1 /**************************************************************************
2 * Copyright(c) 1998-2003, 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 **************************************************************************/
15 #include "AliITSVertexerZ.h"
17 #include<TClonesArray.h>
21 #include "AliESDVertex.h"
22 #include "AliITSgeomTGeo.h"
23 #include "AliITSRecPoint.h"
24 #include "AliITSRecPointContainer.h"
25 #include "AliITSZPoint.h"
27 /////////////////////////////////////////////////////////////////
28 // this class implements a fast method to determine
29 // the Z coordinate of the primary vertex
30 // for p-p collisions it seems to give comparable or better results
31 // with respect to what obtained with AliITSVertexerPPZ
32 // It can be used successfully with Pb-Pb collisions
33 ////////////////////////////////////////////////////////////////
35 ClassImp(AliITSVertexerZ)
39 //______________________________________________________________________
40 AliITSVertexerZ::AliITSVertexerZ():AliITSVertexer(),
55 // Default constructor
57 SetFirstLayerModules();
58 SetSecondLayerModules();
68 //______________________________________________________________________
69 AliITSVertexerZ::AliITSVertexerZ(Float_t x0, Float_t y0):AliITSVertexer(),
84 // Standard Constructor
86 SetFirstLayerModules();
87 SetSecondLayerModules();
95 SetVtxStart((Double_t)x0,(Double_t)y0,0.);
99 //______________________________________________________________________
100 AliITSVertexerZ::~AliITSVertexerZ() {
105 //______________________________________________________________________
106 void AliITSVertexerZ::ConfigIterations(Int_t noiter,Float_t *ptr){
107 // configure the iterative procedure to gain efficiency for
108 // pp events with very low multiplicity
109 Float_t defaults[5]={0.02,0.05,0.1,0.2,0.3};
112 Error("ConfigIterations","Maximum number of iterations is 5\n");
115 for(Int_t j=0;j<5;j++)fPhiDiffIter[j]=defaults[j];
116 if(ptr)for(Int_t j=0;j<fMaxIter;j++)fPhiDiffIter[j]=ptr[j];
119 //______________________________________________________________________
120 Int_t AliITSVertexerZ::GetPeakRegion(TH1F*h, Int_t &binmin, Int_t &binmax){
121 // Finds a region around a peak in the Z histogram
122 // Case of 2 peaks is treated
123 Int_t imax=h->GetNbinsX();
125 Int_t bi1=h->GetMaximumBin();
127 for(Int_t i=imax;i>=1;i--){
128 if(h->GetBinContent(i)>maxval){
129 maxval=h->GetBinContent(i);
140 TH1F *copy = new TH1F(*h);
141 copy->SetBinContent(bi1,0.);
142 copy->SetBinContent(bi2,0.);
143 Int_t l1=TMath::Max(bi1-3,1);
144 Int_t l2=TMath::Min(bi1+3,h->GetNbinsX());
145 Float_t cont1=copy->Integral(l1,l2);
146 Int_t ll1=TMath::Max(bi2-3,1);
147 Int_t ll2=TMath::Min(bi2+3,h->GetNbinsX());
148 Float_t cont2=copy->Integral(ll1,ll2);
162 if(bi2-bi1==1) npeaks=1;
169 //______________________________________________________________________
170 AliESDVertex* AliITSVertexerZ::FindVertexForCurrentEvent(TTree *itsClusterTree){
