Functionality to create AOD files from ESD files added in AliReconstruction.

[u/mrichter/AliRoot.git] / PHOS / AliPHOSTrackSegmentMakerv1.cxx

/**************************************************************************
 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
 *                                                                        *
 * Author: The ALICE Off-line Project.                                    *
 * Contributors are mentioned in the code where appropriate.              *
 *                                                                        *
 * Permission to use, copy, modify and distribute this software and its   *
 * documentation strictly for non-commercial purposes is hereby granted   *
 * without fee, provided that the above copyright notice appears in all   *
 * copies and that both the copyright notice and this permission notice   *
 * appear in the supporting documentation. The authors make no claims     *
 * about the suitability of this software for any purpose. It is          *
 * provided "as is" without express or implied warranty.                  *
 **************************************************************************/
/* $Id$ */

/* History of cvs commits:
 *
 * $Log$
 * Revision 1.83  2007/03/06 21:07:37  kharlov
 * DP: xz CPV-EMC distance filled to TS
 *
 * Revision 1.82  2007/03/06 06:54:48  kharlov
 * DP:Calculation of cluster properties dep. on vertex added
 *
 * Revision 1.81  2007/02/05 10:02:40  kharlov
 * Module numbering is corrected
 *
 * Revision 1.80  2006/08/28 10:01:56  kharlov
 * Effective C++ warnings fixed (Timur Pocheptsov)
 *
 * Revision 1.79  2006/04/25 12:41:15  hristov
 * Moving non-persistent data to AliESDfriend (Yu.Belikov)
 *
 * Revision 1.78  2005/11/18 13:04:51  hristov
 * Bug fix
 *
 * Revision 1.77  2005/11/17 23:34:36  hristov
 * Corrected logics
 *
 * Revision 1.76  2005/11/17 22:29:12  hristov
 * Faster version, no attempt to match tracks outside the PHOS acceptance
 *
 * Revision 1.75  2005/11/17 12:35:27  hristov
 * Use references instead of objects. Avoid to create objects when they are not really needed
 *
 * Revision 1.74  2005/07/08 14:01:36  hristov
 * Tracking in non-uniform nmagnetic field (Yu.Belikov)
 *
 * Revision 1.73  2005/05/28 14:19:05  schutz
 * Compilation warnings fixed by T.P.
 *
 */

//_________________________________________________________________________
// Implementation version 1 of algorithm class to construct PHOS track segments
// Track segment for PHOS is list of 
//        EMC RecPoint + (possibly) CPV RecPoint
// To find TrackSegments we do the following: 
//  for each EMC RecPoints we look at
//   CPV RecPoints in the radious fRcpv. 
//  If there is such a CPV RecPoint, 
//   we make "Link" it is just indexes of EMC and CPV RecPoint and distance
//   between them in the PHOS plane. 
//  Then we sort "Links" and starting from the 
//   least "Link" pointing to the unassined EMC and CPV RecPoints assing them to 
//   new TrackSegment. 
// If there is no CPV RecPoint we make TrackSegment 
// consisting from EMC alone. There is no TrackSegments without EMC RecPoint.
//// In principle this class should be called from AliPHOSReconstructor, but 
// one can use it as well in standalone mode.
// Use  case:
//  root [0] AliPHOSTrackSegmentMakerv1 * t = new AliPHOSTrackSegmentMaker("galice.root", "tracksegmentsname", "recpointsname")
//  Warning in <TDatabasePDG::TDatabasePDG>: object already instantiated
//               // reads gAlice from header file "galice.root", uses recpoints stored in the branch names "recpointsname" (default = "Default")
//               // and saves recpoints in branch named "tracksegmentsname" (default = "recpointsname")                       
//  root [1] t->ExecuteTask()
//  root [3] t->SetTrackSegmentsBranch("max distance 5 cm")
//  root [4] t->ExecuteTask("deb all time") 
//                 
//*-- Author: Dmitri Peressounko (RRC Ki & SUBATECH) & Yves Schutz (SUBATECH) 
//

