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>
22 #include "AliITSLoader.h"
23 #include "AliITSgeom.h"
24 #include "AliITSDetTypeRec.h"
25 #include "AliITSRecPoint.h"
26 #include "AliITSZPoint.h"
27 #include "AliHeader.h"
28 #include "AliGenEventHeader.h"
30 /////////////////////////////////////////////////////////////////
31 // this class implements a fast method to determine
32 // the Z coordinate of the primary vertex
33 // for p-p collisions it seems to give comparable or better results
34 // with respect to what obtained with AliITSVertexerPPZ
35 // It can be used successfully with Pb-Pb collisions
36 ////////////////////////////////////////////////////////////////
38 ClassImp(AliITSVertexerZ)
42 //______________________________________________________________________
43 AliITSVertexerZ::AliITSVertexerZ():AliITSVertexer(),
60 // Default constructor
62 SetFirstLayerModules();
63 SetSecondLayerModules();
73 //______________________________________________________________________
74 AliITSVertexerZ::AliITSVertexerZ(TString fn, Float_t x0, Float_t y0):AliITSVertexer(fn),
91 // Standard Constructor
93 SetFirstLayerModules();
94 SetSecondLayerModules();
105 //______________________________________________________________________
106 AliITSVertexerZ::AliITSVertexerZ(const AliITSVertexerZ &vtxr) : AliITSVertexer(vtxr),
107 fFirstL1(vtxr.fFirstL1),
108 fLastL1(vtxr.fLastL1),
109 fFirstL2(vtxr.fFirstL2),
110 fLastL2(vtxr.fLastL2),
111 fDiffPhiMax(vtxr.fDiffPhiMax),
114 fZFound(vtxr.fZFound),
116 fZCombc(vtxr.fZCombc),
117 fLowLim(vtxr.fLowLim),
118 fHighLim(vtxr.fHighLim),
119 fStepCoarse(vtxr.fStepCoarse),
120 fTolerance(vtxr.fTolerance),
121 fMaxIter(vtxr.fMaxIter),
122 fWindowWidth(vtxr.fWindowWidth){
127 //______________________________________________________________________
128 AliITSVertexerZ& AliITSVertexerZ::operator=(const AliITSVertexerZ& vtxr ){
129 // Assignment operator
131 this->~AliITSVertexerZ();
132 new(this) AliITSVertexerZ(vtxr);
136 //______________________________________________________________________
137 AliITSVertexerZ::~AliITSVertexerZ() {
142 //______________________________________________________________________
143 void AliITSVertexerZ::ConfigIterations(Int_t noiter,Float_t *ptr){
144 // configure the iterative procedure to gain efficiency for
145 // pp events with very low multiplicity
146 Float_t defaults[5]={0.05,0.1,0.2,0.3,0.5};
149 Error("ConfigIterations","Maximum number of iterations is 5\n");
152 for(Int_t j=0;j<5;j++)fPhiDiffIter[j]=defaults[j];
153 if(ptr)for(Int_t j=0;j<fMaxIter;j++)fPhiDiffIter[j]=ptr[j];
156 //______________________________________________________________________
157 Int_t AliITSVertexerZ::GetPeakRegion(TH1F*h, Int_t &binmin, Int_t &binmax) const {
158 // Finds a region around a peak in the Z histogram
159 // Case of 2 peaks is treated
160 Int_t imax=h->GetNbinsX();
162 Int_t bi1=h->GetMaximumBin();
164 for(Int_t i=imax;i>=1;i--){
165 if(h->GetBinContent(i)>maxval){
166 maxval=h->GetBinContent(i);
177 TH1F *copy = new TH1F(*h);
