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ALICE interface to Pythia8
[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//-----------------------------------------------------------------
6d8df534 17// Implementation of the vertexer from tracks
2d57349e 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:
6d8df534 25// F.Prino, Torino, prino@to.infn.it
2d57349e 26//-----------------------------------------------------------------
27
28//---- Root headers --------
a7ede274 29#include <TSystem.h>
30#include <TDirectory.h>
31#include <TFile.h>
2d57349e 32#include <TTree.h>
ec1be5d5 33#include <TMatrixD.h>
2d57349e 34//---- AliRoot headers -----
35#include "AliStrLine.h"
6d8df534 36#include "AliExternalTrackParam.h"
af885e0f 37#include "AliESDEvent.h"
2d57349e 38#include "AliESDtrack.h"
6d8df534 39#include "AliVertexerTracks.h"
2d57349e 40
41ClassImp(AliVertexerTracks)
42
43
44//----------------------------------------------------------------------------
45AliVertexerTracks::AliVertexerTracks():
07680cae 46TObject(),
47fVert(),
48fCurrentVertex(0),
dc3719f3 49fFieldkG(-999.),
fee9ef0d 50fConstraint(kFALSE),
51fOnlyFitter(kFALSE),
0c69be49 52fMinTracks(1),
fe12e09c 53fMinITSClusters(5),
6d8df534 54fTrkArraySel(),
55fIdSel(0),
07680cae 56fTrksToSkip(0),
57fNTrksToSkip(0),
58fDCAcut(0),
59fAlgo(1),
fe12e09c 60fNSigma(3),
fee9ef0d 61fMaxd0z0(0.5),
50ff0bcd 62fITSrefit(kTRUE),
3b768a1d 63fnSigmaForUi00(1.5),
07680cae 64fDebug(0)
2d57349e 65{
66//
67// Default constructor
68//
3b768a1d 69 SetVtxStart();
07680cae 70 SetVtxStartSigma();
2d57349e 71 SetMinTracks();
07680cae 72 SetMinITSClusters();
73 SetNSigmad0();
fee9ef0d 74 SetMaxd0z0();
2d57349e 75}
dc3719f3 76//----------------------------------------------------------------------------
77AliVertexerTracks::AliVertexerTracks(Double_t fieldkG):
07680cae 78TObject(),
79fVert(),
80fCurrentVertex(0),
dc3719f3 81fFieldkG(-999.),
fee9ef0d 82fConstraint(kFALSE),
83fOnlyFitter(kFALSE),
0c69be49 84fMinTracks(1),
fe12e09c 85fMinITSClusters(5),
6d8df534 86fTrkArraySel(),
87fIdSel(0),
07680cae 88fTrksToSkip(0),
89fNTrksToSkip(0),
90fDCAcut(0),
91fAlgo(1),
fe12e09c 92fNSigma(3),
fee9ef0d 93fMaxd0z0(0.5),
50ff0bcd 94fITSrefit(kTRUE),
3b768a1d 95fnSigmaForUi00(1.5),
07680cae 96fDebug(0)
2d57349e 97{
98//
99// Standard constructor
100//
3b768a1d 101 SetVtxStart();
07680cae 102 SetVtxStartSigma();
2d57349e 103 SetMinTracks();
07680cae 104 SetMinITSClusters();
105 SetNSigmad0();
dc3719f3 106 SetMaxd0z0();
107 SetFieldkG(fieldkG);
2d57349e 108}
109//-----------------------------------------------------------------------------
fee9ef0d 110AliVertexerTracks::~AliVertexerTracks()
111{
2d57349e 112 // Default Destructor
eae1677e 113 // The objects pointed by the following pointer are not owned
2d57349e 114 // by this class and are not deleted
ec1be5d5 115 fCurrentVertex = 0;
146c29df 116 if(fTrksToSkip) { delete [] fTrksToSkip; fTrksToSkip=NULL; }
6d8df534 117 if(fIdSel) { delete [] fIdSel; fIdSel=NULL; }
ec1be5d5 118}
c5e3e5d1 119//----------------------------------------------------------------------------
af885e0f 120AliESDVertex* AliVertexerTracks::FindPrimaryVertex(const AliESDEvent *esdEvent)
ec1be5d5 121{
c5e3e5d1 122//
ec1be5d5 123// Primary vertex for current ESD event
eae1677e 124// (Two iterations:
fee9ef0d 125// 1st with 5*fNSigma*sigma cut w.r.t. to initial vertex
126// + cut on sqrt(d0d0+z0z0) if fConstraint=kFALSE
127// 2nd with fNSigma*sigma cut w.r.t. to vertex found in 1st iteration)
07680cae 128//
129 fCurrentVertex = 0;
130
dc3719f3 131 // accept 1-track case only if constraint is available
132 if(!fConstraint && fMinTracks==1) fMinTracks=2;
133
fee9ef0d 134 // read tracks from ESD
6d8df534 135 Int_t nTrks = (Int_t)esdEvent->GetNumberOfTracks();
136 if(nTrks<1) {
137 TooFewTracks();
80d36431 138 return fCurrentVertex;
139 }
6d8df534 140 //
713e5fbf 141
a7ede274 142 TDirectory * olddir = gDirectory;
143 TFile f("VertexerTracks.root","recreate");
6d8df534 144 TObjArray trkArrayOrig(nTrks);
145 UShort_t *idOrig = new UShort_t[nTrks];
07680cae 146
6d8df534 147 Int_t nTrksOrig=0;
148 for(Int_t i=0; i<nTrks; i++) {
149 AliESDtrack *esdt = esdEvent->GetTrack(i);
eae1677e 150 // check tracks to skip
6d8df534 151 Bool_t skipThis = kFALSE;
eae1677e 152 for(Int_t j=0; j<fNTrksToSkip; j++) {
6d8df534 153 if(esdt->GetID()==fTrksToSkip[j]) {
eae1677e 154 if(fDebug) printf("skipping track: %d\n",i);
155 skipThis = kTRUE;
156 }
157 }
a7ede274 158 if(skipThis) continue;
6d8df534 159 if(fITSrefit) {
160 if(!(esdt->GetStatus()&AliESDtrack::kITSrefit)) continue;
161 // check number of clusters in ITS
162 if(esdt->GetNcls(0)<fMinITSClusters) continue;
50ff0bcd 163 }
6d8df534 164 Double_t x,p[5],cov[15];
165 esdt->GetExternalParameters(x,p);
166 esdt->GetExternalCovariance(cov);
167 AliExternalTrackParam *t = new AliExternalTrackParam(x,esdt->GetAlpha(),p,cov);
168 trkArrayOrig.AddLast(t);
169 idOrig[nTrksOrig]=(UShort_t)esdt->GetID();
170 nTrksOrig++;
07680cae 171 }
fee9ef0d 172
6d8df534 173 FindPrimaryVertex(&trkArrayOrig,idOrig);
174
175 trkArrayOrig.Delete();
176 delete [] idOrig; idOrig=NULL;
177 f.Close();
178 gSystem->Unlink("VertexerTracks.root");
179 olddir->cd();
180
181 return fCurrentVertex;
182}
183//----------------------------------------------------------------------------
184AliESDVertex* AliVertexerTracks::FindPrimaryVertex(TObjArray *trkArrayOrig,
185 UShort_t *idOrig)
186{
187//
188// Primary vertex using the AliExternalTrackParam's in the TObjArray.
