1 /**************************************************************************
2 * Copyright(c) 2006-2008, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
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 **************************************************************************/
17 #include "AliESDVertex.h"
19 #include "AliStrLine.h"
20 #include "AliTracker.h"
21 #include "AliRunLoader.h"
22 #include "AliITSLoader.h"
23 #include "AliITSDetTypeRec.h"
24 #include "AliITSRecPoint.h"
25 #include "AliITSgeomTGeo.h"
26 #include "AliVertexerTracks.h"
27 #include "AliITSVertexer3D.h"
28 /////////////////////////////////////////////////////////////////
29 // this class implements a method to determine
30 // the 3 coordinates of the primary vertex
32 // It can be used successfully with Pb-Pb collisions
33 ////////////////////////////////////////////////////////////////
35 ClassImp(AliITSVertexer3D)
39 //______________________________________________________________________
40 AliITSVertexer3D::AliITSVertexer3D():AliITSVertexer(),
43 fCoarseDiffPhiCut(0.),
53 // Default constructor
54 SetCoarseDiffPhiCut();
65 //______________________________________________________________________
66 AliITSVertexer3D::AliITSVertexer3D(TString fn): AliITSVertexer(fn),
67 fLines("AliStrLine",1000),
69 fCoarseDiffPhiCut(0.),
79 // Standard constructor
80 SetCoarseDiffPhiCut();
91 //______________________________________________________________________
92 AliITSVertexer3D::~AliITSVertexer3D() {
97 //______________________________________________________________________
98 void AliITSVertexer3D::ResetVert3D(){
103 fVert3D.SetDispersion(0.);
104 fVert3D.SetNContributors(0);
106 //______________________________________________________________________
107 AliESDVertex* AliITSVertexer3D::FindVertexForCurrentEvent(Int_t evnumber){
108 // Defines the AliESDVertex for the current event
110 AliDebug(1,Form("FindVertexForCurrentEvent - 3D - PROCESSING EVENT %d",evnumber));
113 Int_t nolines = FindTracklets(evnumber,0);
115 if(nolines<2)return fCurrentVertex;
116 Int_t rc=Prepare3DVertex(0);
117 if(rc==0) fVert3D=AliVertexerTracks::TrackletVertexFinder(&fLines,0);
118 /* uncomment to debug
119 printf("Vertex found in first iteration:\n");
121 printf("Start second iteration\n");
122 end of debug lines */
123 if(fVert3D.GetNContributors()>0){
125 nolines = FindTracklets(evnumber,1);
127 rc=Prepare3DVertex(1);
128 if(rc==0) fVert3D=AliVertexerTracks::TrackletVertexFinder(&fLines,0);
131 /* uncomment to debug
132 printf("Vertex found in second iteration:\n");
134 end of debug lines */
136 Float_t vRadius=TMath::Sqrt(fVert3D.GetXv()*fVert3D.GetXv()+fVert3D.GetYv()*fVert3D.GetYv());
137 if(vRadius<GetPipeRadius() && fVert3D.GetNContributors()>0){
138 Double_t position[3]={fVert3D.GetXv(),fVert3D.GetYv(),fVert3D.GetZv()};
139 Double_t covmatrix[6];
140 fVert3D.GetCovMatrix(covmatrix);
141 Double_t chi2=99999.;
142 Int_t nContr=fVert3D.GetNContributors();
143 fCurrentVertex = new AliESDVertex(position,covmatrix,chi2,nContr);
144 fCurrentVertex->SetTitle("vertexer: 3D");
145 fCurrentVertex->SetName("Vertex");
146 fCurrentVertex->SetDispersion(fVert3D.GetDispersion());
148 FindMultiplicity(evnumber);
149 return fCurrentVertex;
152 //______________________________________________________________________
153 Int_t AliITSVertexer3D::FindTracklets(Int_t evnumber, Int_t optCuts){
154 // All the possible combinations between recpoints on layer 1and 2 are
155 // considered. Straight lines (=tracklets)are formed.
