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Adding the indices of the tracks used for the vertex reconstruction (A.Dainese)
[u/mrichter/AliRoot.git] / STEER / AliVertexerTracks.cxx
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2d57349e 1/**************************************************************************
2 * Copyright(c) 1998-2003, 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// Implementation of the vertexer from ESD tracks
18//
19// Origin: AliITSVertexerTracks
20// A.Dainese, Padova,
21// andrea.dainese@pd.infn.it
22// M.Masera, Torino,
23// massimo.masera@to.infn.it
24// Moved to STEER and adapted to ESD tracks:
25// F.Prino, Torino, prino@to.infn.it
26//-----------------------------------------------------------------
27
28//---- Root headers --------
29#include <TTree.h>
ec1be5d5 30#include <TMatrixD.h>
2d57349e 31//---- AliRoot headers -----
32#include "AliStrLine.h"
33#include "AliVertexerTracks.h"
c5e3e5d1 34#include "AliESD.h"
2d57349e 35#include "AliESDtrack.h"
36
37ClassImp(AliVertexerTracks)
38
39
40//----------------------------------------------------------------------------
41AliVertexerTracks::AliVertexerTracks():
07680cae 42TObject(),
43fVert(),
44fCurrentVertex(0),
fe12e09c 45fMinTracks(2),
46fMinITSClusters(5),
07680cae 47fTrkArray(),
48fTrksToSkip(0),
49fNTrksToSkip(0),
50fDCAcut(0),
51fAlgo(1),
fe12e09c 52fNSigma(3),
07680cae 53fDebug(0)
2d57349e 54{
55//
56// Default constructor
57//
58 SetVtxStart();
07680cae 59 SetVtxStartSigma();
2d57349e 60 SetMinTracks();
07680cae 61 SetMinITSClusters();
62 SetNSigmad0();
2d57349e 63}
64//-----------------------------------------------------------------------------
65AliVertexerTracks::AliVertexerTracks(Double_t xStart, Double_t yStart):
07680cae 66TObject(),
67fVert(),
68fCurrentVertex(0),
fe12e09c 69fMinTracks(2),
70fMinITSClusters(5),
07680cae 71fTrkArray(),
72fTrksToSkip(0),
73fNTrksToSkip(0),
74fDCAcut(0),
75fAlgo(1),
fe12e09c 76fNSigma(3),
07680cae 77fDebug(0)
2d57349e 78{
79//
80// Standard constructor
81//
82 SetVtxStart(xStart,yStart);
07680cae 83 SetVtxStartSigma();
2d57349e 84 SetMinTracks();
07680cae 85 SetMinITSClusters();
86 SetNSigmad0();
2d57349e 87}
88//-----------------------------------------------------------------------------
89AliVertexerTracks::~AliVertexerTracks() {
90 // Default Destructor
eae1677e 91 // The objects pointed by the following pointer are not owned
2d57349e 92 // by this class and are not deleted
ec1be5d5 93 fCurrentVertex = 0;
07680cae 94 delete[] fTrksToSkip;
ec1be5d5 95}
96//---------------------------------------------------------------------------
97void AliVertexerTracks::SetSkipTracks(Int_t n,Int_t *skipped) {
98//
99// Mark the tracks not ot be used in the vertex finding
100//
101 fNTrksToSkip = n;
102 fTrksToSkip = new Int_t[n];
103 for(Int_t i=0;i<n;i++) fTrksToSkip[i] = skipped[i];
104 return;
105}
2d57349e 106//----------------------------------------------------------------------------
ec1be5d5 107Int_t AliVertexerTracks::PrepareTracks(TTree &trkTree, Int_t OptImpParCut) {
2d57349e 108//
109// Propagate tracks to initial vertex position and store them in a TObjArray
110//
ec1be5d5 111 Double_t maxd0rphi = 3.;
2d57349e 112 Int_t nTrks = 0;
07680cae 113 Double_t sigmaCurr[3],sigmaVtx[3],posVtx[3];
eae1677e 114 Double_t covVtx[6],covVtxXY;
07680cae 115 Float_t d0z0[2],covd0z0[3];
116 Double_t momentum[3],postrk[3];
117 Double_t pt,sigma,sigmavtxphi,phitrk;
ec1be5d5 118 Double_t field=GetField();
2d57349e 119
07680cae 120 AliESDVertex *initVertex = new AliESDVertex(fNominalPos,fNominalSigma);
121
2d57349e 122 Int_t nEntries = (Int_t)trkTree.GetEntries();
5834e9a1 123 if(!fTrkArray.IsEmpty()) fTrkArray.Delete();
124 // fTrkArray.Expand(nEntries);
2d57349e 125
ec1be5d5 126 if(fDebug) {
127 printf(" PrepareTracks()\n");
128 }
129
2d57349e 130 for(Int_t i=0; i<nEntries; i++) {
131 AliESDtrack *track = new AliESDtrack;
132 trkTree.SetBranchAddress("tracks",&track);
133 trkTree.GetEvent(i);
134
07680cae 135
136
137 // propagate track to vertex
eae1677e 138 if(OptImpParCut==1) { // OptImpParCut==1
07680cae 139 track->RelateToVertex(initVertex,field,100.);
