1 #ifndef ALIITSVERTEXERTRACKS_H
2 #define ALIITSVERTEXERTRACKS_H
3 /* Copyright(c) 1998-2003, ALICE Experiment at CERN, All rights reserved. *
4 * See cxx source for full Copyright notice */
7 //-------------------------------------------------------
8 // Class for primary vertex determination with ITS tracks
10 // Origin: A.Dainese, Padova, andrea.dainese@pd.infn.it
11 // M.Masera, Torino, massimo.masera@to.infn.it
12 //-------------------------------------------------------
14 /*****************************************************************************
16 * This class determines the primary vertex position using ITS tracks. *
17 * This is done in two steps: *
18 * 1) Vertex Finding: a reasonable estimate of the vertex position is *
19 * obtained from a mean of "points of closest approach" between all *
20 * possible pairs of tracks. *
21 * 2) Vertex Fitting: once tracks are propagated to the position given by *
22 * first step, the optimal estimate of the position of vertex is obtained *
23 * from a weighted average of the track positions. A covariance *
24 * matrix and a chi2 for the vertex are given. *
26 *****************************************************************************/
27 #include "AliITSVertexer.h"
28 #include "AliITSSimpleVertex.h"
30 #include <TObjArray.h>
34 class AliITSSimpleVertex;
38 class AliITSVertexerTracks : public AliITSVertexer {
41 // default constructor
42 AliITSVertexerTracks();
43 // standard constructor
44 AliITSVertexerTracks(TFile *inFile,TFile *outFile,
45 Int_t fEv=0,Int_t lEv=0,
46 Double_t xStart=0.,Double_t yStart=0.);
47 // alternative constructor
48 AliITSVertexerTracks(TString fn,Double_t xStart=0,Double_t yStart=0);
50 virtual ~AliITSVertexerTracks();
51 // return vertex from the set of tracks in the tree
52 AliESDVertex* VertexOnTheFly(TTree &trkTree);
53 // computes the vertex for the current event
54 virtual AliESDVertex* FindPrimaryVertexForCurrentEvent(Int_t evnumb);
55 virtual AliESDVertex* FindVertexForCurrentEvent(Int_t evnumb){
56 Warning(" FindVertexForCurrentEvent","Deprecated method use FindPrimaryVertexForCurrentEvent instead");
57 return FindPrimaryVertexForCurrentEvent(evnumb);
59 // computes the vertex for the current event using the ESD
60 AliESDVertex* FindPrimaryVertexForCurrentEvent(AliESD *esdEvent);
61 AliESDVertex* FindVertexForCurrentEvent(AliESD *esdEvent){
62 Warning(" FindVertexForCurrentEvent","Deprecated method use FindPrimaryVertexForCurrentEvent instead");
63 return FindPrimaryVertexForCurrentEvent(esdEvent);
65 // computes the vertex for each event and stores it on file
66 virtual void FindVertices();
67 // computes the vertex for each event and stores it in the ESD
68 void FindVerticesESD();
70 // computes the vertex for selected tracks
71 // (TrkPos=vector with track positions in ESD)
72 AliITSSimpleVertex* VertexForSelectedTracks(AliESD *esdEvent,Int_t nofCand, Int_t *trkPos, Int_t opt=1);
73 // opt=1 (default) finds minimum-distance point among all the selected tracks
74 // approximated as straight lines
75 // and uses errors on track parameters as weights
76 // opt=2 finds minimum-distance point among all the selected tracks
77 // approximated as straight lines
78 // opt=3 finds the average point among DCA points of all pairs of tracks
80 // opt=4 finds the average point among DCA points of all pairs of tracks
81 // approximated as straight lines
82 // and uses errors on track parameters as weights
83 // opt=5 finds the average point among DCA points of all pairs of tracks
84 // approximated as straight lines
87 virtual void PrintStatus() const;
88 void SetMinTracks(Int_t n=2) { fMinTracks = n; return; }
89 void SetSkipTracks(Int_t n,Int_t *skipped);
90 void SetVtxStart(Double_t x=0,Double_t y=0)
91 { fNominalPos[0]=x; fNominalPos[1]=y; return; }
92 void SetDCAcut(Double_t maxdca)
93 { fDCAcut=maxdca; return;}
96 // copy constructor (NO copy allowed: the constructor is protected
98 AliITSVertexerTracks(const AliITSVertexerTracks& vtxr);
99 // assignment operator (NO assignment allowed)
100 AliITSVertexerTracks& operator=(const AliITSVertexerTracks& /* vtxr */);
101 TFile *fInFile; // input file (with tracks)
102 TFile *fOutFile; // output file for vertices
103 AliITSSimpleVertex fSimpVert; // vertex after vertex finder
104 Double_t fNominalPos[2]; // initial knowledge on vertex position
105 Int_t fMinTracks; // minimum number of tracks
106 Double_t fDCAcut; // maximum DCA between 2 tracks used for vertex
107 Double_t fMaxChi2PerTrack; // maximum contribition to the chi2
108 TObjArray fTrkArray; // array with tracks to be processed
109 Int_t *fTrksToSkip; // tracks to be skipped for find and fit
110 Int_t fNTrksToSkip; // number of tracks to be skipped
112 Bool_t CheckField() const;
113 void ComputeMaxChi2PerTrack(Int_t nTracks);
114 Int_t PrepareTracks(TTree &trkTree);
115 Int_t PrepareTracks(AliESD* esdEvent,Int_t NofCand, Int_t *TrkPos);
116 Double_t Prepare(AliITStrackV2* itstrack);
118 void VertexFinder(Int_t OptUseWeights=0);
119 void HelixVertexFinder();
120 void StrLinVertexFinderMinDist(Int_t OptUseWeights=0);
121 static void GetStrLinDerivMatrix(Double_t *p0,Double_t *p1,Double_t m[][3],Double_t *d);
122 static void GetStrLinDerivMatrix(Double_t *p0,Double_t *p1,Double_t *sigmasq,Double_t m[][3],Double_t *d);
123 static Double_t GetStrLinMinDist(Double_t *p0,Double_t *p1,Double_t *x0);
124 static Double_t GetDeterminant3X3(Double_t matr[][3]);
128 ClassDef(AliITSVertexerTracks,1) // 3D Vertexing with ITS tracks