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First V0 MC Analysis from H.Ricaud
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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 <TSystem.h>
30#include <TDirectory.h>
31#include <TFile.h>
32#include <TTree.h>
33#include <TMatrixD.h>
34//---- AliRoot headers -----
35#include "AliStrLine.h"
36#include "AliVertexerTracks.h"
37#include "AliESDEvent.h"
38#include "AliESDtrack.h"
39
40ClassImp(AliVertexerTracks)
41
42
43//----------------------------------------------------------------------------
44AliVertexerTracks::AliVertexerTracks():
45TObject(),
46fVert(),
47fCurrentVertex(0),
48fFieldkG(-999.),
49fConstraint(kFALSE),
50fOnlyFitter(kFALSE),
51fMinTracks(1),
52fMinITSClusters(5),
53fTrkArray(),
54fTrksToSkip(0),
55fNTrksToSkip(0),
56fDCAcut(0),
57fAlgo(1),
58fNSigma(3),
59fMaxd0z0(0.5),
60fITSin(kTRUE),
61fITSrefit(kTRUE),
62fnSigmaForUi00(1.5),
63fDebug(0)
64{
65//
66// Default constructor
67//
68 SetVtxStart();
69 SetVtxStartSigma();
70 SetMinTracks();
71 SetMinITSClusters();
72 SetNSigmad0();
73 SetMaxd0z0();
74}
75//----------------------------------------------------------------------------
76AliVertexerTracks::AliVertexerTracks(Double_t fieldkG):
77TObject(),
78fVert(),
79fCurrentVertex(0),
80fFieldkG(-999.),
81fConstraint(kFALSE),
82fOnlyFitter(kFALSE),
83fMinTracks(1),
84fMinITSClusters(5),
85fTrkArray(),
86fTrksToSkip(0),
87fNTrksToSkip(0),
88fDCAcut(0),
89fAlgo(1),
90fNSigma(3),
91fMaxd0z0(0.5),
92fITSin(kTRUE),
93fITSrefit(kTRUE),
94fnSigmaForUi00(1.5),
95fDebug(0)
96{
97//
98// Standard constructor
99//
100 SetVtxStart();
101 SetVtxStartSigma();
102 SetMinTracks();
103 SetMinITSClusters();
104 SetNSigmad0();
105 SetMaxd0z0();
106 SetFieldkG(fieldkG);
107}
108//-----------------------------------------------------------------------------
109AliVertexerTracks::~AliVertexerTracks()
110{
111 // Default Destructor
112 // The objects pointed by the following pointer are not owned
113 // by this class and are not deleted
114 fCurrentVertex = 0;
115 if(fTrksToSkip) { delete [] fTrksToSkip; fTrksToSkip=NULL; }
116}
117//----------------------------------------------------------------------------
118AliESDVertex* AliVertexerTracks::FindPrimaryVertex(const AliESDEvent *esdEvent)
119{
120//
121// Primary vertex for current ESD event
122// (Two iterations:
123// 1st with 5*fNSigma*sigma cut w.r.t. to initial vertex
124// + cut on sqrt(d0d0+z0z0) if fConstraint=kFALSE
125// 2nd with fNSigma*sigma cut w.r.t. to vertex found in 1st iteration)
126// All ESD tracks with inside the beam pipe are then propagated to found vertex
127//
128 fCurrentVertex = 0;
129
130 // accept 1-track case only if constraint is available
131 if(!fConstraint && fMinTracks==1) fMinTracks=2;
132
133 // read tracks from ESD
134 Int_t nTrksTot = (Int_t)esdEvent->GetNumberOfTracks();
135 if(nTrksTot<=0) {
136 if(fDebug) printf("TooFewTracks\n");
137 TooFewTracks(esdEvent);
138 return fCurrentVertex;
139 }
140
141 TDirectory * olddir = gDirectory;
142 TFile f("VertexerTracks.root","recreate");
143 TTree *trkTree = new TTree("TreeT","tracks");
144 AliESDtrack *esdTrack = 0;
145 trkTree->Branch("tracks","AliESDtrack",&esdTrack);
146
147 Bool_t skipThis;
148 for(Int_t i=0; i<nTrksTot; i++) {
149 AliESDtrack *et = esdEvent->GetTrack(i);
150 // check tracks to skip
151 skipThis = kFALSE;
152 for(Int_t j=0; j<fNTrksToSkip; j++) {
153 if(et->GetID()==fTrksToSkip[j]) {
154 if(fDebug) printf("skipping track: %d\n",i);
155 skipThis = kTRUE;
156 }
157 }
158 if(skipThis) continue;
159 if(fITSin) {
160 if(!(et->GetStatus()&AliESDtrack::kITSin)) continue;
161 if(fITSrefit && !(et->GetStatus()&AliESDtrack::kITSrefit)) continue;
162 Int_t nclus=et->GetNcls(0); // check number of clusters in ITS
163 if(nclus<fMinITSClusters) continue;
164 }
165 esdTrack = new AliESDtrack(*et);
166 trkTree->Fill();
167 delete esdTrack;
168 }
169
170 // If fConstraint=kFALSE
171 // run VertexFinder(1) to get rough estimate of initVertex (x,y)
172 if(!fConstraint) {
173 // fill fTrkArray, for VertexFinder()
174 if(!fTrkArray.IsEmpty()) fTrkArray.Delete();
175 PrepareTracks(*trkTree,0);
176 Double_t cutsave = fDCAcut; fDCAcut = 0.1; // 1 mm
177 VertexFinder(1); // using weights, cutting dca < fDCAcut
178 fDCAcut = cutsave;
179 fTrkArray.Delete();
180 if(fVert.GetNContributors()>0) {
181 fVert.GetXYZ(fNominalPos);
182 fNominalPos[0] = fVert.GetXv();
183 fNominalPos[1] = fVert.GetYv();
184 fNominalPos[2] = fVert.GetZv();
185 if(fDebug) printf("No mean vertex: VertexFinder gives (%f, %f, %f)\n",fNominalPos[0],fNominalPos[1],fNominalPos[2]);
186 } else {
187 fNominalPos[0] = 0.;
188 fNominalPos[1] = 0.;
189 fNominalPos[2] = 0.;
190 if(fDebug) printf("No mean vertex and VertexFinder failed\n");
191 }
192 }
193
194 // TWO ITERATIONS:
195 //
196 // ITERATION 1
197 // propagate tracks to fNominalPos vertex
198 // preselect them:
199 // if(constraint) reject for |d0|>5*fNSigma*sigma w.r.t. fNominal... vertex
200 // else reject for |d0|\oplus|z0| > 5 mm w.r.t. fNominal... vertex
201 // ITERATION 2
202 // propagate tracks to best between initVertex and fCurrentVertex
203 // preselect tracks (reject for |d0|>fNSigma*sigma w.r.t. best
204 // between initVertex and fCurrentVertex)