140 initVertex->GetXYZ(posVtx);
141 initVertex->GetSigmaXYZ(sigmaVtx);
eae1677e 142 covVtxXY = 0.;
143 } else { // OptImpParCut==2
07680cae 144 fCurrentVertex->GetSigmaXYZ(sigmaCurr);
145 if((sigmaCurr[0]+sigmaCurr[1])<(fNominalSigma[0]+fNominalSigma[1])) {
146 track->RelateToVertex(fCurrentVertex,field,100.);
147 fCurrentVertex->GetXYZ(posVtx);
148 fCurrentVertex->GetSigmaXYZ(sigmaVtx);
eae1677e 149 fCurrentVertex->GetCovMatrix(covVtx);
150 covVtxXY = covVtx[1];
07680cae 151 } else {
152 track->RelateToVertex(initVertex,field,100.);
153 initVertex->GetXYZ(posVtx);
154 initVertex->GetSigmaXYZ(sigmaVtx);
eae1677e 155 covVtxXY = 0.;
07680cae 156 }
157 }
158
159 // select tracks with d0rphi < maxd0rphi
160 track->GetImpactParameters(d0z0,covd0z0);
161
eae1677e 162 track->GetXYZ(postrk);
163 track->GetPxPyPz(momentum);
164 pt = TMath::Sqrt(momentum[0]*momentum[0]+momentum[1]*momentum[1]);
165
166 phitrk = TMath::ATan2(postrk[1]-posVtx[1],postrk[0]-posVtx[0]);
167 sigmavtxphi = TMath::Sqrt(sigmaVtx[0]*sigmaVtx[0]*
168 TMath::Cos(phitrk)*TMath::Cos(phitrk)+
169 sigmaVtx[1]*sigmaVtx[1]*
170 TMath::Sin(phitrk)*TMath::Sin(phitrk)+
171 covVtxXY*
172 TMath::Cos(phitrk)*TMath::Sin(phitrk));
173 sigma = TMath::Sqrt(Sigmad0rphi(pt)*Sigmad0rphi(pt)+
174 sigmavtxphi*sigmavtxphi);
175 maxd0rphi = fNSigma*sigma;
176 if(OptImpParCut==1) maxd0rphi *= 5.;
177
178 if(fDebug) printf("trk %d; lab %d; |d0| = %f; cut = %f\n",i,track->GetLabel(),TMath::Abs(d0z0[0]),maxd0rphi);
07680cae 179 if(TMath::Abs(d0z0[0]) > maxd0rphi) {
eae1677e 180 if(fDebug) printf(" rejected\n");
07680cae 181 delete track; continue;
182 }
183
2d57349e 184 fTrkArray.AddLast(track);
185 nTrks++;
186 }
07680cae 187
07680cae 188 delete initVertex;
189
2d57349e 190 return nTrks;
191}
192//----------------------------------------------------------------------------
07680cae 193Double_t AliVertexerTracks::Sigmad0rphi(Double_t pt) const {
194//
195// Impact parameter resolution in rphi [cm] vs pt [GeV/c]
196//
197 Double_t a_meas = 11.6;
198 Double_t a_scatt = 65.8;
199 Double_t b = 1.878;
200
201 Double_t sigma = a_meas*a_meas+a_scatt*a_scatt/TMath::Power(pt,b);
202 sigma = 0.0001*TMath::Sqrt(sigma);
203
204 return sigma;
205}
206//----------------------------------------------------------------------------
2d57349e 207AliVertex* AliVertexerTracks::VertexForSelectedTracks(TTree *trkTree) {
208//
209// Return vertex from tracks in trkTree
210//
211
212 // get tracks and propagate them to initial vertex position
ec1be5d5 213 Int_t nTrks = PrepareTracks(*trkTree,1);
2d57349e 214 if(nTrks < fMinTracks) {
215 printf("TooFewTracks\n");
216 Double_t vtx[3]={0,0,0};
217 fVert.SetXYZ(vtx);
218 fVert.SetDispersion(999);
219 fVert.SetNContributors(-5);
5834e9a1 220 fTrkArray.Delete();
2d57349e 221 return &fVert;
222 }
223
224 // Set initial vertex position from ESD
225 if(fAlgo==1) StrLinVertexFinderMinDist(1);
226 if(fAlgo==2) StrLinVertexFinderMinDist(0);
227 if(fAlgo==3) HelixVertexFinder();
228 if(fAlgo==4) VertexFinder(1);
229 if(fAlgo==5) VertexFinder(0);
230 return &fVert;
231}
c5e3e5d1 232//----------------------------------------------------------------------------
ec1be5d5 233AliESDVertex* AliVertexerTracks::FindPrimaryVertex(const AliESD *esdEvent)
234{
c5e3e5d1 235//
ec1be5d5 236// Primary vertex for current ESD event
eae1677e 237// (Two iterations:
238// 1st with 5*fNSigma*sigma(pt) cut w.r.t. to initial vertex;
239// 2nd with fNSigma*sigma(pt) cut w.r.t. to vertex found in 1st iteration)
318aecb9 240// All ESD tracks with inside the beam pipe are then propagated to found vertex
07680cae 241//
242 fCurrentVertex = 0;
243
244 Int_t entr = (Int_t)esdEvent->GetNumberOfTracks();
245 TTree *trkTree = new TTree("TreeT","tracks");
246 AliESDtrack *esdTrack = 0;
247 trkTree->Branch("tracks","AliESDtrack",&esdTrack);
248
eae1677e 249 Bool_t skipThis;
07680cae 250 for(Int_t i=0; i<entr; i++) {
eae1677e 251 // check tracks to skip
252 skipThis = kFALSE;
253 for(Int_t j=0; j<fNTrksToSkip; j++) {
254 if(i==fTrksToSkip[j]) {
255 if(fDebug) printf("skipping track: %d\n",i);
256 skipThis = kTRUE;
257 }
258 }
259 if(skipThis) continue;
