019b6 296 if (fFitMCS == 0) fgFitter->SetFCN(TrackChi2);
297 else fgFitter->SetFCN(TrackChi2MCS);
298 arg[0] = 1;
299 fgFitter->ExecuteCommand("SET PRINT", arg, 1); // More printing !!!!
300 // Parameters according to "fFitStart"
301 // (should be a function to be used at every place where needed ????)
302 if (fFitStart == 0) trackParam = &fTrackParamAtVertex;
303 else trackParam = this->GetTrackParamAtFirstHit();
304 // set first 3 Minuit parameters
04b5ea16 305 // could be tried with no limits for the search (min=max=0) ????
956019b6 306 fgFitter->SetParameter(0, "InvBenP",
307 trackParam->GetInverseBendingMomentum(),
308 0.003, -0.4, 0.4);
309 fgFitter->SetParameter(1, "BenS",
310 trackParam->GetBendingSlope(),
311 0.001, -0.5, 0.5);
312 fgFitter->SetParameter(2, "NonBenS",
313 trackParam->GetNonBendingSlope(),
314 0.001, -0.5, 0.5);
315 if (fFitNParam == 5) {
316 // set last 2 Minuit parameters (no limits for the search: min=max=0)
317 fgFitter->SetParameter(3, "X",
318 trackParam->GetNonBendingCoor(),
319 0.03, 0.0, 0.0);
320 fgFitter->SetParameter(4, "Y",
321 trackParam->GetBendingCoor(),
322 0.10, 0.0, 0.0);
a9e2aefa 323 }
324 // search without gradient calculation in the function
956019b6 325 fgFitter->ExecuteCommand("SET NOGRADIENT", arg, 0);
a9e2aefa 326 // minimization
956019b6 327 fgFitter->ExecuteCommand("MINIMIZE", arg, 0);
a9e2aefa 328 // exit from Minuit
956019b6 329 fgFitter->ExecuteCommand("EXIT", arg, 0); // necessary ????
330 // get results into "invBenP", "benC", "nonBenC" ("x", "y")
331 fgFitter->GetParameter(0, parName, invBenP, errorParam, lower, upper);
332 fgFitter->GetParameter(1, parName, benC, errorParam, lower, upper);
333 fgFitter->GetParameter(2, parName, nonBenC, errorParam, lower, upper);
334 if (fFitNParam == 5) {
335 fgFitter->GetParameter(3, parName, x, errorParam, lower, upper);
336 fgFitter->GetParameter(4, parName, y, errorParam, lower, upper);
a9e2aefa 337 }
338 // result of the fit into track parameters
956019b6 339 trackParam->SetInverseBendingMomentum(invBenP);
340 trackParam->SetBendingSlope(benC);
341 trackParam->SetNonBendingSlope(nonBenC);
342 if (fFitNParam == 5) {
343 trackParam->SetNonBendingCoor(x);
344 trackParam->SetBendingCoor(y);
a9e2aefa 345 }
8429a5e4 346 // global result of the fit
347 Double_t fedm, errdef;
348 Int_t npari, nparx;
349 fgFitter->GetStats(fFitFMin, fedm, errdef, npari, nparx);
a9e2aefa 350}
351
352 //__________________________________________________________________________
353void AliMUONTrack::AddSegment(AliMUONSegment* Segment)
354{
8429a5e4 355 // Add Segment to the track
a9e2aefa 356 AddHitForRec(Segment->GetHitForRec1()); // 1st hit
357 AddHitForRec(Segment->GetHitForRec2()); // 2nd hit
358}
359
360 //__________________________________________________________________________
361void AliMUONTrack::AddHitForRec(AliMUONHitForRec* HitForRec)
362{
8429a5e4 363 // Add HitForRec to the track:
364 // actual TrackHit into TClonesArray of TrackHit's for the event;
365 // pointer to actual TrackHit in TObjArray of pointers to TrackHit's for the track
366 TClonesArray *recTrackHitsPtr = this->fEventReconstructor->GetRecTrackHitsPtr();
367 Int_t eventTrackHits = this->fEventReconstructor->GetNRecTrackHits();
368 // event
369 AliMUONTrackHit* trackHit =
370 new ((*recTrackHitsPtr)[eventTrackHits]) AliMUONTrackHit(HitForRec);
371 this->fEventReconstructor->SetNRecTrackHits(eventTrackHits + 1);
372 // track
373 fTrackHitsPtr->Add(trackHit);
a9e2aefa 374 fNTrackHits++;
375}
376
377 //__________________________________________________________________________
378void AliMUONTrack::SetTrackParamAtHit(Int_t indexHit, AliMUONTrackParam *TrackParam)
379{
380 // Set track parameters at TrackHit with index "indexHit"
381 // from the track parameters pointed to by "TrackParam".
