[u/mrichter/AliRoot.git] / ITS / AliITSVertexerIons.cxx

#include "AliITSVertexerIons.h"
#include "AliITSVertexerPPZ.h"
#include "AliESDVertex.h"
#include "AliRun.h"
#include "AliITS.h"
#include "AliITSgeom.h"
#include "AliITSLoader.h"
#include "AliITSRecPoint.h"
#include <TMath.h>
#include <TTree.h>
#include <TH1.h>
#include <TF1.h>
#include <TObjArray.h>

//////////////////////////////////////////////////////////////////////
// AliITSVertexerIons is a class for full 3D primary vertex         //
// finding optimized for Ion-Ion interactions                       //
//                                                                  // 
//                                                                  //
//                                                                  //
//                                                                  //
// Written by Giuseppe Lo Re and Francesco Riggi                    //
// Giuseppe.Lore@ct.infn.it                                         //
// Franco.Riggi@ct.infn.it                                          //
//                                                                  //
// Release date: Mar 2004                                           //
//                                                                  //
//                                                                  //       
//////////////////////////////////////////////////////////////////////


ClassImp(AliITSVertexerIons)
  
//______________________________________________________________________
  AliITSVertexerIons::AliITSVertexerIons():AliITSVertexer() {
  // Default Constructor

  fITS = 0;
  SetNpThreshold();
  SetMaxDeltaPhi();
  SetMaxDeltaZ();
}

//______________________________________________________________________
AliITSVertexerIons::AliITSVertexerIons(TString fn):AliITSVertexer(fn) {
  // Standard constructor
  
  fITS = 0;
  SetNpThreshold();
  SetMaxDeltaPhi();
  SetMaxDeltaZ();
}

//______________________________________________________________________
AliITSVertexerIons::AliITSVertexerIons(const AliITSVertexerIons &source):AliITSVertexer(source) {
  // Copy constructor
  // Copies are not allowed. The method is protected to avoid misuse.
  Error("AliITSVertexerIons","Copy constructor not allowed\n");
}

//_________________________________________________________________________
AliITSVertexerIons& AliITSVertexerIons::operator=(const AliITSVertexerIons &/*source*/) {
  // Assignment operator
  // Assignment is not allowed. The method is protected to avoid misuse.
  Error("= operator","Assignment operator not allowed\n");
  return *this;
}


//______________________________________________________________________
AliITSVertexerIons::~AliITSVertexerIons() {
  // Default Destructor
  fITS = 0;
}

//______________________________________________________________________
AliESDVertex* AliITSVertexerIons::FindVertexForCurrentEvent(Int_t evnumber){ 
// Defines the AliESDVertex for the current event

  fCurrentVertex = 0;

  AliRunLoader *rl = AliRunLoader::GetRunLoader();
  AliITSLoader* itsloader =  (AliITSLoader*) rl->GetLoader("ITSLoader");
  if(!fITS) {
    fITS =(AliITS *)gAlice->GetDetector("ITS");
    if(!fITS) {
      Error("FindVertexForCurrentEvent","AliITS object was not found");
      return fCurrentVertex;
    }
  }
  fITS->SetTreeAddress();
  AliITSgeom *g2 = fITS->GetITSgeom();
  TClonesArray  *recpoints = fITS->RecPoints();
  AliITSRecPoint *pnt;
  TTree *tr =  itsloader->TreeR();

  Int_t npoints=0;
  Int_t nopoints1=40000;
  Int_t nopoints2=40000;
  Float_t l[3], p[3];

  Double_t *z1, *z2, *y1, *y2, *x1, *x2, *phi1, *phi2, *r1, *r2;
  z1=new Double_t[nopoints1];
  z2=new Double_t[nopoints2];
  y1=new Double_t[nopoints1];
  y2=new Double_t[nopoints2];
  x1=new Double_t[nopoints1];
  x2=new Double_t[nopoints2];
  phi1=new Double_t[nopoints1];
  phi2=new Double_t[nopoints2];
  r1=new Double_t[nopoints1];
  r2=new Double_t[nopoints2];