178 copy->SetBinContent(bi1,0.);
179 copy->SetBinContent(bi2,0.);
180 Int_t l1=TMath::Max(bi1-3,1);
181 Int_t l2=TMath::Min(bi1+3,h->GetNbinsX());
182 Float_t cont1=copy->Integral(l1,l2);
183 Int_t ll1=TMath::Max(bi2-3,1);
184 Int_t ll2=TMath::Min(bi2+3,h->GetNbinsX());
185 Float_t cont2=copy->Integral(ll1,ll2);
199 if(bi2-bi1==1) npeaks=1;
206 //______________________________________________________________________
207 AliESDVertex* AliITSVertexerZ::FindVertexForCurrentEvent(Int_t evnumber){
208 // Defines the AliESDVertex for the current event
209 VertexZFinder(evnumber);
211 for(Int_t iteraz=0;iteraz<fMaxIter;iteraz++){
212 if(fCurrentVertex) ntrackl=fCurrentVertex->GetNContributors();
213 if(!fCurrentVertex || ntrackl==0 || ntrackl==-1){
214 Float_t diffPhiMaxOrig=fDiffPhiMax;
215 fDiffPhiMax=GetPhiMaxIter(iteraz);
216 VertexZFinder(evnumber);
217 fDiffPhiMax=diffPhiMaxOrig;
220 FindMultiplicity(evnumber);
221 return fCurrentVertex;
227 //______________________________________________________________________
228 void AliITSVertexerZ::VertexZFinder(Int_t evnumber){
229 // Defines the AliESDVertex for the current event
231 AliRunLoader *rl =AliRunLoader::GetRunLoader();
232 AliITSLoader* itsLoader = (AliITSLoader*)rl->GetLoader("ITSLoader");
233 AliITSgeom* geom = itsLoader->GetITSgeom();
234 itsLoader->LoadRecPoints();
235 rl->GetEvent(evnumber);
237 AliITSDetTypeRec detTypeRec;
239 TTree *tR = itsLoader->TreeR();
240 detTypeRec.SetTreeAddressR(tR);
241 TClonesArray *itsRec = 0;
242 // lc and gc are local and global coordinates for layer 1
243 Float_t lc[3]; for(Int_t ii=0; ii<3; ii++) lc[ii]=0.;
244 Float_t gc[3]; for(Int_t ii=0; ii<3; ii++) gc[ii]=0.;
245 // lc2 and gc2 are local and global coordinates for layer 2
246 Float_t lc2[3]; for(Int_t ii=0; ii<3; ii++) lc2[ii]=0.;
247 Float_t gc2[3]; for(Int_t ii=0; ii<3; ii++) gc2[ii]=0.;
249 itsRec = detTypeRec.RecPoints();
251 branch = tR->GetBranch("ITSRecPoints");
255 // By default fFirstL1=0 and fLastL1=79
256 // This loop counts the number of recpoints on layer1 (central modules)
257 for(Int_t module= fFirstL1; module<=fLastL1;module++){
258 // Keep only central modules
259 // if(module%4==0 || module%4==3)continue;
260 // cout<<"Procesing module "<<module<<" ";
261 branch->GetEvent(module);
262 // cout<<"Number of clusters "<<clusters->GetEntries()<<endl;
263 nrpL1+= itsRec->GetEntries();
264 detTypeRec.ResetRecPoints();
266 //By default fFirstL2=80 and fLastL2=239
267 //This loop counts the number of RP on layer 2
268 for(Int_t module= fFirstL2; module<=fLastL2;module++){
269 branch->GetEvent(module);
270 nrpL2+= itsRec->GetEntries();
271 detTypeRec.ResetRecPoints();
273 if(nrpL1 == 0 || nrpL2 == 0){
275 itsLoader->UnloadRecPoints();
276 fCurrentVertex = new AliESDVertex(0.,5.3,-2);
279 // The vertex finding is attempted only if the number of RP is !=0 on
281 Float_t *xc1 = new Float_t [nrpL1]; // coordinates of the L1 Recpoints
282 Float_t *yc1 = new Float_t [nrpL1];
283 Float_t *zc1 = new Float_t [nrpL1];