// --- ROOT system ---
#include "TTree.h"
#include "TBenchmark.h"

// --- Standard library ---
#include "Riostream.h"
// --- AliRoot header files ---
#include "AliPHOSGeometry.h"
#include "AliPHOSTrackSegmentMakerv1.h"
#include "AliPHOSTrackSegment.h"
#include "AliPHOSLink.h"
#include "AliPHOSGetter.h"
#include "AliESD.h"
#include "AliESDtrack.h"

ClassImp( AliPHOSTrackSegmentMakerv1) 


//____________________________________________________________________________
AliPHOSTrackSegmentMakerv1::AliPHOSTrackSegmentMakerv1() :
  AliPHOSTrackSegmentMaker(),
  fDefaultInit(kTRUE),
  fWrite(kFALSE),
  fNTrackSegments(0),
  fRcpv(0.f),
  fRtpc(0.f),
  fLinkUpArray(0),
  fEmcFirst(0),
  fEmcLast(0),
  fCpvFirst(0),
  fCpvLast(0),
  fModule(0),
  fTrackSegmentsInRun(0)
  
{
  // default ctor (to be used mainly by Streamer)
  InitParameters() ; 
}

//____________________________________________________________________________
AliPHOSTrackSegmentMakerv1::AliPHOSTrackSegmentMakerv1(const TString & alirunFileName, const TString & eventFolderName) :
  AliPHOSTrackSegmentMaker(alirunFileName, eventFolderName),
  fDefaultInit(kFALSE),
  fWrite(kFALSE),
  fNTrackSegments(0),
  fRcpv(0.f),
  fRtpc(0.f),
  fLinkUpArray(0),
  fEmcFirst(0),
  fEmcLast(0),
  fCpvFirst(0),
  fCpvLast(0),
  fModule(0),
  fTrackSegmentsInRun(0)
{
  // ctor
  InitParameters() ; 
  Init() ;
  fESD = 0;
}


AliPHOSTrackSegmentMakerv1::AliPHOSTrackSegmentMakerv1(const AliPHOSTrackSegmentMakerv1 & tsm) :
  AliPHOSTrackSegmentMaker(tsm),
  fDefaultInit(kFALSE),
  fWrite(kFALSE),
  fNTrackSegments(0),
  fRcpv(0.f),
  fRtpc(0.f),
  fLinkUpArray(0),
  fEmcFirst(0),
  fEmcLast(0),
  fCpvFirst(0),
  fCpvLast(0),
  fModule(0),
  fTrackSegmentsInRun(0)
{
  // cpy ctor: no implementation yet
  // requested by the Coding Convention
  Fatal("cpy ctor", "not implemented") ;
}


//____________________________________________________________________________
 AliPHOSTrackSegmentMakerv1::~AliPHOSTrackSegmentMakerv1()
{ 
  // dtor
  // fDefaultInit = kTRUE if TrackSegmentMaker created by default ctor (to get just the parameters)
  if (!fDefaultInit)  
    delete fLinkUpArray ;
}


//____________________________________________________________________________
const TString AliPHOSTrackSegmentMakerv1::BranchName() const 
{  
 
  return GetName() ;
}

//____________________________________________________________________________
void  AliPHOSTrackSegmentMakerv1::FillOneModule()
{
  // Finds first and last indexes between which 
  // clusters from one PHOS module are

  AliPHOSGetter * gime = AliPHOSGetter::Instance() ; 
  
  TObjArray * emcRecPoints = gime->EmcRecPoints() ; 
  TObjArray * cpvRecPoints = gime->CpvRecPoints() ; 
 
  //First EMC clusters
  Int_t totalEmc = emcRecPoints->GetEntriesFast() ;
  for(fEmcFirst = fEmcLast; (fEmcLast < totalEmc) &&  
	((dynamic_cast<AliPHOSRecPoint *>(emcRecPoints->At(fEmcLast)))->GetPHOSMod() == fModule ); 
      fEmcLast ++)  ;
  
