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4811a3f4 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: AliTrackerBase.cxx 38069 2009-12-24 16:56:18Z belikov $ */
17
18//-------------------------------------------------------------------------
19// Implementation of the AliTrackerBase class
075f4221 20// that is the base for the AliTracker class
21// Origin: Marian.Ivanov@cern.ch
4811a3f4 22//-------------------------------------------------------------------------
23#include <TClass.h>
24#include <TMath.h>
25#include <TGeoManager.h>
26
27#include "AliLog.h"
28#include "AliTrackerBase.h"
29#include "AliExternalTrackParam.h"
075f4221 30#include "AliTrackPointArray.h"
363db7c3 31#include "TVectorD.h"
4811a3f4 32
33extern TGeoManager *gGeoManager;
34
35ClassImp(AliTrackerBase)
36
37AliTrackerBase::AliTrackerBase():
38 TObject(),
39 fX(0),
40 fY(0),
41 fZ(0),
42 fSigmaX(0.005),
43 fSigmaY(0.005),
44 fSigmaZ(0.010)
45{
46 //--------------------------------------------------------------------
47 // The default constructor.
48 //--------------------------------------------------------------------
49 if (!TGeoGlobalMagField::Instance()->GetField())
50 AliWarning("Field map is not set.");
51}
52
53//__________________________________________________________________________
54AliTrackerBase::AliTrackerBase(const AliTrackerBase &atr):
55 TObject(atr),
56 fX(atr.fX),
57 fY(atr.fY),
58 fZ(atr.fZ),
59 fSigmaX(atr.fSigmaX),
60 fSigmaY(atr.fSigmaY),
61 fSigmaZ(atr.fSigmaZ)
62{
63 //--------------------------------------------------------------------
64 // The default constructor.
65 //--------------------------------------------------------------------
66 if (!TGeoGlobalMagField::Instance()->GetField())
67 AliWarning("Field map is not set.");
68}
69
70//__________________________________________________________________________
71Double_t AliTrackerBase::GetBz()
72{
73 AliMagF* fld = (AliMagF*)TGeoGlobalMagField::Instance()->GetField();
74 if (!fld) return 0.5*kAlmost0Field;
75 Double_t bz = fld->SolenoidField();
76 return TMath::Sign(0.5*kAlmost0Field,bz) + bz;
77}
78
79//__________________________________________________________________________
80Double_t AliTrackerBase::GetBz(const Double_t *r) {
81 //------------------------------------------------------------------
82 // Returns Bz (kG) at the point "r" .
83 //------------------------------------------------------------------
84 AliMagF* fld = (AliMagF*)TGeoGlobalMagField::Instance()->GetField();
85 if (!fld) return 0.5*kAlmost0Field;
86 Double_t bz = fld->GetBz(r);
87 return TMath::Sign(0.5*kAlmost0Field,bz) + bz;
88}
89
90//__________________________________________________________________________
91void AliTrackerBase::GetBxByBz(const Double_t r[3], Double_t b[3]) {
92 //------------------------------------------------------------------
93 // Returns Bx, By and Bz (kG) at the point "r" .
94 //------------------------------------------------------------------
95 AliMagF* fld = (AliMagF*)TGeoGlobalMagField::Instance()->GetField();
96 if (!fld) {
97 b[0] = b[1] = 0.;
98 b[2] = 0.5*kAlmost0Field;
99 return;
100 }
101
102 if (fld->IsUniform()) {
103 b[0] = b[1] = 0.;
104 b[2] = fld->SolenoidField();
105 } else {
106 fld->Field(r,b);
107 }
108 b[2] = (TMath::Sign(0.5*kAlmost0Field,b[2]) + b[2]);
109 return;
110}
111
112Double_t AliTrackerBase::MeanMaterialBudget(const Double_t *start, const Double_t *end, Double_t *mparam)
113{
114 //
115 // Calculate mean material budget and material properties between
116 // the points "start" and "end".