156 // The tracklets are processed in Prepare3DVertex
157 AliRunLoader *rl =AliRunLoader::GetRunLoader();
158 AliITSLoader* itsLoader = (AliITSLoader*)rl->GetLoader("ITSLoader");
159 // AliITSgeom* geom = itsLoader->GetITSgeom();
160 itsLoader->LoadRecPoints();
161 rl->GetEvent(evnumber);
163 AliITSDetTypeRec detTypeRec;
165 TTree *tR = itsLoader->TreeR();
166 detTypeRec.SetTreeAddressR(tR);
167 TClonesArray *itsRec = 0;
168 // lc1 and gc1 are local and global coordinates for layer 1
169 // Float_t lc1[3]={0.,0.,0.};
170 Float_t gc1[3]={0.,0.,0.};
171 // lc2 and gc2 are local and global coordinates for layer 2
172 // Float_t lc2[3]={0.,0.,0.};
173 Float_t gc2[3]={0.,0.,0.};
175 itsRec = detTypeRec.RecPoints();
177 branch = tR->GetBranch("ITSRecPoints");
179 // Set values for cuts
180 Float_t xbeam=0., ybeam=0.;
182 Float_t deltaPhi=fCoarseDiffPhiCut;
183 Float_t deltaR=fCoarseMaxRCut;
184 Float_t dZmax=fZCutDiamond;
186 xbeam=fVert3D.GetXv();
187 ybeam=fVert3D.GetYv();
188 zvert=fVert3D.GetZv();
189 deltaPhi = fDiffPhiMax;
193 Int_t nrpL1 = 0; // number of rec points on layer 1
194 Int_t nrpL2 = 0; // number of rec points on layer 2
196 // By default irstL1=0 and lastL1=79
197 Int_t firstL1 = AliITSgeomTGeo::GetModuleIndex(1,1,1);
198 Int_t lastL1 = AliITSgeomTGeo::GetModuleIndex(2,1,1)-1;
199 for(Int_t module= firstL1; module<=lastL1;module++){ // count number of recopints on layer 1
200 branch->GetEvent(module);
201 nrpL1+= itsRec->GetEntries();
202 detTypeRec.ResetRecPoints();
204 //By default firstL2=80 and lastL2=239
205 Int_t firstL2 = AliITSgeomTGeo::GetModuleIndex(2,1,1);
206 Int_t lastL2 = AliITSgeomTGeo::GetModuleIndex(3,1,1)-1;
207 for(Int_t module= firstL2; module<=lastL2;module++){ // count number of recopints on layer 2
208 branch->GetEvent(module);
209 nrpL2+= itsRec->GetEntries();
210 detTypeRec.ResetRecPoints();
212 if(nrpL1 == 0 || nrpL2 == 0){
213 itsLoader->UnloadRecPoints();
216 AliDebug(1,Form("RecPoints on Layer 1,2 = %d, %d\n",nrpL1,nrpL2));
218 Double_t a[3]={xbeam,ybeam,0.};
219 Double_t b[3]={xbeam,ybeam,10.};
220 AliStrLine zeta(a,b,kTRUE);
221 Float_t bField=AliTracker::GetBz()/10.; //T
222 SetMeanPPtSelTracks(bField);
225 // Loop on modules of layer 1
226 for(Int_t modul1= firstL1; modul1<=lastL1;modul1++){ // Loop on modules of layer 1
227 UShort_t ladder=int(modul1/4)+1; // ladders are numbered starting from 1
228 branch->GetEvent(modul1);
229 Int_t nrecp1 = itsRec->GetEntries();
230 static TClonesArray prpl1("AliITSRecPoint",nrecp1);
232 for(Int_t j=0;j<nrecp1;j++){
233 AliITSRecPoint *recp = (AliITSRecPoint*)itsRec->At(j);
234 new(prpl1[j])AliITSRecPoint(*recp);
236 detTypeRec.ResetRecPoints();
237 for(Int_t j=0;j<nrecp1;j++){
238 AliITSRecPoint *recp1 = (AliITSRecPoint*)prpl1.At(j);
239 // Local coordinates of this recpoint
241 lc[0]=recp1->GetDetLocalX();
242 lc[2]=recp1->GetDetLocalZ();
244 recp1->GetGlobalXYZ(gc1);