  //Now CPV clusters
  Int_t totalCpv = cpvRecPoints->GetEntriesFast() ;

    for(fCpvFirst = fCpvLast; (fCpvLast < totalCpv) && 
         ((dynamic_cast<AliPHOSRecPoint *>(cpvRecPoints->At(fCpvLast)))->GetPHOSMod() == fModule ); 
       fCpvLast ++) ;
      
}

//____________________________________________________________________________
void  AliPHOSTrackSegmentMakerv1::GetDistanceInPHOSPlane(AliPHOSEmcRecPoint * emcClu,
                                                         AliPHOSCpvRecPoint * cpvClu, 
                                                         Int_t &trackindex, 
                                                         Float_t &dx, Float_t &dz) const
{
  // Calculates the distance between the EMC RecPoint and the CPV RecPoint
  // Clusters are sorted in "rows" and "columns" of width 1 cm

//  Float_t delta = 1 ;  // Width of the rows in sorting of RecPoints (in cm)
//                       // if you change this value, change it as well in xxxRecPoint::Compare()
  Float_t distance2Track = fRtpc ; 

  trackindex = -1 ; // closest track within fRCpv 

  TVector3 vecEmc ;   // Local position of EMC recpoint
  TVector3 vecP ;     // Momentum direction at CPV plain
  TVector3 vecPloc ;     // Momentum direction at CPV plain
  
  //toofar = kTRUE ;
  if(emcClu->GetPHOSMod() != cpvClu->GetPHOSMod()){
    dx=999. ;
    dz=999. ;
    return ;
  }

  emcClu->GetLocalPosition(vecEmc) ;

  AliPHOSGetter * gime = AliPHOSGetter::Instance() ; 
  const AliPHOSGeometry * geom = gime->PHOSGeometry() ; 
    
  Double_t xCPV,zCPV ; //EMC-projected coordinates of CPV cluster 
  TVector3 cpvGlobal; // Global position of the CPV recpoint
  geom->GetGlobal((AliRecPoint*)cpvClu,cpvGlobal);
  Double_t vtxCPV[3]={cpvGlobal.X(),cpvGlobal.Y(),cpvGlobal.Z()} ;

  if (fESD == 0x0) {
     //if no track information available, assume straight line from IP to emcal
     Int_t dummyMod ;
     geom->ImpactOnEmc(vtxCPV,cpvGlobal.Theta(),cpvGlobal.Phi(),dummyMod,xCPV,zCPV) ;
     dx=xCPV - vecEmc.X() ;
     dz=zCPV - vecEmc.Z() ;
     return ;
  } 

  //if there is ESD try to correct distance using TPC information on particle direct in CPV 
  if (fESD != 0x0) {

    Double_t rCPV = cpvGlobal.Pt() ;// Radius from IP to current point 

    // Extrapolate the global track direction if any to CPV and find the closest track
    Int_t nTracks = fESD->GetNumberOfTracks();
    Int_t iClosestTrack = -1;
    Double_t minDistance = 1.e6;
    TVector3 inPHOS ; 

    AliESDtrack *track;
    Double_t xyz[3] ;
    Double_t pxyz[3]; 
    for (Int_t iTrack=0; iTrack<nTracks; iTrack++) {
      track = fESD->GetTrack(iTrack);
      if (!track->GetXYZAt(rCPV, fESD->GetMagneticField(), xyz))
           continue; //track coord on the cylinder of PHOS radius
      if ((TMath::Abs(xyz[0])+TMath::Abs(xyz[1])+TMath::Abs(xyz[2]))<=0)
	   continue;
      //Check if this track hits PHOS
      inPHOS.SetXYZ(xyz[0],xyz[1],xyz[2]);
      distance2Track = inPHOS.Angle(cpvGlobal) ;
      // Find the closest track to the CPV recpoint
      if (distance2Track < minDistance) {
         minDistance = distance2Track;
	 iClosestTrack = iTrack;
      }
    }