382 AliMUONTrackHit* trackHit = (AliMUONTrackHit*) ((*fTrackHitsPtr)[indexHit]);
383 trackHit->SetTrackParam(TrackParam);
384}
385
386 //__________________________________________________________________________
387void AliMUONTrack::SetTrackParamAtVertex()
388{
389 // Set track parameters at vertex.
390 // TrackHit's are assumed to be only in stations(1..) 4 and 5,
391 // and sorted according to increasing Z..
392 // Parameters are calculated from information in HitForRec's
393 // of first and last TrackHit's.
394 AliMUONTrackParam *trackParam =
395 &fTrackParamAtVertex; // pointer to track parameters
396 // Pointer to HitForRec of first TrackHit
397 AliMUONHitForRec *firstHit =
398 ((AliMUONTrackHit*) (fTrackHitsPtr->First()))->GetHitForRecPtr();
399 // Pointer to HitForRec of last TrackHit
400 AliMUONHitForRec *lastHit =
401 ((AliMUONTrackHit*) (fTrackHitsPtr->Last()))->GetHitForRecPtr();
402 // Z difference between first and last hits
403 Double_t deltaZ = firstHit->GetZ() - lastHit->GetZ();
404 // bending slope in stations(1..) 4 and 5
405 Double_t bendingSlope =
406 (firstHit->GetBendingCoor() - lastHit->GetBendingCoor()) / deltaZ;
407 trackParam->SetBendingSlope(bendingSlope);
408 // impact parameter
409 Double_t impactParam =
410 firstHit->GetBendingCoor() - bendingSlope * firstHit->GetZ(); // same if from firstHit and lastHit ????
411 // signed bending momentum
412 Double_t signedBendingMomentum =
413 fEventReconstructor->GetBendingMomentumFromImpactParam(impactParam);
414 trackParam->SetInverseBendingMomentum(1.0 / signedBendingMomentum);
415 // bending slope at vertex
416 trackParam->
417 SetBendingSlope(bendingSlope +
418 impactParam / fEventReconstructor->GetSimpleBPosition());
419 // non bending slope
420 Double_t nonBendingSlope =
421 (firstHit->GetNonBendingCoor() - lastHit->GetNonBendingCoor()) / deltaZ;
422 trackParam->SetNonBendingSlope(nonBendingSlope);
423 // vertex coordinates at (0,0,0)
424 trackParam->SetZ(0.0);
425 trackParam->SetBendingCoor(0.0);
426 trackParam->SetNonBendingCoor(0.0);
427}
428
429 //__________________________________________________________________________
430void TrackChi2(Int_t &NParam, Double_t *Gradient, Double_t &Chi2, Double_t *Param, Int_t Flag)
431{
432 // Return the "Chi2" to be minimized with Minuit for track fitting,
433 // with "NParam" parameters
434 // and their current values in array pointed to by "Param".
435 // Assumes that the track hits are sorted according to increasing Z.
436 // Track parameters at each TrackHit are updated accordingly.
