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 "AliITSDetTypeRec.h"
22 #include "AliITSRecPoint.h"
23 #include "AliITSgeomTGeo.h"
24 #include "AliVertexerTracks.h"
25 #include "AliITSVertexer3D.h"
26 #include "AliITSVertexerZ.h"
27 /////////////////////////////////////////////////////////////////
28 // this class implements a method to determine
29 // the 3 coordinates of the primary vertex
31 // It can be used successfully with Pb-Pb collisions
32 ////////////////////////////////////////////////////////////////
34 ClassImp(AliITSVertexer3D)
38 //______________________________________________________________________
39 AliITSVertexer3D::AliITSVertexer3D():AliITSVertexer(),
40 fLines("AliStrLine",1000),
42 fCoarseDiffPhiCut(0.),
52 // Default constructor
53 SetCoarseDiffPhiCut();
64 //______________________________________________________________________
65 AliITSVertexer3D::~AliITSVertexer3D() {
70 //______________________________________________________________________
71 void AliITSVertexer3D::ResetVert3D(){
76 fVert3D.SetDispersion(0.);
77 fVert3D.SetNContributors(0);
79 //______________________________________________________________________
80 AliESDVertex* AliITSVertexer3D::FindVertexForCurrentEvent(TTree *itsClusterTree){
81 // Defines the AliESDVertex for the current event
83 AliDebug(1,"FindVertexForCurrentEvent - 3D - PROCESSING NEXT EVENT");
86 Int_t nolines = FindTracklets(itsClusterTree,0);
89 Int_t rc=Prepare3DVertex(0);
90 if(rc==0) fVert3D=AliVertexerTracks::TrackletVertexFinder(&fLines,0);
92 printf("Vertex found in first iteration:\n");
94 printf("Start second iteration\n");
96 if(fVert3D.GetNContributors()>0){
98 nolines = FindTracklets(itsClusterTree,1);
100 rc=Prepare3DVertex(1);
101 if(rc==0) fVert3D=AliVertexerTracks::TrackletVertexFinder(&fLines,0);
104 /* uncomment to debug
105 printf("Vertex found in second iteration:\n");
107 end of debug lines */
109 Float_t vRadius=TMath::Sqrt(fVert3D.GetXv()*fVert3D.GetXv()+fVert3D.GetYv()*fVert3D.GetYv());
110 if(vRadius<GetPipeRadius() && fVert3D.GetNContributors()>0){
111 Double_t position[3]={fVert3D.GetXv(),fVert3D.GetYv(),fVert3D.GetZv()};
112 Double_t covmatrix[6];
113 fVert3D.GetCovMatrix(covmatrix);
114 Double_t chi2=99999.;
115 Int_t nContr=fVert3D.GetNContributors();
116 fCurrentVertex = new AliESDVertex(position,covmatrix,chi2,nContr);
117 fCurrentVertex->SetTitle("vertexer: 3D");
118 fCurrentVertex->SetName("SPDVertex3D");
119 fCurrentVertex->SetDispersion(fVert3D.GetDispersion());
123 AliITSVertexerZ vertz(GetNominalPos()[0],GetNominalPos()[1]);
124 AliDebug(1,"Call Vertexer Z\n");
125 AliESDVertex* vtxz = vertz.FindVertexForCurrentEvent(itsClusterTree);
127 Double_t position[3]={GetNominalPos()[0],GetNominalPos()[1],vtxz->GetZv()};
128 Double_t covmatrix[6];
129 vtxz->GetCovMatrix(covmatrix);
130 Double_t chi2=99999.;
131 Int_t nContr=vtxz->GetNContributors();
132 fCurrentVertex = new AliESDVertex(position,covmatrix,chi2,nContr);
133 fCurrentVertex->SetTitle("vertexer: Z");
134 fCurrentVertex->SetName("SPDVertexZ");
136 // printf("Vertexer Z success\n");
140 FindMultiplicity(itsClusterTree);
141 return fCurrentVertex;
144 //______________________________________________________________________
145 Int_t AliITSVertexer3D::FindTracklets(TTree *itsClusterTree, Int_t optCuts){
146 // All the possible combinations between recpoints on layer 1and 2 are
147 // considered. Straight lines (=tracklets)are formed.