171 // Defines the AliESDVertex for the current event
172 VertexZFinder(itsClusterTree);
174 for(Int_t iteraz=0;iteraz<fMaxIter;iteraz++){
175 if(fCurrentVertex) ntrackl=fCurrentVertex->GetNContributors();
176 if(!fCurrentVertex || ntrackl==0 || ntrackl==-1){
177 Float_t diffPhiMaxOrig=fDiffPhiMax;
178 fDiffPhiMax=GetPhiMaxIter(iteraz);
179 VertexZFinder(itsClusterTree);
180 fDiffPhiMax=diffPhiMaxOrig;
183 if(fComputeMultiplicity) FindMultiplicity(itsClusterTree);
184 return fCurrentVertex;
187 //______________________________________________________________________
188 void AliITSVertexerZ::VertexZFinder(TTree *itsClusterTree){
189 // Defines the AliESDVertex for the current event
191 Double_t startPos[3]={GetNominalPos()[0],GetNominalPos()[1],GetNominalPos()[2]};
192 Double_t startCov[6]={GetNominalCov()[0],GetNominalCov()[1],GetNominalCov()[2],
193 GetNominalCov()[3],GetNominalCov()[4],GetNominalCov()[5]};
195 TClonesArray *itsRec = 0;
196 // lc1 and gc1 are local and global coordinates for layer 1
197 Float_t gc1[3]={0.,0.,0.}; // ; for(Int_t ii=0; ii<3; ii++) gc1[ii]=0.;
198 // lc2 and gc2 are local and global coordinates for layer 2
199 Float_t gc2[3]={0.,0.,0.}; //; for(Int_t ii=0; ii<3; ii++) gc2[ii]=0.;
200 AliITSRecPointContainer* rpcont=AliITSRecPointContainer::Instance();
201 itsRec=rpcont->FetchClusters(0,itsClusterTree);
202 if(!rpcont->IsSPDActive()){
203 AliWarning("Null pointer for RecPoints branch, vertex not calculated");
205 fCurrentVertex = new AliESDVertex(startPos,startCov,99999.,-2);
211 nrpL1=rpcont->GetNClustersInLayerFast(1);
212 nrpL2=rpcont->GetNClustersInLayerFast(2);
214 if(nrpL1 == 0 || nrpL2 == 0){
215 AliDebug(1,Form("No RecPoints in at least one SPD layer (%d %d)",nrpL1,nrpL2));
217 fCurrentVertex = new AliESDVertex(startPos,startCov,99999.,-2);
220 // Force a coarse bin size of 200 microns if the number of clusters on layer 2
222 if(nrpL2<fPPsetting[0])SetBinWidthCoarse(fPPsetting[1]);
223 // By default nbincoarse=(10+10)/0.01=2000
224 Int_t nbincoarse = static_cast<Int_t>((fHighLim-fLowLim)/fStepCoarse);
225 if(fZCombc)delete fZCombc;
226 fZCombc = new TH1F("fZCombc","Z",nbincoarse,fLowLim,fLowLim+nbincoarse*fStepCoarse);
228 /* Test the ffect of mutiple scatternig on error. Negligible
229 // Multiple scattering
230 Float_t beta=1.,pmed=0.875; //pmed=875 MeV (for tracks with dphi<0.01 rad)
231 Float_t beta2=beta*beta;
232 Float_t p2=pmed*pmed;
233 Float_t rBP=3; //Beam Pipe radius = 3cm
234 Float_t dBP=0.08/35.3; // 800 um of Be
235 Float_t dL1=0.01; //approx. 1% of radiation length
236 Float_t theta2BP=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(dBP);
237 Float_t theta2L1=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(dL1);
239 Int_t nEntriesMod[kNSPDMod];
240 TClonesArray* recpArr[kNSPDMod];
241 for(Int_t modul=0; modul<kNSPDMod; ++modul) {
242 if(!fUseModule[modul]) {
243 nEntriesMod[modul]=0;