04b5ea16 437 // Multiple Coulomb scattering is not taken into account
956019b6 438 AliMUONTrack *trackBeingFitted;
a9e2aefa 439 AliMUONTrackHit* hit;
440 AliMUONTrackParam param1;
441 Int_t hitNumber;
442 Double_t zHit;
443 Chi2 = 0.0; // initialize Chi2
444 // copy of track parameters to be fitted
956019b6 445 trackBeingFitted = (AliMUONTrack*) AliMUONTrack::Fitter()->GetObjectFit();
446 if (trackBeingFitted->GetFitStart() == 0)
447 param1 = *(trackBeingFitted->GetTrackParamAtVertex());
448 else param1 = *(trackBeingFitted->GetTrackParamAtFirstHit());
a9e2aefa 449 // Minuit parameters to be fitted into this copy
450 param1.SetInverseBendingMomentum(Param[0]);
451 param1.SetBendingSlope(Param[1]);
452 param1.SetNonBendingSlope(Param[2]);
453 if (NParam == 5) {
454 param1.SetNonBendingCoor(Param[3]);
455 param1.SetBendingCoor(Param[4]);
456 }
457 // Follow track through all planes of track hits
458 for (hitNumber = 0; hitNumber < trackBeingFitted->GetNTrackHits(); hitNumber++) {
459 hit = (AliMUONTrackHit*) (*(trackBeingFitted->GetTrackHitsPtr()))[hitNumber];
460 zHit = hit->GetHitForRecPtr()->GetZ();
461 // do something special if 2 hits with same Z ????
462 // security against infinite loop ????
463 (&param1)->ExtrapToZ(zHit); // extrapolation
464 hit->SetTrackParam(&param1);
465 // Increment Chi2
466 // done hit per hit, with hit resolution,
467 // and not with point and angle like in "reco_muon.F" !!!!
468 // Needs to add multiple scattering contribution ????
469 Double_t dX =
470 hit->GetHitForRecPtr()->GetNonBendingCoor() - (&param1)->GetNonBendingCoor();
471 Double_t dY =
472 hit->GetHitForRecPtr()->GetBendingCoor() - (&param1)->GetBendingCoor();
473 Chi2 =
474 Chi2 +
475 dX * dX / hit->GetHitForRecPtr()->GetNonBendingReso2() +
476 dY * dY / hit->GetHitForRecPtr()->GetBendingReso2();
477 }
478}
04b5ea16 479
480 //__________________________________________________________________________
481void TrackChi2MCS(Int_t &NParam, Double_t *Gradient, Double_t &Chi2, Double_t *Param, Int_t Flag)
482{
483 // Return the "Chi2" to be minimized with Minuit for track fitting,
484 // with "NParam" parameters
485 // and their current values in array pointed to by "Param".
486 // Assumes that the track hits are sorted according to increasing Z.
487 // Track parameters at each TrackHit are updated accordingly.
488 // Multiple Coulomb scattering is taken into account with covariance matrix.
956019b6 489 AliMUONTrack *trackBeingFitted;
04b5ea16 490 AliMUONTrackParam param1;
491 Chi2 = 0.0; // initialize Chi2
492 // copy of track parameters to be fitted
956019b6 493 trackBeingFitted = (AliMUONTrack*) AliMUONTrack::Fitter()->GetObjectFit();
494 if (trackBeingFitted->GetFitStart() == 0)
495 param1 = *(trackBeingFitted->GetTrackParamAtVertex());
496 else param1 = *(trackBeingFitted->GetTrackParamAtFirstHit());
04b5ea16 497 // Minuit parameters to be fitted into this copy
498 param1.SetInverseBendingMomentum(Param[0]);
499 param1.SetBendingSlope(Param[1]);
500 param1.SetNonBendingSlope(Param[2]);
501 if (NParam == 5) {
502 param1.SetNonBendingCoor(Param[3]);
503 param1.SetBendingCoor(Param[4]);
504 }
505
956019b6 506 AliMUONTrackHit *hit;
507 Bool_t goodDeterminant;
04b5ea16 508 Int_t hitNumber, hitNumber1, hitNumber2, hitNumber3;
509 Double_t zHit[10], paramBendingCoor[10], paramNonBendingCoor[10], ap[10];
510 Double_t hitBendingCoor[10], hitNonBendingCoor[10];
511 Double_t hitBendingReso2[10], hitNonBendingReso2[10];
956019b6 512 // dimension 10 in parameter ??? related to AliMUONConstants::NTrackingCh() !!!!