284 Float_t *phi1 = new Float_t [nrpL1];
285 Float_t *err1 = new Float_t [nrpL1];
286 Float_t *xc2 = new Float_t [nrpL2]; // coordinates of the L1 Recpoints
287 Float_t *yc2 = new Float_t [nrpL2];
288 Float_t *zc2 = new Float_t [nrpL2];
289 Float_t *phi2 = new Float_t [nrpL2];
290 Float_t *err2 = new Float_t [nrpL2];
291 Int_t ind = 0;// running index for RP
292 // Force a coarse bin size of 200 microns if the number of clusters on layer 2
294 if(nrpL2<fPPsetting[0])SetBinWidthCoarse(fPPsetting[1]);
295 // By default nbincoarse=(10+10)/0.01=2000
296 Int_t nbincoarse = static_cast<Int_t>((fHighLim-fLowLim)/fStepCoarse);
297 if(fZCombc)delete fZCombc;
298 fZCombc = new TH1F("fZCombc","Z",nbincoarse,fLowLim,fLowLim+nbincoarse*fStepCoarse);
300 // Loop on modules of layer 1
302 for(Int_t module= fFirstL1; module<=fLastL1;module++){
303 // if(module%4==0 || module%4==3)continue;
304 branch->GetEvent(module);
305 Int_t nrecp1 = itsRec->GetEntries();
306 for(Int_t j=0;j<nrecp1;j++){
307 AliITSRecPoint *recp = (AliITSRecPoint*)itsRec->At(j);
308 // Local coordinates of this recpoint
309 lc[0]=recp->GetDetLocalX();
310 lc[2]=recp->GetDetLocalZ();
311 geom->LtoG(module,lc,gc);
312 // Global coordinates of this recpoints
313 gc[0]-=fX0; // Possible beam offset in the bending plane
318 // azimuthal angle is computed in the interval 0 --> 2*pi
319 phi1[ind] = TMath::ATan2(gc[1],gc[0]);
320 if(phi1[ind]<0)phi1[ind]=2*TMath::Pi()+phi1[ind];
321 err1[ind]=recp->GetSigmaZ2();
324 detTypeRec.ResetRecPoints();
326 ind = 0; // the running index is reset for Layer 2
327 for(Int_t module= fFirstL2; module<=fLastL2;module++){
328 branch->GetEvent(module);
329 Int_t nrecp2 = itsRec->GetEntries();
330 for(Int_t j=0;j<nrecp2;j++){
331 AliITSRecPoint *recp = (AliITSRecPoint*)itsRec->At(j);
332 lc[0]=recp->GetDetLocalX();
333 lc[2]=recp->GetDetLocalZ();
334 geom->LtoG(module,lc,gc);
340 phi2[ind] = TMath::ATan2(gc[1],gc[0]);
341 if(phi2[ind]<0)phi2[ind]=2*TMath::Pi()+phi2[ind];
342 err2[ind]=recp->GetSigmaZ2();
345 detTypeRec.ResetRecPoints();
348 /* Test the ffect of mutiple scatternig on error. Negligible
349 // Multiple scattering
350 Float_t beta=1.,pmed=0.875; //pmed=875 MeV (for tracks with dphi<0.01 rad)
351 Float_t beta2=beta*beta;
352 Float_t p2=pmed*pmed;
353 Float_t rBP=3; //Beam Pipe radius = 3cm
354 Float_t dBP=0.08/35.3; // 800 um of Be
355 Float_t dL1=0.01; //approx. 1% of radiation length
356 Float_t theta2BP=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(dBP);
357 Float_t theta2L1=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(dL1);
359 TClonesArray *points = new TClonesArray("AliITSZPoint",nrpL1*nrpL2);
360 TClonesArray &pts = *points;
362 for(Int_t i=0;i<nrpL1;i++){ // loop on L1 RP
363 Float_t r1=TMath::Sqrt(xc1[i]*xc1[i]+yc1[i]*yc1[i]); // radius L1 RP
364 for(Int_t j=0;j<nrpL2;j++){ // loop on L2 RP
365 Float_t diff = TMath::Abs(phi2[j]-phi1[i]); // diff in azimuth
366 if(diff>TMath::Pi())diff=2.*TMath::Pi()-diff; //diff<pi
367 if(diff<fDiffPhiMax){ // cut on 10 milliradians by def.