07680cae 260 AliESDtrack *et = esdEvent->GetTrack(i);
261 esdTrack = new AliESDtrack(*et);
5834e9a1 262 if(!(esdTrack->GetStatus()&AliESDtrack::kITSin)) {delete esdTrack;continue;}
263 if(!(esdTrack->GetStatus()&AliESDtrack::kITSrefit)) {delete esdTrack;continue;}
07680cae 264 Int_t nclus=esdTrack->GetNcls(0); // check number of clusters in ITS
5834e9a1 265 if(nclus<fMinITSClusters) {delete esdTrack;continue;}
07680cae 266 trkTree->Fill();
5834e9a1 267 delete esdTrack;
07680cae 268 }
5834e9a1 269 // delete esdTrack;
318aecb9 270
07680cae 271
272 // ITERATION 1
273 // propagate tracks to initVertex
eae1677e 274 // preselect them (reject for |d0|>5*fNSigma*sigma w.r.t. initVertex)
07680cae 275 Int_t nTrks;
276 nTrks = PrepareTracks(*trkTree,1);
277 if(fDebug) printf(" tracks prepared - step 1: %d\n",nTrks);
278 if(nTrks < fMinTracks) {
279 printf("TooFewTracks\n");
eae1677e 280 TooFewTracks(esdEvent);
281 if(fDebug) fCurrentVertex->PrintStatus();
5834e9a1 282 fTrkArray.Delete();
283 delete trkTree;
07680cae 284 return fCurrentVertex;
285 }
286
287 // vertex finder
288 switch (fAlgo) {
289 case 1: StrLinVertexFinderMinDist(1); break;
290 case 2: StrLinVertexFinderMinDist(0); break;
291 case 3: HelixVertexFinder(); break;
292 case 4: VertexFinder(1); break;
293 case 5: VertexFinder(0); break;
294 default: printf("Wrong algorithm\n"); break;
295 }
296 if(fDebug) printf(" vertex finding completed\n");
297
298 // vertex fitter
eae1677e 299 VertexFitter(kTRUE);
07680cae 300 if(fDebug) printf(" vertex fit completed\n");
5834e9a1 301 fTrkArray.Delete();
07680cae 302 // ITERATION 2
303 // propagate tracks to best between initVertex and fCurrentVertex
304 // preselect tracks (reject for |d0|>fNSigma*sigma w.r.t. best
305 // between initVertex and fCurrentVertex)
306 nTrks = PrepareTracks(*trkTree,2);
307 delete trkTree;
308 if(fDebug) printf(" tracks prepared - step 2: %d\n",nTrks);
309 if(nTrks < fMinTracks) {
310 printf("TooFewTracks\n");
eae1677e 311 TooFewTracks(esdEvent);
312 if(fDebug) fCurrentVertex->PrintStatus();
5834e9a1 313 fTrkArray.Delete();
07680cae 314 return fCurrentVertex;
315 }
316
317 // vertex finder
318 switch (fAlgo) {
319 case 1: StrLinVertexFinderMinDist(1); break;
320 case 2: StrLinVertexFinderMinDist(0); break;
321 case 3: HelixVertexFinder(); break;
322 case 4: VertexFinder(1); break;
323 case 5: VertexFinder(0); break;
324 default: printf("Wrong algorithm\n"); break;
325 }
326 if(fDebug) printf(" vertex finding completed\n");
327
328 // fitter
eae1677e 329 VertexFitter(kTRUE);
07680cae 330 if(fDebug) printf(" vertex fit completed\n");
331
eae1677e 332
5834e9a1 333 fTrkArray.Delete();
eae1677e 334
335 // take true pos from ESD
07680cae 336 Double_t tp[3];
337 esdEvent->GetVertex()->GetTruePos(tp);
338 fCurrentVertex->SetTruePos(tp);
eae1677e 339 if(fNominalSigma[0]>1.) {
340 fCurrentVertex->SetTitle("VertexerTracksNoConstraint");
341 } else {
342 fCurrentVertex->SetTitle("VertexerTracksWithConstraint");
343 }
344
345 if(fDebug) fCurrentVertex->PrintStatus();
346 if(fTrksToSkip) delete [] fTrksToSkip;
318aecb9 347
348 // propagate tracks to found vertex
349 if(TMath::Sqrt(fCurrentVertex->GetXv()*fCurrentVertex->GetXv()+fCurrentVertex->GetYv()*fCurrentVertex->GetYv())<3.) {
350 for(Int_t ii=0; ii<entr; ii++) {
351 AliESDtrack *et = esdEvent->GetTrack(ii);
352 if(!et->GetStatus()&AliESDtrack::kITSin) continue;
353 if(et->GetX()>3.) continue;
354 et->RelateToVertex(fCurrentVertex,GetField(),100.);
355 }
356 } else {
357 AliWarning("Found vertex outside beam pipe!");
358 }
359
07680cae 360 return fCurrentVertex;
361}
362//----------------------------------------------------------------------------
363AliESDVertex* AliVertexerTracks::FindPrimaryVertexOld(const AliESD *esdEvent)
364{
365//
366// Primary vertex for current ESD event (one iteration with |d0rphi|<3cm)
c5e3e5d1 367//
ec1be5d5 368 fCurrentVertex = 0;
369
370 Int_t entr = (Int_t)esdEvent->GetNumberOfTracks();
371 TTree *trkTree = new TTree("TreeT","tracks");
372 AliESDtrack *esdTrack = 0;
373 trkTree->Branch("tracks","AliESDtrack",&esdTrack);
374
375 for(Int_t i=0; i<entr; i++) {
376 AliESDtrack *et = esdEvent->GetTrack(i);