04b5ea16 513 Int_t numberOfHit = TMath::Min(trackBeingFitted->GetNTrackHits(), 10);
514 TMatrix *covBending = new TMatrix(numberOfHit, numberOfHit);
515 TMatrix *covNonBending = new TMatrix(numberOfHit, numberOfHit);
516
517 // Predicted coordinates and multiple scattering angles are first calculated
518 for (hitNumber = 0; hitNumber < numberOfHit; hitNumber++) {
519 hit = (AliMUONTrackHit*) (*(trackBeingFitted->GetTrackHitsPtr()))[hitNumber];
520 zHit[hitNumber] = hit->GetHitForRecPtr()->GetZ();
521 // do something special if 2 hits with same Z ????
522 // security against infinite loop ????
523 (&param1)->ExtrapToZ(zHit[hitNumber]); // extrapolation
524 hit->SetTrackParam(&param1);
956019b6 525 paramBendingCoor[hitNumber] = (&param1)->GetBendingCoor();
526 paramNonBendingCoor[hitNumber] = (&param1)->GetNonBendingCoor();
527 hitBendingCoor[hitNumber] = hit->GetHitForRecPtr()->GetBendingCoor();
528 hitNonBendingCoor[hitNumber] = hit->GetHitForRecPtr()->GetNonBendingCoor();
529 hitBendingReso2[hitNumber] = hit->GetHitForRecPtr()->GetBendingReso2();
530 hitNonBendingReso2[hitNumber] = hit->GetHitForRecPtr()->GetNonBendingReso2();
04b5ea16 531 ap[hitNumber] = MultipleScatteringAngle2(hit); // multiple scatt. angle ^2
532 }
533
534 // Calculates the covariance matrix
956019b6 535 // One chamber is taken into account between successive hits.
536 // "ap" should be changed for taking into account the eventual missing hits
537 // by defining an "equivalent" chamber thickness !!!!
04b5ea16 538 for (hitNumber1 = 0; hitNumber1 < numberOfHit; hitNumber1++) {
539 for (hitNumber2 = hitNumber1; hitNumber2 < numberOfHit; hitNumber2++) {
956019b6 540 // initialization to 0 (diagonal plus upper triangular part)
541 (*covBending)(hitNumber2, hitNumber1) = 0.0;
542 // contribution from multiple scattering in bending plane:
543 // loop over upstream hits
544 for (hitNumber3 = 0; hitNumber3 < hitNumber1; hitNumber3++) {
04b5ea16 545 (*covBending)(hitNumber2, hitNumber1) =
546 (*covBending)(hitNumber2, hitNumber1) +
547 ((zHit[hitNumber1] - zHit[hitNumber3]) *
548 (zHit[hitNumber2] - zHit[hitNumber3]) * ap[hitNumber3]);
956019b6 549 }
550 // equal contribution from multiple scattering in non bending plane
04b5ea16 551 (*covNonBending)(hitNumber2, hitNumber1) =
552 (*covBending)(hitNumber2, hitNumber1);
956019b6 553 if (hitNumber1 == hitNumber2) {
554 // Diagonal elements: add contribution from position measurements
555 // in bending plane
556 (*covBending)(hitNumber2, hitNumber1) =
557 (*covBending)(hitNumber2, hitNumber1) + hitBendingReso2[hitNumber1];
558 // and in non bending plane
04b5ea16 559 (*covNonBending)(hitNumber2, hitNumber1) =
956019b6 560 (*covNonBending)(hitNumber2, hitNumber1) + hitNonBendingReso2[hitNumber1];
561 }
562 else {
563 // Non diagonal elements: symmetrization
564 // for bending plane
565 (*covBending)(hitNumber1, hitNumber2) =
566 (*covBending)(hitNumber2, hitNumber1);
567 // and non bending plane
568 (*covNonBending)(hitNumber1, hitNumber2) =
569 (*covNonBending)(hitNumber2, hitNumber1);
570 }
571 } // for (hitNumber2 = hitNumber1;...
572 } // for (hitNumber1 = 0;...
04b5ea16 573
574 // Inverts covariance matrix
956019b6 575 goodDeterminant = kTRUE;
576 // check whether the Invert method returns flag if matrix cannot be inverted,
577 // and do not calculate the Determinant in that case !!!!