205 for(Int_t iter=0; iter<2; iter++) {
206 if(fOnlyFitter && iter==0) continue;
207 Int_t nTrksPrep = PrepareTracks(*trkTree,iter+1);
208 if(fDebug) printf(" tracks prepared - iteration %d: %d\n",iter+1,nTrksPrep);
209 if(nTrksPrep < fMinTracks) {
210 if(fDebug) printf("TooFewTracks\n");
211 TooFewTracks(esdEvent);
212 if(fDebug) fCurrentVertex->PrintStatus();
213 fTrkArray.Delete();
214 delete trkTree;
215 f.Close();
216 gSystem->Unlink("VertexerTracks.root");
217 olddir->cd();
218 return fCurrentVertex;
219 }
220
221 // vertex finder
222 if(!fOnlyFitter) {
223 if(nTrksPrep==1){
224 if(fDebug) printf("Just one track\n");
225 OneTrackVertFinder();
226 }else{
227 switch (fAlgo) {
228 case 1: StrLinVertexFinderMinDist(1); break;
229 case 2: StrLinVertexFinderMinDist(0); break;
230 case 3: HelixVertexFinder(); break;
231 case 4: VertexFinder(1); break;
232 case 5: VertexFinder(0); break;
233 default: printf("Wrong algorithm\n"); break;
234 }
235 }
236 if(fDebug) printf(" Vertex finding completed\n");
237 }
238
239 // vertex fitter
240 VertexFitter(fConstraint);
241 if(fDebug) printf(" Vertex fit completed\n");
242 if(iter==0) fTrkArray.Delete();
243 } // end loop on the two iterations
244
245
246 if(fConstraint) {
247 if(fOnlyFitter) {
248 fCurrentVertex->SetTitle("VertexerTracksWithConstraintOnlyFitter");
249 } else {
250 fCurrentVertex->SetTitle("VertexerTracksWithConstraint");
251 }
252 } else {
253 fCurrentVertex->SetTitle("VertexerTracksNoConstraint");
254 }
255
256
257 // set indices of used tracks
258 UShort_t *indices = 0;
259 AliESDtrack *ett = 0;
260 if(fCurrentVertex->GetNContributors()>0) {
261 indices = new UShort_t[fCurrentVertex->GetNContributors()];
262 for(Int_t jj=0;jj<(Int_t)fTrkArray.GetEntriesFast();jj++) {
263 ett = (AliESDtrack*)fTrkArray.At(jj);
264 indices[jj] = (UShort_t)ett->GetID();
265 }
266 fCurrentVertex->SetIndices(fCurrentVertex->GetNContributors(),indices);
267 }
268 delete [] indices;
269
270 delete trkTree;
271 f.Close();
272 gSystem->Unlink("VertexerTracks.root");
273 olddir->cd();
274
275 fTrkArray.Delete();
276
277 if(fTrksToSkip) { delete [] fTrksToSkip; fTrksToSkip=NULL; }
278
279
280 if(fDebug) fCurrentVertex->PrintStatus();
281 if(fDebug) fCurrentVertex->PrintIndices();
282
283
284 return fCurrentVertex;
285}
286//------------------------------------------------------------------------
287Double_t AliVertexerTracks::GetDeterminant3X3(Double_t matr[][3])
288{
289 //
290 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];
291 return det;
292}
293//-------------------------------------------------------------------------
294void AliVertexerTracks::GetStrLinDerivMatrix(Double_t *p0,Double_t *p1,Double_t (*m)[3],Double_t *d)
295{
296 //
297 Double_t x12=p0[0]-p1[0];
298 Double_t y12=p0[1]-p1[1];
299 Double_t z12=p0[2]-p1[2];
300 Double_t kk=x12*x12+y12*y12+z12*z12;
301 m[0][0]=2-2/kk*x12*x12;
302 m[0][1]=-2/kk*x12*y12;
303 m[0][2]=-2/kk*x12*z12;
304 m[1][0]=-2/kk*x12*y12;
305 m[1][1]=2-2/kk*y12*y12;
306 m[1][2]=-2/kk*y12*z12;
307 m[2][0]=-2/kk*x12*z12;
308 m[2][1]=-2*y12*z12;
309 m[2][2]=2-2/kk*z12*z12;
310 d[0]=2*p0[0]-2/kk*p0[0]*x12*x12-2/kk*p0[2]*x12*z12-2/kk*p0[1]*x12*y12;
311 d[1]=2*p0[1]-2/kk*p0[1]*y12*y12-2/kk*p0[0]*x12*y12-2/kk*p0[2]*z12*y12;
312 d[2]=2*p0[2]-2/kk*p0[2]*z12*z12-2/kk*p0[0]*x12*z12-2/kk*p0[1]*z12*y12;
313
314}
315//--------------------------------------------------------------------------
316void AliVertexerTracks::GetStrLinDerivMatrix(Double_t *p0,Double_t *p1,Double_t *sigmasq,Double_t (*m)[3],Double_t *d)
317{
318 //
319 Double_t x12=p1[0]-p0[0];
320 Double_t y12=p1[1]-p0[1];
321 Double_t z12=p1[2]-p0[2];
322
323 Double_t den= x12*x12*sigmasq[1]*sigmasq[2]+y12*y12*sigmasq[0]*sigmasq[2]+z12*z12*sigmasq[0]*sigmasq[1];
324
325 Double_t kk= 2*(x12*x12/sigmasq[0]+y12*y12/sigmasq[1]+z12*z12/sigmasq[2]);
326
327 Double_t cc[3];
328 cc[0]=-x12/sigmasq[0];
329 cc[1]=-y12/sigmasq[1];
330 cc[2]=-z12/sigmasq[2];
331
332 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;
333
334 Double_t ss= -p0[0]*cc[0]-p0[1]*cc[1]-p0[2]*cc[2];
335
336 Double_t aa[3];
337 aa[0]=x12*sigmasq[1]*sigmasq[2]/den;
338 aa[1]=y12*sigmasq[0]*sigmasq[2]/den;
339 aa[2]=z12*sigmasq[0]*sigmasq[1]/den;
340
341 m[0][0]=aa[0]*(aa[0]*kk+2*cc[0])+2*cc[0]*aa[0]+2/sigmasq[0];
342 m[0][1]=aa[1]*(aa[0]*kk+2*cc[0])+2*cc[1]*aa[0];
343 m[0][2]=aa[2]*(aa[0]*kk+2*cc[0])+2*cc[2]*aa[0];
344
345 m[1][0]=aa[0]*(aa[1]*kk+2*cc[1])+2*cc[0]*aa[1];
346 m[1][1]=aa[1]*(aa[1]*kk+2*cc[1])+2*cc[1]*aa[1]+2/sigmasq[1];
347 m[1][2]=aa[2]*(aa[1]*kk+2*cc[1])+2*cc[2]*aa[1];
348
349 m[2][0]=aa[0]*(aa[2]*kk+2*cc[2])+2*cc[0]*aa[2];
350 m[2][1]=aa[1]*(aa[2]*kk+2*cc[2])+2*cc[1]*aa[2];
351 m[2][2]=aa[2]*(aa[2]*kk+2*cc[2])+2*cc[2]*aa[2]+2/sigmasq[2];
352
353 d[0]=-ww*(aa[0]*kk+2*cc[0])-2*ss*aa[0]+2*p0[0]/sigmasq[0];
354 d[1]=-ww*(aa[1]*kk+2*cc[1])-2*ss*aa[1]+2*p0[1]/sigmasq[1];
355 d[2]=-ww*(aa[2]*kk+2*cc[2])-2*ss*aa[2]+2*p0[2]/sigmasq[2];
356
357 }
358//--------------------------------------------------------------------------
359Double_t AliVertexerTracks::GetStrLinMinDist(Double_t *p0,Double_t *p1,Double_t *x0)
360{
361 //
362 Double_t x12=p0[0]-p1[0];
363 Double_t y12=p0[1]-p1[1];
364 Double_t z12=p0[2]-p1[2];
365 Double_t x10=p0[0]-x0[0];
366 Double_t y10=p0[1]-x0[1];