377 esdTrack = new AliESDtrack(*et);
5834e9a1 378 if(!(esdTrack->GetStatus()&AliESDtrack::kITSin)) {delete esdTrack;continue;}
379 if(!(esdTrack->GetStatus()&AliESDtrack::kITSrefit)) {delete esdTrack;continue;}
ec1be5d5 380 Int_t nclus=esdTrack->GetNcls(0); // check number of clusters in ITS
07680cae 381 if(nclus<fMinITSClusters) continue;
ec1be5d5 382
383 trkTree->Fill();
5834e9a1 384 delete esdTrack;
c5e3e5d1 385 }
5834e9a1 386 // delete esdTrack;
c5e3e5d1 387
ec1be5d5 388 // preselect tracks and propagate them to initial vertex position
07680cae 389 Int_t nTrks = PrepareTracks(*trkTree,1);
ec1be5d5 390 delete trkTree;
391 if(fDebug) printf(" tracks prepared: %d\n",nTrks);
392 if(nTrks < fMinTracks) {
c5e3e5d1 393 printf("TooFewTracks\n");
ec1be5d5 394 fCurrentVertex = new AliESDVertex(0.,0.,-1);
5834e9a1 395 fTrkArray.Delete();
ec1be5d5 396 return fCurrentVertex;
397 }
c5e3e5d1 398
ec1be5d5 399 // VERTEX FINDER
400 switch (fAlgo) {
401 case 1: StrLinVertexFinderMinDist(1); break;
402 case 2: StrLinVertexFinderMinDist(0); break;
403 case 3: HelixVertexFinder(); break;
404 case 4: VertexFinder(1); break;
405 case 5: VertexFinder(0); break;
406 default: printf("Wrong algorithm\n"); break;
407 }
c5e3e5d1 408
ec1be5d5 409 // VERTEX FITTER
ec1be5d5 410 VertexFitter();
411 if(fDebug) printf(" vertex fit completed\n");
c5e3e5d1 412
ec1be5d5 413
414 Double_t tp[3];
415 esdEvent->GetVertex()->GetTruePos(tp);
416 fCurrentVertex->SetTruePos(tp);
417 fCurrentVertex->SetTitle("VertexerTracks");
418
5834e9a1 419 fTrkArray.Delete();
ec1be5d5 420 return fCurrentVertex;
421}
2d57349e 422//----------------------------------------------------------------------------
423AliVertex* AliVertexerTracks::VertexForSelectedTracks(TObjArray *trkArray) {
424//
425// Return vertex from array of tracks
426//
427
428 // get tracks and propagate them to initial vertex position
429 Int_t nTrks = trkArray->GetEntriesFast();
430 if(nTrks < fMinTracks) {
431 printf("TooFewTracks\n");
432 Double_t vtx[3]={0,0,0};
433 fVert.SetXYZ(vtx);
434 fVert.SetDispersion(999);
435 fVert.SetNContributors(-5);
5834e9a1 436 fTrkArray.Delete();
2d57349e 437 return &fVert;
438 }
439 TTree *trkTree = new TTree("TreeT","tracks");
440 AliESDtrack *esdTrack = 0;
441 trkTree->Branch("tracks","AliESDtrack",&esdTrack);
442 for(Int_t i=0; i<nTrks; i++){
443 esdTrack = (AliESDtrack*)trkArray->At(i);
444 trkTree->Fill();
445 }
446
2e5c8fc7 447 AliVertex *vtx = VertexForSelectedTracks(trkTree);
448 delete trkTree;
449 return vtx;
2d57349e 450}
451
452//---------------------------------------------------------------------------
453void AliVertexerTracks::VertexFinder(Int_t optUseWeights) {
454
455 // Get estimate of vertex position in (x,y) from tracks DCA
456
457 Double_t initPos[3];
458 initPos[2] = 0.;
459 for(Int_t i=0;i<2;i++)initPos[i]=fNominalPos[i];
460 Int_t nacc = (Int_t)fTrkArray.GetEntriesFast();
461 Double_t aver[3]={0.,0.,0.};
462 Double_t aversq[3]={0.,0.,0.};
463 Double_t sigmasq[3]={0.,0.,0.};
464 Double_t sigma=0;
465 Int_t ncombi = 0;
466 AliESDtrack *track1;
467 AliESDtrack *track2;
ec1be5d5 468 Double_t pos[3],dir[3];
2d57349e 469 Double_t alpha,mindist;
470 Double_t field=GetField();
471
472 for(Int_t i=0; i<nacc; i++){
473 track1 = (AliESDtrack*)fTrkArray.At(i);
474 alpha=track1->GetAlpha();
475 mindist = TMath::Cos(alpha)*fNominalPos[0]+TMath::Sin(alpha)*fNominalPos[1];
ec1be5d5 476 track1->GetXYZAt(mindist,field,pos);
477 track1->GetPxPyPzAt(mindist,field,dir);
478 AliStrLine *line1 = new AliStrLine(pos,dir);
08df6187 479
ec1be5d5 480 // AliStrLine *line1 = new AliStrLine();
481 // track1->ApproximateHelixWithLine(mindist,field,line1);
2d57349e 482
483 for(Int_t j=i+1; j<nacc; j++){
484 track2 = (AliESDtrack*)fTrkArray.At(j);
485 alpha=track2->GetAlpha();
486 mindist = TMath::Cos(alpha)*fNominalPos[0]+TMath::Sin(alpha)*fNominalPos[1];
ec1be5d5 487 track2->GetXYZAt(mindist,field,pos);
488 track2->GetPxPyPzAt(mindist,field,dir);
489 AliStrLine *line2 = new AliStrLine(pos,dir);
490 // AliStrLine *line2 = new AliStrLine();
491 // track2->ApproximateHelixWithLine(mindist,field,line2);
2d57349e 492 Double_t distCA=line2->GetDCA(line1);