148 // The tracklets are processed in Prepare3DVertex
149 AliITSDetTypeRec detTypeRec;
151 TTree *tR = itsClusterTree;
152 detTypeRec.SetTreeAddressR(tR);
153 TClonesArray *itsRec = 0;
154 // lc1 and gc1 are local and global coordinates for layer 1
155 // Float_t lc1[3]={0.,0.,0.};
156 Float_t gc1[3]={0.,0.,0.};
157 // lc2 and gc2 are local and global coordinates for layer 2
158 // Float_t lc2[3]={0.,0.,0.};
159 Float_t gc2[3]={0.,0.,0.};
161 itsRec = detTypeRec.RecPoints();
163 branch = tR->GetBranch("ITSRecPoints");
165 // Set values for cuts
166 Float_t xbeam=0., ybeam=0.;
168 Float_t deltaPhi=fCoarseDiffPhiCut;
169 Float_t deltaR=fCoarseMaxRCut;
170 Float_t dZmax=fZCutDiamond;
172 xbeam=fVert3D.GetXv();
173 ybeam=fVert3D.GetYv();
174 zvert=fVert3D.GetZv();
175 deltaPhi = fDiffPhiMax;
179 Int_t nrpL1 = 0; // number of rec points on layer 1
180 Int_t nrpL2 = 0; // number of rec points on layer 2
182 // By default irstL1=0 and lastL1=79
183 Int_t firstL1 = AliITSgeomTGeo::GetModuleIndex(1,1,1);
184 Int_t lastL1 = AliITSgeomTGeo::GetModuleIndex(2,1,1)-1;
185 for(Int_t module= firstL1; module<=lastL1;module++){ // count number of recopints on layer 1
186 branch->GetEvent(module);
187 nrpL1+= itsRec->GetEntries();
188 detTypeRec.ResetRecPoints();
190 //By default firstL2=80 and lastL2=239
191 Int_t firstL2 = AliITSgeomTGeo::GetModuleIndex(2,1,1);
192 Int_t lastL2 = AliITSgeomTGeo::GetModuleIndex(3,1,1)-1;
193 for(Int_t module= firstL2; module<=lastL2;module++){ // count number of recopints on layer 2
194 branch->GetEvent(module);
195 nrpL2+= itsRec->GetEntries();
196 detTypeRec.ResetRecPoints();
198 if(nrpL1 == 0 || nrpL2 == 0){
201 AliDebug(1,Form("RecPoints on Layer 1,2 = %d, %d\n",nrpL1,nrpL2));
203 Double_t a[3]={xbeam,ybeam,0.};
204 Double_t b[3]={xbeam,ybeam,10.};
205 AliStrLine zeta(a,b,kTRUE);
206 Float_t bField=AliTracker::GetBz()/10.; //T
207 SetMeanPPtSelTracks(bField);
210 // Loop on modules of layer 1
211 for(Int_t modul1= firstL1; modul1<=lastL1;modul1++){ // Loop on modules of layer 1
212 if(!fUseModule[modul1]) continue;
213 UShort_t ladder=int(modul1/4)+1; // ladders are numbered starting from 1
214 branch->GetEvent(modul1);
215 Int_t nrecp1 = itsRec->GetEntries();
216 static TClonesArray prpl1("AliITSRecPoint",nrecp1);
218 for(Int_t j=0;j<nrecp1;j++){
219 AliITSRecPoint *recp = (AliITSRecPoint*)itsRec->At(j);
220 new(prpl1[j])AliITSRecPoint(*recp);
222 detTypeRec.ResetRecPoints();
223 for(Int_t j=0;j<nrecp1;j++){
224 AliITSRecPoint *recp1 = (AliITSRecPoint*)prpl1.At(j);
225 // Local coordinates of this recpoint
227 lc[0]=recp1->GetDetLocalX();
228 lc[2]=recp1->GetDetLocalZ();
230 recp1->GetGlobalXYZ(gc1);
231 Double_t phi1 = TMath::ATan2(gc1[1]-ybeam,gc1[0]-xbeam);