367 Double_t z10=p0[2]-x0[2];
368 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);
369}
370//---------------------------------------------------------------------------
371void AliVertexerTracks::OneTrackVertFinder()
372{
373 // find vertex for events with 1 track, using DCA to nominal beam axis
374 if(fDebug) printf("Number of prepared tracks =%d - Call OneTrackVertFinder",fTrkArray.GetEntries());
375 AliESDtrack *track1;
376 track1 = (AliESDtrack*)fTrkArray.At(0);
377 Double_t field=GetFieldkG();
378 Double_t alpha=track1->GetAlpha();
379 Double_t mindist = TMath::Cos(alpha)*fNominalPos[0]+TMath::Sin(alpha)*fNominalPos[1];
380 Double_t pos[3],dir[3];
381 track1->GetXYZAt(mindist,field,pos);
382 track1->GetPxPyPzAt(mindist,field,dir);
383 AliStrLine *line1 = new AliStrLine(pos,dir);
384 Double_t p1[3]={fNominalPos[0],fNominalPos[1],0.};
385 Double_t p2[3]={fNominalPos[0],fNominalPos[1],10.};
386 AliStrLine *zeta=new AliStrLine(p1,p2,kTRUE);
387 Double_t crosspoint[3]={0.,0.,0.};
388 Double_t sigma=999.;
389 Int_t nContrib=-1;
390 Int_t retcode = zeta->Cross(line1,crosspoint);
391 if(retcode>=0){
392 sigma=line1->GetDistFromPoint(crosspoint);
393 nContrib=1;
394 }
395 delete zeta;
396 delete line1;
397 fVert.SetXYZ(crosspoint);
398 fVert.SetDispersion(sigma);
399 fVert.SetNContributors(nContrib);
400}
401//---------------------------------------------------------------------------
402void AliVertexerTracks::HelixVertexFinder()
403{
404 // Get estimate of vertex position in (x,y) from tracks DCA
405
406
407 Double_t initPos[3];
408 initPos[2] = 0.;
409 for(Int_t i=0;i<2;i++)initPos[i]=fNominalPos[i];
410 Double_t field=GetFieldkG();
411
412 Int_t nacc = (Int_t)fTrkArray.GetEntriesFast();
413
414 Double_t aver[3]={0.,0.,0.};
415 Double_t averquad[3]={0.,0.,0.};
416 Double_t sigmaquad[3]={0.,0.,0.};
417 Double_t sigma=0;
418 Int_t ncombi = 0;
419 AliESDtrack *track1;
420 AliESDtrack *track2;
421 Double_t distCA;
422 Double_t x, par[5];
423 Double_t alpha, cs, sn;
424 Double_t crosspoint[3];
425 for(Int_t i=0; i<nacc; i++){
426 track1 = (AliESDtrack*)fTrkArray.At(i);
427
428
429 for(Int_t j=i+1; j<nacc; j++){
430 track2 = (AliESDtrack*)fTrkArray.At(j);
431
432 distCA=track2->PropagateToDCA(track1,field);
433 if(fDCAcut<=0 ||(fDCAcut>0&&distCA<fDCAcut)){
434 track1->GetExternalParameters(x,par);
435 alpha=track1->GetAlpha();
436 cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
437 Double_t x1=x*cs - par[0]*sn;
438 Double_t y1=x*sn + par[0]*cs;
439 Double_t z1=par[1];
440 Double_t sx1=sn*sn*track1->GetSigmaY2(), sy1=cs*cs*track1->GetSigmaY2();
441 track2->GetExternalParameters(x,par);
442 alpha=track2->GetAlpha();
443 cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
444 Double_t x2=x*cs - par[0]*sn;
445 Double_t y2=x*sn + par[0]*cs;
446 Double_t z2=par[1];
447 Double_t sx2=sn*sn*track2->GetSigmaY2(), sy2=cs*cs*track2->GetSigmaY2();
448 Double_t sz1=track1->GetSigmaZ2(), sz2=track2->GetSigmaZ2();
449 Double_t wx1=sx2/(sx1+sx2), wx2=1.- wx1;
450 Double_t wy1=sy2/(sy1+sy2), wy2=1.- wy1;
451 Double_t wz1=sz2/(sz1+sz2), wz2=1.- wz1;
452 crosspoint[0]=wx1*x1 + wx2*x2;
453 crosspoint[1]=wy1*y1 + wy2*y2;
454 crosspoint[2]=wz1*z1 + wz2*z2;
455
456 ncombi++;
457 for(Int_t jj=0;jj<3;jj++)aver[jj]+=crosspoint[jj];
458 for(Int_t jj=0;jj<3;jj++)averquad[jj]+=(crosspoint[jj]*crosspoint[jj]);
459 }
460 }
461
462 }
463 if(ncombi>0){
464 for(Int_t jj=0;jj<3;jj++){
465 initPos[jj] = aver[jj]/ncombi;
466 averquad[jj]/=ncombi;
467 sigmaquad[jj]=averquad[jj]-initPos[jj]*initPos[jj];
468 sigma+=sigmaquad[jj];
469 }
470 sigma=TMath::Sqrt(TMath::Abs(sigma));
471 }
472 else {
473 Warning("HelixVertexFinder","Finder did not succed");
474 sigma=999;
475 }
476 fVert.SetXYZ(initPos);
477 fVert.SetDispersion(sigma);
478 fVert.SetNContributors(ncombi);
479}
480//----------------------------------------------------------------------------
481Int_t AliVertexerTracks::PrepareTracks(TTree &trkTree,Int_t optImpParCut)
482{
483//
484// Propagate tracks to initial vertex position and store them in a TObjArray
485//
486 Double_t maxd0rphi;
487 Double_t maxd0z0 = fMaxd0z0; // default is 5 mm
488 Int_t nTrks = 0;
489 Double_t sigmaCurr[3];
490 Double_t normdistx,normdisty;
491 Float_t d0z0[2],covd0z0[3];
492 Double_t sigma;
493 Double_t field=GetFieldkG();
494
495 AliESDVertex *initVertex = new AliESDVertex(fNominalPos,fNominalCov,1,1);
496
497 Int_t nEntries = (Int_t)trkTree.GetEntries();
498 if(!fTrkArray.IsEmpty()) fTrkArray.Delete();
499
500 if(fDebug) {
501 printf(" PrepareTracks()\n");
502 }
503
504 for(Int_t i=0; i<nEntries; i++) {
505 AliESDtrack *track = new AliESDtrack;
506 trkTree.SetBranchAddress("tracks",&track);
507 trkTree.GetEvent(i);
508
509 // propagate track to vertex
510 if(optImpParCut<=1 || fOnlyFitter) { // optImpParCut==1 or 0
511 track->RelateToVertex(initVertex,field,100.);
512 } else { // optImpParCut==2
513 fCurrentVertex->GetSigmaXYZ(sigmaCurr);
514 normdistx = TMath::Abs(fCurrentVertex->GetXv()-fNominalPos[0])/TMath::Sqrt(sigmaCurr[0]*sigmaCurr[0]+fNominalCov[0]);
515 normdisty = TMath::Abs(fCurrentVertex->GetYv()-fNominalPos[1])/TMath::Sqrt(sigmaCurr[1]*sigmaCurr[1]+fNominalCov[2]);
516 if(normdistx < 3. && normdisty < 3. &&