189// idOrig must contain the track IDs from AliESDtrack::GetID()
190// (Two iterations:
191// 1st with 5*fNSigma*sigma cut w.r.t. to initial vertex
192// + cut on sqrt(d0d0+z0z0) if fConstraint=kFALSE
193// 2nd with fNSigma*sigma cut w.r.t. to vertex found in 1st iteration)
194//
195 fCurrentVertex = 0;
196
197 // accept 1-track case only if constraint is available
198 if(!fConstraint && fMinTracks==1) fMinTracks=2;
199
200 // read tracks from ESD
201 Int_t nTrksOrig = (Int_t)trkArrayOrig->GetEntriesFast();
43c9dae1 202 if(fDebug) printf("Initial number of tracks: %d\n",nTrksOrig);
6d8df534 203 if(nTrksOrig<=0) {
204 if(fDebug) printf("TooFewTracks\n");
205 TooFewTracks();
206 return fCurrentVertex;
207 }
208
fee9ef0d 209 // If fConstraint=kFALSE
210 // run VertexFinder(1) to get rough estimate of initVertex (x,y)
211 if(!fConstraint) {
6d8df534 212 // fill fTrkArraySel, for VertexFinder()
213 fIdSel = new UShort_t[nTrksOrig];
214 PrepareTracks(*trkArrayOrig,idOrig,0);
215 if(fIdSel) { delete [] fIdSel; fIdSel=NULL; }
216 Double_t cutsave = fDCAcut;
217 fDCAcut = (fITSrefit ? 0.1 : 0.5);
fee9ef0d 218 VertexFinder(1); // using weights, cutting dca < fDCAcut
219 fDCAcut = cutsave;
fee9ef0d 220 if(fVert.GetNContributors()>0) {
221 fVert.GetXYZ(fNominalPos);
222 fNominalPos[0] = fVert.GetXv();
223 fNominalPos[1] = fVert.GetYv();
224 fNominalPos[2] = fVert.GetZv();
225 if(fDebug) printf("No mean vertex: VertexFinder gives (%f, %f, %f)\n",fNominalPos[0],fNominalPos[1],fNominalPos[2]);
226 } else {
227 fNominalPos[0] = 0.;
228 fNominalPos[1] = 0.;
229 fNominalPos[2] = 0.;
230 if(fDebug) printf("No mean vertex and VertexFinder failed\n");
0c69be49 231 }
07680cae 232 }
fee9ef0d 233
234 // TWO ITERATIONS:
235 //
236 // ITERATION 1
237 // propagate tracks to fNominalPos vertex
238 // preselect them:
239 // if(constraint) reject for |d0|>5*fNSigma*sigma w.r.t. fNominal... vertex
240 // else reject for |d0|\oplus|z0| > 5 mm w.r.t. fNominal... vertex
07680cae 241 // ITERATION 2
242 // propagate tracks to best between initVertex and fCurrentVertex
243 // preselect tracks (reject for |d0|>fNSigma*sigma w.r.t. best
244 // between initVertex and fCurrentVertex)
6d8df534 245 for(Int_t iter=1; iter<=2; iter++) {
246 if(fOnlyFitter && iter==1) continue;
247 if(fIdSel) { delete [] fIdSel; fIdSel=NULL; }
248 fIdSel = new UShort_t[nTrksOrig];
249 Int_t nTrksSel = PrepareTracks(*trkArrayOrig,idOrig,iter);
250 if(fDebug) printf("N tracks selected in iteration %d: %d\n",iter,nTrksSel);
251 if(nTrksSel < fMinTracks) {
252 TooFewTracks();
fee9ef0d 253 return fCurrentVertex;
254 }
07680cae 255
fee9ef0d 256 // vertex finder
257 if(!fOnlyFitter) {
6d8df534 258 if(nTrksSel==1) {
fee9ef0d 259 if(fDebug) printf("Just one track\n");
260 OneTrackVertFinder();
6d8df534 261 } else {
fee9ef0d 262 switch (fAlgo) {
263 case 1: StrLinVertexFinderMinDist(1); break;
264 case 2: StrLinVertexFinderMinDist(0); break;
265 case 3: HelixVertexFinder(); break;
266 case 4: VertexFinder(1); break;
267 case 5: VertexFinder(0); break;
268 default: printf("Wrong algorithm\n"); break;
269 }
270 }
271 if(fDebug) printf(" Vertex finding completed\n");
0c69be49 272 }
07680cae 273
fee9ef0d 274 // vertex fitter
6d8df534 275 VertexFitter();
fee9ef0d 276 } // end loop on the two iterations
07680cae 277
fee9ef0d 278
50ff0bcd 279 // set indices of used tracks
280 UShort_t *indices = 0;
50ff0bcd 281 if(fCurrentVertex->GetNContributors()>0) {
282 indices = new UShort_t[fCurrentVertex->GetNContributors()];
6d8df534 283 for(Int_t jj=0; jj<(Int_t)fTrkArraySel.GetEntriesFast(); jj++)
284 indices[jj] = fIdSel[jj];
50ff0bcd 285 fCurrentVertex->SetIndices(fCurrentVertex->GetNContributors(),indices);
286 }
6d8df534 287 delete [] indices; indices=NULL;
288 //
fee9ef0d 289
6d8df534 290 // set vertex title
291 TString title="VertexerTracksNoConstraint";
292 if(fConstraint) {
293 title="VertexerTracksWithConstraint";
294 if(fOnlyFitter) title.Append("OnlyFitter");
295 }
296 fCurrentVertex->SetTitle(title.Data());
297 //
a7ede274 298
6d8df534 299 if(fDebug) {
300 fCurrentVertex->PrintStatus();
301 fCurrentVertex->PrintIndices();
302 }
50ff0bcd 303
6d8df534 304 // clean up
305 delete [] fIdSel; fIdSel=NULL;
306 fTrkArraySel.Delete();
146c29df 307 if(fTrksToSkip) { delete [] fTrksToSkip; fTrksToSkip=NULL; }
6d8df534 308 //
fee9ef0d 309
07680cae 310 return fCurrentVertex;
311}
50ff0bcd 312//------------------------------------------------------------------------
fee9ef0d 313Double_t AliVertexerTracks::GetDeterminant3X3(Double_t matr[][3])
314{
50ff0bcd 315 //
316 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];
317 return det;
318}
319//-------------------------------------------------------------------------
fee9ef0d 320void AliVertexerTracks::GetStrLinDerivMatrix(Double_t *p0,Double_t *p1,Double_t (*m)[3],Double_t *d)
321{
50ff0bcd 322 //
323 Double_t x12=p0[0]-p1[0];
324 Double_t y12=p0[1]-p1[1];
325 Double_t z12=p0[2]-p1[2];
326 Double_t kk=x12*x12+y12*y12+z12*z12;
327 m[0][0]=2-2/kk*x12*x12;
328 m[0][1]=-2/kk*x12*y12;
329 m[0][2]=-2/kk*x12*z12;
330 m[1][0]=-2/kk*x12*y12;
331 m[1][1]=2-2/kk*y12*y12;
332 m[1][2]=-2/kk*y12*z12;
333 m[2][0]=-2/kk*x12*z12;
334 m[2][1]=-2*y12*z12;
335 m[2][2]=2-2/kk*z12*z12;
336 d[0]=2*p0[0]-2/kk*p0[0]*x12*x12-2/kk*p0[2]*x12*z12-2/kk*p0[1]*x12*y12;
337 d[1]=2*p0[1]-2/kk*p0[1]*y12*y12-2/kk*p0[0]*x12*y12-2/kk*p0[2]*z12*y12;
338 d[2]=2*p0[2]-2/kk*p0[2]*z12*z12-2/kk*p0[0]*x12*z12-2/kk*p0[1]*z12*y12;
c5e3e5d1 339
50ff0bcd 340}
341//--------------------------------------------------------------------------
fee9ef0d 342void AliVertexerTracks::GetStrLinDerivMatrix(Double_t *p0,Double_t *p1,Double_t *sigmasq,Double_t (*m)[3],Double_t *d)
343{
50ff0bcd 344 //
345 Double_t x12=p1[0]-p0[0];
346 Double_t y12=p1[1]-p0[1];
347 Double_t z12=p1[2]-p0[2];
c5e3e5d1 348
50ff0bcd 349 Double_t den= x12*x12*sigmasq[1]*sigmasq[2]+y12*y12*sigmasq[0]*sigmasq[2]+z12*z12*sigmasq[0]*sigmasq[1];
c5e3e5d1 350
50ff0bcd 351 Double_t kk= 2*(x12*x12/sigmasq[0]+y12*y12/sigmasq[1]+z12*z12/sigmasq[2]);
c5e3e5d1 352
50ff0bcd 353 Double_t cc[3];
354 cc[0]=-x12/sigmasq[0];
355 cc[1]=-y12/sigmasq[1];
356 cc[2]=-z12/sigmasq[2];
ec1be5d5 357
50ff0bcd 358 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;
ec1be5d5 359
50ff0bcd 360 Double_t ss= -p0[0]*cc[0]-p0[1]*cc[1]-p0[2]*cc[2];
2d57349e 361
50ff0bcd 362 Double_t aa[3];
363 aa[0]=x12*sigmasq[1]*sigmasq[2]/den;
364 aa[1]=y12*sigmasq[0]*sigmasq[2]/den;
365 aa[2]=z12*sigmasq[0]*sigmasq[1]/den;
2d57349e 366