    if (iClosestTrack != -1) {
      track = fESD->GetTrack(iClosestTrack);
      if (track->GetPxPyPzAt(rCPV, fESD->GetMagneticField(), pxyz)) { // track momentum ibid.
        vecP.SetXYZ(pxyz[0],pxyz[1],pxyz[2]);
        Int_t dummyMod ;
	geom->ImpactOnEmc(vtxCPV,vecP.Theta(),vecP.Phi(),dummyMod,xCPV,zCPV) ;
      }
    }
    
    if(minDistance < fRtpc ){
      trackindex = iClosestTrack ; 
    }
  }
  if(trackindex!=-1){
    dx=xCPV - vecEmc.X() ;
    dz=zCPV - vecEmc.Z() ;
  }
  else{
    dz=999. ;
    dx=999. ;
  }
  return ;
}
//____________________________________________________________________________
void  AliPHOSTrackSegmentMakerv1::Init()
{
  // Make all memory allocations that are not possible in default constructor
  
  AliPHOSGetter* gime = AliPHOSGetter::Instance();
  if(!gime)
    gime = AliPHOSGetter::Instance(GetTitle(), fEventFolderName.Data());
  
  fLinkUpArray  = new TClonesArray("AliPHOSLink", 1000); 
  if ( !gime->TrackSegmentMaker() ) {
    gime->PostTrackSegmentMaker(this);
  }
}

//____________________________________________________________________________
void  AliPHOSTrackSegmentMakerv1::InitParameters()
{
  //Initializes parameters
  fRcpv      = 10. ;
  fRtpc      = 4. ;
  fEmcFirst  = 0 ;    
  fEmcLast   = 0 ;   
  fCpvFirst  = 0 ;   
  fCpvLast   = 0 ;   
  fLinkUpArray = 0 ;
  fWrite                   = kTRUE ;
  fTrackSegmentsInRun       = 0 ; 
  SetEventRange(0,-1) ;
}


//____________________________________________________________________________
void  AliPHOSTrackSegmentMakerv1::MakeLinks()const
{ 
  // Finds distances (links) between all EMC and CPV clusters, 
  // which are not further apart from each other than fRcpv 
  // and sort them in accordance with this distance
  
  AliPHOSGetter * gime = AliPHOSGetter::Instance() ; 
  TObjArray * emcRecPoints = gime->EmcRecPoints() ; 
  TObjArray * cpvRecPoints = gime->CpvRecPoints() ; 

  fLinkUpArray->Clear() ;    

  AliPHOSCpvRecPoint * cpv ;
  AliPHOSEmcRecPoint * emcclu ;

  Int_t iLinkUp  = 0 ;
  
  Int_t iEmcRP;
  for(iEmcRP = fEmcFirst; iEmcRP < fEmcLast; iEmcRP++ ) {
    emcclu = dynamic_cast<AliPHOSEmcRecPoint *>(emcRecPoints->At(iEmcRP)) ;

    //Bool_t toofar ;        
    Int_t iCpv = 0 ;    
    for(iCpv = fCpvFirst; iCpv < fCpvLast;iCpv++ ) { 
      
      cpv = dynamic_cast<AliPHOSCpvRecPoint *>(cpvRecPoints->At(iCpv)) ;
      Int_t track = -1 ; 
      Float_t dx,dz ;
      GetDistanceInPHOSPlane(emcclu, cpv, track,dx,dz) ;     
      if(TMath::Sqrt(dx*dx+dz*dz) < fRcpv ){ 
        new ((*fLinkUpArray)[iLinkUp++])  AliPHOSLink(dx, dz, iEmcRP, iCpv, track) ;
      }      
    }
  } 
  
  fLinkUpArray->Sort() ;  //first links with smallest distances
}

//____________________________________________________________________________
void  AliPHOSTrackSegmentMakerv1::MakePairs()
{ 
  // Using the previously made list of "links", we found the smallest link - i.e. 
  // link with the least distance between EMC and CPV and pointing to still 
  // unassigned RecParticles. We assign these RecPoints to TrackSegment and 
  // remove them from the list of "unassigned". 