368 Float_t r2=TMath::Sqrt(xc2[j]*xc2[j]+yc2[j]*yc2[j]); // radius L2 RP
369 // Float_t tgth=(zc2[j]-zc1[i])/(r2-r1); // slope
370 Float_t zr0=(r2*zc1[i]-r1*zc2[j])/(r2-r1); //Z @ null radius
371 Float_t ezr0q=(r2*r2*err1[i]+r1*r1*err2[j])/(r2-r1)/(r2-r1); //error on Z @ null radius
373 ezr0q+=r1*r1*(1+tgth*tgth)*theta2L1/2; // multiple scattering in layer 1
374 ezr0q+=rBP*rBP*(1+tgth*tgth)*theta2BP/2; // multiple scattering in beam pipe
376 new(pts[nopoints++])AliITSZPoint(zr0,ezr0q);
395 Double_t contents = fZCombc->GetEntries()- fZCombc->GetBinContent(0)-fZCombc->GetBinContent(nbincoarse+1);
397 // Warning("FindVertexForCurrentEvent","Insufficient number of rec. points\n");
399 itsLoader->UnloadRecPoints();
400 fCurrentVertex = new AliESDVertex(0.,5.3,-1);
407 if(hc->GetBinContent(hc->GetMaximumBin())<3)hc->Rebin(3);
409 Int_t nPeaks=GetPeakRegion(hc,binmin,binmax);
410 if(nPeaks==2)AliWarning("2 peaks found");
413 Float_t lim1 = hc->GetBinLowEdge(binmin);
414 Float_t lim2 = hc->GetBinLowEdge(binmax)+hc->GetBinWidth(binmax);
416 if(nPeaks ==1 && (lim2-lim1)<fWindowWidth){
417 Float_t c=(lim1+lim2)/2.;
418 lim1=c-fWindowWidth/2.;
419 lim2=c+fWindowWidth/2.;
421 Int_t niter = 0, ncontr=0;
425 Float_t semilarg=TMath::Min((lim2-zm),(zm-lim1));
433 for(Int_t i =0; i<points->GetEntriesFast(); i++){
434 AliITSZPoint* p=(AliITSZPoint*)points->UncheckedAt(i);
435 if(p->GetZ()>lim1 && p->GetZ()<lim2){
436 Float_t deno = p->GetErrZ();
443 ezm=TMath::Sqrt(1./ezm);
445 } while(niter<10 && TMath::Abs((zm-lim1)-(lim2-zm))>fTolerance);
446 fCurrentVertex = new AliESDVertex(zm,ezm,ncontr);
447 fCurrentVertex->SetTitle("vertexer: B");
449 itsLoader->UnloadRecPoints();
453 //_____________________________________________________________________
454 void AliITSVertexerZ::ResetHistograms(){
455 // delete TH1 data members
456 if(fZCombc)delete fZCombc;
460 //______________________________________________________________________
461 void AliITSVertexerZ::FindVertices(){
462 // computes the vertices of the events in the range FirstEvent - LastEvent
463 AliRunLoader *rl = AliRunLoader::GetRunLoader();
464 AliITSLoader* itsLoader = (AliITSLoader*) rl->GetLoader("ITSLoader");
465 itsLoader->ReloadRecPoints();
466 for(Int_t i=fFirstEvent;i<=fLastEvent;i++){
467 // cout<<"Processing event "<<i<<endl;
469 FindVertexForCurrentEvent(i);
471 WriteCurrentVertex();
476 //________________________________________________________
477 void AliITSVertexerZ::PrintStatus() const {
478 // Print current status
479 cout <<"=======================================================\n";
480 cout <<" First layer first and last modules: "<<fFirstL1<<", ";
481 cout <<fLastL1<<endl;
482 cout <<" Second layer first and last modules: "<<fFirstL2<<", ";
483 cout <<fLastL2<<endl;
484 cout <<" Max Phi difference: "<<fDiffPhiMax<<endl;
485 cout <<"Limits for Z histograms: "<<fLowLim<<"; "<<fHighLim<<endl;
486 cout <<"Bin sizes for coarse z histos "<<fStepCoarse<<endl;
487 cout <<" Current Z "<<fZFound<<"; Z sig "<<fZsig<<endl;
488 cout <<" Debug flag: "<<fDebug<<endl;
489 cout <<"First event to be processed "<<fFirstEvent;
490 cout <<"\n Last event to be processed "<<fLastEvent<<endl;
492 cout<<"fZCombc exists - entries="<<fZCombc->GetEntries()<<endl;
495 cout<<"fZCombc does not exist\n";
498 cout <<"=======================================================\n";