517 (sigmaCurr[0]+sigmaCurr[1])<(TMath::Sqrt(fNominalCov[0])+TMath::Sqrt(fNominalCov[2]))) {
518 track->RelateToVertex(fCurrentVertex,field,100.);
519 } else {
520 track->RelateToVertex(initVertex,field,100.);
521 }
522 }
523
524 track->GetImpactParameters(d0z0,covd0z0);
525 sigma = TMath::Sqrt(covd0z0[0]);
526 maxd0rphi = fNSigma*sigma;
527 if(optImpParCut==1) maxd0rphi *= 5.;
528
529
530
531 if(fDebug) printf("trk %d; lab %d; |d0| = %f; d0 cut = %f; |z0| = %f; |d0|oplus|z0| = %f; d0z0 cut = %f\n",i,track->GetLabel(),TMath::Abs(d0z0[0]),maxd0rphi,TMath::Abs(d0z0[1]),TMath::Sqrt(d0z0[0]*d0z0[0]+d0z0[1]*d0z0[1]),maxd0z0);
532
533 // during iterations 1 and 2, if fConstraint=kFALSE,
534 // select tracks with d0oplusz0 < maxd0z0
535 if(optImpParCut>=1 && !fConstraint && nEntries>=3 &&
536 fVert.GetNContributors()>0) {
537 if(TMath::Sqrt(d0z0[0]*d0z0[0]+d0z0[1]*d0z0[1]) > maxd0z0) {
538 if(fDebug) printf(" rejected\n");
539 delete track; continue;
540 }
541 }
542
543 // select tracks with d0rphi < maxd0rphi
544 if(optImpParCut>0 && TMath::Abs(d0z0[0]) > maxd0rphi) {
545 if(fDebug) printf(" rejected\n");
546 delete track; continue;
547 }
548
549 fTrkArray.AddLast(track);
550 nTrks++;
551 }
552
553 delete initVertex;
554
555 return nTrks;
556}
557//---------------------------------------------------------------------------
558AliESDVertex* AliVertexerTracks::RemoveTracksFromVertex(AliESDVertex *inVtx,
559 TTree *trksTree,
560 Float_t *diamondxy)
561{
562//
563// Removes tracks in trksTree from fit of inVtx
564//
565
566 if(!strstr(inVtx->GetTitle(),"VertexerTracksWithConstraint")) {
567 printf("ERROR: primary vertex has no constraint: cannot remove tracks\n");
568 return 0x0;
569 }
570 if(!strstr(inVtx->GetTitle(),"VertexerTracksWithConstraintOnlyFitter"))
571 printf("WARNING: result of tracks' removal will be only approximately correct\n");
572
573 TMatrixD rv(3,1);
574 rv(0,0) = inVtx->GetXv();
575 rv(1,0) = inVtx->GetYv();
576 rv(2,0) = inVtx->GetZv();
577 TMatrixD vV(3,3);
578 Double_t cov[6];
579 inVtx->GetCovMatrix(cov);
580 vV(0,0) = cov[0];
581 vV(0,1) = cov[1]; vV(1,0) = cov[1];
582 vV(1,1) = cov[2];
583 vV(0,2) = cov[3]; vV(2,0) = cov[3];
584 vV(1,2) = cov[4]; vV(2,1) = cov[4];
585 vV(2,2) = cov[5];
586
587 TMatrixD sumWi(TMatrixD::kInverted,vV);
588 TMatrixD sumWiri(sumWi,TMatrixD::kMult,rv);
589
590 Int_t nUsedTrks = inVtx->GetNContributors();
591 Double_t chi2 = inVtx->GetChi2();
592
593 AliESDtrack *track = 0;
594 trksTree->SetBranchAddress("tracks",&track);
595 Int_t ntrks = trksTree->GetEntries();
596 for(Int_t i=0;i<ntrks;i++) {
597 trksTree->GetEvent(i);
598 if(!inVtx->UsesTrack(track->GetID())) {
599 printf("track %d was not used in vertex fit\n",track->GetID());
600 continue;
601 }
602 Double_t alpha = track->GetAlpha();
603 Double_t xl = diamondxy[0]*TMath::Cos(alpha)+diamondxy[1]*TMath::Sin(alpha);
604 track->AliExternalTrackParam::PropagateTo(xl,GetFieldkG());
605 // vector of track global coordinates
606 TMatrixD ri(3,1);
607 // covariance matrix of ri
608 TMatrixD wWi(3,3);
609
610 // get space point from track
611 if(!TrackToPoint(track,ri,wWi)) continue;
612
613 TMatrixD wWiri(wWi,TMatrixD::kMult,ri);
614
615 sumWi -= wWi;
616 sumWiri -= wWiri;
617
618 // track chi2
619 TMatrixD deltar = rv; deltar -= ri;
620 TMatrixD wWideltar(wWi,TMatrixD::kMult,deltar);
621 Double_t chi2i = deltar(0,0)*wWideltar(0,0)+
622 deltar(1,0)*wWideltar(1,0)+
623 deltar(2,0)*wWideltar(2,0);
624 // remove from total chi2
625 chi2 -= chi2i;
626
627 nUsedTrks--;
628 if(nUsedTrks<2) {
629 printf("Trying to remove too many tracks!\n");
630 return 0x0;
631 }
632 }
633
634 TMatrixD rvnew(3,1);
635 TMatrixD vVnew(3,3);
636
637 // new inverted of weights matrix
638 TMatrixD invsumWi(TMatrixD::kInverted,sumWi);
639 vVnew = invsumWi;
640 // new position of primary vertex
641 rvnew.Mult(vVnew,sumWiri);
642
643 Double_t position[3];
644 position[0] = rvnew(0,0);
645 position[1] = rvnew(1,0);
646 position[2] = rvnew(2,0);
647 cov[0] = vVnew(0,0);
648 cov[1] = vVnew(0,1);
649 cov[2] = vVnew(1,1);
650 cov[3] = vVnew(0,2);
651 cov[4] = vVnew(1,2);
652 cov[5] = vVnew(2,2);
653
654 // store data in the vertex object
655 AliESDVertex *outVtx = new AliESDVertex(position,cov,chi2,nUsedTrks);
656 outVtx->SetTitle(inVtx->GetTitle());
657 UShort_t *inindices = inVtx->GetIndices();
658 UShort_t *outindices = new UShort_t[outVtx->GetNContributors()];
659 Int_t j=0;
660 Bool_t copyindex;
661 for(Int_t k=0; k<inVtx->GetNIndices(); k++) {
662 copyindex=kTRUE;
663 for(Int_t l=0; l<ntrks; l++) {
664 trksTree->GetEvent(l);
665 if(inindices[k]==track->GetID()) copyindex=kFALSE;
666 }
667 if(copyindex) {
668 outindices[j] = inindices[k]; j++;
669 }
670 }
671 outVtx->SetIndices(outVtx->GetNContributors(),outindices);
672 delete [] outindices;
673
674 if(fDebug) {
675 printf("Vertex before removing tracks:\n");
676 inVtx->PrintStatus();
677 inVtx->PrintIndices();
678 printf("Vertex after removing tracks:\n");
679 outVtx->PrintStatus();
680 outVtx->PrintIndices();
681 }
682
683 return outVtx;
684}
685//---------------------------------------------------------------------------
686void AliVertexerTracks::SetSkipTracks(Int_t n,Int_t *skipped)
687{
688//
689// Mark the tracks not to be used in the vertex reconstruction.