246 recpArr[modul]=rpcont->UncheckedGetClusters(modul);
247 nEntriesMod[modul]=recpArr[modul]->GetEntriesFast();
251 Int_t maxdim=TMath::Min(nrpL1*nrpL2,50000); // temporary; to limit the size in PbPb
252 static TClonesArray points("AliITSZPoint",maxdim);
254 for(Int_t modul1= fFirstL1; modul1<=fLastL1;modul1++){ // Loop on modules of layer 1
255 if(!fUseModule[modul1]) continue;
256 UShort_t ladder=int(modul1/4)+1; // ladders are numbered starting from 1
257 TClonesArray *prpl1=recpArr[modul1]; //rpcont->UncheckedGetClusters(modul1);
258 Int_t nrecp1 = nEntriesMod[modul1]; //prpl1->GetEntries();
259 for(Int_t j1=0;j1<nrecp1;j1++){
260 AliITSRecPoint *recp1 = (AliITSRecPoint*)prpl1->At(j1);
261 recp1->GetGlobalXYZ(gc1);
262 gc1[0]-=GetNominalPos()[0]; // Possible beam offset in the bending plane
263 gc1[1]-=GetNominalPos()[1]; // " "
264 Float_t phi1 = TMath::ATan2(gc1[1],gc1[0]);
265 if(phi1<0)phi1+=TMath::TwoPi();
266 for(Int_t ladl2=0 ; ladl2<fLadOnLay2*2+1;ladl2++){
267 for(Int_t k=0;k<4;k++){
268 Int_t ladmod=fLadders[ladder-1]+ladl2;
269 if(ladmod>AliITSgeomTGeo::GetNLadders(2)) ladmod=ladmod-AliITSgeomTGeo::GetNLadders(2);
270 Int_t modul2=AliITSgeomTGeo::GetModuleIndex(2,ladmod,k+1);
271 if(!fUseModule[modul2]) continue;
272 itsRec=recpArr[modul2]; // rpcont->UncheckedGetClusters(modul2);
273 Int_t nrecp2 = nEntriesMod[modul2]; // itsRec->GetEntries();
274 for(Int_t j2=0;j2<nrecp2;j2++){
275 AliITSRecPoint *recp2 = (AliITSRecPoint*)itsRec->At(j2);
276 recp2->GetGlobalXYZ(gc2);
277 gc2[0]-=GetNominalPos()[0];
278 gc2[1]-=GetNominalPos()[1];
279 Float_t phi2 = TMath::ATan2(gc2[1],gc2[0]);
280 if(phi2<0)phi2+=TMath::TwoPi();
282 Float_t diff = TMath::Abs(phi2-phi1);
283 if(diff>TMath::Pi())diff=TMath::TwoPi()-diff;
284 if(diff<fDiffPhiMax){
285 Float_t r1=TMath::Sqrt(gc1[0]*gc1[0]+gc1[1]*gc1[1]);
287 Float_t erz1=recp1->GetSigmaZ2();
288 Float_t r2=TMath::Sqrt(gc2[0]*gc2[0]+gc2[1]*gc2[1]);
290 Float_t erz2=recp2->GetSigmaZ2();
291 // Float_t tgth=(zc2[j]-zc1[i])/(r2-r1); // slope (used for multiple scattering)
292 Float_t zr0=(r2*zc1-r1*zc2)/(r2-r1); //Z @ null radius
293 Float_t ezr0q=(r2*r2*erz1+r1*r1*erz2)/((r2-r1)*(r2-r1)); //error on Z @ null radius
295 // Multiple scattering
296 ezr0q+=r1*r1*(1+tgth*tgth)*theta2L1/2; // multiple scattering in layer 1
297 ezr0q+=rBP*rBP*(1+tgth*tgth)*theta2BP/2; // multiple scattering in beam pipe
299 if(nopoints<maxdim) new(points[nopoints++])AliITSZPoint(zr0,ezr0q);
310 Double_t contents = fZCombc->GetEntries()- fZCombc->GetBinContent(0)-fZCombc->GetBinContent(nbincoarse+1);
312 // Warning("FindVertexForCurrentEvent","Insufficient number of rec. points\n");
314 fCurrentVertex = new AliESDVertex(startPos,startCov,99999.,-1);
322 if(hc->GetBinContent(hc->GetMaximumBin())<3)hc->Rebin(4);
324 Int_t nPeaks=GetPeakRegion(hc,binmin,binmax);
325 if(nPeaks==2)AliDebug(2,"2 peaks found");
328 Float_t lim1 = hc->GetBinLowEdge(binmin);