117 //
118 // "mparam" - parameters used for the energy and multiple scattering
119 // corrections:
120 //
121 // mparam[0] - mean density: sum(x_i*rho_i)/sum(x_i) [g/cm3]
122 // mparam[1] - equivalent rad length fraction: sum(x_i/X0_i) [adimensional]
123 // mparam[2] - mean A: sum(x_i*A_i)/sum(x_i) [adimensional]
124 // mparam[3] - mean Z: sum(x_i*Z_i)/sum(x_i) [adimensional]
125 // mparam[4] - length: sum(x_i) [cm]
126 // mparam[5] - Z/A mean: sum(x_i*Z_i/A_i)/sum(x_i) [adimensional]
127 // mparam[6] - number of boundary crosses
128 //
129 // Origin: Marian Ivanov, Marian.Ivanov@cern.ch
130 //
131 // Corrections and improvements by
132 // Andrea Dainese, Andrea.Dainese@lnl.infn.it,
133 // Andrei Gheata, Andrei.Gheata@cern.ch
134 //
135
136 mparam[0]=0; mparam[1]=1; mparam[2] =0; mparam[3] =0;
137 mparam[4]=0; mparam[5]=0; mparam[6]=0;
138 //
139 Double_t bparam[6]; // total parameters
140 Double_t lparam[6]; // local parameters
141
142 for (Int_t i=0;i<6;i++) bparam[i]=0;
143
144 if (!gGeoManager) {
2ad9a021 145 AliFatalClass("No TGeo\n");
4811a3f4 146 return 0.;
147 }
148 //
149 Double_t length;
150 Double_t dir[3];
151 length = TMath::Sqrt((end[0]-start[0])*(end[0]-start[0])+
152 (end[1]-start[1])*(end[1]-start[1])+
153 (end[2]-start[2])*(end[2]-start[2]));
154 mparam[4]=length;
155 if (length<TGeoShape::Tolerance()) return 0.0;
156 Double_t invlen = 1./length;
157 dir[0] = (end[0]-start[0])*invlen;
158 dir[1] = (end[1]-start[1])*invlen;
159 dir[2] = (end[2]-start[2])*invlen;
160
161 // Initialize start point and direction
162 TGeoNode *currentnode = 0;
163 TGeoNode *startnode = gGeoManager->InitTrack(start, dir);
164 if (!startnode) {
165 AliErrorClass(Form("start point out of geometry: x %f, y %f, z %f",
166 start[0],start[1],start[2]));
167 return 0.0;
168 }
169 TGeoMaterial *material = startnode->GetVolume()->GetMedium()->GetMaterial();
170 lparam[0] = material->GetDensity();
171 lparam[1] = material->GetRadLen();
172 lparam[2] = material->GetA();
173 lparam[3] = material->GetZ();
174 lparam[4] = length;
175 lparam[5] = lparam[3]/lparam[2];
176 if (material->IsMixture()) {
177 TGeoMixture * mixture = (TGeoMixture*)material;
178 lparam[5] =0;
179 Double_t sum =0;
180 for (Int_t iel=0;iel<mixture->GetNelements();iel++){
181 sum += mixture->GetWmixt()[iel];
182 lparam[5]+= mixture->GetZmixt()[iel]*mixture->GetWmixt()[iel]/mixture->GetAmixt()[iel];
183 }
184 lparam[5]/=sum;
185 }
186
187 // Locate next boundary within length without computing safety.
