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 "AliVertex.h"
25 #include "AliTracker.h"
27 #include <TObjArray.h>
33 class AliVertexerTracks : public TObject {
37 AliVertexerTracks(Double_t xStart, Double_t yStart);
38 virtual ~AliVertexerTracks();
40 // computes the vertex from the set of tracks in the tree
41 AliVertex* VertexForSelectedTracks(TTree *trkTree);
42 AliVertex* VertexForSelectedTracks(TObjArray *trkArray);
44 void SetMinTracks(Int_t n=2) { fMinTracks = n; return; }
45 void SetVtxStart(Double_t x=0,Double_t y=0)
46 { fNominalPos[0]=x; fNominalPos[1]=y; return; }
47 void SetDCAcut(Double_t maxdca)
48 { fDCAcut=maxdca; return;}
49 void SetFinderAlgorithm(Int_t opt=1)
53 Double_t GetField() const { return AliTracker::GetBz();}
55 Int_t PrepareTracks(TTree &trkTree);
56 void VertexFinder(Int_t optUseWeights=0);
57 void HelixVertexFinder();
58 void StrLinVertexFinderMinDist(Int_t OptUseWeights=0);
59 static void GetStrLinDerivMatrix(Double_t *p0,Double_t *p1,Double_t m[][3],Double_t *d);
60 static void GetStrLinDerivMatrix(Double_t *p0,Double_t *p1,Double_t *sigmasq,Double_t m[][3],Double_t *d);
61 static Double_t GetStrLinMinDist(Double_t *p0,Double_t *p1,Double_t *x0);
62 static Double_t GetDeterminant3X3(Double_t matr[][3]);
64 AliVertex fVert; // vertex after vertex finder
65 Double_t fNominalPos[2]; // initial knowledge on vertex position
66 Int_t fMinTracks; // minimum number of tracks
67 TObjArray fTrkArray; // array with tracks to be processed
68 Double_t fDCAcut; // maximum DCA between 2 tracks used for vertex
69 Int_t fAlgo; // option for vertex finding algorythm
70 // fAlgo=1 (default) finds minimum-distance point among all selected tracks
71 // approximated as straight lines
72 // and uses errors on track parameters as weights
73 // fAlgo=2 finds minimum-distance point among all the selected tracks
74 // approximated as straight lines
75 // fAlgo=3 finds the average point among DCA points of all pairs of tracks
77 // fAlgo=4 finds the average point among DCA points of all pairs of tracks
78 // approximated as straight lines
79 // and uses errors on track parameters as weights
80 // fAlgo=5 finds the average point among DCA points of all pairs of tracks
81 // approximated as straight lines
84 ClassDef(AliVertexerTracks,1) // 3D Vertexing with ESD tracks