50ff0bcd 367 m[0][0]=aa[0]*(aa[0]*kk+2*cc[0])+2*cc[0]*aa[0]+2/sigmasq[0];
368 m[0][1]=aa[1]*(aa[0]*kk+2*cc[0])+2*cc[1]*aa[0];
369 m[0][2]=aa[2]*(aa[0]*kk+2*cc[0])+2*cc[2]*aa[0];
2d57349e 370
50ff0bcd 371 m[1][0]=aa[0]*(aa[1]*kk+2*cc[1])+2*cc[0]*aa[1];
372 m[1][1]=aa[1]*(aa[1]*kk+2*cc[1])+2*cc[1]*aa[1]+2/sigmasq[1];
373 m[1][2]=aa[2]*(aa[1]*kk+2*cc[1])+2*cc[2]*aa[1];
2d57349e 374
50ff0bcd 375 m[2][0]=aa[0]*(aa[2]*kk+2*cc[2])+2*cc[0]*aa[2];
376 m[2][1]=aa[1]*(aa[2]*kk+2*cc[2])+2*cc[1]*aa[2];
377 m[2][2]=aa[2]*(aa[2]*kk+2*cc[2])+2*cc[2]*aa[2]+2/sigmasq[2];
08df6187 378
50ff0bcd 379 d[0]=-ww*(aa[0]*kk+2*cc[0])-2*ss*aa[0]+2*p0[0]/sigmasq[0];
380 d[1]=-ww*(aa[1]*kk+2*cc[1])-2*ss*aa[1]+2*p0[1]/sigmasq[1];
381 d[2]=-ww*(aa[2]*kk+2*cc[2])-2*ss*aa[2]+2*p0[2]/sigmasq[2];
2d57349e 382
2d57349e 383 }
50ff0bcd 384//--------------------------------------------------------------------------
fee9ef0d 385Double_t AliVertexerTracks::GetStrLinMinDist(Double_t *p0,Double_t *p1,Double_t *x0)
386{
50ff0bcd 387 //
388 Double_t x12=p0[0]-p1[0];
389 Double_t y12=p0[1]-p1[1];
390 Double_t z12=p0[2]-p1[2];
391 Double_t x10=p0[0]-x0[0];
392 Double_t y10=p0[1]-x0[1];
393 Double_t z10=p0[2]-x0[2];
394 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);
2d57349e 395}
396//---------------------------------------------------------------------------
fee9ef0d 397void AliVertexerTracks::OneTrackVertFinder()
398{
0c69be49 399 // find vertex for events with 1 track, using DCA to nominal beam axis
6d8df534 400 if(fDebug) printf("Number of prepared tracks =%d - Call OneTrackVertFinder",fTrkArraySel.GetEntries());
401 AliExternalTrackParam *track1;
402 track1 = (AliExternalTrackParam*)fTrkArraySel.At(0);
dc3719f3 403 Double_t field=GetFieldkG();
0c69be49 404 Double_t alpha=track1->GetAlpha();
405 Double_t mindist = TMath::Cos(alpha)*fNominalPos[0]+TMath::Sin(alpha)*fNominalPos[1];
406 Double_t pos[3],dir[3];
407 track1->GetXYZAt(mindist,field,pos);
408 track1->GetPxPyPzAt(mindist,field,dir);
409 AliStrLine *line1 = new AliStrLine(pos,dir);
410 Double_t p1[3]={fNominalPos[0],fNominalPos[1],0.};
411 Double_t p2[3]={fNominalPos[0],fNominalPos[1],10.};
412 AliStrLine *zeta=new AliStrLine(p1,p2,kTRUE);
413 Double_t crosspoint[3]={0.,0.,0.};
414 Double_t sigma=999.;
415 Int_t nContrib=-1;
416 Int_t retcode = zeta->Cross(line1,crosspoint);
417 if(retcode>=0){
418 sigma=line1->GetDistFromPoint(crosspoint);
419 nContrib=1;
420 }
421 delete zeta;
422 delete line1;
423 fVert.SetXYZ(crosspoint);
424 fVert.SetDispersion(sigma);
425 fVert.SetNContributors(nContrib);
426}
427//---------------------------------------------------------------------------
fee9ef0d 428void AliVertexerTracks::HelixVertexFinder()
429{
2d57349e 430 // Get estimate of vertex position in (x,y) from tracks DCA
431
432
433 Double_t initPos[3];
434 initPos[2] = 0.;
435 for(Int_t i=0;i<2;i++)initPos[i]=fNominalPos[i];
dc3719f3 436 Double_t field=GetFieldkG();
2d57349e 437
6d8df534 438 Int_t nacc = (Int_t)fTrkArraySel.GetEntriesFast();
2d57349e 439
440 Double_t aver[3]={0.,0.,0.};
441 Double_t averquad[3]={0.,0.,0.};
442 Double_t sigmaquad[3]={0.,0.,0.};
443 Double_t sigma=0;
444 Int_t ncombi = 0;
6d8df534 445 AliExternalTrackParam *track1;
446 AliExternalTrackParam *track2;
2d57349e 447 Double_t distCA;
6d8df534 448 Double_t x;
2d57349e 449 Double_t alpha, cs, sn;
450 Double_t crosspoint[3];
451 for(Int_t i=0; i<nacc; i++){
6d8df534 452 track1 = (AliExternalTrackParam*)fTrkArraySel.At(i);
2d57349e 453
454
455 for(Int_t j=i+1; j<nacc; j++){
6d8df534 456 track2 = (AliExternalTrackParam*)fTrkArraySel.At(j);
2d57349e 457
458 distCA=track2->PropagateToDCA(track1,field);
2d57349e 459 if(fDCAcut<=0 ||(fDCAcut>0&&distCA<fDCAcut)){
6d8df534 460 x=track1->GetX();
2d57349e 461 alpha=track1->GetAlpha();
462 cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
6d8df534 463 Double_t x1=x*cs - track1->GetY()*sn;
464 Double_t y1=x*sn + track1->GetY()*cs;
465 Double_t z1=track1->GetZ();
466
2d57349e 467 Double_t sx1=sn*sn*track1->GetSigmaY2(), sy1=cs*cs*track1->GetSigmaY2();
6d8df534 468 x=track2->GetX();
2d57349e 469 alpha=track2->GetAlpha();
470 cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
6d8df534 471 Double_t x2=x*cs - track2->GetY()*sn;
472 Double_t y2=x*sn + track2->GetY()*cs;
473 Double_t z2=track2->GetZ();
2d57349e 474 Double_t sx2=sn*sn*track2->GetSigmaY2(), sy2=cs*cs*track2->GetSigmaY2();
475 Double_t sz1=track1->GetSigmaZ2(), sz2=track2->GetSigmaZ2();
476 Double_t wx1=sx2/(sx1+sx2), wx2=1.- wx1;
477 Double_t wy1=sy2/(sy1+sy2), wy2=1.- wy1;
478 Double_t wz1=sz2/(sz1+sz2), wz2=1.- wz1;
479 crosspoint[0]=wx1*x1 + wx2*x2;
480 crosspoint[1]=wy1*y1 + wy2*y2;
481 crosspoint[2]=wz1*z1 + wz2*z2;
482
483 ncombi++;
484 for(Int_t jj=0;jj<3;jj++)aver[jj]+=crosspoint[jj];
485 for(Int_t jj=0;jj<3;jj++)averquad[jj]+=(crosspoint[jj]*crosspoint[jj]);
486 }
487 }
488
489 }
490 if(ncombi>0){
491 for(Int_t jj=0;jj<3;jj++){
492 initPos[jj] = aver[jj]/ncombi;
493 averquad[jj]/=ncombi;
494 sigmaquad[jj]=averquad[jj]-initPos[jj]*initPos[jj];
495 sigma+=sigmaquad[jj];
496 }
497 sigma=TMath::Sqrt(TMath::Abs(sigma));
498 }
499 else {
500 Warning("HelixVertexFinder","Finder did not succed");
501 sigma=999;
502 }
503 fVert.SetXYZ(initPos);
504 fVert.SetDispersion(sigma);
505 fVert.SetNContributors(ncombi);
506}
50ff0bcd 507//----------------------------------------------------------------------------
6d8df534 508Int_t AliVertexerTracks::PrepareTracks(TObjArray &trkArrayOrig,
509 UShort_t *idOrig,
510 Int_t optImpParCut)
fee9ef0d 511{
50ff0bcd 512//
513// Propagate tracks to initial vertex position and store them in a TObjArray
514//
6d8df534 515 if(fDebug) printf(" PrepareTracks()\n");
516
517 Int_t nTrksOrig = (Int_t)trkArrayOrig.GetEntriesFast();
518 Int_t nTrksSel = 0;
fee9ef0d 519 Double_t maxd0rphi;
43c9dae1 520 Double_t maxd0z0 = (fITSrefit ? fMaxd0z0 : 10.*fMaxd0z0);
50ff0bcd 521 Double_t sigmaCurr[3];
fee9ef0d 522 Double_t normdistx,normdisty;
6d8df534 523 Double_t d0z0[2],covd0z0[3];
43c9dae1 524 Double_t sigmad0;
6d8df534 525 Double_t field = GetFieldkG();
50ff0bcd 526
527 AliESDVertex *initVertex = new AliESDVertex(fNominalPos,fNominalCov,1,1);
528
6d8df534 529 if(!fTrkArraySel.IsEmpty()) fTrkArraySel.Delete();
50ff0bcd 530
6d8df534 531 AliExternalTrackParam *track=0;
50ff0bcd 532
6d8df534 533 for(Int_t i=0; i<nTrksOrig; i++) {
534 track = new AliExternalTrackParam(*(AliExternalTrackParam*)trkArrayOrig.At(i));
535 // only TPC tracks in |eta|<0.9
536 if(!fITSrefit && TMath::Abs(track->GetTgl())>1.) {