188 // Propagate either with length (if no boundary found) or just cross boundary
189 gGeoManager->FindNextBoundaryAndStep(length, kFALSE);
190 Double_t step = 0.0; // Step made
191 Double_t snext = gGeoManager->GetStep();
192 // If no boundary within proposed length, return current density
193 if (!gGeoManager->IsOnBoundary()) {
194 mparam[0] = lparam[0];
195 mparam[1] = lparam[4]/lparam[1];
196 mparam[2] = lparam[2];
197 mparam[3] = lparam[3];
198 mparam[4] = lparam[4];
199 return lparam[0];
200 }
201 // Try to cross the boundary and see what is next
202 Int_t nzero = 0;
203 while (length>TGeoShape::Tolerance()) {
204 currentnode = gGeoManager->GetCurrentNode();
205 if (snext<2.*TGeoShape::Tolerance()) nzero++;
206 else nzero = 0;
207 if (nzero>3) {
208 // This means navigation has problems on one boundary
209 // Try to cross by making a small step
210 AliErrorClass("Cannot cross boundary\n");
211 mparam[0] = bparam[0]/step;
212 mparam[1] = bparam[1];
213 mparam[2] = bparam[2]/step;
214 mparam[3] = bparam[3]/step;
215 mparam[5] = bparam[5]/step;
216 mparam[4] = step;
217 mparam[0] = 0.; // if crash of navigation take mean density 0
218 mparam[1] = 1000000; // and infinite rad length
219 return bparam[0]/step;
220 }
221 mparam[6]+=1.;
222 step += snext;
223 bparam[1] += snext/lparam[1];
224 bparam[2] += snext*lparam[2];
225 bparam[3] += snext*lparam[3];
226 bparam[5] += snext*lparam[5];
227 bparam[0] += snext*lparam[0];
228
229 if (snext>=length) break;
230 if (!currentnode) break;
231 length -= snext;
232 material = currentnode->GetVolume()->GetMedium()->GetMaterial();
233 lparam[0] = material->GetDensity();
234 lparam[1] = material->GetRadLen();
235 lparam[2] = material->GetA();
236 lparam[3] = material->GetZ();
237 lparam[5] = lparam[3]/lparam[2];
238 if (material->IsMixture()) {
239 TGeoMixture * mixture = (TGeoMixture*)material;
240 lparam[5]=0;
241 Double_t sum =0;
242 for (Int_t iel=0;iel<mixture->GetNelements();iel++){
243 sum+= mixture->GetWmixt()[iel];
244 lparam[5]+= mixture->GetZmixt()[iel]*mixture->GetWmixt()[iel]/mixture->GetAmixt()[iel];
245 }
246 lparam[5]/=sum;
247 }
248 gGeoManager->FindNextBoundaryAndStep(length, kFALSE);
249 snext = gGeoManager->GetStep();
250 }
251 mparam[0] = bparam[0]/step;
252 mparam[1] = bparam[1];
253 mparam[2] = bparam[2]/step;
254 mparam[3] = bparam[3]/step;
255 mparam[5] = bparam[5]/step;
256 return bparam[0]/step;
257}
258
259
260Bool_t
261AliTrackerBase::PropagateTrackTo(AliExternalTrackParam *track, Double_t xToGo,
13545423 262 Double_t mass, Double_t maxStep, Bool_t rotateTo, Double_t maxSnp, Int_t sign, Bool_t addTimeStep){
4811a3f4 263 //----------------------------------------------------------------
264 //
265 // Propagates the track to the plane X=xk (cm) using the magnetic field map
266 // and correcting for the crossed material.
267 //
268 // mass - mass used in propagation - used for energy loss correction
269 // maxStep - maximal step for propagation
270 //
271 // Origin: Marian Ivanov, Marian.Ivanov@cern.ch
272 //
273 //----------------------------------------------------------------
274 const Double_t kEpsilon = 0.00001;
275 Double_t xpos = track->GetX();
