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f826d409 | 1 | //---------------------------------------------------------------------------- |
2 | // Implementation of the AliKFVertex class | |
3 | // . | |
4 | // @author S.Gorbunov, I.Kisel | |
5 | // @version 1.0 | |
6 | // @since 13.05.07 | |
7 | // | |
8 | // Class to reconstruct and store primary and secondary vertices | |
9 | // The method is described in CBM-SOFT note 2007-003, | |
10 | // ``Reconstruction of decayed particles based on the Kalman filter'', | |
11 | // http://www.gsi.de/documents/DOC-2007-May-14-1.pdf | |
12 | // | |
13 | // This class is ALICE interface to general mathematics in AliKFParticleCore | |
14 | // | |
15 | // -= Copyright © ALICE HLT Group =- | |
16 | //____________________________________________________________________________ | |
17 | ||
18 | ||
19 | #include "AliKFVertex.h" | |
20 | ||
21 | ||
effa6338 | 22 | ClassImp(AliKFVertex) |
f826d409 | 23 | |
24 | ||
25 | AliKFVertex::AliKFVertex( const AliESDVertex &vertex ) | |
26 | { | |
27 | // Constructor from ALICE ESD vertex | |
28 | ||
29 | vertex.GetXYZ( fP ); | |
30 | vertex.GetCovMatrix( fC ); | |
31 | fChi2 = vertex.GetChi2(); | |
32 | fNDF = 2*vertex.GetNContributors() - 3; | |
33 | fQ = 0; | |
34 | fAtProductionVertex = 0; | |
35 | fIsLinearized = 0; | |
36 | fSFromDecay = 0; | |
37 | } | |
38 | ||
4bbc290d | 39 | |
f826d409 | 40 | void AliKFVertex::ConstructPrimaryVertex( const AliKFParticle *vDaughters[], |
4bbc290d | 41 | int NDaughters, Bool_t vtxFlag[], |
42 | Double_t ChiCut ) | |
f826d409 | 43 | { |
44 | //* Primary vertex finder with simple rejection of outliers | |
f826d409 | 45 | if( NDaughters<2 ) return; |
4bbc290d | 46 | Construct( vDaughters, NDaughters ); |
47 | for( int i=0; i<NDaughters; i++ ) vtxFlag[i] = 1; | |
48 | ||
49 | Int_t nRest = NDaughters; | |
50 | while( nRest>2 ) | |
51 | { | |
52 | Double_t worstChi = 0.; | |
53 | Int_t worstDaughter = 0; | |
54 | for( Int_t it=0; it<NDaughters; it++ ){ | |
55 | if( !vtxFlag[it] ) continue; | |
56 | const AliKFParticle &p = *(vDaughters[it]); | |
57 | AliKFVertex tmp = *this - p; | |
58 | Double_t chi = p.GetDeviationFromVertex( tmp ); | |
59 | if( worstChi < chi ){ | |
60 | worstChi = chi; | |
61 | worstDaughter = it; | |
62 | } | |
63 | } | |
64 | if( worstChi < ChiCut ) break; | |
65 | ||
66 | vtxFlag[worstDaughter] = 0; | |
67 | *this -= *(vDaughters[worstDaughter]); | |
68 | nRest--; | |
69 | } | |
70 | ||
71 | if( nRest<=2 && GetChi2()>ChiCut*ChiCut*GetNDF() ){ | |
72 | for( int i=0; i<NDaughters; i++ ) vtxFlag[i] = 0; | |
73 | fNDF = -3; | |
74 | fChi2 = 0; | |
75 | } | |
f826d409 | 76 | } |