43c9dae1 537 if(fDebug) printf(" rejecting track with tgl = %f\n",track->GetTgl());
6d8df534 538 delete track;
539 continue;
540 }
50ff0bcd 541
542 // propagate track to vertex
43c9dae1 543 if(optImpParCut<2 || fOnlyFitter) { // optImpParCut==1 or 0
6d8df534 544 track->PropagateToDCA(initVertex,field,100.,d0z0,covd0z0);
fee9ef0d 545 } else { // optImpParCut==2
50ff0bcd 546 fCurrentVertex->GetSigmaXYZ(sigmaCurr);
fee9ef0d 547 normdistx = TMath::Abs(fCurrentVertex->GetXv()-fNominalPos[0])/TMath::Sqrt(sigmaCurr[0]*sigmaCurr[0]+fNominalCov[0]);
80d36431 548 normdisty = TMath::Abs(fCurrentVertex->GetYv()-fNominalPos[1])/TMath::Sqrt(sigmaCurr[1]*sigmaCurr[1]+fNominalCov[2]);
fee9ef0d 549 if(normdistx < 3. && normdisty < 3. &&
80d36431 550 (sigmaCurr[0]+sigmaCurr[1])<(TMath::Sqrt(fNominalCov[0])+TMath::Sqrt(fNominalCov[2]))) {
6d8df534 551 track->PropagateToDCA(fCurrentVertex,field,100.,d0z0,covd0z0);
50ff0bcd 552 } else {
6d8df534 553 track->PropagateToDCA(initVertex,field,100.,d0z0,covd0z0);
50ff0bcd 554 }
555 }
556
43c9dae1 557 sigmad0 = TMath::Sqrt(covd0z0[0]);
558 maxd0rphi = fNSigma*sigmad0;
fee9ef0d 559 if(optImpParCut==1) maxd0rphi *= 5.;
43c9dae1 560 //sigmad0z0 = TMath::Sqrt(covd0z0[0]+covd0z0[2]); // for future improvement
561 //maxd0z0 = 10.*fNSigma*sigmad0z0;
fee9ef0d 562
6d8df534 563 if(fDebug) printf("trk %d; id %d; |d0| = %f; d0 cut = %f; |z0| = %f; |d0|oplus|z0| = %f; d0z0 cut = %f\n",i,(Int_t)idOrig[i],TMath::Abs(d0z0[0]),maxd0rphi,TMath::Abs(d0z0[1]),TMath::Sqrt(d0z0[0]*d0z0[0]+d0z0[1]*d0z0[1]),maxd0z0);
fee9ef0d 564
43c9dae1 565 // if fConstraint=kFALSE, during iterations 1 and 2 ||
566 // if fConstraint=kTRUE, during iteration 2,
fee9ef0d 567 // select tracks with d0oplusz0 < maxd0z0
43c9dae1 568 if((!fConstraint && optImpParCut>0 && fVert.GetNContributors()>0) ||
569 ( fConstraint && optImpParCut==2)) {
570 if(nTrksOrig>=3 &&
571 TMath::Sqrt(d0z0[0]*d0z0[0]+d0z0[1]*d0z0[1])>maxd0z0) {
fee9ef0d 572 if(fDebug) printf(" rejected\n");
573 delete track; continue;
574 }
575 }
43c9dae1 576
fee9ef0d 577
578 // select tracks with d0rphi < maxd0rphi
6d8df534 579 if(optImpParCut>0 && TMath::Abs(d0z0[0])>maxd0rphi) {
50ff0bcd 580 if(fDebug) printf(" rejected\n");
581 delete track; continue;
582 }
583
6d8df534 584 fTrkArraySel.AddLast(track);
585 fIdSel[nTrksSel] = idOrig[i];
586 nTrksSel++;
50ff0bcd 587 }
588
589 delete initVertex;
590
6d8df534 591 return nTrksSel;
50ff0bcd 592}
593//---------------------------------------------------------------------------
fee9ef0d 594AliESDVertex* AliVertexerTracks::RemoveTracksFromVertex(AliESDVertex *inVtx,
6d8df534 595 TObjArray *trkArray,
596 UShort_t *id,
fee9ef0d 597 Float_t *diamondxy)
598{
50ff0bcd 599//
fee9ef0d 600// Removes tracks in trksTree from fit of inVtx
50ff0bcd 601//
fee9ef0d 602
146c29df 603 if(!strstr(inVtx->GetTitle(),"VertexerTracksWithConstraint")) {
604 printf("ERROR: primary vertex has no constraint: cannot remove tracks\n");
605 return 0x0;
606 }
fee9ef0d 607 if(!strstr(inVtx->GetTitle(),"VertexerTracksWithConstraintOnlyFitter"))
608 printf("WARNING: result of tracks' removal will be only approximately correct\n");
609
610 TMatrixD rv(3,1);
611 rv(0,0) = inVtx->GetXv();
612 rv(1,0) = inVtx->GetYv();
613 rv(2,0) = inVtx->GetZv();
614 TMatrixD vV(3,3);
615 Double_t cov[6];
616 inVtx->GetCovMatrix(cov);
617 vV(0,0) = cov[0];
618 vV(0,1) = cov[1]; vV(1,0) = cov[1];
619 vV(1,1) = cov[2];
620 vV(0,2) = cov[3]; vV(2,0) = cov[3];
621 vV(1,2) = cov[4]; vV(2,1) = cov[4];
622 vV(2,2) = cov[5];
623
624 TMatrixD sumWi(TMatrixD::kInverted,vV);
625 TMatrixD sumWiri(sumWi,TMatrixD::kMult,rv);
626
627 Int_t nUsedTrks = inVtx->GetNContributors();
628 Double_t chi2 = inVtx->GetChi2();
629
6d8df534 630 AliExternalTrackParam *track = 0;
631 Int_t ntrks = (Int_t)trkArray->GetEntriesFast();
fee9ef0d 632 for(Int_t i=0;i<ntrks;i++) {
6d8df534 633 track = (AliExternalTrackParam*)trkArray->At(i);
634 if(!inVtx->UsesTrack(id[i])) {
635 printf("track %d was not used in vertex fit\n",id[i]);
fee9ef0d 636 continue;
637 }
638 Double_t alpha = track->GetAlpha();
639 Double_t xl = diamondxy[0]*TMath::Cos(alpha)+diamondxy[1]*TMath::Sin(alpha);
6d8df534 640 track->PropagateTo(xl,GetFieldkG());
fee9ef0d 641 // vector of track global coordinates
642 TMatrixD ri(3,1);
643 // covariance matrix of ri
644 TMatrixD wWi(3,3);
645
646 // get space point from track
647 if(!TrackToPoint(track,ri,wWi)) continue;
648
649 TMatrixD wWiri(wWi,TMatrixD::kMult,ri);
650
651 sumWi -= wWi;
652 sumWiri -= wWiri;
653
654 // track chi2
655 TMatrixD deltar = rv; deltar -= ri;
656 TMatrixD wWideltar(wWi,TMatrixD::kMult,deltar);
657 Double_t chi2i = deltar(0,0)*wWideltar(0,0)+
658 deltar(1,0)*wWideltar(1,0)+
659 deltar(2,0)*wWideltar(2,0);
660 // remove from total chi2
661 chi2 -= chi2i;
662
663 nUsedTrks--;
664 if(nUsedTrks<2) {
665 printf("Trying to remove too many tracks!\n");
666 return 0x0;
667 }
668 }
669
670 TMatrixD rvnew(3,1);
671 TMatrixD vVnew(3,3);
672
673 // new inverted of weights matrix
674 TMatrixD invsumWi(TMatrixD::kInverted,sumWi);
675 vVnew = invsumWi;
676 // new position of primary vertex
677 rvnew.Mult(vVnew,sumWiri);
678
679 Double_t position[3];
680 position[0] = rvnew(0,0);
681 position[1] = rvnew(1,0);
682 position[2] = rvnew(2,0);
683 cov[0] = vVnew(0,0);
684 cov[1] = vVnew(0,1);
685 cov[2] = vVnew(1,1);
686 cov[3] = vVnew(0,2);
687 cov[4] = vVnew(1,2);
688 cov[5] = vVnew(2,2);
689
690 // store data in the vertex object
691 AliESDVertex *outVtx = new AliESDVertex(position,cov,chi2,nUsedTrks);
692 outVtx->SetTitle(inVtx->GetTitle());
fee9ef0d 693 UShort_t *inindices = inVtx->GetIndices();
694 UShort_t *outindices = new UShort_t[outVtx->GetNContributors()];
695 Int_t j=0;
fee9ef0d 696 for(Int_t k=0; k<inVtx->GetNIndices(); k++) {
6d8df534 697 Bool_t copyindex=kTRUE;
fee9ef0d 698 for(Int_t l=0; l<ntrks; l++) {
6d8df534 699 if(inindices[k]==id[l]) copyindex=kFALSE;
fee9ef0d 700 }
701 if(copyindex) {
702 outindices[j] = inindices[k]; j++;
703 }
704 }
705 outVtx->SetIndices(outVtx->GetNContributors(),outindices);
706 delete [] outindices;
707
708 if(fDebug) {
709 printf("Vertex before removing tracks:\n");
710 inVtx->PrintStatus();
711 inVtx->PrintIndices();
712 printf("Vertex after removing tracks:\n");
713 outVtx->PrintStatus();
714 outVtx->PrintIndices();
715 }
716
717 return outVtx;
718}
719//---------------------------------------------------------------------------
720void AliVertexerTracks::SetSkipTracks(Int_t n,Int_t *skipped)
721{
722//
723// Mark the tracks not to be used in the vertex reconstruction.