329 Float_t lim2 = hc->GetBinLowEdge(binmax)+hc->GetBinWidth(binmax);
330 Float_t widthSR=lim2-lim1;
332 if(nPeaks ==1 && (lim2-lim1)<fWindowWidth){
333 Float_t c=(lim1+lim2)/2.;
334 lim1=c-fWindowWidth/2.;
335 lim2=c+fWindowWidth/2.;
337 Int_t niter = 0, ncontr=0;
341 Float_t semilarg=TMath::Min((lim2-zm),(zm-lim1));
349 for(Int_t i =0; i<points.GetEntries(); i++){
350 AliITSZPoint* p=(AliITSZPoint*)points.UncheckedAt(i);
351 if(p->GetZ()>lim1 && p->GetZ()<lim2){
352 Float_t deno = p->GetErrZ();
360 ezm=TMath::Sqrt(1./ezm);
363 } while(niter<10 && TMath::Abs((zm-lim1)-(lim2-zm))>fTolerance);
364 if(nPeaks==2) ezm=widthSR;
365 Double_t position[3]={GetNominalPos()[0],GetNominalPos()[1],zm};
366 Double_t covmatrix[6]={GetNominalCov()[0],0.,GetNominalCov()[2],0.,0.,ezm};
367 fCurrentVertex = new AliESDVertex(position,covmatrix,99999.,ncontr);
368 fCurrentVertex->SetTitle("vertexer: Z");
369 fCurrentVertex->SetDispersion(fDiffPhiMax);
372 if(ncontr>fMinTrackletsForPilup){
374 Int_t ncontr2=FindSecondPeak(fZCombc,binmin,binmax,secPeakPos);
375 if(ncontr2>=fMinTrackletsForPilup){
380 AliESDVertex secondVert(secPeakPos,0.1,ncontr2);
381 fVertArray = new AliESDVertex[2];
382 fVertArray[0]=(*fCurrentVertex);
383 fVertArray[1]=secondVert;
387 fVertArray = new AliESDVertex[1];
388 fVertArray[0]=(*fCurrentVertex);
395 //_____________________________________________________________________
396 Int_t AliITSVertexerZ::FindSecondPeak(TH1F* h, Int_t binmin,Int_t binmax, Float_t& secPeakPos){
397 for(Int_t i=binmin-1;i<=binmax+1;i++){
398 h->SetBinContent(i,0.);
400 Int_t secPeakBin=h->GetMaximumBin();
401 secPeakPos=h->GetBinCenter(secPeakBin);
402 Int_t secPeakCont=(Int_t)h->GetBinContent(secPeakBin);
403 secPeakCont+=(Int_t)h->GetBinContent(secPeakBin-1);
404 secPeakCont+=(Int_t)h->GetBinContent(secPeakBin+1);
405 secPeakCont+=(Int_t)h->GetBinContent(secPeakBin-2);
406 secPeakCont+=(Int_t)h->GetBinContent(secPeakBin+2);
410 //_____________________________________________________________________
411 void AliITSVertexerZ::ResetHistograms(){
412 // delete TH1 data members
413 if(fZCombc)delete fZCombc;
417 //________________________________________________________
418 void AliITSVertexerZ::PrintStatus() const {
419 // Print current status
420 cout <<"=======================================================\n";
421 cout <<" First layer first and last modules: "<<fFirstL1<<", ";
422 cout <<fLastL1<<endl;
423 cout <<" Second layer first and last modules: "<<fFirstL2<<", ";
424 cout <<fLastL2<<endl;
425 cout <<" Max Phi difference: "<<fDiffPhiMax<<endl;
426 cout <<"Limits for Z histograms: "<<fLowLim<<"; "<<fHighLim<<endl;
427 cout <<"Bin sizes for coarse z histos "<<fStepCoarse<<endl;
428 cout <<" Current Z "<<fZFound<<"; Z sig "<<fZsig<<endl;
430 cout<<"fZCombc exists - entries="<<fZCombc->GetEntries()<<endl;
433 cout<<"fZCombc does not exist\n";
436 cout <<"=======================================================\n";