13545423 276 Int_t dir = (xpos<xToGo) ? 1:-1;
4811a3f4 277 //
278 while ( (xToGo-xpos)*dir > kEpsilon){
279 Double_t step = dir*TMath::Min(TMath::Abs(xToGo-xpos), maxStep);
280 Double_t x = xpos+step;
281 Double_t xyz0[3],xyz1[3],param[7];
282 track->GetXYZ(xyz0); //starting global position
283
284 Double_t bz=GetBz(xyz0); // getting the local Bz
285
286 if (!track->GetXYZAt(x,bz,xyz1)) return kFALSE; // no prolongation
287 xyz1[2]+=kEpsilon; // waiting for bug correction in geo
288
7391b629 289 if (maxSnp>0 && TMath::Abs(track->GetSnpAt(x,bz)) >= maxSnp) return kFALSE;
4811a3f4 290 if (!track->PropagateTo(x,bz)) return kFALSE;
291
292 MeanMaterialBudget(xyz0,xyz1,param);
13545423 293 Double_t xrho=param[0]*param[4], xx0=param[1];
294 if (sign) {if (sign<0) xrho = -xrho;} // sign is imposed
295 else { // determine automatically the sign from direction
296 if (dir>0) xrho = -xrho; // outward should be negative
297 }
298 //
4811a3f4 299 if (!track->CorrectForMeanMaterial(xx0,xrho,mass)) return kFALSE;
300 if (rotateTo){
dc981549 301 track->GetXYZ(xyz1); // global position
302 Double_t alphan = TMath::ATan2(xyz1[1], xyz1[0]);
7391b629 303 if (maxSnp>0) {
304 if (TMath::Abs(track->GetSnp()) >= maxSnp) return kFALSE;
305 //
306 Double_t ca=TMath::Cos(alphan-track->GetAlpha()), sa=TMath::Sin(alphan-track->GetAlpha());
307 Double_t sf=track->GetSnp(), cf=TMath::Sqrt((1.-sf)*(1.+sf));
308 Double_t sinNew = sf*ca - cf*sa;
309 if (TMath::Abs(sinNew) >= maxSnp) return kFALSE;
310 }
dc981549 311 if (!track->AliExternalTrackParam::Rotate(alphan)) return kFALSE;
4811a3f4 312 }
313 xpos = track->GetX();
13545423 314 if (addTimeStep && track->IsStartedTimeIntegral()) {
dc981549 315 if (!rotateTo) track->GetXYZ(xyz1); // if rotateTo==kTRUE, then xyz1 is already extracted
13545423 316 Double_t dX=xyz0[0]-xyz1[0],dY=xyz0[1]-xyz1[1],dZ=xyz0[2]-xyz1[2];
317 Double_t d=TMath::Sqrt(dX*dX + dY*dY + dZ*dZ);
318 if (sign) {if (sign>0) d = -d;} // step sign is imposed, positive means inward direction
319 else { // determine automatically the sign from direction
320 if (dir<0) d = -d;
321 }
322 track->AddTimeStep(d);
323 }
4811a3f4 324 }
325 return kTRUE;
326}
327
328Bool_t
329AliTrackerBase::PropagateTrackToBxByBz(AliExternalTrackParam *track,
13545423 330 Double_t xToGo,Double_t mass, Double_t maxStep, Bool_t rotateTo, Double_t maxSnp,Int_t sign, Bool_t addTimeStep){
4811a3f4 331 //----------------------------------------------------------------
332 //
333 // Propagates the track to the plane X=xk (cm)
334 // taking into account all the three components of the magnetic field
335 // and correcting for the crossed material.
336 //
337 // mass - mass used in propagation - used for energy loss correction
338 // maxStep - maximal step for propagation
339 //
340 // Origin: Marian Ivanov, Marian.Ivanov@cern.ch
341 //
342 //----------------------------------------------------------------
343 const Double_t kEpsilon = 0.00001;
344 Double_t xpos = track->GetX();
13545423 345 Int_t dir = (xpos<xToGo) ? 1:-1;
4811a3f4 346 //
347 while ( (xToGo-xpos)*dir > kEpsilon){
348 Double_t step = dir*TMath::Min(TMath::Abs(xToGo-xpos), maxStep);