724// Tracks are identified by AliESDtrack::GetID()
725//
726 fNTrksToSkip = n; fTrksToSkip = new Int_t[n];
50ff0bcd 727 for(Int_t i=0;i<n;i++) fTrksToSkip[i] = skipped[i];
728 return;
729}
730//---------------------------------------------------------------------------
fee9ef0d 731void AliVertexerTracks::SetVtxStart(AliESDVertex *vtx)
732{
50ff0bcd 733//
734// Set initial vertex knowledge
735//
736 vtx->GetXYZ(fNominalPos);
737 vtx->GetCovMatrix(fNominalCov);
fee9ef0d 738 SetConstraintOn();
50ff0bcd 739 return;
740}
2d57349e 741//---------------------------------------------------------------------------
fee9ef0d 742void AliVertexerTracks::StrLinVertexFinderMinDist(Int_t optUseWeights)
dc3719f3 743{
6d8df534 744 AliExternalTrackParam *track1;
dc3719f3 745 Double_t field=GetFieldkG();
6d8df534 746 const Int_t knacc = (Int_t)fTrkArraySel.GetEntriesFast();
dc3719f3 747 TClonesArray *linarray = new TClonesArray("AliStrLine",1000);
748 TClonesArray &lines = *linarray;
749 for(Int_t i=0; i<knacc; i++){
6d8df534 750 track1 = (AliExternalTrackParam*)fTrkArraySel.At(i);
dc3719f3 751 Double_t alpha=track1->GetAlpha();
752 Double_t mindist = TMath::Cos(alpha)*fNominalPos[0]+TMath::Sin(alpha)*fNominalPos[1];
753 Double_t pos[3],dir[3],sigmasq[3];
754 track1->GetXYZAt(mindist,field,pos);
755 track1->GetPxPyPzAt(mindist,field,dir);
756 sigmasq[0]=TMath::Sin(alpha)*TMath::Sin(alpha)*track1->GetSigmaY2();
757 sigmasq[1]=TMath::Cos(alpha)*TMath::Cos(alpha)*track1->GetSigmaY2();
758 sigmasq[2]=track1->GetSigmaZ2();
146c29df 759 TMatrixD ri(3,1);
760 TMatrixD wWi(3,3);
761 if(!TrackToPoint(track1,ri,wWi)) continue;
762 Double_t wmat[9];
763 Int_t iel=0;
764 for(Int_t ia=0;ia<3;ia++){
765 for(Int_t ib=0;ib<3;ib++){
766 wmat[iel]=wWi(ia,ib);
767 iel++;
768 }
769 }
770 new(lines[i]) AliStrLine(pos,sigmasq,wmat,dir);
dc3719f3 771 }
772 fVert=TrackletVertexFinder(linarray,optUseWeights);
773 linarray->Delete();
774 delete linarray;
775}
776//---------------------------------------------------------------------------
146c29df 777AliESDVertex AliVertexerTracks::TrackletVertexFinder(TClonesArray *lines, Int_t optUseWeights)
fee9ef0d 778{
2d57349e 779 // Calculate the point at minimum distance to prepared tracks
780
dc3719f3 781 const Int_t knacc = (Int_t)lines->GetEntriesFast();
782 Double_t initPos[3]={0.,0.,0.};
2d57349e 783
2d57349e 784 Double_t (*vectP0)[3]=new Double_t [knacc][3];
785 Double_t (*vectP1)[3]=new Double_t [knacc][3];
786
787 Double_t sum[3][3];
788 Double_t dsum[3]={0,0,0};
146c29df 789 TMatrixD sumWi(3,3);
790 for(Int_t i=0;i<3;i++){
791 for(Int_t j=0;j<3;j++){
792 sum[i][j]=0;
793 sumWi(i,j)=0.;
794 }
795 }
796
2d57349e 797 for(Int_t i=0; i<knacc; i++){
dc3719f3 798 AliStrLine* line1 = (AliStrLine*)lines->At(i);
799 Double_t p0[3],cd[3],sigmasq[3];
146c29df 800 Double_t wmat[9];
2d57349e 801 line1->GetP0(p0);
802 line1->GetCd(cd);
dc3719f3 803 line1->GetSigma2P0(sigmasq);
146c29df 804 line1->GetWMatrix(wmat);
805 TMatrixD wWi(3,3);
806 Int_t iel=0;
807 for(Int_t ia=0;ia<3;ia++){
808 for(Int_t ib=0;ib<3;ib++){
809 wWi(ia,ib)=wmat[iel];
810 iel++;
811 }
812 }
813
814 sumWi+=wWi;
815
2d57349e 816 Double_t p1[3]={p0[0]+cd[0],p0[1]+cd[1],p0[2]+cd[2]};
817 vectP0[i][0]=p0[0];
818 vectP0[i][1]=p0[1];
819 vectP0[i][2]=p0[2];
820 vectP1[i][0]=p1[0];
821 vectP1[i][1]=p1[1];
822 vectP1[i][2]=p1[2];
823
824 Double_t matr[3][3];
825 Double_t dknow[3];
826 if(optUseWeights==0)GetStrLinDerivMatrix(p0,p1,matr,dknow);
dc3719f3 827 else GetStrLinDerivMatrix(p0,p1,sigmasq,matr,dknow);
828
2d57349e 829
830 for(Int_t iii=0;iii<3;iii++){
831 dsum[iii]+=dknow[iii];
832 for(Int_t lj=0;lj<3;lj++) sum[iii][lj]+=matr[iii][lj];
833 }
2d57349e 834 }
146c29df 835
836 TMatrixD invsumWi(TMatrixD::kInverted,sumWi);
837 Double_t covmatrix[6];
838 covmatrix[0] = invsumWi(0,0);
839 covmatrix[1] = invsumWi(0,1);
840 covmatrix[2] = invsumWi(1,1);
841 covmatrix[3] = invsumWi(0,2);
842 covmatrix[4] = invsumWi(1,2);
843 covmatrix[5] = invsumWi(2,2);
844
2d57349e 845 Double_t vett[3][3];
846 Double_t det=GetDeterminant3X3(sum);
dc3719f3 847 Double_t sigma=0;
2d57349e 848
fee9ef0d 849 if(det!=0){
850 for(Int_t zz=0;zz<3;zz++){
851 for(Int_t ww=0;ww<3;ww++){
852 for(Int_t kk=0;kk<3;kk++) vett[ww][kk]=sum[ww][kk];
853 }
854 for(Int_t kk=0;kk<3;kk++) vett[kk][zz]=dsum[kk];
855 initPos[zz]=GetDeterminant3X3(vett)/det;
856 }
857
858
859 for(Int_t i=0; i<knacc; i++){
860 Double_t p0[3]={0,0,0},p1[3]={0,0,0};
861 for(Int_t ii=0;ii<3;ii++){
862 p0[ii]=vectP0[i][ii];
863 p1[ii]=vectP1[i][ii];
864 }
865 sigma+=GetStrLinMinDist(p0,p1,initPos);
866 }
867
868 sigma=TMath::Sqrt(sigma);
869 }else{
50ff0bcd 870 sigma=999;
871 }
146c29df 872 AliESDVertex theVert(initPos,covmatrix,99999.,knacc);
873 theVert.SetDispersion(sigma);
50ff0bcd 874 delete vectP0;
875 delete vectP1;
dc3719f3 876 return theVert;
50ff0bcd 877}
878//---------------------------------------------------------------------------
6d8df534 879Bool_t AliVertexerTracks::TrackToPoint(AliExternalTrackParam *t,
0bf2e2b4 880 TMatrixD &ri,TMatrixD &wWi,
881 Bool_t uUi3by3) const
fee9ef0d 882{
883//
6d8df534 884// Extract from the AliExternalTrackParam the global coordinates ri and covariance matrix
fee9ef0d 885// wWi of the space point that it represents (to be used in VertexFitter())
886//
887
888
889 Double_t rotAngle = t->GetAlpha();
890 if(rotAngle<0.) rotAngle += 2.*TMath::Pi();
891 Double_t cosRot = TMath::Cos(rotAngle);
892 Double_t sinRot = TMath::Sin(rotAngle);
893
894 ri(0,0) = t->GetX()*cosRot-t->GetY()*sinRot;
895 ri(1,0) = t->GetX()*sinRot+t->GetY()*cosRot;
896 ri(2,0) = t->GetZ();
897
0bf2e2b4 898
899
900 if(!uUi3by3) {
901 // matrix to go from global (x,y,z) to local (y,z);
902 TMatrixD qQi(2,3);
903 qQi(0,0) = -sinRot;
904 qQi(0,1) = cosRot;