245 Double_t phi1 = TMath::ATan2(gc1[1]-ybeam,gc1[0]-xbeam);
246 if(phi1<0)phi1=2*TMath::Pi()+phi1;
247 for(Int_t ladl2=0 ; ladl2<fLadOnLay2*2+1;ladl2++){
248 for(Int_t k=0;k<4;k++){
249 Int_t ladmod=fLadders[ladder-1]+ladl2;
250 if(ladmod>AliITSgeomTGeo::GetNLadders(2)) ladmod=ladmod-AliITSgeomTGeo::GetNLadders(2);
251 Int_t modul2=AliITSgeomTGeo::GetModuleIndex(2,ladmod,k+1);
252 branch->GetEvent(modul2);
253 Int_t nrecp2 = itsRec->GetEntries();
254 for(Int_t j2=0;j2<nrecp2;j2++){
255 AliITSRecPoint *recp2 = (AliITSRecPoint*)itsRec->At(j2);
257 lc2[0]=recp2->GetDetLocalX();
258 lc2[2]=recp2->GetDetLocalZ();
260 recp2->GetGlobalXYZ(gc2);
261 Double_t phi2 = TMath::ATan2(gc2[1]-ybeam,gc2[0]-xbeam);
262 if(phi2<0)phi2=2*TMath::Pi()+phi2;
263 Double_t diff = TMath::Abs(phi2-phi1);
264 if(diff>TMath::Pi())diff=2.*TMath::Pi()-diff;
265 if(diff>deltaPhi)continue;
266 AliStrLine line(gc1,gc2,kTRUE);
268 Int_t retcode = line.Cross(&zeta,cp);
269 if(retcode<0)continue;
270 Double_t dca = line.GetDCA(&zeta);
272 if(dca>deltaR)continue;
273 Double_t deltaZ=cp[2]-zvert;
274 if(TMath::Abs(deltaZ)>dZmax)continue;
277 if(fLines.GetEntriesFast()>0)fLines.Clear("C");
280 recp2->GetGlobalCov(cov);
283 Float_t rad1=TMath::Sqrt(gc1[0]*gc1[0]+gc1[1]*gc1[1]);
284 Float_t rad2=TMath::Sqrt(gc2[0]*gc2[0]+gc2[1]*gc2[1]);
285 Float_t factor=(rad1+rad2)/(rad2-rad1); //factor to account for error on tracklet direction
289 Float_t curvRadius=fMeanPtSelTrk/(0.3*bField)*100; //cm
290 Float_t dRad=TMath::Sqrt(TMath::Power((gc1[0]-gc2[0]),2)+TMath::Power((gc1[1]-gc2[1]),2));
291 Float_t aux=dRad/2.+rad1;
292 curvErr=TMath::Sqrt(curvRadius*curvRadius-dRad*dRad/4.)-TMath::Sqrt(curvRadius*curvRadius-aux*aux); //cm
296 sigmasq[0]=(cov[0]+curvErr*curvErr/2.)*factor*factor;
297 sigmasq[1]=(cov[3]+curvErr*curvErr/2.)*factor*factor;
298 sigmasq[2]=cov[5]*factor*factor;
300 // Multiple scattering
302 Float_t beta2=beta*beta;
303 Float_t p2=fMeanPSelTrk*fMeanPSelTrk;
304 Float_t rBP=GetPipeRadius();
305 Float_t dBP=0.08/35.3; // 800 um of Be
306 Float_t dL1=0.01; //approx. 1% of radiation length
307 Float_t theta2BP=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(dBP);
308 Float_t theta2L1=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(dL1);
309 Float_t thetaBP=TMath::Sqrt(theta2BP);
310 Float_t thetaL1=TMath::Sqrt(theta2L1);
311 // Float_t geomfac[3];
312 // geomfac[0]=sin(phi1)*sin(phi1);
313 // geomfac[1]=cos(phi1)*cos(phi1);
314 // Float_t tgth=(gc2[2]-gc1[2])/(rad2-rad1);
315 // geomfac[2]=1+tgth*tgth;
316 for(Int_t ico=0; ico<3;ico++){
317 // printf("Error on coord. %d due to cov matrix+curvErr=%f\n",ico,sigmasq[ico]);
318 // // sigmasq[ico]+=rad1*rad1*geomfac[ico]*theta2L1/2; // multiple scattering in layer 1
319 // // sigmasq[ico]+=rBP*rBP*geomfac[ico]*theta2BP/2; // multiple scattering in beam pipe
320 sigmasq[ico]+=TMath::Power(rad1*TMath::Tan(thetaL1),2)/3.;