  Double_t mxpiu = 0;
  Double_t mxmeno = 0;
  Double_t mypiu = 0;
  Double_t mymeno = 0;
  Double_t r=0;

  Int_t np1=0, np2=0;
  for(Int_t i=g2->GetStartSPD();i<=g2->GetLastSPD();i++) {
    fITS->ResetRecPoints();
    tr->GetEvent(i);
    npoints = recpoints->GetEntries();
    for (Int_t ipoint=0;ipoint<npoints;ipoint++) {
      pnt = (AliITSRecPoint*)recpoints->UncheckedAt(ipoint);
      l[0]=pnt->GetX();
      l[1]=0;
      l[2]=pnt->GetZ();
      g2->LtoG(i, l, p);
      r=TMath::Sqrt(TMath::Power(p[0],2)+TMath::Power(p[1],2));

      if(i<80 && TMath::Abs(p[2])<14.35)  {
		y1[np1]=p[1];
		x1[np1]=p[0];
		z1[np1]=p[2];
		if(p[0]>0) mxpiu++;
		if(p[0]<0) mxmeno++;
		if(p[1]>0) mypiu++;
		if(p[1]<0) mymeno++;
		np1++;
      }
      if(i>=80 && TMath::Abs(p[2])<14.35) {
		y2[np2]=p[1];
		x2[np2]=p[0];
		z2[np2]=p[2];
		np2++;
      }
    }
  }

  if(np1<fNpThreshold) {
    Warning("FindVertexForCurrentEvent","AliITSVertexerIons finder is not reliable for low multiplicity events. Switching to AliITSVertexerPPZ with default parameters...\n");
    Warning("FindVertexForCurrentEvent","N rec points = %d - Threshold is %d",np1,fNpThreshold);
    AliITSVertexerPPZ *dovert = new AliITSVertexerPPZ("default");
    fCurrentVertex =dovert->FindVertexForCurrentEvent(rl->GetEventNumber());
    delete dovert;
    return fCurrentVertex;
  }

  if(!np1 || !np2) {
    Error("FindVertexForCurrentEvent","No points in the pixer layers");
    return fCurrentVertex;
  }  
  if(fDebug>0)   cout << "N. points layer 1 and 2 : " << np1 << " " << np2 << endl;

  Double_t asparx = (mxpiu-mxmeno)/(mxpiu+mxmeno);
  Double_t aspary = (mypiu-mymeno)/(mypiu+mymeno);

  Double_t x0 = 2.86*asparx;
  Double_t y0 = 2.86*aspary;

  if(fDebug>0)   cout << "Rough xy vertex = " << x0 << " " << y0 << endl;  

  for(Int_t i=0;i<np1;i++) {
    x1[i]-=x0;
    y1[i]-=y0;
    PhiFunc(x1[i],y1[i],phi1[i]);
    r1[i]=TMath::Sqrt(x1[i]*x1[i]+y1[i]*y1[i]);
  }
  for(Int_t i=0;i<np2;i++) {
    x2[i]-=x0;
    y2[i]-=y0;
    PhiFunc(x2[i],y2[i],phi2[i]);
    r2[i]=TMath::Sqrt(x2[i]*x2[i]+y2[i]*y2[i]);
  }
   
  Int_t nbinxy=400;
  Int_t nbinz=400;
  TH1F *hxv=new TH1F("hxv","",nbinxy,-5,5);
  TH1F *hyv=new TH1F("hyv","",nbinxy,-5,5);
  TH1F *hzv=new TH1F("hzv","",nbinz,-15,15);

  Double_t dphi;
  for(Int_t j=0; j<np1; j++) {
    for(Int_t k=0; k<np2; k++) {
      dphi=TMath::Abs(phi2[k]-phi1[j]);
      if(dphi>180) dphi = 360-dphi;
      if(dphi>fMaxDeltaPhi) continue; 
      hzv->Fill(z1[j]-(z2[k]-z1[j])/((r2[k]/r1[j])-1));
     }
  }