905 qQi(0,2) = 0.;
906 qQi(1,0) = 0.;
907 qQi(1,1) = 0.;
908 qQi(1,2) = 1.;
909
910 // covariance matrix of local (y,z) - inverted
0bf2e2b4 911 TMatrixD uUi(2,2);
6d8df534 912 uUi(0,0) = t->GetSigmaY2();
913 uUi(0,1) = t->GetSigmaZY();
914 uUi(1,0) = t->GetSigmaZY();
915 uUi(1,1) = t->GetSigmaZ2();
0bf2e2b4 916 //printf(" Ui :\n");
917 //printf(" %f %f\n",uUi(0,0),uUi(0,1));
918 //printf(" %f %f\n",uUi(1,0),uUi(1,1));
919
920 if(uUi.Determinant() <= 0.) return kFALSE;
921 TMatrixD uUiInv(TMatrixD::kInverted,uUi);
922
923 // weights matrix: wWi = qQiT * uUiInv * qQi
924 TMatrixD uUiInvQi(uUiInv,TMatrixD::kMult,qQi);
925 TMatrixD m(qQi,TMatrixD::kTransposeMult,uUiInvQi);
926 wWi = m;
927 } else {
928 if(fVert.GetNContributors()<1) AliFatal("Vertex from finder is empty");
929 // matrix to go from global (x,y,z) to local (x,y,z);
930 TMatrixD qQi(3,3);
931 qQi(0,0) = cosRot;
932 qQi(0,1) = sinRot;
933 qQi(0,2) = 0.;
934 qQi(1,0) = -sinRot;
935 qQi(1,1) = cosRot;
936 qQi(1,2) = 0.;
937 qQi(2,0) = 0.;
938 qQi(2,1) = 0.;
939 qQi(2,2) = 1.;
940
941 // covariance of fVert along the track
942 Double_t p[3],pt,ptot;
943 t->GetPxPyPz(p);
944 pt = TMath::Sqrt(p[0]*p[0]+p[1]*p[1]);
945 ptot = TMath::Sqrt(pt*pt+p[2]*p[2]);
3b768a1d 946 Double_t cphi = p[0]/pt; //cos(phi)=px/pt
947 Double_t sphi = p[1]/pt; //sin(phi)=py/pt
948 Double_t clambda = pt/ptot; //cos(lambda)=pt/ptot
949 Double_t slambda = p[2]/ptot; //sin(lambda)=pz/ptot
0bf2e2b4 950 Double_t covfVert[6];
951 fVert.GetCovMatrix(covfVert);
952 Double_t covfVertalongt =
3b768a1d 953 covfVert[0]*cphi*cphi*clambda*clambda
954 +covfVert[1]*2.*cphi*sphi*clambda*clambda
955 +covfVert[3]*2.*cphi*clambda*slambda
956 +covfVert[2]*sphi*sphi*clambda*clambda
957 +covfVert[4]*2.*sphi*clambda*slambda
958 +covfVert[5]*slambda*slambda;
0bf2e2b4 959 // covariance matrix of local (x,y,z) - inverted
960 TMatrixD uUi(3,3);
3b768a1d 961 uUi(0,0) = covfVertalongt * fnSigmaForUi00 * fnSigmaForUi00;
0bf2e2b4 962 if(fDebug) printf("=====> sqrtUi00 cm %f\n",TMath::Sqrt(uUi(0,0)));
963 uUi(0,1) = 0.;
964 uUi(0,2) = 0.;
965 uUi(1,0) = 0.;
6d8df534 966 uUi(1,1) = t->GetSigmaY2();
967 uUi(1,2) = t->GetSigmaZY();
0bf2e2b4 968 uUi(2,0) = 0.;
6d8df534 969 uUi(2,1) = t->GetSigmaZY();
970 uUi(2,2) = t->GetSigmaZ2();
0bf2e2b4 971 //printf(" Ui :\n");
972 //printf(" %f %f\n",uUi(0,0),uUi(0,1));
973 //printf(" %f %f\n",uUi(1,0),uUi(1,1));
fee9ef0d 974
0bf2e2b4 975 if(uUi.Determinant() <= 0.) return kFALSE;
976 TMatrixD uUiInv(TMatrixD::kInverted,uUi);
977
978 // weights matrix: wWi = qQiT * uUiInv * qQi
979 TMatrixD uUiInvQi(uUiInv,TMatrixD::kMult,qQi);
980 TMatrixD m(qQi,TMatrixD::kTransposeMult,uUiInvQi);
981 wWi = m;
982 }
983
fee9ef0d 984
985 return kTRUE;
986}
987//---------------------------------------------------------------------------
6d8df534 988void AliVertexerTracks::TooFewTracks()
fee9ef0d 989{
50ff0bcd 990//
6d8df534 991// When the number of tracks is < fMinTracks,
992// deal with vertices not found and prepare to exit
50ff0bcd 993//
6d8df534 994 if(fDebug) printf("TooFewTracks\n");
2d57349e 995
50ff0bcd 996 Double_t pos[3],err[3];
50ff0bcd 997 pos[0] = fNominalPos[0];
998 err[0] = TMath::Sqrt(fNominalCov[0]);
999 pos[1] = fNominalPos[1];
1000 err[1] = TMath::Sqrt(fNominalCov[2]);
6d8df534 1001 pos[2] = fNominalPos[2];
1002 err[2] = TMath::Sqrt(fNominalCov[5]);
1003 Int_t ncontr = (err[0]>1. ? -1 : -3);
50ff0bcd 1004 fCurrentVertex = 0;
1005 fCurrentVertex = new AliESDVertex(pos,err);
1006 fCurrentVertex->SetNContributors(ncontr);
2d57349e 1007
fee9ef0d 1008 if(fConstraint) {
1009 fCurrentVertex->SetTitle("VertexerTracksWithConstraint");
1010 } else {
50ff0bcd 1011 fCurrentVertex->SetTitle("VertexerTracksNoConstraint");
fee9ef0d 1012 }
2d57349e 1013
6d8df534 1014 if(!fTrkArraySel.IsEmpty()) fTrkArraySel.Delete();
1015 if(fIdSel) {delete [] fIdSel; fIdSel=NULL;}
1016 if(fTrksToSkip) {delete [] fTrksToSkip; fTrksToSkip=NULL;}
1017
50ff0bcd 1018 return;
1019}
1020//---------------------------------------------------------------------------
fee9ef0d 1021void AliVertexerTracks::VertexFinder(Int_t optUseWeights)
1022{
2d57349e 1023
50ff0bcd 1024 // Get estimate of vertex position in (x,y) from tracks DCA
1025
1026 Double_t initPos[3];
1027 initPos[2] = 0.;
1028 for(Int_t i=0;i<2;i++)initPos[i]=fNominalPos[i];
6d8df534 1029 Int_t nacc = (Int_t)fTrkArraySel.GetEntriesFast();
50ff0bcd 1030 Double_t aver[3]={0.,0.,0.};
1031 Double_t aversq[3]={0.,0.,0.};
1032 Double_t sigmasq[3]={0.,0.,0.};
1033 Double_t sigma=0;
1034 Int_t ncombi = 0;
6d8df534 1035 AliExternalTrackParam *track1;
1036 AliExternalTrackParam *track2;
50ff0bcd 1037 Double_t pos[3],dir[3];
1038 Double_t alpha,mindist;
dc3719f3 1039 Double_t field=GetFieldkG();
2d57349e 1040
50ff0bcd 1041 for(Int_t i=0; i<nacc; i++){
6d8df534 1042 track1 = (AliExternalTrackParam*)fTrkArraySel.At(i);
50ff0bcd 1043 alpha=track1->GetAlpha();
1044 mindist = TMath::Cos(alpha)*fNominalPos[0]+TMath::Sin(alpha)*fNominalPos[1];
1045 track1->GetXYZAt(mindist,field,pos);
1046 track1->GetPxPyPzAt(mindist,field,dir);
1047 AliStrLine *line1 = new AliStrLine(pos,dir);
2d57349e 1048
50ff0bcd 1049 // AliStrLine *line1 = new AliStrLine();
1050 // track1->ApproximateHelixWithLine(mindist,field,line1);
1051
1052 for(Int_t j=i+1; j<nacc; j++){
6d8df534 1053 track2 = (AliExternalTrackParam*)fTrkArraySel.At(j);
50ff0bcd 1054 alpha=track2->GetAlpha();
1055 mindist = TMath::Cos(alpha)*fNominalPos[0]+TMath::Sin(alpha)*fNominalPos[1];
1056 track2->GetXYZAt(mindist,field,pos);
1057 track2->GetPxPyPzAt(mindist,field,dir);
1058 AliStrLine *line2 = new AliStrLine(pos,dir);
1059 // AliStrLine *line2 = new AliStrLine();
1060 // track2->ApproximateHelixWithLine(mindist,field,line2);
1061 Double_t distCA=line2->GetDCA(line1);