690// Tracks are identified by AliESDtrack::GetID()
691//
692 fNTrksToSkip = n; fTrksToSkip = new Int_t[n];
693 for(Int_t i=0;i<n;i++) fTrksToSkip[i] = skipped[i];
694 return;
695}
696//---------------------------------------------------------------------------
697void AliVertexerTracks::SetVtxStart(AliESDVertex *vtx)
698{
699//
700// Set initial vertex knowledge
701//
702 vtx->GetXYZ(fNominalPos);
703 vtx->GetCovMatrix(fNominalCov);
704 SetConstraintOn();
705 return;
706}
707//---------------------------------------------------------------------------
708void AliVertexerTracks::StrLinVertexFinderMinDist(Int_t optUseWeights)
709{
710 AliESDtrack *track1;
711 Double_t field=GetFieldkG();
712 const Int_t knacc = (Int_t)fTrkArray.GetEntriesFast();
713 TClonesArray *linarray = new TClonesArray("AliStrLine",1000);
714 TClonesArray &lines = *linarray;
715 for(Int_t i=0; i<knacc; i++){
716 track1 = (AliESDtrack*)fTrkArray.At(i);
717 Double_t alpha=track1->GetAlpha();
718 Double_t mindist = TMath::Cos(alpha)*fNominalPos[0]+TMath::Sin(alpha)*fNominalPos[1];
719 Double_t pos[3],dir[3],sigmasq[3];
720 track1->GetXYZAt(mindist,field,pos);
721 track1->GetPxPyPzAt(mindist,field,dir);
722 sigmasq[0]=TMath::Sin(alpha)*TMath::Sin(alpha)*track1->GetSigmaY2();
723 sigmasq[1]=TMath::Cos(alpha)*TMath::Cos(alpha)*track1->GetSigmaY2();
724 sigmasq[2]=track1->GetSigmaZ2();
725 TMatrixD ri(3,1);
726 TMatrixD wWi(3,3);
727 if(!TrackToPoint(track1,ri,wWi)) continue;
728 Double_t wmat[9];
729 Int_t iel=0;
730 for(Int_t ia=0;ia<3;ia++){
731 for(Int_t ib=0;ib<3;ib++){
732 wmat[iel]=wWi(ia,ib);
733 iel++;
734 }
735 }
736 new(lines[i]) AliStrLine(pos,sigmasq,wmat,dir);
737 }
738 fVert=TrackletVertexFinder(linarray,optUseWeights);
739 linarray->Delete();
740 delete linarray;
741}
742//---------------------------------------------------------------------------
743AliESDVertex AliVertexerTracks::TrackletVertexFinder(TClonesArray *lines, Int_t optUseWeights)
744{
745 // Calculate the point at minimum distance to prepared tracks
746
747 const Int_t knacc = (Int_t)lines->GetEntriesFast();
748 Double_t initPos[3]={0.,0.,0.};
749
750 Double_t (*vectP0)[3]=new Double_t [knacc][3];
751 Double_t (*vectP1)[3]=new Double_t [knacc][3];
752
753 Double_t sum[3][3];
754 Double_t dsum[3]={0,0,0};
755 TMatrixD sumWi(3,3);
756 for(Int_t i=0;i<3;i++){
757 for(Int_t j=0;j<3;j++){
758 sum[i][j]=0;
759 sumWi(i,j)=0.;
760 }
761 }
762
763 for(Int_t i=0; i<knacc; i++){
764 AliStrLine* line1 = (AliStrLine*)lines->At(i);
765 Double_t p0[3],cd[3],sigmasq[3];
766 Double_t wmat[9];
767 line1->GetP0(p0);
768 line1->GetCd(cd);
769 line1->GetSigma2P0(sigmasq);
770 line1->GetWMatrix(wmat);
771 TMatrixD wWi(3,3);
772 Int_t iel=0;
773 for(Int_t ia=0;ia<3;ia++){
774 for(Int_t ib=0;ib<3;ib++){
775 wWi(ia,ib)=wmat[iel];
776 iel++;
777 }
778 }
779
780 sumWi+=wWi;
781
782 Double_t p1[3]={p0[0]+cd[0],p0[1]+cd[1],p0[2]+cd[2]};
783 vectP0[i][0]=p0[0];
784 vectP0[i][1]=p0[1];
785 vectP0[i][2]=p0[2];
786 vectP1[i][0]=p1[0];
787 vectP1[i][1]=p1[1];
788 vectP1[i][2]=p1[2];
789
790 Double_t matr[3][3];
791 Double_t dknow[3];
792 if(optUseWeights==0)GetStrLinDerivMatrix(p0,p1,matr,dknow);
793 else GetStrLinDerivMatrix(p0,p1,sigmasq,matr,dknow);
794
795
796 for(Int_t iii=0;iii<3;iii++){
797 dsum[iii]+=dknow[iii];
798 for(Int_t lj=0;lj<3;lj++) sum[iii][lj]+=matr[iii][lj];
799 }
800 }
801
802 TMatrixD invsumWi(TMatrixD::kInverted,sumWi);
803 Double_t covmatrix[6];
804 covmatrix[0] = invsumWi(0,0);
805 covmatrix[1] = invsumWi(0,1);
806 covmatrix[2] = invsumWi(1,1);
807 covmatrix[3] = invsumWi(0,2);
808 covmatrix[4] = invsumWi(1,2);
809 covmatrix[5] = invsumWi(2,2);
810
811 Double_t vett[3][3];
812 Double_t det=GetDeterminant3X3(sum);
813 Double_t sigma=0;
814
815 if(det!=0){
816 for(Int_t zz=0;zz<3;zz++){
817 for(Int_t ww=0;ww<3;ww++){
818 for(Int_t kk=0;kk<3;kk++) vett[ww][kk]=sum[ww][kk];
819 }
820 for(Int_t kk=0;kk<3;kk++) vett[kk][zz]=dsum[kk];
821 initPos[zz]=GetDeterminant3X3(vett)/det;
822 }
823
824
825 for(Int_t i=0; i<knacc; i++){
826 Double_t p0[3]={0,0,0},p1[3]={0,0,0};
827 for(Int_t ii=0;ii<3;ii++){
828 p0[ii]=vectP0[i][ii];
829 p1[ii]=vectP1[i][ii];
830 }
831 sigma+=GetStrLinMinDist(p0,p1,initPos);
832 }
833
834 sigma=TMath::Sqrt(sigma);
835 }else{
836 sigma=999;
837 }
838 AliESDVertex theVert(initPos,covmatrix,99999.,knacc);
839 theVert.SetDispersion(sigma);
840 delete vectP0;
841 delete vectP1;
842 return theVert;
843}
844//---------------------------------------------------------------------------
845Bool_t AliVertexerTracks::TrackToPoint(AliESDtrack *t,
846 TMatrixD &ri,TMatrixD &wWi,
847 Bool_t uUi3by3) const
848{
849//
850// Extract from the AliESDtrack the global coordinates ri and covariance matrix
851// wWi of the space point that it represents (to be used in VertexFitter())
852//
853
854
855 Double_t rotAngle = t->GetAlpha();
856 if(rotAngle<0.) rotAngle += 2.*TMath::Pi();
857 Double_t cosRot = TMath::Cos(rotAngle);
858 Double_t sinRot = TMath::Sin(rotAngle);
859
860 ri(0,0) = t->GetX()*cosRot-t->GetY()*sinRot;
861 ri(1,0) = t->GetX()*sinRot+t->GetY()*cosRot;
862 ri(2,0) = t->GetZ();
863
864
865
866 if(!uUi3by3) {
867 // matrix to go from global (x,y,z) to local (y,z);
868 TMatrixD qQi(2,3);
869 qQi(0,0) = -sinRot;
870 qQi(0,1) = cosRot;
871 qQi(0,2) = 0.;
872 qQi(1,0) = 0.;
873 qQi(1,1) = 0.;
874 qQi(1,2) = 1.;
875
876 // covariance matrix of local (y,z) - inverted