  // Fitting ...
  Double_t max;
  Int_t bin_max;
  Double_t maxcenter;
  
  max = hzv->GetMaximum();
  bin_max=hzv->GetMaximumBin();
  maxcenter=hzv->GetBinCenter(bin_max);
  Double_t dxy=1.5;
  
  TF1 *fz = new TF1 ("fz","([0]*exp(-0.5*((x-[1])/[2])*((x-[1])/[2])))+[3]",maxcenter-dxy,maxcenter+dxy);  
  fz->SetParameter(0,max);
  fz->SetParameter(1,maxcenter);
  fz->SetParameter(2,0.1);
  fz->SetLineColor(kRed);
  hzv->Fit("fz","RQ0");

  if(TMath::Abs(x0)>0.4 || TMath::Abs(y0)>0.4) {
    Warning("FindVertexForCurrentEvent","AliITSVertexerIonsGeneral finder is not reliable for events with x and y vertex coordinates too far from the origin of the reference system. Their values will be set to 0.\n");
    Double_t position[3]={0,0,fz->GetParameter(1)};
    Double_t resolution[3]={0,0,0};
    Double_t snr[3]={0,0,0};
    Char_t name[30];
    if(fDebug>0)Info("FindVertexForCurrentEvent","Vertex found for event %d",evnumber);
    sprintf(name,"Vertex");
    fCurrentVertex = new AliESDVertex(position,resolution,snr,name);
    return fCurrentVertex;
  }
  
  for(Int_t j=0; j<np1; j++) {
    for(Int_t k=0; k<np2; k++) {
      if(TMath::Abs((z1[j]-(z2[k]-z1[j])/((r2[k]/r1[j])-1))-fz->GetParameter(1))>fMaxDeltaZ) continue;
      if(y2[k]==y1[j]) continue;
      hxv->Fill(x0+(x2[k]-((x2[k]-x1[j])/(y2[k]-y1[j]))*y2[k]));
      if(x2[k]==x1[j]) continue;
      hyv->Fill(y0+(y2[k]-((y2[k]-y1[j])/(x2[k]-x1[j]))*x2[k]));
    }
  }
    
  TF1 *fx = new TF1 ("fx","([0]*exp(-0.5*((x-[1])/[2])*((x-[1])/[2])))+[3]+[4]*x+[5]*x*x",x0-dxy,x0+dxy);  
  fx->SetParameter(0,100);
  Double_t dist=0.3;
  Double_t xapprox=FindMaxAround(x0,hxv,dist);
  if(fDebug>0) cout << "xapprox = " << xapprox << endl;
  fx->SetParameter(1,xapprox);
  Double_t difcentroid=0.07;
  fx->SetParLimits(1,xapprox-difcentroid,xapprox+difcentroid);
  fx->SetParameter(2,0.1);
  fx->SetLineColor(kRed);
  hxv->Fit("fx","RQW0"); 
  
  TF1 *fy = new TF1 ("fy","([0]*exp(-0.5*((x-[1])/[2])*((x-[1])/[2])))+[3]+[4]*x+[5]*x*x",y0-dxy,y0+dxy);  
  fy->SetParameter(0,100);
  Double_t yapprox=FindMaxAround(y0,hyv,dist);
  if(fDebug>0) cout << "yapprox = " << yapprox << endl;
  fy->SetParameter(1,yapprox);
  fy->SetParLimits(1,yapprox-difcentroid,yapprox+difcentroid);
  fy->SetParameter(2,0.1);
  fy->SetLineColor(kRed);
  hyv->Fit("fy","RQW0");
  
  delete [] z1;
  delete [] z2;
  delete [] y1;
  delete [] y2;
  delete [] x1;
  delete [] x2;
  delete [] r1;
  delete [] r2;
  delete [] phi1;
  delete [] phi2;
  delete hxv;
  delete hyv;
  delete hzv;
  