321 sigmasq[ico]+=TMath::Power(rBP*TMath::Tan(thetaBP),2)/3.;
323 // printf("Multipl. scatt. contr %d = %f (LAY1), %f (BP)\n",ico,rad1*rad1*geomfac[ico]*theta2L1/2,rBP*rBP*geomfac[ico]*theta2BP/2);
324 // printf("Total error on coord %d = %f\n",ico,sigmasq[ico]);
326 Float_t wmat[9]={1.,0.,0.,0.,1.,0.,0.,0.,1.};
327 if(sigmasq[0]!=0.) wmat[0]=1./sigmasq[0];
328 if(sigmasq[1]!=0.) wmat[4]=1./sigmasq[1];
329 if(sigmasq[2]!=0.) wmat[8]=1./sigmasq[2];
330 new(fLines[nolines++])AliStrLine(gc1,sigmasq,wmat,gc2,kTRUE);
333 detTypeRec.ResetRecPoints();
339 if(nolines == 0)return -2;
343 //______________________________________________________________________
344 void AliITSVertexer3D::FindVertices(){
345 // computes the vertices of the events in the range FirstEvent - LastEvent
346 AliRunLoader *rl = AliRunLoader::GetRunLoader();
347 AliITSLoader* itsLoader = (AliITSLoader*) rl->GetLoader("ITSLoader");
348 itsLoader->ReloadRecPoints();
349 for(Int_t i=fFirstEvent;i<=fLastEvent;i++){
351 FindVertexForCurrentEvent(i);
353 WriteCurrentVertex();
359 //______________________________________________________________________
360 Int_t AliITSVertexer3D::Prepare3DVertex(Int_t optCuts){
361 // Finds the 3D vertex information using tracklets
367 Float_t deltaR=fCoarseMaxRCut;
368 Float_t dZmax=fZCutDiamond;
370 xbeam=fVert3D.GetXv();
371 ybeam=fVert3D.GetYv();
372 zvert=fVert3D.GetZv();
378 Float_t rl=-fCoarseMaxRCut;
379 Float_t rh=fCoarseMaxRCut;
381 Float_t zl=-fZCutDiamond;
382 Float_t zh=fZCutDiamond;
383 Float_t binsizer=(rh-rl)/nbr;
384 Float_t binsizez=(zh-zl)/nbz;
385 TH3F *h3d = new TH3F("h3d","xyz distribution",nbr,rl,rh,nbr,rl,rh,nbz,zl,zh);
387 // cleanup of the TCLonesArray of tracklets (i.e. fakes are removed)
388 Int_t *validate = new Int_t [fLines.GetEntriesFast()];
389 for(Int_t i=0; i<fLines.GetEntriesFast();i++)validate[i]=0;
390 for(Int_t i=0; i<fLines.GetEntriesFast()-1;i++){
391 if(validate[i]==1)continue;
392 AliStrLine *l1 = (AliStrLine*)fLines.At(i);
393 for(Int_t j=i+1;j<fLines.GetEntriesFast();j++){
394 AliStrLine *l2 = (AliStrLine*)fLines.At(j);
395 Float_t dca=l1->GetDCA(l2);
396 if(dca > fDCAcut || dca<0.00001) continue;
398 Int_t retc = l1->Cross(l2,point);
400 Double_t deltaZ=point[2]-zvert;
401 if(TMath::Abs(deltaZ)>dZmax)continue;
402 Double_t rad=TMath::Sqrt(point[0]*point[0]+point[1]*point[1]);
403 if(rad>fCoarseMaxRCut)continue;
404 Double_t deltaX=point[0]-xbeam;
405 Double_t deltaY=point[1]-ybeam;
406 Double_t raddist=TMath::Sqrt(deltaX*deltaX+deltaY*deltaY);
407 if(raddist>deltaR)continue;
410 h3d->Fill(point[0],point[1],point[2]);
416 Int_t numbtracklets=0;
417 for(Int_t i=0; i<fLines.GetEntriesFast();i++)if(validate[i]>=1)numbtracklets++;
418 if(numbtracklets<2){delete [] validate; delete h3d; return retcode; }
420 for(Int_t i=0; i<fLines.GetEntriesFast();i++){
421 if(validate[i]<1)fLines.RemoveAt(i);
424 AliDebug(1,Form("Number of tracklets (after compress)%d ",fLines.GetEntriesFast()));