877 Double_t cc[15];
878 t->GetExternalCovariance(cc);
879 TMatrixD uUi(2,2);
880 uUi(0,0) = cc[0];
881 uUi(0,1) = cc[1];
882 uUi(1,0) = cc[1];
883 uUi(1,1) = cc[2];
884 //printf(" Ui :\n");
885 //printf(" %f %f\n",uUi(0,0),uUi(0,1));
886 //printf(" %f %f\n",uUi(1,0),uUi(1,1));
887
888 if(uUi.Determinant() <= 0.) return kFALSE;
889 TMatrixD uUiInv(TMatrixD::kInverted,uUi);
890
891 // weights matrix: wWi = qQiT * uUiInv * qQi
892 TMatrixD uUiInvQi(uUiInv,TMatrixD::kMult,qQi);
893 TMatrixD m(qQi,TMatrixD::kTransposeMult,uUiInvQi);
894 wWi = m;
895 } else {
896 if(fVert.GetNContributors()<1) AliFatal("Vertex from finder is empty");
897 // matrix to go from global (x,y,z) to local (x,y,z);
898 TMatrixD qQi(3,3);
899 qQi(0,0) = cosRot;
900 qQi(0,1) = sinRot;
901 qQi(0,2) = 0.;
902 qQi(1,0) = -sinRot;
903 qQi(1,1) = cosRot;
904 qQi(1,2) = 0.;
905 qQi(2,0) = 0.;
906 qQi(2,1) = 0.;
907 qQi(2,2) = 1.;
908
909 // covariance of fVert along the track
910 Double_t p[3],pt,ptot;
911 t->GetPxPyPz(p);
912 pt = TMath::Sqrt(p[0]*p[0]+p[1]*p[1]);
913 ptot = TMath::Sqrt(pt*pt+p[2]*p[2]);
914 Double_t cphi = p[0]/pt; //cos(phi)=px/pt
915 Double_t sphi = p[1]/pt; //sin(phi)=py/pt
916 Double_t clambda = pt/ptot; //cos(lambda)=pt/ptot
917 Double_t slambda = p[2]/ptot; //sin(lambda)=pz/ptot
918 Double_t covfVert[6];
919 fVert.GetCovMatrix(covfVert);
920 Double_t covfVertalongt =
921 covfVert[0]*cphi*cphi*clambda*clambda
922 +covfVert[1]*2.*cphi*sphi*clambda*clambda
923 +covfVert[3]*2.*cphi*clambda*slambda
924 +covfVert[2]*sphi*sphi*clambda*clambda
925 +covfVert[4]*2.*sphi*clambda*slambda
926 +covfVert[5]*slambda*slambda;
927 Double_t cc[15];
928 t->GetExternalCovariance(cc);
929 // covariance matrix of local (x,y,z) - inverted
930 TMatrixD uUi(3,3);
931 uUi(0,0) = covfVertalongt * fnSigmaForUi00 * fnSigmaForUi00;
932 if(fDebug) printf("=====> sqrtUi00 cm %f\n",TMath::Sqrt(uUi(0,0)));
933 uUi(0,1) = 0.;
934 uUi(0,2) = 0.;
935 uUi(1,0) = 0.;
936 uUi(1,1) = cc[0];
937 uUi(1,2) = cc[1];
938 uUi(2,0) = 0.;
939 uUi(2,1) = cc[1];
940 uUi(2,2) = cc[2];
941 //printf(" Ui :\n");
942 //printf(" %f %f\n",uUi(0,0),uUi(0,1));
943 //printf(" %f %f\n",uUi(1,0),uUi(1,1));
944
945 if(uUi.Determinant() <= 0.) return kFALSE;
946 TMatrixD uUiInv(TMatrixD::kInverted,uUi);
947
948 // weights matrix: wWi = qQiT * uUiInv * qQi
949 TMatrixD uUiInvQi(uUiInv,TMatrixD::kMult,qQi);
950 TMatrixD m(qQi,TMatrixD::kTransposeMult,uUiInvQi);
951 wWi = m;
952 }
953
954
955 return kTRUE;
956}
957//---------------------------------------------------------------------------
958void AliVertexerTracks::TooFewTracks(const AliESDEvent* esdEvent)
959{
960//
961// When the number of tracks is < fMinTracks
962//
963
964 // deal with vertices not found
965 Double_t pos[3],err[3];
966 Int_t ncontr=0;
967 pos[0] = fNominalPos[0];
968 err[0] = TMath::Sqrt(fNominalCov[0]);
969 pos[1] = fNominalPos[1];
970 err[1] = TMath::Sqrt(fNominalCov[2]);
971 pos[2] = esdEvent->GetVertex()->GetZv();
972 err[2] = esdEvent->GetVertex()->GetZRes();
973 if(err[0]>1. && esdEvent->GetVertex()->GetNContributors()<=0)
974 ncontr = -1; // (x,y,z) = (0,0,0)
975 if(err[0]>1. && esdEvent->GetVertex()->GetNContributors()>0)
976 ncontr = -2; // (x,y,z) = (0,0,z_fromSPD)
977 if(err[0]<1. && esdEvent->GetVertex()->GetNContributors()<=0)
978 ncontr = -3; // (x,y,z) = (x_mean,y_mean,0)
979 if(err[0]<1. && esdEvent->GetVertex()->GetNContributors()>0)
980 ncontr = -4; // (x,y,z) = (x_mean,y_mean,z_fromSPD)
981 fCurrentVertex = 0;
982 fCurrentVertex = new AliESDVertex(pos,err);
983 fCurrentVertex->SetNContributors(ncontr);
984
985 if(fConstraint) {
986 fCurrentVertex->SetTitle("VertexerTracksWithConstraint");
987 } else {
988 fCurrentVertex->SetTitle("VertexerTracksNoConstraint");
989 }
990
991 return;
992}
993//---------------------------------------------------------------------------
994void AliVertexerTracks::VertexFinder(Int_t optUseWeights)
995{
996
997 // Get estimate of vertex position in (x,y) from tracks DCA
998
999 Double_t initPos[3];
1000 initPos[2] = 0.;
1001 for(Int_t i=0;i<2;i++)initPos[i]=fNominalPos[i];
1002 Int_t nacc = (Int_t)fTrkArray.GetEntriesFast();
1003 Double_t aver[3]={0.,0.,0.};
1004 Double_t aversq[3]={0.,0.,0.};
1005 Double_t sigmasq[3]={0.,0.,0.};
1006 Double_t sigma=0;
1007 Int_t ncombi = 0;
1008 AliESDtrack *track1;
1009 AliESDtrack *track2;
1010 Double_t pos[3],dir[3];
1011 Double_t alpha,mindist;
1012 Double_t field=GetFieldkG();
1013
1014 for(Int_t i=0; i<nacc; i++){
1015 track1 = (AliESDtrack*)fTrkArray.At(i);
1016 alpha=track1->GetAlpha();
1017 mindist = TMath::Cos(alpha)*fNominalPos[0]+TMath::Sin(alpha)*fNominalPos[1];
1018 track1->GetXYZAt(mindist,field,pos);
1019 track1->GetPxPyPzAt(mindist,field,dir);
1020 AliStrLine *line1 = new AliStrLine(pos,dir);
1021
1022 // AliStrLine *line1 = new AliStrLine();
1023 // track1->ApproximateHelixWithLine(mindist,field,line1);
1024
1025 for(Int_t j=i+1; j<nacc; j++){
1026 track2 = (AliESDtrack*)fTrkArray.At(j);
1027 alpha=track2->GetAlpha();
1028 mindist = TMath::Cos(alpha)*fNominalPos[0]+TMath::Sin(alpha)*fNominalPos[1];
1029 track2->GetXYZAt(mindist,field,pos);
1030 track2->GetPxPyPzAt(mindist,field,dir);
1031 AliStrLine *line2 = new AliStrLine(pos,dir);
1032 // AliStrLine *line2 = new AliStrLine();
1033 // track2->ApproximateHelixWithLine(mindist,field,line2);
1034 Double_t distCA=line2->GetDCA(line1);