493 if(fDCAcut<=0 || (fDCAcut>0&&distCA<fDCAcut)){
494 Double_t pnt1[3],pnt2[3],crosspoint[3];
495
496 if(optUseWeights<=0){
497 Int_t retcode = line2->Cross(line1,crosspoint);
498 if(retcode>=0){
499 ncombi++;
500 for(Int_t jj=0;jj<3;jj++)aver[jj]+=crosspoint[jj];
501 for(Int_t jj=0;jj<3;jj++)aversq[jj]+=(crosspoint[jj]*crosspoint[jj]);
502 }
503 }
504 if(optUseWeights>0){
505 Int_t retcode = line1->CrossPoints(line2,pnt1,pnt2);
506 if(retcode>=0){
507 Double_t alpha, cs, sn;
508 alpha=track1->GetAlpha();
509 cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
510 Double_t sx1=sn*sn*track1->GetSigmaY2(), sy1=cs*cs*track1->GetSigmaY2();
511 alpha=track2->GetAlpha();
512 cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
513 Double_t sx2=sn*sn*track2->GetSigmaY2(), sy2=cs*cs*track2->GetSigmaY2();
514 Double_t sz1=track1->GetSigmaZ2(), sz2=track2->GetSigmaZ2();
515 Double_t wx1=sx2/(sx1+sx2), wx2=1.- wx1;
516 Double_t wy1=sy2/(sy1+sy2), wy2=1.- wy1;
517 Double_t wz1=sz2/(sz1+sz2), wz2=1.- wz1;
518 crosspoint[0]=wx1*pnt1[0] + wx2*pnt2[0];
519 crosspoint[1]=wy1*pnt1[1] + wy2*pnt2[1];
520 crosspoint[2]=wz1*pnt1[2] + wz2*pnt2[2];
521
522 ncombi++;
523 for(Int_t jj=0;jj<3;jj++)aver[jj]+=crosspoint[jj];
524 for(Int_t jj=0;jj<3;jj++)aversq[jj]+=(crosspoint[jj]*crosspoint[jj]);
525 }
526 }
527 }
528 delete line2;
529 }
530 delete line1;
531 }
532 if(ncombi>0){
533 for(Int_t jj=0;jj<3;jj++){
534 initPos[jj] = aver[jj]/ncombi;
535 aversq[jj]/=ncombi;
536 sigmasq[jj]=aversq[jj]-initPos[jj]*initPos[jj];
537 sigma+=sigmasq[jj];
538 }
539 sigma=TMath::Sqrt(TMath::Abs(sigma));
540 }
541 else {
542 Warning("VertexFinder","Finder did not succed");
543 sigma=999;
544 }
545 fVert.SetXYZ(initPos);
546 fVert.SetDispersion(sigma);
547 fVert.SetNContributors(ncombi);
548}
549//---------------------------------------------------------------------------
550void AliVertexerTracks::HelixVertexFinder() {
551
552 // Get estimate of vertex position in (x,y) from tracks DCA
553
554
555 Double_t initPos[3];
556 initPos[2] = 0.;
557 for(Int_t i=0;i<2;i++)initPos[i]=fNominalPos[i];
558 Double_t field=GetField();
559
560 Int_t nacc = (Int_t)fTrkArray.GetEntriesFast();
561
562 Double_t aver[3]={0.,0.,0.};
563 Double_t averquad[3]={0.,0.,0.};
564 Double_t sigmaquad[3]={0.,0.,0.};
565 Double_t sigma=0;
566 Int_t ncombi = 0;
567 AliESDtrack *track1;
568 AliESDtrack *track2;
569 Double_t distCA;
570 Double_t x, par[5];
571 Double_t alpha, cs, sn;
572 Double_t crosspoint[3];
573 for(Int_t i=0; i<nacc; i++){
574 track1 = (AliESDtrack*)fTrkArray.At(i);
575
576
577 for(Int_t j=i+1; j<nacc; j++){
578 track2 = (AliESDtrack*)fTrkArray.At(j);
579
580 distCA=track2->PropagateToDCA(track1,field);
581
582 if(fDCAcut<=0 ||(fDCAcut>0&&distCA<fDCAcut)){
583 track1->GetExternalParameters(x,par);
584 alpha=track1->GetAlpha();
585 cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
586 Double_t x1=x*cs - par[0]*sn;
587 Double_t y1=x*sn + par[0]*cs;
588 Double_t z1=par[1];
589 Double_t sx1=sn*sn*track1->GetSigmaY2(), sy1=cs*cs*track1->GetSigmaY2();
590 track2->GetExternalParameters(x,par);
591 alpha=track2->GetAlpha();
592 cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
593 Double_t x2=x*cs - par[0]*sn;
594 Double_t y2=x*sn + par[0]*cs;
595 Double_t z2=par[1];
596 Double_t sx2=sn*sn*track2->GetSigmaY2(), sy2=cs*cs*track2->GetSigmaY2();
597 Double_t sz1=track1->GetSigmaZ2(), sz2=track2->GetSigmaZ2();
598 Double_t wx1=sx2/(sx1+sx2), wx2=1.- wx1;
599 Double_t wy1=sy2/(sy1+sy2), wy2=1.- wy1;
600 Double_t wz1=sz2/(sz1+sz2), wz2=1.- wz1;
601 crosspoint[0]=wx1*x1 + wx2*x2;
602 crosspoint[1]=wy1*y1 + wy2*y2;
603 crosspoint[2]=wz1*z1 + wz2*z2;
604
605 ncombi++;
606 for(Int_t jj=0;jj<3;jj++)aver[jj]+=crosspoint[jj];
607 for(Int_t jj=0;jj<3;jj++)averquad[jj]+=(crosspoint[jj]*crosspoint[jj]);
608 }
609 }
610
611 }
612 if(ncombi>0){
613 for(Int_t jj=0;jj<3;jj++){
614 initPos[jj] = aver[jj]/ncombi;
615 averquad[jj]/=ncombi;
616 sigmaquad[jj]=averquad[jj]-initPos[jj]*initPos[jj];
617 sigma+=sigmaquad[jj];
618 }
619 sigma=TMath::Sqrt(TMath::Abs(sigma));
620 }
621 else {
622 Warning("HelixVertexFinder","Finder did not succed");
623 sigma=999;
624 }
