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c7bafca9 | 1 | /************************************************************************** |
2 | * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. * | |
3 | * * | |
4 | * Author: The ALICE Off-line Project. * | |
5 | * Contributors are mentioned in the code where appropriate. * | |
6 | * * | |
7 | * Permission to use, copy, modify and distribute this software and its * | |
8 | * documentation strictly for non-commercial purposes is hereby granted * | |
9 | * without fee, provided that the above copyright notice appears in all * | |
10 | * copies and that both the copyright notice and this permission notice * | |
11 | * appear in the supporting documentation. The authors make no claims * | |
12 | * about the suitability of this software for any purpose. It is * | |
13 | * provided "as is" without express or implied warranty. * | |
14 | **************************************************************************/ | |
15 | ||
16 | //------------------------------------------------------------------------- | |
17 | // Implementation of the V0 vertexer class | |
18 | // reads tracks writes out V0 vertices | |
19 | // fills the ESD with the V0s | |
20 | // Origin: Iouri Belikov, IReS, Strasbourg, Jouri.Belikov@cern.ch | |
21 | //------------------------------------------------------------------------- | |
22 | #include <TObjArray.h> | |
23 | #include <TTree.h> | |
24 | ||
25 | #include "AliESD.h" | |
26 | #include "AliESDv0.h" | |
27 | #include "AliESDtrack.h" | |
28 | #include "AliV0vertexer.h" | |
29 | ||
30 | ClassImp(AliV0vertexer) | |
31 | ||
32 | Int_t AliV0vertexer::Tracks2V0vertices(AliESD *event) { | |
33 | //-------------------------------------------------------------------- | |
34 | //This function reconstructs V0 vertices | |
35 | //-------------------------------------------------------------------- | |
36 | ||
37 | Int_t nentr=event->GetNumberOfTracks(); | |
38 | Double_t b=event->GetMagneticField(); | |
39 | ||
da46f3ca | 40 | if (nentr<2) return 0; |
41 | ||
c7bafca9 | 42 | TArrayI neg(nentr/2); |
43 | TArrayI pos(nentr/2); | |
44 | ||
45 | Int_t nneg=0, npos=0, nvtx=0; | |
46 | ||
47 | Int_t i; | |
48 | for (i=0; i<nentr; i++) { | |
49 | AliESDtrack *esdTrack=event->GetTrack(i); | |
50 | UInt_t status=esdTrack->GetStatus(); | |
51 | UInt_t flags=AliESDtrack::kITSin|AliESDtrack::kTPCin| | |
52 | AliESDtrack::kTPCpid|AliESDtrack::kESDpid; | |
53 | ||
54 | if ((status&AliESDtrack::kITSrefit)==0) | |
55 | if (flags!=status) continue; | |
56 | ||
57 | Double_t d=esdTrack->GetD(fX,fY,b); | |
58 | if (TMath::Abs(d)<fDPmin) continue; | |
59 | if (TMath::Abs(d)>fRmax) continue; | |
60 | ||
61 | if (esdTrack->GetSign() < 0.) neg[nneg++]=i; | |
62 | else pos[npos++]=i; | |
63 | } | |
64 | ||
65 | ||
66 | for (i=0; i<nneg; i++) { | |
67 | Int_t nidx=neg[i]; | |
68 | AliESDtrack *ntrk=event->GetTrack(nidx); | |
69 | ||
70 | for (Int_t k=0; k<npos; k++) { | |
71 | Int_t pidx=pos[k]; | |
72 | AliESDtrack *ptrk=event->GetTrack(pidx); | |
73 | ||
74 | if (TMath::Abs(ntrk->GetD(fX,fY,b))<fDNmin) | |
75 | if (TMath::Abs(ptrk->GetD(fX,fY,b))<fDNmin) continue; | |
76 | ||
77 | Double_t xn, xp, dca=ntrk->GetDCA(ptrk,b,xn,xp); | |
78 | if (dca > fDCAmax) continue; | |
79 | if ((xn+xp) > 2*fRmax) continue; | |
80 | if ((xn+xp) < 2*fRmin) continue; | |
81 | ||
82 | AliExternalTrackParam nt(*ntrk), pt(*ptrk); | |
83 | Bool_t corrected=kFALSE; | |
84 | if ((nt.GetX() > 3.) && (xn < 3.)) { | |
85 | //correct for the beam pipe material | |
86 | corrected=kTRUE; | |
87 | } | |
88 | if ((pt.GetX() > 3.) && (xp < 3.)) { | |
89 | //correct for the beam pipe material | |
90 | corrected=kTRUE; | |
91 | } | |
92 | if (corrected) { | |
93 | dca=nt.GetDCA(&pt,b,xn,xp); | |
94 | if (dca > fDCAmax) continue; | |
95 | if ((xn+xp) > 2*fRmax) continue; | |
96 | if ((xn+xp) < 2*fRmin) continue; | |
97 | } | |
98 | ||
99 | nt.PropagateTo(xn,b); pt.PropagateTo(xp,b); | |
100 | ||
101 | AliESDv0 vertex(nt,nidx,pt,pidx); | |
102 | if (vertex.GetChi2() > fChi2max) continue; | |
103 | ||
104 | /* Think of something better here ! | |
105 | nt.PropagateToVertex(); if (TMath::Abs(nt.GetZ())<0.04) continue; | |
106 | pt.PropagateToVertex(); if (TMath::Abs(pt.GetZ())<0.04) continue; | |
107 | */ | |
108 | ||
109 | Double_t x,y,z; vertex.GetXYZ(x,y,z); | |
110 | Double_t px,py,pz; vertex.GetPxPyPz(px,py,pz); | |
111 | Double_t p2=px*px+py*py+pz*pz; | |
112 | Double_t cost=((x-fX)*px + (y-fY)*py + (z-fZ)*pz)/ | |
113 | TMath::Sqrt(p2*((x-fX)*(x-fX) + (y-fY)*(y-fY) + (z-fZ)*(z-fZ))); | |
114 | ||
115 | //if (cost < (5*fCPAmax-0.9-TMath::Sqrt(r2)*(fCPAmax-1))/4.1) continue; | |
116 | if (cost < fCPAmax) continue; | |
117 | vertex.SetDcaDaughters(dca); | |
118 | //vertex.ChangeMassHypothesis(); //default is Lambda0 | |
119 | ||
120 | event->AddV0(&vertex); | |
121 | ||
122 | nvtx++; | |
123 | } | |
124 | } | |
125 | ||
126 | Info("Tracks2V0vertices","Number of reconstructed V0 vertices: %d",nvtx); | |
127 | ||
da46f3ca | 128 | return nvtx; |
c7bafca9 | 129 | } |
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