1035 //printf("%d %d %f\n",i,j,distCA);
1036 if(fDCAcut<=0 || (fDCAcut>0&&distCA<fDCAcut)){
1037 Double_t pnt1[3],pnt2[3],crosspoint[3];
1038
1039 if(optUseWeights<=0){
1040 Int_t retcode = line2->Cross(line1,crosspoint);
1041 if(retcode>=0){
1042 ncombi++;
1043 for(Int_t jj=0;jj<3;jj++)aver[jj]+=crosspoint[jj];
1044 for(Int_t jj=0;jj<3;jj++)aversq[jj]+=(crosspoint[jj]*crosspoint[jj]);
1045 }
1046 }
1047 if(optUseWeights>0){
1048 Int_t retcode = line1->CrossPoints(line2,pnt1,pnt2);
1049 if(retcode>=0){
1050 Double_t cs, sn;
1051 alpha=track1->GetAlpha();
1052 cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
1053 Double_t sx1=sn*sn*track1->GetSigmaY2(), sy1=cs*cs*track1->GetSigmaY2();
1054 alpha=track2->GetAlpha();
1055 cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
1056 Double_t sx2=sn*sn*track2->GetSigmaY2(), sy2=cs*cs*track2->GetSigmaY2();
1057 Double_t sz1=track1->GetSigmaZ2(), sz2=track2->GetSigmaZ2();
1058 Double_t wx1=sx2/(sx1+sx2), wx2=1.- wx1;
1059 Double_t wy1=sy2/(sy1+sy2), wy2=1.- wy1;
1060 Double_t wz1=sz2/(sz1+sz2), wz2=1.- wz1;
1061 crosspoint[0]=wx1*pnt1[0] + wx2*pnt2[0];
1062 crosspoint[1]=wy1*pnt1[1] + wy2*pnt2[1];
1063 crosspoint[2]=wz1*pnt1[2] + wz2*pnt2[2];
1064
1065 ncombi++;
1066 for(Int_t jj=0;jj<3;jj++)aver[jj]+=crosspoint[jj];
1067 for(Int_t jj=0;jj<3;jj++)aversq[jj]+=(crosspoint[jj]*crosspoint[jj]);
1068 }
1069 }
1070 }
1071 delete line2;
1072 }
1073 delete line1;
1074 }
1075 if(ncombi>0){
1076 for(Int_t jj=0;jj<3;jj++){
1077 initPos[jj] = aver[jj]/ncombi;
1078 //printf("%f\n",initPos[jj]);
1079 aversq[jj]/=ncombi;
1080 sigmasq[jj]=aversq[jj]-initPos[jj]*initPos[jj];
1081 sigma+=sigmasq[jj];
1082 }
1083 sigma=TMath::Sqrt(TMath::Abs(sigma));
1084 }
1085 else {
1086 Warning("VertexFinder","Finder did not succed");
1087 sigma=999;
1088 }
1089 fVert.SetXYZ(initPos);
1090 fVert.SetDispersion(sigma);
1091 fVert.SetNContributors(ncombi);
1092}
1093//---------------------------------------------------------------------------
1094void AliVertexerTracks::VertexFitter(Bool_t useConstraint)
1095{
1096//
1097// The optimal estimate of the vertex position is given by a "weighted
1098// average of tracks positions".
1099// Original method: V. Karimaki, CMS Note 97/0051
1100//
1101 Double_t initPos[3];
1102 if(!fOnlyFitter) {
1103 fVert.GetXYZ(initPos);
1104 } else {
1105 initPos[0]=fNominalPos[0];
1106 initPos[1]=fNominalPos[1];
1107 initPos[2]=fNominalPos[2];
1108 }
1109
1110 Int_t nTrks = (Int_t)fTrkArray.GetEntries();
1111 if(nTrks==1) useConstraint=kTRUE;
1112 if(fDebug) {
1113 printf("--- VertexFitter(): start\n");
1114 printf(" Number of tracks in array: %d\n",nTrks);
1115 printf(" Minimum # tracks required in fit: %d\n",fMinTracks);
1116 printf(" Vertex position after finder: %f,%f,%f\n",initPos[0],initPos[1],initPos[2]);
1117 if(useConstraint) printf(" This vertex will be used in fit: (%f+-%f,%f+-%f)\n",fNominalPos[0],TMath::Sqrt(fNominalCov[0]),fNominalPos[1],TMath::Sqrt(fNominalCov[2]));
1118 }
1119
1120 // special treatment for few-tracks fits (e.g. secondary vertices)
1121 Bool_t uUi3by3 = kFALSE; if(nTrks<5 && !useConstraint) uUi3by3 = kTRUE;
1122
1123 Int_t i,j,k,step=0;
1124 TMatrixD rv(3,1);
1125 TMatrixD vV(3,3);
1126 rv(0,0) = initPos[0];
1127 rv(1,0) = initPos[1];
1128 rv(2,0) = 0.;
1129 Double_t xlStart,alpha;
1130 Int_t nUsedTrks;
1131 Double_t chi2,chi2i,chi2b;
1132 AliESDtrack *t = 0;
1133 Int_t failed = 0;
1134
1135 // initial vertex covariance matrix
1136 TMatrixD vVb(3,3);
1137 vVb(0,0) = fNominalCov[0];
1138 vVb(0,1) = fNominalCov[1];
1139 vVb(0,2) = 0.;
1140 vVb(1,0) = fNominalCov[1];
1141 vVb(1,1) = fNominalCov[2];
1142 vVb(1,2) = 0.;
1143 vVb(2,0) = 0.;
1144 vVb(2,1) = 0.;
1145 vVb(2,2) = fNominalCov[5];
1146 TMatrixD vVbInv(TMatrixD::kInverted,vVb);
1147 TMatrixD rb(3,1);
1148 rb(0,0) = fNominalPos[0];
1149 rb(1,0) = fNominalPos[1];
1150 rb(2,0) = fNominalPos[2];
1151 TMatrixD vVbInvrb(vVbInv,TMatrixD::kMult,rb);
1152
1153
1154 // 2 steps:
1155 // 1st - estimate of vtx using all tracks
1156 // 2nd - estimate of global chi2
1157 for(step=0; step<2; step++) {
1158 if(fDebug) printf(" step = %d\n",step);
1159 chi2 = 0.;
1160 nUsedTrks = 0;
1161
1162 if(step==1) { initPos[0]=rv(0,0); initPos[0]=rv(1,0); }
1163
1164 TMatrixD sumWiri(3,1);
1165 TMatrixD sumWi(3,3);
1166 for(i=0; i<3; i++) {
1167 sumWiri(i,0) = 0.;
1168 for(j=0; j<3; j++) sumWi(j,i) = 0.;
1169 }
1170
1171 // mean vertex constraint
1172 if(useConstraint) {
1173 for(i=0;i<3;i++) {
1174 sumWiri(i,0) += vVbInvrb(i,0);
1175 for(k=0;k<3;k++) sumWi(i,k) += vVbInv(i,k);
1176 }
1177 // chi2
1178 TMatrixD deltar = rv; deltar -= rb;
1179 TMatrixD vVbInvdeltar(vVbInv,TMatrixD::kMult,deltar);
1180 chi2b = deltar(0,0)*vVbInvdeltar(0,0)+
1181 deltar(1,0)*vVbInvdeltar(1,0)+
1182 deltar(2,0)*vVbInvdeltar(2,0);
1183 chi2 += chi2b;
1184 }
1185
1186 // loop on tracks
1187 for(k=0; k<nTrks; k++) {
1188 // get track from track array
1189 t = (AliESDtrack*)fTrkArray.At(k);
1190 alpha = t->GetAlpha();
1191 xlStart = initPos[0]*TMath::Cos(alpha)+initPos[1]*TMath::Sin(alpha);
1192 // to vtxSeed (from finder)
1193 t->AliExternalTrackParam::PropagateTo(xlStart,GetFieldkG());
1194
1195 // vector of track global coordinates
1196 TMatrixD ri(3,1);
1197 // covariance matrix of ri
1198 TMatrixD wWi(3,3);
1199
1200 // get space point from track
1201 if(!TrackToPoint(t,ri,wWi,uUi3by3)) continue;