fee9ef0d 1062 //printf("%d %d %f\n",i,j,distCA);
1063 if(fDCAcut<=0 || (fDCAcut>0&&distCA<fDCAcut)){
50ff0bcd 1064 Double_t pnt1[3],pnt2[3],crosspoint[3];
2d57349e 1065
50ff0bcd 1066 if(optUseWeights<=0){
1067 Int_t retcode = line2->Cross(line1,crosspoint);
1068 if(retcode>=0){
1069 ncombi++;
1070 for(Int_t jj=0;jj<3;jj++)aver[jj]+=crosspoint[jj];
1071 for(Int_t jj=0;jj<3;jj++)aversq[jj]+=(crosspoint[jj]*crosspoint[jj]);
1072 }
1073 }
1074 if(optUseWeights>0){
1075 Int_t retcode = line1->CrossPoints(line2,pnt1,pnt2);
1076 if(retcode>=0){
5c03260f 1077 Double_t cs, sn;
50ff0bcd 1078 alpha=track1->GetAlpha();
1079 cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
1080 Double_t sx1=sn*sn*track1->GetSigmaY2(), sy1=cs*cs*track1->GetSigmaY2();
1081 alpha=track2->GetAlpha();
1082 cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
1083 Double_t sx2=sn*sn*track2->GetSigmaY2(), sy2=cs*cs*track2->GetSigmaY2();
1084 Double_t sz1=track1->GetSigmaZ2(), sz2=track2->GetSigmaZ2();
1085 Double_t wx1=sx2/(sx1+sx2), wx2=1.- wx1;
1086 Double_t wy1=sy2/(sy1+sy2), wy2=1.- wy1;
1087 Double_t wz1=sz2/(sz1+sz2), wz2=1.- wz1;
1088 crosspoint[0]=wx1*pnt1[0] + wx2*pnt2[0];
1089 crosspoint[1]=wy1*pnt1[1] + wy2*pnt2[1];
1090 crosspoint[2]=wz1*pnt1[2] + wz2*pnt2[2];
1091
1092 ncombi++;
1093 for(Int_t jj=0;jj<3;jj++)aver[jj]+=crosspoint[jj];
1094 for(Int_t jj=0;jj<3;jj++)aversq[jj]+=(crosspoint[jj]*crosspoint[jj]);
1095 }
1096 }
1097 }
1098 delete line2;
1099 }
1100 delete line1;
71d84967 1101 }
50ff0bcd 1102 if(ncombi>0){
1103 for(Int_t jj=0;jj<3;jj++){
1104 initPos[jj] = aver[jj]/ncombi;
fee9ef0d 1105 //printf("%f\n",initPos[jj]);
50ff0bcd 1106 aversq[jj]/=ncombi;
1107 sigmasq[jj]=aversq[jj]-initPos[jj]*initPos[jj];
1108 sigma+=sigmasq[jj];
1109 }
1110 sigma=TMath::Sqrt(TMath::Abs(sigma));
1111 }
1112 else {
1113 Warning("VertexFinder","Finder did not succed");
1114 sigma=999;
1115 }
1116 fVert.SetXYZ(initPos);
1117 fVert.SetDispersion(sigma);
1118 fVert.SetNContributors(ncombi);
2d57349e 1119}
ec1be5d5 1120//---------------------------------------------------------------------------
6d8df534 1121void AliVertexerTracks::VertexFitter()
fee9ef0d 1122{
ec1be5d5 1123//
1124// The optimal estimate of the vertex position is given by a "weighted
0bf2e2b4 1125// average of tracks positions".
fee9ef0d 1126// Original method: V. Karimaki, CMS Note 97/0051
ec1be5d5 1127//
6d8df534 1128 Bool_t useConstraint = fConstraint;
ec1be5d5 1129 Double_t initPos[3];
0bf2e2b4 1130 if(!fOnlyFitter) {
1131 fVert.GetXYZ(initPos);
1132 } else {
1133 initPos[0]=fNominalPos[0];
1134 initPos[1]=fNominalPos[1];
1135 initPos[2]=fNominalPos[2];
1136 }
1137
6d8df534 1138 Int_t nTrksSel = (Int_t)fTrkArraySel.GetEntries();
1139 if(nTrksSel==1) useConstraint=kTRUE;
ec1be5d5 1140 if(fDebug) {
0bf2e2b4 1141 printf("--- VertexFitter(): start\n");
6d8df534 1142 printf(" Number of tracks in array: %d\n",nTrksSel);
ec1be5d5 1143 printf(" Minimum # tracks required in fit: %d\n",fMinTracks);
3b768a1d 1144 printf(" Vertex position after finder: %f,%f,%f\n",initPos[0],initPos[1],initPos[2]);
fee9ef0d 1145 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]));
ec1be5d5 1146 }
1147
0bf2e2b4 1148 // special treatment for few-tracks fits (e.g. secondary vertices)
6d8df534 1149 Bool_t uUi3by3 = kFALSE; if(nTrksSel<5 && !useConstraint) uUi3by3 = kTRUE;
0bf2e2b4 1150
ec1be5d5 1151 Int_t i,j,k,step=0;
1152 TMatrixD rv(3,1);
1153 TMatrixD vV(3,3);
1154 rv(0,0) = initPos[0];
1155 rv(1,0) = initPos[1];
1156 rv(2,0) = 0.;
1157 Double_t xlStart,alpha;
6d8df534 1158 Int_t nTrksUsed;
fee9ef0d 1159 Double_t chi2,chi2i,chi2b;
6d8df534 1160 AliExternalTrackParam *t = 0;
ec1be5d5 1161 Int_t failed = 0;
1162
50ff0bcd 1163 // initial vertex covariance matrix
1164 TMatrixD vVb(3,3);
1165 vVb(0,0) = fNominalCov[0];
1166 vVb(0,1) = fNominalCov[1];
1167 vVb(0,2) = 0.;
1168 vVb(1,0) = fNominalCov[1];
1169 vVb(1,1) = fNominalCov[2];
1170 vVb(1,2) = 0.;
1171 vVb(2,0) = 0.;
1172 vVb(2,1) = 0.;
1173 vVb(2,2) = fNominalCov[5];
1174 TMatrixD vVbInv(TMatrixD::kInverted,vVb);
1175 TMatrixD rb(3,1);
1176 rb(0,0) = fNominalPos[0];
1177 rb(1,0) = fNominalPos[1];
1178 rb(2,0) = fNominalPos[2];
1179 TMatrixD vVbInvrb(vVbInv,TMatrixD::kMult,rb);
1180
1181
eae1677e 1182 // 2 steps:
1183 // 1st - estimate of vtx using all tracks
1184 // 2nd - estimate of global chi2
1185 for(step=0; step<2; step++) {
ec1be5d5 1186 if(fDebug) printf(" step = %d\n",step);
1187 chi2 = 0.;
6d8df534 1188 nTrksUsed = 0;
ec1be5d5 1189
0bf2e2b4 1190 if(step==1) { initPos[0]=rv(0,0); initPos[0]=rv(1,0); }
1191
ec1be5d5 1192 TMatrixD sumWiri(3,1);
1193 TMatrixD sumWi(3,3);
1194 for(i=0; i<3; i++) {
1195 sumWiri(i,0) = 0.;
1196 for(j=0; j<3; j++) sumWi(j,i) = 0.;
1197 }
1198
fee9ef0d 1199 // mean vertex constraint
1200 if(useConstraint) {
50ff0bcd 1201 for(i=0;i<3;i++) {
1202 sumWiri(i,0) += vVbInvrb(i,0);
1203 for(k=0;k<3;k++) sumWi(i,k) += vVbInv(i,k);
07680cae 1204 }
fee9ef0d 1205 // chi2
1206 TMatrixD deltar = rv; deltar -= rb;
1207 TMatrixD vVbInvdeltar(vVbInv,TMatrixD::kMult,deltar);
1208 chi2b = deltar(0,0)*vVbInvdeltar(0,0)+
1209 deltar(1,0)*vVbInvdeltar(1,0)+
1210 deltar(2,0)*vVbInvdeltar(2,0);
1211 chi2 += chi2b;
07680cae 1212 }
1213
ec1be5d5 1214 // loop on tracks
6d8df534 1215 for(k=0; k<nTrksSel; k++) {
ec1be5d5 1216 // get track from track array
6d8df534 1217 t = (AliExternalTrackParam*)fTrkArraySel.At(k);
ec1be5d5 1218 alpha = t->GetAlpha();
1219 xlStart = initPos[0]*TMath::Cos(alpha)+initPos[1]*TMath::Sin(alpha);
fee9ef0d 1220 // to vtxSeed (from finder)
6d8df534 1221 t->PropagateTo(xlStart,GetFieldkG());
fee9ef0d 1222
ec1be5d5 1223 // vector of track global coordinates
1224 TMatrixD ri(3,1);
fee9ef0d 1225 // covariance matrix of ri
1226 TMatrixD wWi(3,3);
1227
