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 /////////////////////////////////////////////////////////////////
27 // this class implements a method to determine
28 // the 3 coordinates of the primary vertex
30 // It can be used successfully with Pb-Pb collisions
31 ////////////////////////////////////////////////////////////////
33 ClassImp(AliITSVertexer3D)
37 //______________________________________________________________________
38 AliITSVertexer3D::AliITSVertexer3D():AliITSVertexer(),
39 fLines("AliStrLine",1000),
41 fCoarseDiffPhiCut(0.),
51 // Default constructor
52 SetCoarseDiffPhiCut();
63 //______________________________________________________________________
64 AliITSVertexer3D::~AliITSVertexer3D() {
69 //______________________________________________________________________
70 void AliITSVertexer3D::ResetVert3D(){
75 fVert3D.SetDispersion(0.);
76 fVert3D.SetNContributors(0);
78 //______________________________________________________________________
79 AliESDVertex* AliITSVertexer3D::FindVertexForCurrentEvent(TTree *itsClusterTree){
80 // Defines the AliESDVertex for the current event
82 AliDebug(1,"FindVertexForCurrentEvent - 3D - PROCESSING NEXT EVENT");
85 Int_t nolines = FindTracklets(itsClusterTree,0);
87 if(nolines<2)return fCurrentVertex;
88 Int_t rc=Prepare3DVertex(0);
89 if(rc==0) fVert3D=AliVertexerTracks::TrackletVertexFinder(&fLines,0);
91 printf("Vertex found in first iteration:\n");
93 printf("Start second iteration\n");
95 if(fVert3D.GetNContributors()>0){
97 nolines = FindTracklets(itsClusterTree,1);
99 rc=Prepare3DVertex(1);
100 if(rc==0) fVert3D=AliVertexerTracks::TrackletVertexFinder(&fLines,0);
103 /* uncomment to debug
104 printf("Vertex found in second iteration:\n");
106 end of debug lines */
108 Float_t vRadius=TMath::Sqrt(fVert3D.GetXv()*fVert3D.GetXv()+fVert3D.GetYv()*fVert3D.GetYv());
109 if(vRadius<GetPipeRadius() && fVert3D.GetNContributors()>0){
110 Double_t position[3]={fVert3D.GetXv(),fVert3D.GetYv(),fVert3D.GetZv()};
111 Double_t covmatrix[6];
112 fVert3D.GetCovMatrix(covmatrix);
113 Double_t chi2=99999.;
114 Int_t nContr=fVert3D.GetNContributors();
115 fCurrentVertex = new AliESDVertex(position,covmatrix,chi2,nContr);
116 fCurrentVertex->SetTitle("vertexer: 3D");
117 fCurrentVertex->SetName("Vertex");
118 fCurrentVertex->SetDispersion(fVert3D.GetDispersion());
120 FindMultiplicity(itsClusterTree);
121 return fCurrentVertex;
124 //______________________________________________________________________
125 Int_t AliITSVertexer3D::FindTracklets(TTree *itsClusterTree, Int_t optCuts){
126 // All the possible combinations between recpoints on layer 1and 2 are
127 // considered. Straight lines (=tracklets)are formed.
128 // The tracklets are processed in Prepare3DVertex
129 AliITSDetTypeRec detTypeRec;
131 TTree *tR = itsClusterTree;
132 detTypeRec.SetTreeAddressR(tR);
133 TClonesArray *itsRec = 0;
134 // lc1 and gc1 are local and global coordinates for layer 1
135 // Float_t lc1[3]={0.,0.,0.};
136 Float_t gc1[3]={0.,0.,0.};
137 // lc2 and gc2 are local and global coordinates for layer 2
138 // Float_t lc2[3]={0.,0.,0.};
139 Float_t gc2[3]={0.,0.,0.};
141 itsRec = detTypeRec.RecPoints();
143 branch = tR->GetBranch("ITSRecPoints");
145 // Set values for cuts
146 Float_t xbeam=0., ybeam=0.;
148 Float_t deltaPhi=fCoarseDiffPhiCut;
149 Float_t deltaR=fCoarseMaxRCut;
150 Float_t dZmax=fZCutDiamond;