04b5ea16 578 if (covBending->Determinant() != 0) {
579 covBending->Invert();
580 } else {
956019b6 581 goodDeterminant = kFALSE;
04b5ea16 582 cout << "Warning in ChiMCS Determinant Bending=0: " << endl;
583 }
956019b6 584 if (covNonBending->Determinant() != 0) {
04b5ea16 585 covNonBending->Invert();
586 } else {
956019b6 587 goodDeterminant = kFALSE;
04b5ea16 588 cout << "Warning in ChiMCS Determinant non Bending=0: " << endl;
589 }
956019b6 590
591 // It would be worth trying to calculate the inverse of the covariance matrix
592 // only once per fit, since it cannot change much in principle,
593 // and it would save a lot of computing time !!!!
04b5ea16 594
595 // Calculates Chi2
956019b6 596 if (goodDeterminant) { // with Multiple Scattering if inversion correct
04b5ea16 597 for (hitNumber1=0; hitNumber1 < numberOfHit ; hitNumber1++){
598 for (hitNumber2=0; hitNumber2 < numberOfHit; hitNumber2++){
599 Chi2 = Chi2 +
600 ((*covBending)(hitNumber2, hitNumber1) *
601 (hitBendingCoor[hitNumber1] - paramBendingCoor[hitNumber1]) *
602 (hitBendingCoor[hitNumber2] - paramBendingCoor[hitNumber2]));
603 Chi2 = Chi2 +
604 ((*covNonBending)(hitNumber2, hitNumber1) *
605 (hitNonBendingCoor[hitNumber1] - paramNonBendingCoor[hitNumber1]) *
606 (hitNonBendingCoor[hitNumber2] - paramNonBendingCoor[hitNumber2]));
607 }
608 }
609 } else { // without Multiple Scattering if inversion impossible
610 for (hitNumber1=0; hitNumber1 < numberOfHit ; hitNumber1++) {
611 Chi2 = Chi2 +
612 ((hitBendingCoor[hitNumber1] - paramBendingCoor[hitNumber1]) *
613 (hitBendingCoor[hitNumber1] - paramBendingCoor[hitNumber1]) /
614 hitBendingReso2[hitNumber1]);
615 Chi2 = Chi2 +
616 ((hitNonBendingCoor[hitNumber1] - paramNonBendingCoor[hitNumber1]) *
617 (hitNonBendingCoor[hitNumber1] - paramNonBendingCoor[hitNumber1]) /
618 hitNonBendingReso2[hitNumber1]);
619 }
620 }
621
622 delete covBending;
623 delete covNonBending;
624}
625
626Double_t MultipleScatteringAngle2(AliMUONTrackHit *TrackHit)
627{
628 // Returns square of multiple Coulomb scattering angle
629 // at TrackHit pointed to by "TrackHit"
630 Double_t slopeBending, slopeNonBending, radiationLength, inverseBendingMomentum2, inverseTotalMomentum2;
631 Double_t varMultipleScatteringAngle;
956019b6 632 AliMUONTrack *trackBeingFitted = (AliMUONTrack*) AliMUONTrack::Fitter()->GetObjectFit();
04b5ea16 633 AliMUONTrackParam *param = TrackHit->GetTrackParam();
956019b6 634 // Better implementation in AliMUONTrack class ????
04b5ea16 635 slopeBending = param->GetBendingSlope();
636 slopeNonBending = param->GetNonBendingSlope();
637 // thickness in radiation length for the current track,
638 // taking local angle into account
639 radiationLength =
640 trackBeingFitted->GetEventReconstructor()->GetChamberThicknessInX0() *
641 TMath::Sqrt(1.0 +
642 slopeBending * slopeBending + slopeNonBending * slopeNonBending);
643 inverseBendingMomentum2 =
644 param->GetInverseBendingMomentum() * param->GetInverseBendingMomentum();
645 inverseTotalMomentum2 =
956019b6 646 inverseBendingMomentum2 * (1.0 + slopeBending * slopeBending) /
04b5ea16 647 (1.0 + slopeBending *slopeBending + slopeNonBending * slopeNonBending);
648 varMultipleScatteringAngle = 0.0136 * (1.0 + 0.038 * TMath::Log(radiationLength));
956019b6 649 // The velocity is assumed to be 1 !!!!
04b5ea16 650 varMultipleScatteringAngle = inverseTotalMomentum2 * radiationLength *
651 varMultipleScatteringAngle * varMultipleScatteringAngle;
652 return varMultipleScatteringAngle;
653}