232 if(phi1<0)phi1=2*TMath::Pi()+phi1;
233 for(Int_t ladl2=0 ; ladl2<fLadOnLay2*2+1;ladl2++){
234 for(Int_t k=0;k<4;k++){
235 Int_t ladmod=fLadders[ladder-1]+ladl2;
236 if(ladmod>AliITSgeomTGeo::GetNLadders(2)) ladmod=ladmod-AliITSgeomTGeo::GetNLadders(2);
237 Int_t modul2=AliITSgeomTGeo::GetModuleIndex(2,ladmod,k+1);
238 if(!fUseModule[modul2]) continue;
239 branch->GetEvent(modul2);
240 Int_t nrecp2 = itsRec->GetEntries();
241 for(Int_t j2=0;j2<nrecp2;j2++){
242 AliITSRecPoint *recp2 = (AliITSRecPoint*)itsRec->At(j2);
244 lc2[0]=recp2->GetDetLocalX();
245 lc2[2]=recp2->GetDetLocalZ();
247 recp2->GetGlobalXYZ(gc2);
248 Double_t phi2 = TMath::ATan2(gc2[1]-ybeam,gc2[0]-xbeam);
249 if(phi2<0)phi2=2*TMath::Pi()+phi2;
250 Double_t diff = TMath::Abs(phi2-phi1);
251 if(diff>TMath::Pi())diff=2.*TMath::Pi()-diff;
252 if(diff>deltaPhi)continue;
253 AliStrLine line(gc1,gc2,kTRUE);
255 Int_t retcode = line.Cross(&zeta,cp);
256 if(retcode<0)continue;
257 Double_t dca = line.GetDCA(&zeta);
259 if(dca>deltaR)continue;
260 Double_t deltaZ=cp[2]-zvert;
261 if(TMath::Abs(deltaZ)>dZmax)continue;
264 if(fLines.GetEntriesFast()>0)fLines.Clear("C");
267 recp2->GetGlobalCov(cov);
270 Float_t rad1=TMath::Sqrt(gc1[0]*gc1[0]+gc1[1]*gc1[1]);
271 Float_t rad2=TMath::Sqrt(gc2[0]*gc2[0]+gc2[1]*gc2[1]);
272 Float_t factor=(rad1+rad2)/(rad2-rad1); //factor to account for error on tracklet direction
276 Float_t curvRadius=fMeanPtSelTrk/(0.3*bField)*100; //cm
277 Float_t dRad=TMath::Sqrt(TMath::Power((gc1[0]-gc2[0]),2)+TMath::Power((gc1[1]-gc2[1]),2));
278 Float_t aux=dRad/2.+rad1;
279 curvErr=TMath::Sqrt(curvRadius*curvRadius-dRad*dRad/4.)-TMath::Sqrt(curvRadius*curvRadius-aux*aux); //cm
283 sigmasq[0]=(cov[0]+curvErr*curvErr/2.)*factor*factor;
284 sigmasq[1]=(cov[3]+curvErr*curvErr/2.)*factor*factor;
285 sigmasq[2]=cov[5]*factor*factor;
287 // Multiple scattering
289 Float_t beta2=beta*beta;
290 Float_t p2=fMeanPSelTrk*fMeanPSelTrk;
291 Float_t rBP=GetPipeRadius();
292 Float_t dBP=0.08/35.3; // 800 um of Be
293 Float_t dL1=0.01; //approx. 1% of radiation length
294 Float_t theta2BP=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(dBP);
295 Float_t theta2L1=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(dL1);
296 Float_t thetaBP=TMath::Sqrt(theta2BP);
297 Float_t thetaL1=TMath::Sqrt(theta2L1);
298 // Float_t geomfac[3];
299 // geomfac[0]=sin(phi1)*sin(phi1);
300 // geomfac[1]=cos(phi1)*cos(phi1);
301 // Float_t tgth=(gc2[2]-gc1[2])/(rad2-rad1);
302 // geomfac[2]=1+tgth*tgth;
303 for(Int_t ico=0; ico<3;ico++){
304 // printf("Error on coord. %d due to cov matrix+curvErr=%f\n",ico,sigmasq[ico]);
305 // // sigmasq[ico]+=rad1*rad1*geomfac[ico]*theta2L1/2; // multiple scattering in layer 1