152 xbeam=fVert3D.GetXv();
153 ybeam=fVert3D.GetYv();
154 zvert=fVert3D.GetZv();
155 deltaPhi = fDiffPhiMax;
159 Int_t nrpL1 = 0; // number of rec points on layer 1
160 Int_t nrpL2 = 0; // number of rec points on layer 2
162 // By default irstL1=0 and lastL1=79
163 Int_t firstL1 = AliITSgeomTGeo::GetModuleIndex(1,1,1);
164 Int_t lastL1 = AliITSgeomTGeo::GetModuleIndex(2,1,1)-1;
165 for(Int_t module= firstL1; module<=lastL1;module++){ // count number of recopints on layer 1
166 branch->GetEvent(module);
167 nrpL1+= itsRec->GetEntries();
168 detTypeRec.ResetRecPoints();
170 //By default firstL2=80 and lastL2=239
171 Int_t firstL2 = AliITSgeomTGeo::GetModuleIndex(2,1,1);
172 Int_t lastL2 = AliITSgeomTGeo::GetModuleIndex(3,1,1)-1;
173 for(Int_t module= firstL2; module<=lastL2;module++){ // count number of recopints on layer 2
174 branch->GetEvent(module);
175 nrpL2+= itsRec->GetEntries();
176 detTypeRec.ResetRecPoints();
178 if(nrpL1 == 0 || nrpL2 == 0){
181 AliDebug(1,Form("RecPoints on Layer 1,2 = %d, %d\n",nrpL1,nrpL2));
183 Double_t a[3]={xbeam,ybeam,0.};
184 Double_t b[3]={xbeam,ybeam,10.};
185 AliStrLine zeta(a,b,kTRUE);
186 Float_t bField=AliTracker::GetBz()/10.; //T
187 SetMeanPPtSelTracks(bField);
190 // Loop on modules of layer 1
191 for(Int_t modul1= firstL1; modul1<=lastL1;modul1++){ // Loop on modules of layer 1
192 UShort_t ladder=int(modul1/4)+1; // ladders are numbered starting from 1
193 branch->GetEvent(modul1);
194 Int_t nrecp1 = itsRec->GetEntries();
195 static TClonesArray prpl1("AliITSRecPoint",nrecp1);
197 for(Int_t j=0;j<nrecp1;j++){
198 AliITSRecPoint *recp = (AliITSRecPoint*)itsRec->At(j);
199 new(prpl1[j])AliITSRecPoint(*recp);
201 detTypeRec.ResetRecPoints();
202 for(Int_t j=0;j<nrecp1;j++){
203 AliITSRecPoint *recp1 = (AliITSRecPoint*)prpl1.At(j);
204 // Local coordinates of this recpoint
206 lc[0]=recp1->GetDetLocalX();
207 lc[2]=recp1->GetDetLocalZ();
209 recp1->GetGlobalXYZ(gc1);
210 Double_t phi1 = TMath::ATan2(gc1[1]-ybeam,gc1[0]-xbeam);
211 if(phi1<0)phi1=2*TMath::Pi()+phi1;
212 for(Int_t ladl2=0 ; ladl2<fLadOnLay2*2+1;ladl2++){
213 for(Int_t k=0;k<4;k++){
214 Int_t ladmod=fLadders[ladder-1]+ladl2;
215 if(ladmod>AliITSgeomTGeo::GetNLadders(2)) ladmod=ladmod-AliITSgeomTGeo::GetNLadders(2);
216 Int_t modul2=AliITSgeomTGeo::GetModuleIndex(2,ladmod,k+1);
217 branch->GetEvent(modul2);
218 Int_t nrecp2 = itsRec->GetEntries();
219 for(Int_t j2=0;j2<nrecp2;j2++){
220 AliITSRecPoint *recp2 = (AliITSRecPoint*)itsRec->At(j2);
222 lc2[0]=recp2->GetDetLocalX();
223 lc2[2]=recp2->GetDetLocalZ();
225 recp2->GetGlobalXYZ(gc2);
226 Double_t phi2 = TMath::ATan2(gc2[1]-ybeam,gc2[0]-xbeam);
227 if(phi2<0)phi2=2*TMath::Pi()+phi2;
228 Double_t diff = TMath::Abs(phi2-phi1);
229 if(diff>TMath::Pi())diff=2.*TMath::Pi()-diff;
230 if(diff>deltaPhi)continue;
231 AliStrLine line(gc1,gc2,kTRUE);
233 Int_t retcode = line.Cross(&zeta,cp);
234 if(retcode<0)continue;
235 Double_t dca = line.GetDCA(&zeta);
237 if(dca>deltaR)continue;
238 Double_t deltaZ=cp[2]-zvert;
239 if(TMath::Abs(deltaZ)>dZmax)continue;
242 if(fLines.GetEntriesFast()>0)fLines.Clear("C");
245 recp2->GetGlobalCov(cov);
248 Float_t rad1=TMath::Sqrt(gc1[0]*gc1[0]+gc1[1]*gc1[1]);
249 Float_t rad2=TMath::Sqrt(gc2[0]*gc2[0]+gc2[1]*gc2[1]);
250 Float_t factor=(rad1+rad2)/(rad2-rad1); //factor to account for error on tracklet direction
254 Float_t curvRadius=fMeanPtSelTrk/(0.3*bField)*100; //cm