  AliPHOSGetter * gime = AliPHOSGetter::Instance() ; 

  TObjArray * emcRecPoints = gime->EmcRecPoints() ; 
  TObjArray * cpvRecPoints = gime->CpvRecPoints() ; 
  TClonesArray * trackSegments = gime->TrackSegments();
    
  //Make arrays to mark clusters already chosen
  Int_t * emcExist = 0;
  if(fEmcLast > fEmcFirst)
    emcExist = new Int_t[fEmcLast-fEmcFirst] ;
  
  Int_t index;
  for(index = 0; index <fEmcLast-fEmcFirst; index ++)
    emcExist[index] = 1 ;
  
  Bool_t * cpvExist = 0;
  if(fCpvLast > fCpvFirst)
    cpvExist = new Bool_t[fCpvLast-fCpvFirst] ;
  for(index = 0; index <fCpvLast-fCpvFirst; index ++)
    cpvExist[index] = kTRUE ;
  
  
  // Finds the smallest links and makes pairs of CPV and EMC clusters with smallest distance 
  TIter nextUp(fLinkUpArray) ;
  
  AliPHOSLink * linkUp ;
  
  AliPHOSCpvRecPoint * nullpointer = 0 ;
  
  while ( (linkUp =  static_cast<AliPHOSLink *>(nextUp()) ) ){  

    if(emcExist[linkUp->GetEmc()-fEmcFirst] != -1){

      if(cpvExist[linkUp->GetCpv()-fCpvFirst]){ //CPV still exist
         Float_t dx,dz ;
         linkUp->GetXZ(dx,dz) ;
	 new ((* trackSegments)[fNTrackSegments]) 
	   AliPHOSTrackSegment(dynamic_cast<AliPHOSEmcRecPoint *>(emcRecPoints->At(linkUp->GetEmc())) , 
			       dynamic_cast<AliPHOSCpvRecPoint *>(cpvRecPoints->At(linkUp->GetCpv())) , 
			       linkUp->GetTrack(),dx,dz) ;
	 
       (dynamic_cast<AliPHOSTrackSegment *>(trackSegments->At(fNTrackSegments)))->SetIndexInList(fNTrackSegments);
       fNTrackSegments++ ;
       emcExist[linkUp->GetEmc()-fEmcFirst] = -1 ; //Mark emc  that Cpv was found 
       //mark CPV recpoint as already used 
       cpvExist[linkUp->GetCpv()-fCpvFirst] = kFALSE ;
      } //if CpvUp still exist
    } 
  }        

  //look through emc recPoints left without CPV
  if(emcExist){ //if there is emc rec point
    Int_t iEmcRP ;
    for(iEmcRP = 0; iEmcRP < fEmcLast-fEmcFirst  ; iEmcRP++ ){
      if(emcExist[iEmcRP] > 0 ){
       new ((*trackSegments)[fNTrackSegments])  
         AliPHOSTrackSegment(dynamic_cast<AliPHOSEmcRecPoint *>(emcRecPoints->At(iEmcRP+fEmcFirst)), 
                           nullpointer) ;
       (dynamic_cast<AliPHOSTrackSegment *>(trackSegments->At(fNTrackSegments)))->SetIndexInList(fNTrackSegments);
       fNTrackSegments++;    
      } 
    }
  }
  delete [] emcExist ; 
  delete [] cpvExist ; 
}

//____________________________________________________________________________
void  AliPHOSTrackSegmentMakerv1::Exec(Option_t *option)
{
  // Steering method to perform track segment construction for events
  // in the range from fFirstEvent to fLastEvent.
  // This range is optionally set by SetEventRange().
  // if fLastEvent=-1 (by default), then process events until the end.
  
