1 #ifndef ALIVERTEXERTRACKS_H
2 #define ALIVERTEXERTRACKS_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 vertex determination with ESD tracks
10 // Origin: AliITSVertexerTracks
11 // A.Dainese, Padova, andrea.dainese@pd.infn.it
12 // M.Masera, Torino, massimo.masera@to.infn.it
13 // Moved to STEER and adapted to ESD tracks:
14 // F.Prino, Torino, prino@to.infn.it
15 //-------------------------------------------------------
17 /*****************************************************************************
19 * This class determines the vertex of a set of ESD tracks. *
20 * Different algorithms are implemented, see data member fAlgo. *
22 *****************************************************************************/
24 #include "AliESDVertex.h"
25 #include "AliTracker.h"
28 #include <TObjArray.h>
33 class AliVertexerTracks : public TObject {
37 AliVertexerTracks(Double_t xStart, Double_t yStart);
38 virtual ~AliVertexerTracks();
41 // computes the vertex from the set of tracks in the tree
42 AliVertex* VertexForSelectedTracks(TTree *trkTree);
43 AliVertex* VertexForSelectedTracks(TObjArray *trkArray);
44 AliESDVertex* FindPrimaryVertex(const AliESD *esdEvent);
45 void SetMinTracks(Int_t n=2) { fMinTracks = n; return; }
46 void SetSkipTracks(Int_t n,Int_t *skipped);
47 void SetDebug(Int_t optdebug=0) {fDebug=optdebug;}
48 void SetVtxStart(Double_t x=0,Double_t y=0)
49 { fNominalPos[0]=x; fNominalPos[1]=y; return; }
50 void SetDCAcut(Double_t maxdca)
51 { fDCAcut=maxdca; return;}
52 void SetFinderAlgorithm(Int_t opt=1)
56 Double_t GetField() const { return AliTracker::GetBz();}
57 void ComputeMaxChi2PerTrack(Int_t nTracks);
58 Int_t PrepareTracks(TTree &trkTree, Int_t OptImpParCut);
59 void VertexFinder(Int_t optUseWeights=0);
60 void HelixVertexFinder();
61 void StrLinVertexFinderMinDist(Int_t OptUseWeights=0);
62 static void GetStrLinDerivMatrix(Double_t *p0,Double_t *p1,Double_t m[][3],Double_t *d);
63 static void GetStrLinDerivMatrix(Double_t *p0,Double_t *p1,Double_t *sigmasq,Double_t m[][3],Double_t *d);
64 static Double_t GetStrLinMinDist(Double_t *p0,Double_t *p1,Double_t *x0);
65 static Double_t GetDeterminant3X3(Double_t matr[][3]);
68 AliVertex fVert; // vertex after vertex finder
69 AliESDVertex *fCurrentVertex; // ESD vertex after fitter
70 Double_t fNominalPos[2]; // initial knowledge on vertex position
71 Int_t fMinTracks; // minimum number of tracks
72 Double_t fMaxChi2PerTrack; // maximum contribition to the chi2
73 TObjArray fTrkArray; // array with tracks to be processed
74 Int_t *fTrksToSkip; // tracks to be skipped for find and fit
75 Int_t fNTrksToSkip; // number of tracks to be skipped
76 Double_t fDCAcut; // maximum DCA between 2 tracks used for vertex
77 Int_t fAlgo; // option for vertex finding algorythm
78 Int_t fDebug; //! debug flag - verbose printing if >0
79 // fAlgo=1 (default) finds minimum-distance point among all selected tracks
80 // approximated as straight lines
81 // and uses errors on track parameters as weights
82 // fAlgo=2 finds minimum-distance point among all the selected tracks
83 // approximated as straight lines
84 // fAlgo=3 finds the average point among DCA points of all pairs of tracks
86 // fAlgo=4 finds the average point among DCA points of all pairs of tracks
87 // approximated as straight lines
88 // and uses errors on track parameters as weights
89 // fAlgo=5 finds the average point among DCA points of all pairs of tracks
90 // approximated as straight lines
93 ClassDef(AliVertexerTracks,3) // 3D Vertexing with ESD tracks