255 Float_t dRad=TMath::Sqrt(TMath::Power((gc1[0]-gc2[0]),2)+TMath::Power((gc1[1]-gc2[1]),2));
256 Float_t aux=dRad/2.+rad1;
257 curvErr=TMath::Sqrt(curvRadius*curvRadius-dRad*dRad/4.)-TMath::Sqrt(curvRadius*curvRadius-aux*aux); //cm
261 sigmasq[0]=(cov[0]+curvErr*curvErr/2.)*factor*factor;
262 sigmasq[1]=(cov[3]+curvErr*curvErr/2.)*factor*factor;
263 sigmasq[2]=cov[5]*factor*factor;
265 // Multiple scattering
267 Float_t beta2=beta*beta;
268 Float_t p2=fMeanPSelTrk*fMeanPSelTrk;
269 Float_t rBP=GetPipeRadius();
270 Float_t dBP=0.08/35.3; // 800 um of Be
271 Float_t dL1=0.01; //approx. 1% of radiation length
272 Float_t theta2BP=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(dBP);
273 Float_t theta2L1=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(dL1);
274 Float_t thetaBP=TMath::Sqrt(theta2BP);
275 Float_t thetaL1=TMath::Sqrt(theta2L1);
276 // Float_t geomfac[3];
277 // geomfac[0]=sin(phi1)*sin(phi1);
278 // geomfac[1]=cos(phi1)*cos(phi1);
279 // Float_t tgth=(gc2[2]-gc1[2])/(rad2-rad1);
280 // geomfac[2]=1+tgth*tgth;
281 for(Int_t ico=0; ico<3;ico++){
282 // printf("Error on coord. %d due to cov matrix+curvErr=%f\n",ico,sigmasq[ico]);
283 // // sigmasq[ico]+=rad1*rad1*geomfac[ico]*theta2L1/2; // multiple scattering in layer 1
284 // // sigmasq[ico]+=rBP*rBP*geomfac[ico]*theta2BP/2; // multiple scattering in beam pipe
285 sigmasq[ico]+=TMath::Power(rad1*TMath::Tan(thetaL1),2)/3.;
286 sigmasq[ico]+=TMath::Power(rBP*TMath::Tan(thetaBP),2)/3.;
288 // printf("Multipl. scatt. contr %d = %f (LAY1), %f (BP)\n",ico,rad1*rad1*geomfac[ico]*theta2L1/2,rBP*rBP*geomfac[ico]*theta2BP/2);
289 // printf("Total error on coord %d = %f\n",ico,sigmasq[ico]);
291 Float_t wmat[9]={1.,0.,0.,0.,1.,0.,0.,0.,1.};
292 if(sigmasq[0]!=0.) wmat[0]=1./sigmasq[0];
293 if(sigmasq[1]!=0.) wmat[4]=1./sigmasq[1];
294 if(sigmasq[2]!=0.) wmat[8]=1./sigmasq[2];
295 new(fLines[nolines++])AliStrLine(gc1,sigmasq,wmat,gc2,kTRUE);
298 detTypeRec.ResetRecPoints();
304 if(nolines == 0)return -2;
308 //______________________________________________________________________
309 Int_t AliITSVertexer3D::Prepare3DVertex(Int_t optCuts){
310 // Finds the 3D vertex information using tracklets
316 Float_t deltaR=fCoarseMaxRCut;
317 Float_t dZmax=fZCutDiamond;
319 xbeam=fVert3D.GetXv();
320 ybeam=fVert3D.GetYv();
321 zvert=fVert3D.GetZv();
327 Float_t rl=-fCoarseMaxRCut;
328 Float_t rh=fCoarseMaxRCut;
330 Float_t zl=-fZCutDiamond;
331 Float_t zh=fZCutDiamond;
332 Float_t binsizer=(rh-rl)/nbr;
333 Float_t binsizez=(zh-zl)/nbz;
334 TH3F *h3d = new TH3F("h3d","xyz distribution",nbr,rl,rh,nbr,rl,rh,nbz,zl,zh);
336 // cleanup of the TCLonesArray of tracklets (i.e. fakes are removed)
337 Int_t *validate = new Int_t [fLines.GetEntriesFast()];
338 for(Int_t i=0; i<fLines.GetEntriesFast();i++)validate[i]=0;
339 for(Int_t i=0; i<fLines.GetEntriesFast()-1;i++){
340 if(validate[i]==1)continue;
341 AliStrLine *l1 = (AliStrLine*)fLines.At(i);
342 for(Int_t j=i+1;j<fLines.GetEntriesFast();j++){
343 AliStrLine *l2 = (AliStrLine*)fLines.At(j);
344 Float_t dca=l1->GetDCA(l2);
345 if(dca > fDCAcut || dca<0.00001) continue;
347 Int_t retc = l1->Cross(l2,point);
349 Double_t deltaZ=point[2]-zvert;
350 if(TMath::Abs(deltaZ)>dZmax)continue;
351 Double_t rad=TMath::Sqrt(point[0]*point[0]+point[1]*point[1]);
352 if(rad>fCoarseMaxRCut)continue;
353 Double_t deltaX=point[0]-xbeam;