306 // // sigmasq[ico]+=rBP*rBP*geomfac[ico]*theta2BP/2; // multiple scattering in beam pipe
307 sigmasq[ico]+=TMath::Power(rad1*TMath::Tan(thetaL1),2)/3.;
308 sigmasq[ico]+=TMath::Power(rBP*TMath::Tan(thetaBP),2)/3.;
310 // printf("Multipl. scatt. contr %d = %f (LAY1), %f (BP)\n",ico,rad1*rad1*geomfac[ico]*theta2L1/2,rBP*rBP*geomfac[ico]*theta2BP/2);
311 // printf("Total error on coord %d = %f\n",ico,sigmasq[ico]);
313 Float_t wmat[9]={1.,0.,0.,0.,1.,0.,0.,0.,1.};
314 if(sigmasq[0]!=0.) wmat[0]=1./sigmasq[0];
315 if(sigmasq[1]!=0.) wmat[4]=1./sigmasq[1];
316 if(sigmasq[2]!=0.) wmat[8]=1./sigmasq[2];
317 new(fLines[nolines++])AliStrLine(gc1,sigmasq,wmat,gc2,kTRUE);
320 detTypeRec.ResetRecPoints();
326 if(nolines == 0)return -2;
330 //______________________________________________________________________
331 Int_t AliITSVertexer3D::Prepare3DVertex(Int_t optCuts){
332 // Finds the 3D vertex information using tracklets
338 Float_t deltaR=fCoarseMaxRCut;
339 Float_t dZmax=fZCutDiamond;
341 xbeam=fVert3D.GetXv();
342 ybeam=fVert3D.GetYv();
343 zvert=fVert3D.GetZv();
349 Float_t rl=-fCoarseMaxRCut;
350 Float_t rh=fCoarseMaxRCut;
352 Float_t zl=-fZCutDiamond;
353 Float_t zh=fZCutDiamond;
354 Float_t binsizer=(rh-rl)/nbr;
355 Float_t binsizez=(zh-zl)/nbz;
356 TH3F *h3d = new TH3F("h3d","xyz distribution",nbr,rl,rh,nbr,rl,rh,nbz,zl,zh);
358 // cleanup of the TCLonesArray of tracklets (i.e. fakes are removed)
359 Int_t *validate = new Int_t [fLines.GetEntriesFast()];
360 for(Int_t i=0; i<fLines.GetEntriesFast();i++)validate[i]=0;
361 for(Int_t i=0; i<fLines.GetEntriesFast()-1;i++){
362 if(validate[i]==1)continue;
363 AliStrLine *l1 = (AliStrLine*)fLines.At(i);
364 for(Int_t j=i+1;j<fLines.GetEntriesFast();j++){
365 AliStrLine *l2 = (AliStrLine*)fLines.At(j);
366 Float_t dca=l1->GetDCA(l2);
367 if(dca > fDCAcut || dca<0.00001) continue;
369 Int_t retc = l1->Cross(l2,point);
371 Double_t deltaZ=point[2]-zvert;
372 if(TMath::Abs(deltaZ)>dZmax)continue;
373 Double_t rad=TMath::Sqrt(point[0]*point[0]+point[1]*point[1]);
374 if(rad>fCoarseMaxRCut)continue;
375 Double_t deltaX=point[0]-xbeam;
376 Double_t deltaY=point[1]-ybeam;
377 Double_t raddist=TMath::Sqrt(deltaX*deltaX+deltaY*deltaY);
378 if(raddist>deltaR)continue;
381 h3d->Fill(point[0],point[1],point[2]);
387 Int_t numbtracklets=0;
388 for(Int_t i=0; i<fLines.GetEntriesFast();i++)if(validate[i]>=1)numbtracklets++;
389 if(numbtracklets<2){delete [] validate; delete h3d; return retcode; }
391 for(Int_t i=0; i<fLines.GetEntriesFast();i++){
392 if(validate[i]<1)fLines.RemoveAt(i);
395 AliDebug(1,Form("Number of tracklets (after compress)%d ",fLines.GetEntriesFast()));
399 // finds peak in histo
400 TAxis *xax = h3d->GetXaxis();
401 TAxis *yax = h3d->GetYaxis();
402 TAxis *zax = h3d->GetZaxis();