349 Double_t x = xpos+step;
350 Double_t xyz0[3],xyz1[3],param[7];
351 track->GetXYZ(xyz0); //starting global position
352
353 Double_t b[3]; GetBxByBz(xyz0,b); // getting the local Bx, By and Bz
354
355 if (!track->GetXYZAt(x,b[2],xyz1)) return kFALSE; // no prolongation
356 xyz1[2]+=kEpsilon; // waiting for bug correction in geo
357
7391b629 358 if (maxSnp>0 && TMath::Abs(track->GetSnpAt(x,b[2])) >= maxSnp) return kFALSE;
4811a3f4 359 if (!track->PropagateToBxByBz(x,b)) return kFALSE;
360
13545423 361 MeanMaterialBudget(xyz0,xyz1,param);
362 Double_t xrho=param[0]*param[4], xx0=param[1];
363 if (sign) {if (sign<0) xrho = -xrho;} // sign is imposed
364 else { // determine automatically the sign from direction
365 if (dir>0) xrho = -xrho; // outward should be negative
366 }
367 //
4811a3f4 368 if (!track->CorrectForMeanMaterial(xx0,xrho,mass)) return kFALSE;
369 if (rotateTo){
dc981549 370 track->GetXYZ(xyz1); // global position
371 Double_t alphan = TMath::ATan2(xyz1[1], xyz1[0]);
7391b629 372 if (maxSnp>0) {
373 if (TMath::Abs(track->GetSnp()) >= maxSnp) return kFALSE;
374 Double_t ca=TMath::Cos(alphan-track->GetAlpha()), sa=TMath::Sin(alphan-track->GetAlpha());
375 Double_t sf=track->GetSnp(), cf=TMath::Sqrt((1.-sf)*(1.+sf));
376 Double_t sinNew = sf*ca - cf*sa;
377 if (TMath::Abs(sinNew) >= maxSnp) return kFALSE;
378 }
dc981549 379 if (!track->AliExternalTrackParam::Rotate(alphan)) return kFALSE;
4811a3f4 380 }
13545423 381 xpos = track->GetX();
382 if (addTimeStep && track->IsStartedTimeIntegral()) {
dc981549 383 if (!rotateTo) track->GetXYZ(xyz1); // if rotateTo==kTRUE, then xyz1 is already extracted
13545423 384 Double_t dX=xyz0[0]-xyz1[0],dY=xyz0[1]-xyz1[1],dZ=xyz0[2]-xyz1[2];
385 Double_t d=TMath::Sqrt(dX*dX + dY*dY + dZ*dZ);
386 if (sign) {if (sign>0) d = -d;} // step sign is imposed, positive means inward direction
387 else { // determine automatically the sign from direction
388 if (dir<0) d = -d;
389 }
390 track->AddTimeStep(d);
391 }
4811a3f4 392 }
393 return kTRUE;
394}
395
396Double_t AliTrackerBase::GetTrackPredictedChi2(AliExternalTrackParam *track,
397 Double_t mass, Double_t step,
398 const AliExternalTrackParam *backup) {
399 //
400 // This function brings the "track" with particle "mass" [GeV]
401 // to the same local coord. system and the same reference plane as
402 // of the "backup", doing it in "steps" [cm].
403 // Then, it calculates the 5D predicted Chi2 for these two tracks
404 //
405 Double_t chi2=kVeryBig;
406 Double_t alpha=backup->GetAlpha();
407 if (!track->Rotate(alpha)) return chi2;
408
409 Double_t xb=backup->GetX();
410 Double_t sign=(xb < track->GetX()) ? 1. : -1.;
411 if (!PropagateTrackTo(track,xb,mass,step,kFALSE,kAlmost1,sign)) return chi2;
412
413 chi2=track->GetPredictedChi2(backup);
414
415 return chi2;
416}
075f4221 417
418
419
420
421Double_t AliTrackerBase::MakeC(Double_t x1,Double_t y1,
422 Double_t x2,Double_t y2,
423 Double_t x3,Double_t y3)
424{
425 //-----------------------------------------------------------------
426 // Initial approximation of the track curvature
427 //-----------------------------------------------------------------
428 x3 -=x1;
429 x2 -=x1;