  Double_t position[3]={fx->GetParameter(1),fy->GetParameter(1),fz->GetParameter(1)};
  Double_t resolution[3]={fx->GetParameter(2),fy->GetParameter(2),fz->GetParameter(2)};
  Double_t snr[3]={0,0,0};
  
  Char_t name[30];
  if(fDebug>0)Info("FindVertexForCurrentEvent","Vertex found for event %d",evnumber);
  sprintf(name,"Vertex");
  fCurrentVertex = new AliESDVertex(position,resolution,snr,name);
  return fCurrentVertex;
}

//______________________________________________________________________
void AliITSVertexerIons::PhiFunc(Double_t &x,Double_t &y,Double_t &phi) {
  // Method for the computation of the phi angle given x and y. The result is in degrees. 
  if(y>0 && x>0) phi=(TMath::ATan((Double_t)(y/x))*57.29578);
  if(y>0 && x<0) phi=(TMath::ATan((Double_t)(y/x))*57.29578)+180;
  if(y<0 && x<0) phi=(TMath::ATan((Double_t)(y/x))*57.29578)+180;
  if(y<0 && x>0) phi=(TMath::ATan((Double_t)(y/x))*57.29578)+360;;
}

//______________________________________________________________________
void AliITSVertexerIons::FindVertices(){
  // computes the vertices of the events in the range FirstEvent - LastEvent
  AliRunLoader *rl = AliRunLoader::GetRunLoader();
  AliITSLoader* itsloader =  (AliITSLoader*) rl->GetLoader("ITSLoader");
  itsloader->LoadRecPoints("read");
  for(Int_t i=fFirstEvent;i<=fLastEvent;i++){
    rl->GetEvent(i);
    FindVertexForCurrentEvent(i);
    if(fCurrentVertex){
      WriteCurrentVertex();
    }
    else {
      if(fDebug>0){
	cout<<"Vertex not found for event "<<i<<endl;
      }
    }
  }
}

//________________________________________________________
void AliITSVertexerIons::PrintStatus() const {
  // Print current status
  cout <<"=======================================================\n";
  cout <<" Debug flag: "<<fDebug<<endl;
  cout<<"First event to be processed "<<fFirstEvent;
  cout<<"\n Last event to be processed "<<fLastEvent<<endl;
  if(fCurrentVertex)fCurrentVertex->PrintStatus();
}