403 Double_t peak[3]={0.,0.,0.};
404 Float_t contref = 0.;
405 for(Int_t i=xax->GetFirst();i<=xax->GetLast();i++){
406 Float_t xval = xax->GetBinCenter(i);
407 for(Int_t j=yax->GetFirst();j<=yax->GetLast();j++){
408 Float_t yval = yax->GetBinCenter(j);
409 for(Int_t k=zax->GetFirst();k<=zax->GetLast();k++){
410 Float_t bc = h3d->GetBinContent(i,j,k);
411 Float_t zval = zax->GetBinCenter(k);
423 // Second selection loop
424 Float_t bs=(binsizer+binsizez)/2.;
425 for(Int_t i=0; i<fLines.GetEntriesFast();i++){
426 AliStrLine *l1 = (AliStrLine*)fLines.At(i);
427 if(l1->GetDistFromPoint(peak)>2.5*bs)fLines.RemoveAt(i);
430 AliDebug(1,Form("Number of tracklets (after 2nd compression) %d",fLines.GetEntriesFast()));
432 if(fLines.GetEntriesFast()>1){
433 // find a first candidate for the primary vertex
434 fVert3D=AliVertexerTracks::TrackletVertexFinder(&fLines,0);
435 // make a further selection on tracklets based on this first candidate
436 fVert3D.GetXYZ(peak);
437 AliDebug(1,Form("FIRST V candidate: %f ; %f ; %f",peak[0],peak[1],peak[2]));
438 for(Int_t i=0; i<fLines.GetEntriesFast();i++){
439 AliStrLine *l1 = (AliStrLine*)fLines.At(i);
440 if(l1->GetDistFromPoint(peak)> fDCAcut)fLines.RemoveAt(i);
443 AliDebug(1,Form("Number of tracklets (after 3rd compression) %d",fLines.GetEntriesFast()));
444 if(fLines.GetEntriesFast()>1) retcode=0; // this new tracklet selection is used
445 else retcode =1; // the previous tracklet selection will be used
453 //________________________________________________________
454 void AliITSVertexer3D::SetMeanPPtSelTracks(Float_t fieldTesla){
455 // Sets mean values of P and Pt based on the field
456 if(TMath::Abs(fieldTesla-0.5)<0.01){
457 SetMeanPSelTracks(0.885);
458 SetMeanPtSelTracks(0.630);
459 }else if(TMath::Abs(fieldTesla-0.4)<0.01){
460 SetMeanPSelTracks(0.805);
461 SetMeanPtSelTracks(0.580);
462 }else if(TMath::Abs(fieldTesla-0.2)<0.01){
463 SetMeanPSelTracks(0.740);
464 SetMeanPtSelTracks(0.530);
465 }else if(fieldTesla<0.00001){
466 SetMeanPSelTracks(0.730);
467 SetMeanPtSelTracks(0.510);
470 SetMeanPtSelTracks();
475 //________________________________________________________
476 void AliITSVertexer3D::PrintStatus() const {
477 // Print current status
478 printf("=======================================================\n");
479 printf("Loose cut on Delta Phi %f\n",fCoarseDiffPhiCut);
480 printf("Cut on tracklet DCA to Z axis %f\n",fCoarseMaxRCut);
481 printf("Cut on tracklet DCA to beam axis %f\n",fMaxRCut);
482 printf("Cut on diamond (Z) %f\n",fZCutDiamond);
483 printf("Cut on DCA - tracklet to tracklet and to vertex %f\n",fDCAcut);
484 printf(" Max Phi difference: %f\n",fDiffPhiMax);
485 printf("=======================================================\n");