1228 // get space point from track
0bf2e2b4 1229 if(!TrackToPoint(t,ri,wWi,uUi3by3)) continue;
fee9ef0d 1230 TMatrixD wWiri(wWi,TMatrixD::kMult,ri);
ec1be5d5 1231
1232 // track chi2
1233 TMatrixD deltar = rv; deltar -= ri;
1234 TMatrixD wWideltar(wWi,TMatrixD::kMult,deltar);
1235 chi2i = deltar(0,0)*wWideltar(0,0)+
1236 deltar(1,0)*wWideltar(1,0)+
1237 deltar(2,0)*wWideltar(2,0);
1238
ec1be5d5 1239 // add to total chi2
1240 chi2 += chi2i;
1241
ec1be5d5 1242 sumWiri += wWiri;
1243 sumWi += wWi;
1244
6d8df534 1245 nTrksUsed++;
ec1be5d5 1246 } // end loop on tracks
1247
6d8df534 1248 if(nTrksUsed < fMinTracks) {
ec1be5d5 1249 failed=1;
1250 continue;
1251 }
1252
1253 Double_t determinant = sumWi.Determinant();
1254 //cerr<<" determinant: "<<determinant<<endl;
1255 if(determinant < 100.) {
1256 printf("det(V) = 0\n");
1257 failed=1;
1258 continue;
1259 }
1260
0bf2e2b4 1261 if(step==0) {
1262 // inverted of weights matrix
1263 TMatrixD invsumWi(TMatrixD::kInverted,sumWi);
1264 vV = invsumWi;
1265 // position of primary vertex
1266 rv.Mult(vV,sumWiri);
1267 }
eae1677e 1268 } // end loop on the 2 steps
ec1be5d5 1269
ec1be5d5 1270 if(failed) {
6d8df534 1271 TooFewTracks();
ec1be5d5 1272 return;
1273 }
1274
1275 Double_t position[3];
1276 position[0] = rv(0,0);
1277 position[1] = rv(1,0);
1278 position[2] = rv(2,0);
1279 Double_t covmatrix[6];
1280 covmatrix[0] = vV(0,0);
1281 covmatrix[1] = vV(0,1);
1282 covmatrix[2] = vV(1,1);
1283 covmatrix[3] = vV(0,2);
1284 covmatrix[4] = vV(1,2);
1285 covmatrix[5] = vV(2,2);
1286
dc3719f3 1287 // for correct chi2/ndf, count constraint as additional "track"
6d8df534 1288 if(fConstraint) nTrksUsed++;
ec1be5d5 1289 // store data in the vertex object
6d8df534 1290 fCurrentVertex = new AliESDVertex(position,covmatrix,chi2,nTrksUsed);
ec1be5d5 1291
1292 if(fDebug) {
0bf2e2b4 1293 printf(" Vertex after fit:\n");
ec1be5d5 1294 fCurrentVertex->PrintStatus();
0bf2e2b4 1295 printf("--- VertexFitter(): finish\n");
ec1be5d5 1296 }
1297
1298 return;
1299}
50ff0bcd 1300//----------------------------------------------------------------------------
6d8df534 1301AliESDVertex* AliVertexerTracks::VertexForSelectedTracks(TObjArray *trkArray,
1302 UShort_t *id,
1303 Bool_t optUseFitter,
1304 Bool_t optPropagate)
fee9ef0d 1305{
eae1677e 1306//
6d8df534 1307// Return vertex from tracks (AliExternalTrackParam) in array
eae1677e 1308//
1309
fee9ef0d 1310 SetConstraintOff();
1311
50ff0bcd 1312 // get tracks and propagate them to initial vertex position
6d8df534 1313 fIdSel = new UShort_t[(Int_t)trkArray->GetEntriesFast()];
1314 Int_t nTrksSel = PrepareTracks(*trkArray,id,0);
1315 if(nTrksSel < TMath::Max(2,fMinTracks)) {
1316 TooFewTracks();
fee9ef0d 1317 return fCurrentVertex;
50ff0bcd 1318 }
1319
6d8df534 1320 // vertex finder
fee9ef0d 1321 switch (fAlgo) {
1322 case 1: StrLinVertexFinderMinDist(1); break;
1323 case 2: StrLinVertexFinderMinDist(0); break;
1324 case 3: HelixVertexFinder(); break;
1325 case 4: VertexFinder(1); break;
1326 case 5: VertexFinder(0); break;
1327 default: printf("Wrong algorithm\n"); break;
1328 }
fee9ef0d 1329 if(fDebug) printf(" Vertex finding completed\n");
1330
1331 // vertex fitter
6d8df534 1332 if(optUseFitter) {
1333 VertexFitter();
1334 } else {
fee9ef0d 1335 Double_t position[3]={fVert.GetXv(),fVert.GetYv(),fVert.GetZv()};
146c29df 1336 Double_t covmatrix[6];
1337 fVert.GetCovMatrix(covmatrix);
fee9ef0d 1338 Double_t chi2=99999.;
6d8df534 1339 Int_t nTrksUsed=fVert.GetNContributors();
1340 fCurrentVertex = new AliESDVertex(position,covmatrix,chi2,nTrksUsed);
fee9ef0d 1341 }
1342 fCurrentVertex->SetDispersion(fVert.GetDispersion());
1343
1344
1345 // set indices of used tracks and propagate track to found vertex
50ff0bcd 1346 UShort_t *indices = 0;
6d8df534 1347 Double_t d0z0[2],covd0z0[3];
1348 AliExternalTrackParam *t = 0;
fee9ef0d 1349 if(fCurrentVertex->GetNContributors()>0) {
1350 indices = new UShort_t[fCurrentVertex->GetNContributors()];
6d8df534 1351 for(Int_t jj=0; jj<(Int_t)fTrkArraySel.GetEntriesFast(); jj++) {
1352 indices[jj] = fIdSel[jj];
1353 t = (AliExternalTrackParam*)fTrkArraySel.At(jj);
1354 if(optPropagate && optUseFitter) {
fee9ef0d 1355 if(TMath::Sqrt(fCurrentVertex->GetXv()*fCurrentVertex->GetXv()+fCurrentVertex->GetYv()*fCurrentVertex->GetYv())<3.) {
6d8df534 1356 t->PropagateToDCA(fCurrentVertex,GetFieldkG(),100.,d0z0,covd0z0);
fee9ef0d 1357 if(fDebug) printf("Track %d propagated to found vertex\n",jj);
6d8df534 1358 } else {
fee9ef0d 1359 AliWarning("Found vertex outside beam pipe!");
1360 }
1361 }
50ff0bcd 1362 }
fee9ef0d 1363 fCurrentVertex->SetIndices(fCurrentVertex->GetNContributors(),indices);
50ff0bcd 1364 }
6d8df534 1365
1366 // clean up
1367 delete [] indices; indices=NULL;
1368 delete [] fIdSel; fIdSel=NULL;
1369 fTrkArraySel.Delete();
50ff0bcd 1370
fee9ef0d 1371 return fCurrentVertex;
eae1677e 1372}
50ff0bcd 1373//----------------------------------------------------------------------------
6d8df534 1374AliESDVertex* AliVertexerTracks::VertexForSelectedESDTracks(TObjArray *trkArray,
1375 Bool_t optUseFitter,
1376 Bool_t optPropagate)
fee9ef0d 1377{
50ff0bcd 1378//
6d8df534 1379// Return vertex from array of ESD tracks
50ff0bcd 1380//
5834e9a1 1381
6d8df534 1382 Int_t nTrks = (Int_t)trkArray->GetEntriesFast();
1383 UShort_t *id = new UShort_t[nTrks];
1384
1385 AliESDtrack *esdt = 0;
50ff0bcd 1386 for(Int_t i=0; i<nTrks; i++){
6d8df534 1387 esdt = (AliESDtrack*)trkArray->At(i);
1388 id[i] = (UShort_t)esdt->GetID();
50ff0bcd 1389 }
1390
6d8df534 1391 VertexForSelectedTracks(trkArray,id,optUseFitter,optPropagate);
1392
1393 delete [] id; id=NULL;
1394
1395 return fCurrentVertex;
50ff0bcd 1396}
1397//--------------------------------------------------------------------------
43c9dae1 1398