430 y3 -=y1;
431 y2 -=y1;
432 //
433 Double_t det = x3*y2-x2*y3;
434 if (TMath::Abs(det)<1e-10) {
435 return 0;
436 }
437 //
438 Double_t u = 0.5* (x2*(x2-x3)+y2*(y2-y3))/det;
439 Double_t x0 = x3*0.5-y3*u;
440 Double_t y0 = y3*0.5+x3*u;
441 Double_t c2 = 1/TMath::Sqrt(x0*x0+y0*y0);
442 if (det>0) c2*=-1;
443 return c2;
444}
445
446Double_t AliTrackerBase::MakeSnp(Double_t x1,Double_t y1,
447 Double_t x2,Double_t y2,
448 Double_t x3,Double_t y3)
449{
450 //-----------------------------------------------------------------
451 // Initial approximation of the track snp
452 //-----------------------------------------------------------------
453 x3 -=x1;
454 x2 -=x1;
455 y3 -=y1;
456 y2 -=y1;
457 //
458 Double_t det = x3*y2-x2*y3;
459 if (TMath::Abs(det)<1e-10) {
460 return 0;
461 }
462 //
463 Double_t u = 0.5* (x2*(x2-x3)+y2*(y2-y3))/det;
464 Double_t x0 = x3*0.5-y3*u;
465 Double_t y0 = y3*0.5+x3*u;
466 Double_t c2 = 1./TMath::Sqrt(x0*x0+y0*y0);
467 x0*=c2;
468 x0=TMath::Abs(x0);
469 if (y2*x2<0.) x0*=-1;
470 return x0;
471}
472
473Double_t AliTrackerBase::MakeTgl(Double_t x1,Double_t y1,
474 Double_t x2,Double_t y2,
475 Double_t z1,Double_t z2, Double_t c)
476{
477 //-----------------------------------------------------------------
478 // Initial approximation of the tangent of the track dip angle
479 //-----------------------------------------------------------------
480 //
481 x2-=x1;
482 y2-=y1;
483 z2-=z1;
484 Double_t d = TMath::Sqrt(x2*x2+y2*y2); // distance straight line
485 if (TMath::Abs(d*c*0.5)>1) return 0;
486 Double_t angle2 = TMath::ASin(d*c*0.5);
487 angle2 = z2*TMath::Abs(c/(angle2*2.));
488 return angle2;
489}
490
491
492Double_t AliTrackerBase::MakeTgl(Double_t x1,Double_t y1,
493 Double_t x2,Double_t y2,
494 Double_t z1,Double_t z2)
495{
496 //-----------------------------------------------------------------
497 // Initial approximation of the tangent of the track dip angle
498 //-----------------------------------------------------------------
499 return (z1 - z2)/sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
500}
501
502
503AliExternalTrackParam * AliTrackerBase::MakeSeed( AliTrackPoint &point0, AliTrackPoint &point1, AliTrackPoint &point2){
504 //
505 // Make Seed - AliExternalTrackParam from input 3 points
506 // returning seed in local frame of point0
507 //
508 Double_t xyz0[3]={0,0,0};
509 Double_t xyz1[3]={0,0,0};
510 Double_t xyz2[3]={0,0,0};
511 Double_t alpha=point0.GetAngle();
512 Double_t xyz[3]={point0.GetX(),point0.GetY(),point0.GetZ()};
513 Double_t bxyz[3]; GetBxByBz(xyz,bxyz);
514 Double_t bz = bxyz[2];
515 //
516 // get points in frame of point 0
517 //
518 AliTrackPoint p0r = point0.Rotate(alpha);
519 AliTrackPoint p1r = point1.Rotate(alpha);
520 AliTrackPoint p2r = point2.Rotate(alpha);
521 xyz0[0]=p0r.GetX();
522 xyz0[1]=p0r.GetY();
523 xyz0[2]=p0r.GetZ();
524 xyz1[0]=p1r.GetX();
525 xyz1[1]=p1r.GetY();
526 xyz1[2]=p1r.GetZ();
527 xyz2[0]=p2r.GetX();
528 xyz2[1]=p2r.GetY();
529 xyz2[2]=p2r.GetZ();
530 //
531 // make covariance estimate
532 //
533 Double_t covar[15];
534 Double_t param[5]={0,0,0,0,0};
535 for (Int_t m=0; m<15; m++) covar[m]=0;
536 //
537 // calculate intitial param