354 Double_t deltaY=point[1]-ybeam;
355 Double_t raddist=TMath::Sqrt(deltaX*deltaX+deltaY*deltaY);
356 if(raddist>deltaR)continue;
359 h3d->Fill(point[0],point[1],point[2]);
365 Int_t numbtracklets=0;
366 for(Int_t i=0; i<fLines.GetEntriesFast();i++)if(validate[i]>=1)numbtracklets++;
367 if(numbtracklets<2){delete [] validate; delete h3d; return retcode; }
369 for(Int_t i=0; i<fLines.GetEntriesFast();i++){
370 if(validate[i]<1)fLines.RemoveAt(i);
373 AliDebug(1,Form("Number of tracklets (after compress)%d ",fLines.GetEntriesFast()));
377 // finds peak in histo
378 TAxis *xax = h3d->GetXaxis();
379 TAxis *yax = h3d->GetYaxis();
380 TAxis *zax = h3d->GetZaxis();
381 Double_t peak[3]={0.,0.,0.};
382 Float_t contref = 0.;
383 for(Int_t i=xax->GetFirst();i<=xax->GetLast();i++){
384 Float_t xval = xax->GetBinCenter(i);
385 for(Int_t j=yax->GetFirst();j<=yax->GetLast();j++){
386 Float_t yval = yax->GetBinCenter(j);
387 for(Int_t k=zax->GetFirst();k<=zax->GetLast();k++){
388 Float_t bc = h3d->GetBinContent(i,j,k);
389 Float_t zval = zax->GetBinCenter(k);
401 // Second selection loop
402 Float_t bs=(binsizer+binsizez)/2.;
403 for(Int_t i=0; i<fLines.GetEntriesFast();i++){
404 AliStrLine *l1 = (AliStrLine*)fLines.At(i);
405 if(l1->GetDistFromPoint(peak)>2.5*bs)fLines.RemoveAt(i);
408 AliDebug(1,Form("Number of tracklets (after 2nd compression) %d",fLines.GetEntriesFast()));
410 if(fLines.GetEntriesFast()>1){
411 // find a first candidate for the primary vertex
412 fVert3D=AliVertexerTracks::TrackletVertexFinder(&fLines,0);
413 // make a further selection on tracklets based on this first candidate
414 fVert3D.GetXYZ(peak);
415 AliDebug(1,Form("FIRST V candidate: %f ; %f ; %f",peak[0],peak[1],peak[2]));
416 for(Int_t i=0; i<fLines.GetEntriesFast();i++){
417 AliStrLine *l1 = (AliStrLine*)fLines.At(i);
418 if(l1->GetDistFromPoint(peak)> fDCAcut)fLines.RemoveAt(i);
421 AliDebug(1,Form("Number of tracklets (after 3rd compression) %d",fLines.GetEntriesFast()));
422 if(fLines.GetEntriesFast()>1) retcode=0; // this new tracklet selection is used
423 else retcode =1; // the previous tracklet selection will be used
431 //________________________________________________________
432 void AliITSVertexer3D::SetMeanPPtSelTracks(Float_t fieldTesla){
433 // Sets mean values of P and Pt based on the field
434 if(TMath::Abs(fieldTesla-0.5)<0.01){
435 SetMeanPSelTracks(0.885);
436 SetMeanPtSelTracks(0.630);
437 }else if(TMath::Abs(fieldTesla-0.4)<0.01){
438 SetMeanPSelTracks(0.805);
439 SetMeanPtSelTracks(0.580);
440 }else if(TMath::Abs(fieldTesla-0.2)<0.01){
441 SetMeanPSelTracks(0.740);
442 SetMeanPtSelTracks(0.530);
443 }else if(fieldTesla<0.00001){
444 SetMeanPSelTracks(0.730);
445 SetMeanPtSelTracks(0.510);
448 SetMeanPtSelTracks();
453 //________________________________________________________
454 void AliITSVertexer3D::PrintStatus() const {
455 // Print current status
456 printf("=======================================================\n");
457 printf("Loose cut on Delta Phi %f\n",fCoarseDiffPhiCut);
458 printf("Cut on tracklet DCA to Z axis %f\n",fCoarseMaxRCut);
459 printf("Cut on tracklet DCA to beam axis %f\n",fMaxRCut);
460 printf("Cut on diamond (Z) %f\n",fZCutDiamond);
461 printf("Cut on DCA - tracklet to tracklet and to vertex %f\n",fDCAcut);
462 printf(" Max Phi difference: %f\n",fDiffPhiMax);
463 printf("=======================================================\n");