//________________________________________________________
Double_t AliITSVertexerIons::FindMaxAround(Double_t point, TH1F *h, Double_t distance) {
  // It finds the maximum of h within point-distance and distance+point. 
  Int_t maxcontent=0;
  Int_t maxbin=0;
  for(Int_t i=0;i<h->GetNbinsX();i++) {
    Int_t content=(Int_t)h->GetBinContent(i);
    Double_t center=(Double_t)h->GetBinCenter(i);
    if(TMath::Abs(center-point)>distance) continue;
    if(content>maxcontent) {maxcontent=content;maxbin=i;}
  }
  Double_t max=h->GetBinCenter(maxbin);
  return max;
}
Commit	Line	Data
	1	#include "AliITSVertexerIons.h"
	2	#include "AliITSVertexerPPZ.h"
	3	#include "AliESDVertex.h"
	4	#include "AliRun.h"
	5	#include "AliITS.h"
	6	#include "AliITSgeom.h"
	7	#include "AliITSLoader.h"
	8	#include "AliITSRecPoint.h"
	9	#include <TMath.h>
	10	#include <TTree.h>
	11	#include <TH1.h>
	12	#include <TF1.h>
	13	#include <TObjArray.h>
	14
	15	//////////////////////////////////////////////////////////////////////
	16	// AliITSVertexerIons is a class for full 3D primary vertex //
	17	// finding optimized for Ion-Ion interactions //
	18	// //
	19	// //
	20	// //
	21	// //
	22	// Written by Giuseppe Lo Re and Francesco Riggi //
	23	// Giuseppe.Lore@ct.infn.it //
	24	// Franco.Riggi@ct.infn.it //
	25	// //
	26	// Release date: Mar 2004 //
	27	// //
	28	// //
	29	//////////////////////////////////////////////////////////////////////
	30
	31
	32	ClassImp(AliITSVertexerIons)
	33
	34	//______________________________________________________________________
	35	AliITSVertexerIons::AliITSVertexerIons():AliITSVertexer() {
	36	// Default Constructor
	37
	38	fITS = 0;
	39	SetNpThreshold();
	40	SetMaxDeltaPhi();
	41	SetMaxDeltaZ();
	42	}
	43
	44	//______________________________________________________________________
	45	AliITSVertexerIons::AliITSVertexerIons(TString fn):AliITSVertexer(fn) {
	46	// Standard constructor
	47
	48	fITS = 0;
	49	SetNpThreshold();
	50	SetMaxDeltaPhi();
	51	SetMaxDeltaZ();
	52	}
	53
	54	//______________________________________________________________________
	55	AliITSVertexerIons::AliITSVertexerIons(const AliITSVertexerIons &source):AliITSVertexer(source) {
	56	// Copy constructor
	57	// Copies are not allowed. The method is protected to avoid misuse.
	58	Error("AliITSVertexerIons","Copy constructor not allowed\n");
	59	}
	60
	61	//_________________________________________________________________________
	62	AliITSVertexerIons& AliITSVertexerIons::operator=(const AliITSVertexerIons &/source/) {
	63	// Assignment operator
	64	// Assignment is not allowed. The method is protected to avoid misuse.
	65	Error("= operator","Assignment operator not allowed\n");
	66	return *this;
	67	}
	68
	69
	70	//______________________________________________________________________
	71	AliITSVertexerIons::~AliITSVertexerIons() {
	72	// Default Destructor
	73	fITS = 0;
	74	}
	75
	76	//______________________________________________________________________
	77	AliESDVertex* AliITSVertexerIons::FindVertexForCurrentEvent(Int_t evnumber){