625 fVert.SetXYZ(initPos);
626 fVert.SetDispersion(sigma);
627 fVert.SetNContributors(ncombi);
628}
629//---------------------------------------------------------------------------
630void AliVertexerTracks::StrLinVertexFinderMinDist(Int_t optUseWeights){
631
632 // Calculate the point at minimum distance to prepared tracks
633
634 Double_t initPos[3];
635 initPos[2] = 0.;
636 Double_t sigma=0;
637 for(Int_t i=0;i<2;i++)initPos[i]=fNominalPos[i];
638 const Int_t knacc = (Int_t)fTrkArray.GetEntriesFast();
639 Double_t field=GetField();
640
641 AliESDtrack *track1;
642 Double_t (*vectP0)[3]=new Double_t [knacc][3];
643 Double_t (*vectP1)[3]=new Double_t [knacc][3];
644
645 Double_t sum[3][3];
646 Double_t dsum[3]={0,0,0};
647 for(Int_t i=0;i<3;i++)
648 for(Int_t j=0;j<3;j++)sum[i][j]=0;
649 for(Int_t i=0; i<knacc; i++){
650 track1 = (AliESDtrack*)fTrkArray.At(i);
651 Double_t alpha=track1->GetAlpha();
652 Double_t mindist = TMath::Cos(alpha)*fNominalPos[0]+TMath::Sin(alpha)*fNominalPos[1];
ec1be5d5 653 Double_t pos[3],dir[3];
654 track1->GetXYZAt(mindist,field,pos);
655 track1->GetPxPyPzAt(mindist,field,dir);
656 AliStrLine *line1 = new AliStrLine(pos,dir);
657 // AliStrLine *line1 = new AliStrLine();
658 // track1->ApproximateHelixWithLine(mindist,field,line1);
2d57349e 659
660 Double_t p0[3],cd[3];
661 line1->GetP0(p0);
662 line1->GetCd(cd);
663 Double_t p1[3]={p0[0]+cd[0],p0[1]+cd[1],p0[2]+cd[2]};
664 vectP0[i][0]=p0[0];
665 vectP0[i][1]=p0[1];
666 vectP0[i][2]=p0[2];
667 vectP1[i][0]=p1[0];
668 vectP1[i][1]=p1[1];
669 vectP1[i][2]=p1[2];
670
671 Double_t matr[3][3];
672 Double_t dknow[3];
673 if(optUseWeights==0)GetStrLinDerivMatrix(p0,p1,matr,dknow);
674 if(optUseWeights==1){
675 Double_t sigmasq[3];
676 sigmasq[0]=track1->GetSigmaY2();
677 sigmasq[1]=track1->GetSigmaY2();
678 sigmasq[2]=track1->GetSigmaZ2();
679 GetStrLinDerivMatrix(p0,p1,sigmasq,matr,dknow);
680 }
681
682 for(Int_t iii=0;iii<3;iii++){
683 dsum[iii]+=dknow[iii];
684 for(Int_t lj=0;lj<3;lj++) sum[iii][lj]+=matr[iii][lj];
685 }
686 delete line1;
687 }
688
689 Double_t vett[3][3];
690 Double_t det=GetDeterminant3X3(sum);
691
692 if(det!=0){
693 for(Int_t zz=0;zz<3;zz++){
694 for(Int_t ww=0;ww<3;ww++){
695 for(Int_t kk=0;kk<3;kk++) vett[ww][kk]=sum[ww][kk];
696 }
697 for(Int_t kk=0;kk<3;kk++) vett[kk][zz]=dsum[kk];
698 initPos[zz]=GetDeterminant3X3(vett)/det;
699 }
700
701
702 for(Int_t i=0; i<knacc; i++){
703 Double_t p0[3]={0,0,0},p1[3]={0,0,0};
704 for(Int_t ii=0;ii<3;ii++){
705 p0[ii]=vectP0[i][ii];
706 p1[ii]=vectP1[i][ii];
707 }
708 sigma+=GetStrLinMinDist(p0,p1,initPos);
709 }
710
711 sigma=TMath::Sqrt(sigma);
712 }else{
713 Warning("StrLinVertexFinderMinDist","Finder did not succed");
714 sigma=999;
715 }
716 delete vectP0;
717 delete vectP1;
718 fVert.SetXYZ(initPos);
719 fVert.SetDispersion(sigma);
720 fVert.SetNContributors(knacc);
721}
722//_______________________________________________________________________
723Double_t AliVertexerTracks::GetDeterminant3X3(Double_t matr[][3]){
724 //
725 Double_t det=matr[0][0]*matr[1][1]*matr[2][2]-matr[0][0]*matr[1][2]*matr[2][1]-matr[0][1]*matr[1][0]*matr[2][2]+matr[0][1]*matr[1][2]*matr[2][0]+matr[0][2]*matr[1][0]*matr[2][1]-matr[0][2]*matr[1][1]*matr[2][0];
726 return det;
727}
728//____________________________________________________________________________
71d84967 729void AliVertexerTracks::GetStrLinDerivMatrix(Double_t *p0,Double_t *p1,Double_t (*m)[3],Double_t *d){
2d57349e 730
731 //
732 Double_t x12=p0[0]-p1[0];
733 Double_t y12=p0[1]-p1[1];
734 Double_t z12=p0[2]-p1[2];
735 Double_t kk=x12*x12+y12*y12+z12*z12;
736 m[0][0]=2-2/kk*x12*x12;
737 m[0][1]=-2/kk*x12*y12;
738 m[0][2]=-2/kk*x12*z12;
739 m[1][0]=-2/kk*x12*y12;
740 m[1][1]=2-2/kk*y12*y12;
741 m[1][2]=-2/kk*y12*z12;
742 m[2][0]=-2/kk*x12*z12;
743 m[2][1]=-2*y12*z12;
744 m[2][2]=2-2/kk*z12*z12;
745 d[0]=2*p0[0]-2/kk*p0[0]*x12*x12-2/kk*p0[2]*x12*z12-2/kk*p0[1]*x12*y12;
746 d[1]=2*p0[1]-2/kk*p0[1]*y12*y12-2/kk*p0[0]*x12*y12-2/kk*p0[2]*z12*y12;
747 d[2]=2*p0[2]-2/kk*p0[2]*z12*z12-2/kk*p0[0]*x12*z12-2/kk*p0[1]*z12*y12;
748
749}
750//____________________________________________________________________________