538 param[0]=xyz0[1];
539 param[1]=xyz0[2];
540 param[2]=MakeSnp(xyz0[0],xyz0[1],xyz1[0],xyz1[1],xyz2[0],xyz2[1]);
541 param[4]=MakeC(xyz0[0],xyz0[1],xyz1[0],xyz1[1],xyz2[0],xyz2[1]);
542 param[3]=MakeTgl(xyz0[0],xyz0[1],xyz1[0],xyz1[1],xyz0[2],xyz1[2],param[4]);
543
544 //covariance matrix - only diagonal elements
545 //Double_t dist=p0r.GetX()-p2r.GetX();
546 Double_t deltaP=0;
547 covar[0]= p0r.GetCov()[3];
548 covar[2]= p0r.GetCov()[5];
549 //sigma snp
550 deltaP= (MakeSnp(xyz0[0],xyz0[1]+TMath::Sqrt(p0r.GetCov()[3]),xyz1[0],xyz1[1],xyz2[0],xyz2[1])-param[2]);
551 covar[5]+= deltaP*deltaP;
552 deltaP= (MakeSnp(xyz0[0],xyz0[1],xyz1[0],xyz1[1]+TMath::Sqrt(p1r.GetCov()[3]),xyz2[0],xyz2[1])-param[2]);
553 covar[5]+= deltaP*deltaP;
554 deltaP= (MakeSnp(xyz0[0],xyz0[1],xyz1[0],xyz1[1],xyz2[0],xyz2[1]+TMath::Sqrt(p1r.GetCov()[3]))-param[2]);
555 covar[5]+= deltaP*deltaP;
556 //sigma tgl
557 //
558 deltaP=MakeTgl(xyz0[0],xyz0[1],xyz1[0],xyz1[1],xyz0[2]+TMath::Sqrt(p1r.GetCov()[5]),xyz1[2],param[4])-param[3];
559 covar[9]+= deltaP*deltaP;
560 deltaP=MakeTgl(xyz0[0],xyz0[1],xyz1[0],xyz1[1],xyz0[2],xyz1[2]+TMath::Sqrt(p1r.GetCov()[5]),param[4])-param[3];
561 covar[9]+= deltaP*deltaP;
562 //
563
564 deltaP=MakeC(xyz0[0],xyz0[1]+TMath::Sqrt(p0r.GetCov()[3]),xyz1[0],xyz1[1],xyz2[0],xyz2[1])-param[4];
565 covar[14]+= deltaP*deltaP;
566 deltaP=MakeC(xyz0[0],xyz0[1],xyz1[0],xyz1[1]+TMath::Sqrt(p1r.GetCov()[3]),xyz2[0],xyz2[1])-param[4];
567 covar[14]+= deltaP*deltaP;
568 deltaP=MakeC(xyz0[0],xyz0[1],xyz1[0],xyz1[1],xyz2[0],xyz2[1]+TMath::Sqrt(p2r.GetCov()[3]))-param[4];
569 covar[14]+= deltaP*deltaP;
570
571 covar[14]/=(bz*kB2C)*(bz*kB2C);
572 param[4]/=(bz*kB2C); // transform to 1/pt
573 AliExternalTrackParam * trackParam = new AliExternalTrackParam(xyz0[0],alpha,param, covar);
574 if (0) {
575 // consistency check -to put warnings here
576 // small disagrement once Track extrapolation used
577 // nice agreement in seeds with MC track parameters - problem in extrapoloation - to be fixed
578 // to check later
579 Double_t y1,y2,z1,z2;
580 trackParam->GetYAt(xyz1[0],bz,y1);
581 trackParam->GetZAt(xyz1[0],bz,z1);
582 trackParam->GetYAt(xyz2[0],bz,y2);
583 trackParam->GetZAt(xyz2[0],bz,z2);
584 if (TMath::Abs(y1-xyz1[1])> TMath::Sqrt(p1r.GetCov()[3]*5)){
585 AliWarningClass("Seeding problem y1\n");
586 }
587 if (TMath::Abs(y2-xyz2[1])> TMath::Sqrt(p2r.GetCov()[3]*5)){
588 AliWarningClass("Seeding problem y2\n");
589 }
590 if (TMath::Abs(z1-xyz1[2])> TMath::Sqrt(p1r.GetCov()[5]*5)){
591 AliWarningClass("Seeding problem z1\n");
592 }
593 }
594 return trackParam;
595}
596
597Double_t AliTrackerBase::FitTrack(AliExternalTrackParam * trackParam, AliTrackPointArray *pointArray, Double_t mass, Double_t maxStep){
598 //
599 // refit the track - trackParam using the points in point array
600 //
601 const Double_t kMaxSnp=0.99;
602 if (!trackParam) return 0;
603 Int_t npoints=pointArray->GetNPoints();
604 AliTrackPoint point,point2;
605 Double_t pointPos[2]={0,0};
606 Double_t pointCov[3]={0,0,0};
607 // choose coordinate frame
608 // in standard way the coordinate frame should be changed point by point
609 // Some problems with rotation observed