428 // finds peak in histo
429 TAxis *xax = h3d->GetXaxis();
430 TAxis *yax = h3d->GetYaxis();
431 TAxis *zax = h3d->GetZaxis();
432 Double_t peak[3]={0.,0.,0.};
433 Float_t contref = 0.;
434 for(Int_t i=xax->GetFirst();i<=xax->GetLast();i++){
435 Float_t xval = xax->GetBinCenter(i);
436 for(Int_t j=yax->GetFirst();j<=yax->GetLast();j++){
437 Float_t yval = yax->GetBinCenter(j);
438 for(Int_t k=zax->GetFirst();k<=zax->GetLast();k++){
439 Float_t bc = h3d->GetBinContent(i,j,k);
440 Float_t zval = zax->GetBinCenter(k);
452 // Second selection loop
453 Float_t bs=(binsizer+binsizez)/2.;
454 for(Int_t i=0; i<fLines.GetEntriesFast();i++){
455 AliStrLine *l1 = (AliStrLine*)fLines.At(i);
456 if(l1->GetDistFromPoint(peak)>2.5*bs)fLines.RemoveAt(i);
459 AliDebug(1,Form("Number of tracklets (after 2nd compression) %d",fLines.GetEntriesFast()));
461 if(fLines.GetEntriesFast()>1){
462 // find a first candidate for the primary vertex
463 fVert3D=AliVertexerTracks::TrackletVertexFinder(&fLines,0);
464 // make a further selection on tracklets based on this first candidate
465 fVert3D.GetXYZ(peak);
466 AliDebug(1,Form("FIRST V candidate: %f ; %f ; %f",peak[0],peak[1],peak[2]));
467 for(Int_t i=0; i<fLines.GetEntriesFast();i++){
468 AliStrLine *l1 = (AliStrLine*)fLines.At(i);
469 if(l1->GetDistFromPoint(peak)> fDCAcut)fLines.RemoveAt(i);
472 AliDebug(1,Form("Number of tracklets (after 3rd compression) %d",fLines.GetEntriesFast()));
473 if(fLines.GetEntriesFast()>1) retcode=0; // this new tracklet selection is used
474 else retcode =1; // the previous tracklet selection will be used
482 //________________________________________________________
483 void AliITSVertexer3D::SetMeanPPtSelTracks(Float_t fieldTesla){
484 // Sets mean values of P and Pt based on the field
485 if(TMath::Abs(fieldTesla-0.5)<0.01){
486 SetMeanPSelTracks(0.885);
487 SetMeanPtSelTracks(0.630);
488 }else if(TMath::Abs(fieldTesla-0.4)<0.01){
489 SetMeanPSelTracks(0.805);
490 SetMeanPtSelTracks(0.580);
491 }else if(TMath::Abs(fieldTesla-0.2)<0.01){
492 SetMeanPSelTracks(0.740);
493 SetMeanPtSelTracks(0.530);
494 }else if(fieldTesla<0.00001){
495 SetMeanPSelTracks(0.730);
496 SetMeanPtSelTracks(0.510);
499 SetMeanPtSelTracks();
504 //________________________________________________________
505 void AliITSVertexer3D::PrintStatus() const {
506 // Print current status
507 printf("=======================================================\n");
508 printf("Loose cut on Delta Phi %f\n",fCoarseDiffPhiCut);
509 printf("Cut on tracklet DCA to Z axis %f\n",fCoarseMaxRCut);
510 printf("Cut on tracklet DCA to beam axis %f\n",fMaxRCut);
511 printf("Cut on diamond (Z) %f\n",fZCutDiamond);
512 printf("Cut on DCA - tracklet to tracklet and to vertex %f\n",fDCAcut);
513 printf(" Max Phi difference: %f\n",fDiffPhiMax);
514 printf("=======================================================\n");