	78	// Defines the AliESDVertex for the current event
	79
	80	fCurrentVertex = 0;
	81
	82	AliRunLoader *rl = AliRunLoader::GetRunLoader();
	83	AliITSLoader* itsloader = (AliITSLoader*) rl->GetLoader("ITSLoader");
	84	if(!fITS) {
	85	fITS =(AliITS *)gAlice->GetDetector("ITS");
	86	if(!fITS) {
	87	Error("FindVertexForCurrentEvent","AliITS object was not found");
	88	return fCurrentVertex;
	89	}
	90	}
	91	fITS->SetTreeAddress();
	92	AliITSgeom *g2 = fITS->GetITSgeom();
	93	TClonesArray *recpoints = fITS->RecPoints();
	94	AliITSRecPoint *pnt;
	95	TTree *tr = itsloader->TreeR();
	96
	97	Int_t npoints=0;
	98	Int_t nopoints1=40000;
	99	Int_t nopoints2=40000;
	100	Float_t l[3], p[3];
	101
	102	Double_t z1, z2, y1, y2, x1, x2, phi1, phi2, r1, r2;
	103	z1=new Double_t[nopoints1];
	104	z2=new Double_t[nopoints2];
	105	y1=new Double_t[nopoints1];
	106	y2=new Double_t[nopoints2];
	107	x1=new Double_t[nopoints1];
	108	x2=new Double_t[nopoints2];
	109	phi1=new Double_t[nopoints1];
	110	phi2=new Double_t[nopoints2];
	111	r1=new Double_t[nopoints1];
	112	r2=new Double_t[nopoints2];
	113
	114	Double_t mxpiu = 0;
	115	Double_t mxmeno = 0;
	116	Double_t mypiu = 0;
	117	Double_t mymeno = 0;
	118	Double_t r=0;
	119
	120	Int_t np1=0, np2=0;
	121	for(Int_t i=g2->GetStartSPD();i<=g2->GetLastSPD();i++) {
	122	fITS->ResetRecPoints();
	123	tr->GetEvent(i);
	124	npoints = recpoints->GetEntries();
	125	for (Int_t ipoint=0;ipoint<npoints;ipoint++) {
	126	pnt = (AliITSRecPoint*)recpoints->UncheckedAt(ipoint);
	127	l[0]=pnt->GetX();
	128	l[1]=0;
	129	l[2]=pnt->GetZ();
	130	g2->LtoG(i, l, p);
	131	r=TMath::Sqrt(TMath::Power(p[0],2)+TMath::Power(p[1],2));
	132
	133	if(i<80 && TMath::Abs(p[2])<14.35) {
	134	y1[np1]=p[1];
	135	x1[np1]=p[0];
	136	z1[np1]=p[2];
	137	if(p[0]>0) mxpiu++;
	138	if(p[0]<0) mxmeno++;
	139	if(p[1]>0) mypiu++;
	140	if(p[1]<0) mymeno++;
	141	np1++;
	142	}
	143	if(i>=80 && TMath::Abs(p[2])<14.35) {
	144	y2[np2]=p[1];
	145	x2[np2]=p[0];
	146	z2[np2]=p[2];
	147	np2++;
	148	}
	149	}
	150	}
	151
	152	if(np1<fNpThreshold) {
	153	Warning("FindVertexForCurrentEvent","AliITSVertexerIons finder is not reliable for low multiplicity events. Switching to AliITSVertexerPPZ with default parameters...\n");
	154	Warning("FindVertexForCurrentEvent","N rec points = %d - Threshold is %d",np1,fNpThreshold);
	155	AliITSVertexerPPZ *dovert = new AliITSVertexerPPZ("default");
	156	fCurrentVertex =dovert->FindVertexForCurrentEvent(rl->GetEventNumber());
	157	delete dovert;
	158	return fCurrentVertex;
	159	}
	160
	161	if(!np1 \|\| !np2) {
	162	Error("FindVertexForCurrentEvent","No points in the pixer layers");
	163	return fCurrentVertex;
	164	}
	165	if(fDebug>0) cout << "N. points layer 1 and 2 : " << np1 << " " << np2 << endl;
	166
	167	Double_t asparx = (mxpiu-mxmeno)/(mxpiu+mxmeno);
	168	Double_t aspary = (mypiu-mymeno)/(mypiu+mymeno);
	169
	170	Double_t x0 = 2.86*asparx;
	171	Double_t y0 = 2.86*aspary;
	172
	173	if(fDebug>0) cout << "Rough xy vertex = " << x0 << " " << y0 << endl;
	174
	175	for(Int_t i=0;i<np1;i++) {
	176	x1[i]-=x0;