1202 TMatrixD wWiri(wWi,TMatrixD::kMult,ri);
1203
1204 // track chi2
1205 TMatrixD deltar = rv; deltar -= ri;
1206 TMatrixD wWideltar(wWi,TMatrixD::kMult,deltar);
1207 chi2i = deltar(0,0)*wWideltar(0,0)+
1208 deltar(1,0)*wWideltar(1,0)+
1209 deltar(2,0)*wWideltar(2,0);
1210
1211 // add to total chi2
1212 chi2 += chi2i;
1213
1214 sumWiri += wWiri;
1215 sumWi += wWi;
1216
1217 nUsedTrks++;
1218 } // end loop on tracks
1219
1220 if(nUsedTrks < fMinTracks) {
1221 failed=1;
1222 continue;
1223 }
1224
1225 Double_t determinant = sumWi.Determinant();
1226 //cerr<<" determinant: "<<determinant<<endl;
1227 if(determinant < 100.) {
1228 printf("det(V) = 0\n");
1229 failed=1;
1230 continue;
1231 }
1232
1233 if(step==0) {
1234 // inverted of weights matrix
1235 TMatrixD invsumWi(TMatrixD::kInverted,sumWi);
1236 vV = invsumWi;
1237 // position of primary vertex
1238 rv.Mult(vV,sumWiri);
1239 }
1240 } // end loop on the 2 steps
1241
1242 if(failed) {
1243 if(fDebug) printf("TooFewTracks\n");
1244 fCurrentVertex = new AliESDVertex(0.,0.,-1);
1245 return;
1246 }
1247
1248 Double_t position[3];
1249 position[0] = rv(0,0);
1250 position[1] = rv(1,0);
1251 position[2] = rv(2,0);
1252 Double_t covmatrix[6];
1253 covmatrix[0] = vV(0,0);
1254 covmatrix[1] = vV(0,1);
1255 covmatrix[2] = vV(1,1);
1256 covmatrix[3] = vV(0,2);
1257 covmatrix[4] = vV(1,2);
1258 covmatrix[5] = vV(2,2);
1259
1260 // for correct chi2/ndf, count constraint as additional "track"
1261 if(fConstraint) nUsedTrks++;
1262 // store data in the vertex object
1263 fCurrentVertex = new AliESDVertex(position,covmatrix,chi2,nUsedTrks);
1264
1265 if(fDebug) {
1266 printf(" Vertex after fit:\n");
1267 fCurrentVertex->PrintStatus();
1268 printf("--- VertexFitter(): finish\n");
1269 }
1270
1271 return;
1272}
1273//----------------------------------------------------------------------------
1274AliESDVertex* AliVertexerTracks::VertexForSelectedTracks(TTree *trkTree,Bool_t optUseFitter,Bool_t optPropagate)
1275{
1276//
1277// Return vertex from tracks in trkTree
1278//
1279
1280 SetConstraintOff();
1281
1282 // get tracks and propagate them to initial vertex position
1283 Int_t nTrksPrep = PrepareTracks(*trkTree,0);
1284 if(nTrksPrep < TMath::Max(2,fMinTracks) ) {
1285 if(fDebug) printf("TooFewTracks\n");
1286 fCurrentVertex = new AliESDVertex(0.,0.,-1);
1287 return fCurrentVertex;
1288 }
1289
1290 switch (fAlgo) {
1291 case 1: StrLinVertexFinderMinDist(1); break;
1292 case 2: StrLinVertexFinderMinDist(0); break;
1293 case 3: HelixVertexFinder(); break;
1294 case 4: VertexFinder(1); break;
1295 case 5: VertexFinder(0); break;
1296 default: printf("Wrong algorithm\n"); break;
1297 }
1298
1299 if(fDebug) printf(" Vertex finding completed\n");
1300
1301 // vertex fitter
1302 if(optUseFitter){
1303 //SetVtxStart(&fVert);
1304 VertexFitter(fConstraint);
1305 if(fDebug) printf(" Vertex fit completed\n");
1306 }else{
1307 Double_t position[3]={fVert.GetXv(),fVert.GetYv(),fVert.GetZv()};
1308 Double_t covmatrix[6];
1309 fVert.GetCovMatrix(covmatrix);
1310 Double_t chi2=99999.;
1311 Int_t nUsedTrks=fVert.GetNContributors();
1312 fCurrentVertex = new AliESDVertex(position,covmatrix,chi2,nUsedTrks);
1313 }
1314 fCurrentVertex->SetDispersion(fVert.GetDispersion());
1315
1316
1317 // set indices of used tracks and propagate track to found vertex
1318 UShort_t *indices = 0;
1319 AliESDtrack *eta = 0;
1320 if(fCurrentVertex->GetNContributors()>0) {
1321 indices = new UShort_t[fCurrentVertex->GetNContributors()];
1322 for(Int_t jj=0;jj<(Int_t)fTrkArray.GetEntriesFast();jj++) {
1323 eta = (AliESDtrack*)fTrkArray.At(jj);
1324 indices[jj] = (UShort_t)eta->GetID();
1325 if(optPropagate&&optUseFitter){
1326 if(TMath::Sqrt(fCurrentVertex->GetXv()*fCurrentVertex->GetXv()+fCurrentVertex->GetYv()*fCurrentVertex->GetYv())<3.) {
1327 eta->RelateToVertex(fCurrentVertex,GetFieldkG(),100.);
1328 if(fDebug) printf("Track %d propagated to found vertex\n",jj);
1329 }else{
1330 AliWarning("Found vertex outside beam pipe!");
1331 }
1332 }
1333 }
1334 fCurrentVertex->SetIndices(fCurrentVertex->GetNContributors(),indices);
1335 }
1336 delete [] indices;
1337 fTrkArray.Delete();
1338
1339 return fCurrentVertex;
1340}
1341//----------------------------------------------------------------------------
1342AliESDVertex* AliVertexerTracks::VertexForSelectedTracks(TObjArray *trkArray,Bool_t optUseFitter, Bool_t optPropagate)
1343{
1344//
1345// Return vertex from array of tracks
1346//
1347
1348 // get tracks and propagate them to initial vertex position
1349 Int_t nTrks = trkArray->GetEntriesFast();
1350 if(nTrks < TMath::Max(2,fMinTracks) ) {
1351 if(fDebug) printf("TooFewTracks\n");
1352 fCurrentVertex = new AliESDVertex(0.,0.,-1);
1353 return fCurrentVertex;
1354 }
1355 TDirectory * olddir = gDirectory;
1356 TFile f("VertexerTracks.root","recreate");
1357 TTree *trkTree = new TTree("TreeT","tracks");
1358 AliESDtrack *esdTrack = 0;
1359 trkTree->Branch("tracks","AliESDtrack",&esdTrack);
1360 for(Int_t i=0; i<nTrks; i++){
1361 esdTrack = (AliESDtrack*)trkArray->At(i);
1362 trkTree->Fill();
1363 }
1364
1365 AliESDVertex *vtx = VertexForSelectedTracks(trkTree,optUseFitter,optPropagate);
1366 delete trkTree;
1367 f.Close();
1368 gSystem->Unlink("VertexerTracks.root");
1369 olddir->cd();
1370 return vtx;
1371}
1372//--------------------------------------------------------------------------