  if(strstr(option,"tim"))
    gBenchmark->Start("PHOSTSMaker");
 
  if(strstr(option,"print")) {
    Print() ; 
    return ; 
  }
  
  AliPHOSGetter * gime = AliPHOSGetter::Instance() ;  
 
  const AliPHOSGeometry * geom = gime->PHOSGeometry() ; 

  if (fLastEvent == -1) 
    fLastEvent = gime->MaxEvent() - 1 ;
  else 
    fLastEvent = TMath::Min(fFirstEvent,gime->MaxEvent());
  Int_t nEvents   = fLastEvent - fFirstEvent + 1;

  Int_t ievent ; 
  for (ievent = fFirstEvent; ievent <= fLastEvent; ievent++) {
    gime->Event(ievent,"DR") ;
   //Make some initializations 
    fNTrackSegments = 0 ;
    fEmcFirst = 0 ;    
    fEmcLast  = 0 ;   
    fCpvFirst = 0 ;   
    fCpvLast  = 0 ;   
    
    gime->TrackSegments()->Clear();

    GetVertex() ;
    EvalRecPoints() ;

    //    if(!ReadRecPoints(ievent))   continue; //reads RecPoints for event ievent
    
    for(fModule = 1; fModule <= geom->GetNModules() ; fModule++ ) {
      FillOneModule() ; 
      MakeLinks() ;
      MakePairs() ;
    }

    WriteTrackSegments() ;

    if(strstr(option,"deb"))
      PrintTrackSegments(option);
    
    //increment the total number of track segments per run 
    fTrackSegmentsInRun += gime->TrackSegments()->GetEntriesFast() ; 
  }
  
  if(strstr(option,"tim")){
    gBenchmark->Stop("PHOSTSMaker");
    Info("Exec", "took %f seconds for making TS %f seconds per event", 
          gBenchmark->GetCpuTime("PHOSTSMaker"), 
          gBenchmark->GetCpuTime("PHOSTSMaker")/nEvents) ;
   }
  if(fWrite) //do not unload in "on flight" mode
    Unload();
}
//____________________________________________________________________________
void AliPHOSTrackSegmentMakerv1::GetVertex(void)
{ //extract vertex either using ESD or generator
  
  //Try to extract vertex from data
  if(fESD){
    const AliESDVertex *esdVtx = fESD->GetVertex() ;
    if(esdVtx){
      fVtx.SetXYZ(esdVtx->GetXv(),esdVtx->GetYv(),esdVtx->GetZv()) ;
      return ;
    }
  }
  
  AliWarning("Can not read vertex from data, use fixed \n") ;
  fVtx.SetXYZ(0.,0.,0.) ;
 
}
//____________________________________________________________________________
void AliPHOSTrackSegmentMakerv1::EvalRecPoints(void)
{ //calculate parameters of RecPoints using vertex and writing them

  AliPHOSGetter * gime = AliPHOSGetter::Instance() ; 
  TClonesArray * digits = gime->Digits() ;
  AliPHOSClusterizer * cl = gime->Clusterizer() ;
  TObjArray * emcRecPoints = gime->EmcRecPoints() ; 
  if (!emcRecPoints) {
    AliError("No CPV rec. points!");
  }
  else {
    Double_t w0=cl->GetEmcLogWeight() ;
    for(Int_t i=0; i<emcRecPoints->GetEntriesFast() ; i++){
      AliPHOSEmcRecPoint * point = static_cast<AliPHOSEmcRecPoint*>(emcRecPoints->At(i));
      if (point) point->EvalAll(w0,fVtx,digits) ;
      else {
	AliError(Form("No AliPHOSEmcRecPoint is found at %d",i));
      }
    }
    emcRecPoints->Sort() ;
  }