	177	y1[i]-=y0;
	178	PhiFunc(x1[i],y1[i],phi1[i]);
	179	r1[i]=TMath::Sqrt(x1[i]x1[i]+y1[i]y1[i]);
	180	}
	181	for(Int_t i=0;i<np2;i++) {
	182	x2[i]-=x0;
	183	y2[i]-=y0;
	184	PhiFunc(x2[i],y2[i],phi2[i]);
	185	r2[i]=TMath::Sqrt(x2[i]x2[i]+y2[i]y2[i]);
	186	}
	187
	188	Int_t nbinxy=400;
	189	Int_t nbinz=400;
	190	TH1F *hxv=new TH1F("hxv","",nbinxy,-5,5);
	191	TH1F *hyv=new TH1F("hyv","",nbinxy,-5,5);
	192	TH1F *hzv=new TH1F("hzv","",nbinz,-15,15);
	193
	194	Double_t dphi;
	195	for(Int_t j=0; j<np1; j++) {
	196	for(Int_t k=0; k<np2; k++) {
	197	dphi=TMath::Abs(phi2[k]-phi1[j]);
	198	if(dphi>180) dphi = 360-dphi;
	199	if(dphi>fMaxDeltaPhi) continue;
	200	hzv->Fill(z1[j]-(z2[k]-z1[j])/((r2[k]/r1[j])-1));
	201	}
	202	}
	203
	204	// Fitting ...
	205	Double_t max;
	206	Int_t bin_max;
	207	Double_t maxcenter;
	208
	209	max = hzv->GetMaximum();
	210	bin_max=hzv->GetMaximumBin();
	211	maxcenter=hzv->GetBinCenter(bin_max);
	212	Double_t dxy=1.5;
	213
	214	TF1 fz = new TF1 ("fz","([0]exp(-0.5((x-[1])/[2])((x-[1])/[2])))+[3]",maxcenter-dxy,maxcenter+dxy);
	215	fz->SetParameter(0,max);
	216	fz->SetParameter(1,maxcenter);
	217	fz->SetParameter(2,0.1);
	218	fz->SetLineColor(kRed);
	219	hzv->Fit("fz","RQ0");
	220
	221	if(TMath::Abs(x0)>0.4 \|\| TMath::Abs(y0)>0.4) {
	222	Warning("FindVertexForCurrentEvent","AliITSVertexerIonsGeneral finder is not reliable for events with x and y vertex coordinates too far from the origin of the reference system. Their values will be set to 0.\n");
	223	Double_t position[3]={0,0,fz->GetParameter(1)};
	224	Double_t resolution[3]={0,0,0};
	225	Double_t snr[3]={0,0,0};
	226	Char_t name[30];
	227	if(fDebug>0)Info("FindVertexForCurrentEvent","Vertex found for event %d",evnumber);
	228	sprintf(name,"Vertex");
	229	fCurrentVertex = new AliESDVertex(position,resolution,snr,name);
	230	return fCurrentVertex;
	231	}
	232
	233	for(Int_t j=0; j<np1; j++) {
	234	for(Int_t k=0; k<np2; k++) {
	235	if(TMath::Abs((z1[j]-(z2[k]-z1[j])/((r2[k]/r1[j])-1))-fz->GetParameter(1))>fMaxDeltaZ) continue;
	236	if(y2[k]==y1[j]) continue;
	237	hxv->Fill(x0+(x2[k]-((x2[k]-x1[j])/(y2[k]-y1[j]))*y2[k]));
	238	if(x2[k]==x1[j]) continue;
	239	hyv->Fill(y0+(y2[k]-((y2[k]-y1[j])/(x2[k]-x1[j]))*x2[k]));
	240	}
	241	}
	242
	243	TF1 fx = new TF1 ("fx","([0]exp(-0.5((x-[1])/[2])((x-[1])/[2])))+[3]+[4]x+[5]x*x",x0-dxy,x0+dxy);
	244	fx->SetParameter(0,100);
	245	Double_t dist=0.3;
	246	Double_t xapprox=FindMaxAround(x0,hxv,dist);
	247	if(fDebug>0) cout << "xapprox = " << xapprox << endl;
	248	fx->SetParameter(1,xapprox);
	249	Double_t difcentroid=0.07;
	250	fx->SetParLimits(1,xapprox-difcentroid,xapprox+difcentroid);
	251	fx->SetParameter(2,0.1);
	252	fx->SetLineColor(kRed);
	253	hxv->Fit("fx","RQW0");
	254
	255	TF1 fy = new TF1 ("fy","([0]exp(-0.5((x-[1])/[2])((x-[1])/[2])))+[3]+[4]x+[5]x*x",y0-dxy,y0+dxy);
	256	fy->SetParameter(0,100);
	257	Double_t yapprox=FindMaxAround(y0,hyv,dist);
	258	if(fDebug>0) cout << "yapprox = " << yapprox << endl;
	259	fy->SetParameter(1,yapprox);
	260	fy->SetParLimits(1,yapprox-difcentroid,yapprox+difcentroid);