71d84967 751void AliVertexerTracks::GetStrLinDerivMatrix(Double_t *p0,Double_t *p1,Double_t *sigmasq,Double_t (*m)[3],Double_t *d){
2d57349e 752 //
753 Double_t x12=p1[0]-p0[0];
754 Double_t y12=p1[1]-p0[1];
755 Double_t z12=p1[2]-p0[2];
756
757 Double_t den= x12*x12*sigmasq[1]*sigmasq[2]+y12*y12*sigmasq[0]*sigmasq[2]+z12*z12*sigmasq[0]*sigmasq[1];
758
759 Double_t kk= 2*(x12*x12/sigmasq[0]+y12*y12/sigmasq[1]+z12*z12/sigmasq[2]);
760
761 Double_t cc[3];
762 cc[0]=-x12/sigmasq[0];
763 cc[1]=-y12/sigmasq[1];
764 cc[2]=-z12/sigmasq[2];
765
766 Double_t ww=(-p0[0]*x12*sigmasq[1]*sigmasq[2]-p0[1]*y12*sigmasq[0]*sigmasq[2]-p0[2]*z12*sigmasq[0]*sigmasq[1])/den;
767
768 Double_t ss= -p0[0]*cc[0]-p0[1]*cc[1]-p0[2]*cc[2];
769
770 Double_t aa[3];
771 aa[0]=x12*sigmasq[1]*sigmasq[2]/den;
772 aa[1]=y12*sigmasq[0]*sigmasq[2]/den;
773 aa[2]=z12*sigmasq[0]*sigmasq[1]/den;
774
775 m[0][0]=aa[0]*(aa[0]*kk+2*cc[0])+2*cc[0]*aa[0]+2/sigmasq[0];
776 m[0][1]=aa[1]*(aa[0]*kk+2*cc[0])+2*cc[1]*aa[0];
777 m[0][2]=aa[2]*(aa[0]*kk+2*cc[0])+2*cc[2]*aa[0];
778
779 m[1][0]=aa[0]*(aa[1]*kk+2*cc[1])+2*cc[0]*aa[1];
780 m[1][1]=aa[1]*(aa[1]*kk+2*cc[1])+2*cc[1]*aa[1]+2/sigmasq[1];
781 m[1][2]=aa[2]*(aa[1]*kk+2*cc[1])+2*cc[2]*aa[1];
782
783 m[2][0]=aa[0]*(aa[2]*kk+2*cc[2])+2*cc[0]*aa[2];
784 m[2][1]=aa[1]*(aa[2]*kk+2*cc[2])+2*cc[1]*aa[2];
785 m[2][2]=aa[2]*(aa[2]*kk+2*cc[2])+2*cc[2]*aa[2]+2/sigmasq[2];
786
787 d[0]=-ww*(aa[0]*kk+2*cc[0])-2*ss*aa[0]+2*p0[0]/sigmasq[0];
788 d[1]=-ww*(aa[1]*kk+2*cc[1])-2*ss*aa[1]+2*p0[1]/sigmasq[1];
789 d[2]=-ww*(aa[2]*kk+2*cc[2])-2*ss*aa[2]+2*p0[2]/sigmasq[2];
790
71d84967 791 }
2d57349e 792//_____________________________________________________________________________
793Double_t AliVertexerTracks::GetStrLinMinDist(Double_t *p0,Double_t *p1,Double_t *x0){
794 //
795 Double_t x12=p0[0]-p1[0];
796 Double_t y12=p0[1]-p1[1];
797 Double_t z12=p0[2]-p1[2];
798 Double_t x10=p0[0]-x0[0];
799 Double_t y10=p0[1]-x0[1];
800 Double_t z10=p0[2]-x0[2];
801 return ((x10*x10+y10*y10+z10*z10)*(x12*x12+y12*y12+z12*z12)-(x10*x12+y10*y12+z10*z12)*(x10*x12+y10*y12+z10*z12))/(x12*x12+y12*y12+z12*z12);
802}
ec1be5d5 803//---------------------------------------------------------------------------
07680cae 804void AliVertexerTracks::VertexFitter(Bool_t useNominalVtx) {
ec1be5d5 805//
806// The optimal estimate of the vertex position is given by a "weighted
807// average of tracks positions"
808// Original method: CMS Note 97/0051
809//
810 Double_t initPos[3];
811 fVert.GetXYZ(initPos);
812 if(fDebug) {
813 printf(" VertexFitter(): start\n");
814 printf(" Number of tracks in array: %d\n",(Int_t)fTrkArray.GetEntriesFast());
815 printf(" Minimum # tracks required in fit: %d\n",fMinTracks);
816 printf("Vertex position after finder: %f,%f,%f\n",initPos[0],initPos[1],initPos[2]);
eae1677e 817 if(useNominalVtx) printf(" This vertex will be used in fit: (%f+-%f,%f+-%f)\n",fNominalPos[0],fNominalSigma[0],fNominalPos[1],fNominalSigma[1]);
ec1be5d5 818 }
819
820 Int_t i,j,k,step=0;
821 TMatrixD rv(3,1);
822 TMatrixD vV(3,3);
823 rv(0,0) = initPos[0];
824 rv(1,0) = initPos[1];
825 rv(2,0) = 0.;
826 Double_t xlStart,alpha;
827 Double_t rotAngle;
828 Double_t cosRot,sinRot;
829 Double_t cc[15];
830 Int_t nUsedTrks;
831 Double_t chi2,chi2i;
832 Int_t arrEntries = (Int_t)fTrkArray.GetEntries();
833 AliESDtrack *t = 0;
834 Int_t failed = 0;
835
eae1677e 836 // 2 steps:
837 // 1st - estimate of vtx using all tracks
838 // 2nd - estimate of global chi2
839 for(step=0; step<2; step++) {
ec1be5d5 840 if(fDebug) printf(" step = %d\n",step);
841 chi2 = 0.;
842 nUsedTrks = 0;
843
844 TMatrixD sumWiri(3,1);
845 TMatrixD sumWi(3,3);
846 for(i=0; i<3; i++) {
847 sumWiri(i,0) = 0.;
848 for(j=0; j<3; j++) sumWi(j,i) = 0.;
849 }
850
07680cae 851 if(useNominalVtx) {
852 for(i=0; i<3; i++) {
853 sumWiri(i,0) += fNominalPos[i]/fNominalSigma[i]/fNominalSigma[i];
854 sumWi(i,i) += 1./fNominalSigma[i]/fNominalSigma[i];
855 }
856 }
857
858
ec1be5d5 859 // loop on tracks
860 for(k=0; k<arrEntries; k++) {
ec1be5d5 861 // get track from track array
862 t = (AliESDtrack*)fTrkArray.At(k);
863 alpha = t->GetAlpha();
864 xlStart = initPos[0]*TMath::Cos(alpha)+initPos[1]*TMath::Sin(alpha);