610 // rotate method of AliExternalTrackParam should be revisited
611 pointArray->GetPoint(point,0);
612 pointArray->GetPoint(point2,npoints-1);
613 Double_t alpha=TMath::ATan2(point.GetY()-point2.GetY(), point.GetX()-point2.GetX());
614
615 for (Int_t ipoint=npoints-1; ipoint>0; ipoint-=1){
616 pointArray->GetPoint(point,ipoint);
617 AliTrackPoint pr = point.Rotate(alpha);
618 trackParam->Rotate(alpha);
619 Bool_t status = PropagateTrackTo(trackParam,pr.GetX(),mass,maxStep,kFALSE,kMaxSnp);
620 if(!status){
621 AliWarningClass("Problem to propagate\n");
622 break;
623 }
624 if (TMath::Abs(trackParam->GetSnp())>kMaxSnp){
625 AliWarningClass("sin(phi) > kMaxSnp \n");
626 break;
627 }
628 pointPos[0]=pr.GetY();//local y
629 pointPos[1]=pr.GetZ();//local z
630 pointCov[0]=pr.GetCov()[3];//simay^2
631 pointCov[1]=pr.GetCov()[4];//sigmayz
632 pointCov[2]=pr.GetCov()[5];//sigmaz^2
633 trackParam->Update(pointPos,pointCov);
634 }
635 return 0;
636}
363db7c3 637
638
639
640void AliTrackerBase::UpdateTrack(AliExternalTrackParam &track1, const AliExternalTrackParam &track2){
641 //
642 // Update track 1 with track 2
643 //
644 //
645 //
646 TMatrixD vecXk(5,1); // X vector
647 TMatrixD covXk(5,5); // X covariance
648 TMatrixD matHk(5,5); // vector to mesurement
649 TMatrixD measR(5,5); // measurement error
650 TMatrixD vecZk(5,1); // measurement
651 //
652 TMatrixD vecYk(5,1); // Innovation or measurement residual
653 TMatrixD matHkT(5,5);
654 TMatrixD matSk(5,5); // Innovation (or residual) covariance
655 TMatrixD matKk(5,5); // Optimal Kalman gain
656 TMatrixD mat1(5,5); // update covariance matrix
657 TMatrixD covXk2(5,5); //
658 TMatrixD covOut(5,5);
659 //
660 Double_t *param1=(Double_t*) track1.GetParameter();
661 Double_t *covar1=(Double_t*) track1.GetCovariance();
662 Double_t *param2=(Double_t*) track2.GetParameter();
663 Double_t *covar2=(Double_t*) track2.GetCovariance();
664 //
665 // copy data to the matrix
666 for (Int_t ipar=0; ipar<5; ipar++){
667 for (Int_t jpar=0; jpar<5; jpar++){
668 covXk(ipar,jpar) = covar1[track1.GetIndex(ipar, jpar)];
669 measR(ipar,jpar) = covar2[track2.GetIndex(ipar, jpar)];
670 matHk(ipar,jpar)=0;
671 mat1(ipar,jpar)=0;
672 }
673 vecXk(ipar,0) = param1[ipar];
674 vecZk(ipar,0) = param2[ipar];
675 matHk(ipar,ipar)=1;
676 mat1(ipar,ipar)=1;
677 }
678 //
679 //
680 //
681 //
682 //
683 vecYk = vecZk-matHk*vecXk; // Innovation or measurement residual
684 matHkT=matHk.T(); matHk.T();
685 matSk = (matHk*(covXk*matHkT))+measR; // Innovation (or residual) covariance
686 matSk.Invert();
687 matKk = (covXk*matHkT)*matSk; // Optimal Kalman gain
688 vecXk += matKk*vecYk; // updated vector
689 covXk2 = (mat1-(matKk*matHk));
690 covOut = covXk2*covXk;
691 //
692 //
693 //
694 // copy from matrix to parameters
695 if (0) {
696 vecXk.Print();
697 vecZk.Print();
698 //
699 measR.Print();
700 covXk.Print();
701 covOut.Print();
702 //
703 track1.Print();
704 track2.Print();
705 }
706
707 for (Int_t ipar=0; ipar<5; ipar++){
708 param1[ipar]= vecXk(ipar,0) ;
709 for (Int_t jpar=0; jpar<5; jpar++){
710 covar1[track1.GetIndex(ipar, jpar)]=covOut(ipar,jpar);
711 }
712 }
713}
714
715