	261	fy->SetParameter(2,0.1);
	262	fy->SetLineColor(kRed);
	263	hyv->Fit("fy","RQW0");
	264
	265	delete [] z1;
	266	delete [] z2;
	267	delete [] y1;
	268	delete [] y2;
	269	delete [] x1;
	270	delete [] x2;
	271	delete [] r1;
	272	delete [] r2;
	273	delete [] phi1;
	274	delete [] phi2;
	275	delete hxv;
	276	delete hyv;
	277	delete hzv;
	278
	279	Double_t position[3]={fx->GetParameter(1),fy->GetParameter(1),fz->GetParameter(1)};
	280	Double_t resolution[3]={fx->GetParameter(2),fy->GetParameter(2),fz->GetParameter(2)};
	281	Double_t snr[3]={0,0,0};
	282
	283	Char_t name[30];
	284	if(fDebug>0)Info("FindVertexForCurrentEvent","Vertex found for event %d",evnumber);
	285	sprintf(name,"Vertex");
	286	fCurrentVertex = new AliESDVertex(position,resolution,snr,name);
	287	return fCurrentVertex;
	288	}
	289
	290	//______________________________________________________________________
	291	void AliITSVertexerIons::PhiFunc(Double_t &x,Double_t &y,Double_t &phi) {
	292	// Method for the computation of the phi angle given x and y. The result is in degrees.
	293	if(y>0 && x>0) phi=(TMath::ATan((Double_t)(y/x))*57.29578);
	294	if(y>0 && x<0) phi=(TMath::ATan((Double_t)(y/x))*57.29578)+180;
	295	if(y<0 && x<0) phi=(TMath::ATan((Double_t)(y/x))*57.29578)+180;
	296	if(y<0 && x>0) phi=(TMath::ATan((Double_t)(y/x))*57.29578)+360;;
	297	}
	298
	299	//______________________________________________________________________
	300	void AliITSVertexerIons::FindVertices(){
	301	// computes the vertices of the events in the range FirstEvent - LastEvent
	302	AliRunLoader *rl = AliRunLoader::GetRunLoader();
	303	AliITSLoader* itsloader = (AliITSLoader*) rl->GetLoader("ITSLoader");
	304	itsloader->LoadRecPoints("read");
	305	for(Int_t i=fFirstEvent;i<=fLastEvent;i++){
	306	rl->GetEvent(i);
	307	FindVertexForCurrentEvent(i);
	308	if(fCurrentVertex){
	309	WriteCurrentVertex();
	310	}
	311	else {
	312	if(fDebug>0){
	313	cout<<"Vertex not found for event "<<i<<endl;
	314	}
	315	}
	316	}
	317	}
	318
	319	//________________________________________________________
	320	void AliITSVertexerIons::PrintStatus() const {
	321	// Print current status
	322	cout <<"=======================================================\n";
	323	cout <<" Debug flag: "<<fDebug<<endl;
	324	cout<<"First event to be processed "<<fFirstEvent;
	325	cout<<"\n Last event to be processed "<<fLastEvent<<endl;
	326	if(fCurrentVertex)fCurrentVertex->PrintStatus();
	327	}
	328
	329	//________________________________________________________
	330	Double_t AliITSVertexerIons::FindMaxAround(Double_t point, TH1F *h, Double_t distance) {
	331	// It finds the maximum of h within point-distance and distance+point.
	332	Int_t maxcontent=0;
	333	Int_t maxbin=0;
	334	for(Int_t i=0;i<h->GetNbinsX();i++) {
	335	Int_t content=(Int_t)h->GetBinContent(i);
	336	Double_t center=(Double_t)h->GetBinCenter(i);
	337	if(TMath::Abs(center-point)>distance) continue;
	338	if(content>maxcontent) {maxcontent=content;maxbin=i;}
	339	}
	340	Double_t max=h->GetBinCenter(maxbin);
	341	return max;
	342	}
	343
	344