  TObjArray * cpvRecPoints = gime->CpvRecPoints() ;
  if (!cpvRecPoints) {
    AliError("No CPV rec. points!");
  }
  else {
    Double_t w0CPV=cl->GetCpvLogWeight() ;
    for(Int_t i=0; i<cpvRecPoints->GetEntriesFast() ; i++){
      AliPHOSCpvRecPoint * point = static_cast<AliPHOSCpvRecPoint*>(cpvRecPoints->At(i));
      if (point) point->EvalAll(w0CPV,fVtx,digits) ;
      else {
	AliError(Form("No AliPHOSCpvRecPoint is found at %d",i));
      }
    }
    cpvRecPoints->Sort() ;
  }

  //write recaculated RecPoints
  gime->WriteRecPoints("OVERWRITE");
  gime->WriteClusterizer("OVERWRITE");
 

}
//____________________________________________________________________________
void AliPHOSTrackSegmentMakerv1::Unload() 
{
  // Unloads the task from the folder
  AliPHOSGetter * gime = AliPHOSGetter::Instance() ;  
  gime->PhosLoader()->UnloadRecPoints() ;
  gime->PhosLoader()->UnloadTracks() ;
}

//____________________________________________________________________________
void AliPHOSTrackSegmentMakerv1::Print(const Option_t *)const
{
  //  Print TrackSegmentMaker parameters

  TString message("") ;
  if( strcmp(GetName(), "") != 0 ) {
    message = "\n======== AliPHOSTrackSegmentMakerv1 ========\n" ; 
    message += "Making Track segments\n" ;
    message += "with parameters:\n" ; 
    message += "     Maximal EMC - CPV distance (cm) %f\n" ;
    message += "============================================\n" ;
    Info("Print", message.Data(),fRcpv) ;
  }
  else
    Info("Print", "AliPHOSTrackSegmentMakerv1 not initialized ") ;
}

//____________________________________________________________________________
void AliPHOSTrackSegmentMakerv1::WriteTrackSegments()
{
  // Writes found TrackSegments to TreeR. Creates branches 
  // "PHOSTS" and "AliPHOSTrackSegmentMaker" with the same title.
  // In the former branch found TrackSegments are stored, while 
  // in the latter all parameters, with which TS were made. 
  // ROOT does not allow overwriting existing branches, therefore
  // first we check, if branches with the same title already exist.
  // If yes - exits without writing.

  AliPHOSGetter *gime = AliPHOSGetter::Instance() ; 

  TClonesArray * trackSegments = gime->TrackSegments() ; 
  trackSegments->Expand(trackSegments->GetEntriesFast()) ;

  if(fWrite){ //We write TreeT
    TTree * treeT = gime->TreeT();
    
    //First TS
    Int_t bufferSize = 32000 ; 
    TBranch * tsBranch = treeT->Branch("PHOSTS",&trackSegments,bufferSize);
    tsBranch->Fill() ;  
    
    gime->WriteTracks("OVERWRITE");
    gime->WriteTrackSegmentMaker("OVERWRITE");
  }
}


//____________________________________________________________________________
void AliPHOSTrackSegmentMakerv1::PrintTrackSegments(Option_t * option)
{
  // option deb - prints # of found TrackSegments
  // option deb all - prints as well indexed of found RecParticles assigned to the TS

  TClonesArray * trackSegments = AliPHOSGetter::Instance()->TrackSegments() ; 

  Info("PrintTrackSegments", "Results from TrackSegmentMaker:") ; 
  printf("nevent: %d\n", gAlice->GetEvNumber()) ; 
  printf("        Found %d TrackSegments\n", trackSegments->GetEntriesFast() ); 
  
  if(strstr(option,"all")) {  // printing found TS
    printf("TrackSegment #  EMC RP#  CPV RP#\n") ; 
    Int_t index;
    for (index = 0 ; index <trackSegments->GetEntriesFast() ; index++) {
      AliPHOSTrackSegment * ts = (AliPHOSTrackSegment * )trackSegments->At(index) ; 
      printf("   %d           %d        %d \n", ts->GetIndexInList(), ts->GetEmcIndex(), ts->GetCpvIndex() ) ; 
    }	
  }
}