6c94f330 865 t->AliExternalTrackParam::PropagateTo(xlStart,AliTracker::GetBz()); // to vtxSeed
ec1be5d5 866 rotAngle = alpha;
867 if(alpha<0.) rotAngle += 2.*TMath::Pi();
868 cosRot = TMath::Cos(rotAngle);
869 sinRot = TMath::Sin(rotAngle);
870
871 // vector of track global coordinates
872 TMatrixD ri(3,1);
873 ri(0,0) = t->GetX()*cosRot-t->GetY()*sinRot;
874 ri(1,0) = t->GetX()*sinRot+t->GetY()*cosRot;
875 ri(2,0) = t->GetZ();
876
877 // matrix to go from global (x,y,z) to local (y,z);
878 TMatrixD qQi(2,3);
879 qQi(0,0) = -sinRot;
880 qQi(0,1) = cosRot;
881 qQi(0,2) = 0.;
882 qQi(1,0) = 0.;
883 qQi(1,1) = 0.;
884 qQi(1,2) = 1.;
885
886 // covariance matrix of local (y,z) - inverted
887 TMatrixD uUi(2,2);
888 t->GetExternalCovariance(cc);
889 uUi(0,0) = cc[0];
890 uUi(0,1) = cc[1];
891 uUi(1,0) = cc[1];
892 uUi(1,1) = cc[2];
893
894 // weights matrix: wWi = qQiT * uUiInv * qQi
895 if(uUi.Determinant() <= 0.) continue;
896 TMatrixD uUiInv(TMatrixD::kInverted,uUi);
897 TMatrixD uUiInvQi(uUiInv,TMatrixD::kMult,qQi);
898 TMatrixD wWi(qQi,TMatrixD::kTransposeMult,uUiInvQi);
899
900 // track chi2
901 TMatrixD deltar = rv; deltar -= ri;
902 TMatrixD wWideltar(wWi,TMatrixD::kMult,deltar);
903 chi2i = deltar(0,0)*wWideltar(0,0)+
904 deltar(1,0)*wWideltar(1,0)+
905 deltar(2,0)*wWideltar(2,0);
906
907
ec1be5d5 908 // add to total chi2
909 chi2 += chi2i;
910
911 TMatrixD wWiri(wWi,TMatrixD::kMult,ri);
912
913 sumWiri += wWiri;
914 sumWi += wWi;
915
916 nUsedTrks++;
917 } // end loop on tracks
918
919 if(nUsedTrks < fMinTracks) {
920 failed=1;
921 continue;
922 }
923
924 Double_t determinant = sumWi.Determinant();
925 //cerr<<" determinant: "<<determinant<<endl;
926 if(determinant < 100.) {
927 printf("det(V) = 0\n");
928 failed=1;
929 continue;
930 }
931
932 // inverted of weights matrix
933 TMatrixD invsumWi(TMatrixD::kInverted,sumWi);
934 vV = invsumWi;
935
936 // position of primary vertex
937 rv.Mult(vV,sumWiri);
938
eae1677e 939 } // end loop on the 2 steps
ec1be5d5 940
5834e9a1 941 // delete t;
ec1be5d5 942
943 if(failed) {
944 printf("TooFewTracks\n");
945 fCurrentVertex = new AliESDVertex(0.,0.,-1);
946 return;
947 }
948
949 Double_t position[3];
950 position[0] = rv(0,0);
951 position[1] = rv(1,0);
952 position[2] = rv(2,0);
953 Double_t covmatrix[6];
954 covmatrix[0] = vV(0,0);
955 covmatrix[1] = vV(0,1);
956 covmatrix[2] = vV(1,1);
957 covmatrix[3] = vV(0,2);
958 covmatrix[4] = vV(1,2);
959 covmatrix[5] = vV(2,2);
960
961 // store data in the vertex object
962 fCurrentVertex = new AliESDVertex(position,covmatrix,chi2,nUsedTrks);
963
964 if(fDebug) {
965 printf(" VertexFitter(): finish\n");
966 printf(" rv = ( %f , %f , %f )\n\n",rv(0,0),rv(1,0),rv(2,0));
967 fCurrentVertex->PrintStatus();
968 }
969
970 return;
971}
eae1677e 972//---------------------------------------------------------------------------
973void AliVertexerTracks::TooFewTracks(const AliESD* esdEvent) {
974//
975// When the number of tracks is < fMinTracks
976//
977
978 // deal with vertices not found
979 Double_t pos[3],err[3];
980 Int_t ncontr=0;
981 pos[0] = fNominalPos[0];
982 err[0] = fNominalSigma[0];
983 pos[1] = fNominalPos[1];
984 err[1] = fNominalSigma[1];
985 pos[2] = esdEvent->GetVertex()->GetZv();
986 err[2] = esdEvent->GetVertex()->GetZRes();
987 if(err[0]>1. && esdEvent->GetVertex()->GetNContributors()<=0)
988 ncontr = -1; // (x,y,z) = (0,0,0)
989 if(err[0]>1. && esdEvent->GetVertex()->GetNContributors()>0)
990 ncontr = -2; // (x,y,z) = (0,0,z_fromSPD)
991 if(err[0]<1. && esdEvent->GetVertex()->GetNContributors()<=0)
992 ncontr = -3; // (x,y,z) = (x_mean,y_mean,0)
993 if(err[0]<1. && esdEvent->GetVertex()->GetNContributors()>0)
994 ncontr = -4; // (x,y,z) = (x_mean,y_mean,z_fromSPD)
995 fCurrentVertex = 0;
996 fCurrentVertex = new AliESDVertex(pos,err);
997 fCurrentVertex->SetNContributors(ncontr);
998
999 Double_t tp[3];
1000 esdEvent->GetVertex()->GetTruePos(tp);
1001 fCurrentVertex->SetTruePos(tp);
1002 fCurrentVertex->SetTitle("VertexerTracksWithConstraint");
1003 if(ncontr==-1||ncontr==-2)
1004 fCurrentVertex->SetTitle("VertexerTracksNoConstraint");
1005
1006 return;
1007}
5834e9a1 1008