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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 cascade vertexer class | |
18 | // Reads V0s and tracks, writes out cascade vertices | |
19 | // Fills the ESD with the cascades | |
20 | // Origin: Christian Kuhn, IReS, Strasbourg, christian.kuhn@ires.in2p3.fr | |
21 | //------------------------------------------------------------------------- | |
c028b974 | 22 | |
23 | //modified by R. Vernet 30/6/2006 : daughter label | |
24 | //modified by R. Vernet 3/7/2006 : causality | |
5e4ff34d | 25 | //modified by I. Belikov 24/11/2006 : static setter for the default cuts |
c028b974 | 26 | |
af885e0f | 27 | #include "AliESDEvent.h" |
c7bafca9 | 28 | #include "AliESDcascade.h" |
29 | #include "AliCascadeVertexer.h" | |
30 | ||
31 | ClassImp(AliCascadeVertexer) | |
32 | ||
5e4ff34d | 33 | //A set of loose cuts |
34 | Double_t | |
e82eee7e | 35 | AliCascadeVertexer::fgChi2max=33.; //maximal allowed chi2 |
5e4ff34d | 36 | Double_t |
e82eee7e | 37 | AliCascadeVertexer::fgDV0min=0.05; //min V0 impact parameter |
5e4ff34d | 38 | Double_t |
e82eee7e | 39 | AliCascadeVertexer::fgMassWin=0.01; //"window" around the Lambda mass |
5e4ff34d | 40 | Double_t |
e82eee7e | 41 | AliCascadeVertexer::fgDBachMin=0.035; //min bachelor impact parameter |
5e4ff34d | 42 | Double_t |
e82eee7e | 43 | AliCascadeVertexer::fgDCAmax=0.10; //max DCA between the V0 and the track |
5e4ff34d | 44 | Double_t |
85f0f56e | 45 | AliCascadeVertexer::fgCPAmin=0.9985; //min cosine of the cascade pointing angle |
5e4ff34d | 46 | Double_t |
e82eee7e | 47 | AliCascadeVertexer::fgRmin=0.2; //min radius of the fiducial volume |
5e4ff34d | 48 | Double_t |
e82eee7e | 49 | AliCascadeVertexer::fgRmax=100.; //max radius of the fiducial volume |
5e4ff34d | 50 | |
51 | ||
af885e0f | 52 | Int_t AliCascadeVertexer::V0sTracks2CascadeVertices(AliESDEvent *event) { |
c7bafca9 | 53 | //-------------------------------------------------------------------- |
54 | // This function reconstructs cascade vertices | |
55 | // Adapted to the ESD by I.Belikov (Jouri.Belikov@cern.ch) | |
56 | //-------------------------------------------------------------------- | |
81f174b6 | 57 | const AliESDVertex *vtxT3D=event->GetPrimaryVertex(); |
58 | ||
69c49ae1 | 59 | Double_t xPrimaryVertex=vtxT3D->GetXv(); |
60 | Double_t yPrimaryVertex=vtxT3D->GetYv(); | |
61 | Double_t zPrimaryVertex=vtxT3D->GetZv(); | |
5e4ff34d | 62 | |
c7bafca9 | 63 | Double_t b=event->GetMagneticField(); |
64 | Int_t nV0=(Int_t)event->GetNumberOfV0s(); | |
c028b974 | 65 | |
66 | //stores relevant V0s in an array | |
c7bafca9 | 67 | TObjArray vtcs(nV0); |
68 | Int_t i; | |
69 | for (i=0; i<nV0; i++) { | |
70 | AliESDv0 *v=event->GetV0(i); | |
d6a49f20 | 71 | if (v->GetOnFlyStatus()) continue; |
81f174b6 | 72 | if (v->GetD(xPrimaryVertex,yPrimaryVertex,zPrimaryVertex)<fDV0min) continue; |
c7bafca9 | 73 | vtcs.AddLast(v); |
74 | } | |
75 | nV0=vtcs.GetEntriesFast(); | |
76 | ||
c028b974 | 77 | // stores relevant tracks in another array |
c7bafca9 | 78 | Int_t nentr=(Int_t)event->GetNumberOfTracks(); |
79 | TArrayI trk(nentr); Int_t ntr=0; | |
80 | for (i=0; i<nentr; i++) { | |
81 | AliESDtrack *esdtr=event->GetTrack(i); | |
85f0f56e | 82 | ULong_t status=esdtr->GetStatus(); |
c7bafca9 | 83 | |
84 | if ((status&AliESDtrack::kITSrefit)==0) | |
85f0f56e | 85 | if ((status&AliESDtrack::kTPCrefit)==0) continue; |
c7bafca9 | 86 | |
81f174b6 | 87 | if (TMath::Abs(esdtr->GetD(xPrimaryVertex,yPrimaryVertex,b))<fDBachMin) continue; |
c7bafca9 | 88 | |
89 | trk[ntr++]=i; | |
90 | } | |
91 | ||
92 | Double_t massLambda=1.11568; | |
93 | Int_t ncasc=0; | |
94 | ||
95 | // Looking for the cascades... | |
c028b974 | 96 | |
97 | for (i=0; i<nV0; i++) { //loop on V0s | |
98 | ||
c7bafca9 | 99 | AliESDv0 *v=(AliESDv0*)vtcs.UncheckedAt(i); |
100 | v->ChangeMassHypothesis(kLambda0); // the v0 must be Lambda | |
101 | if (TMath::Abs(v->GetEffMass()-massLambda)>fMassWin) continue; | |
c028b974 | 102 | |
103 | for (Int_t j=0; j<ntr; j++) {//loop on tracks | |
c7bafca9 | 104 | Int_t bidx=trk[j]; |
b75d63a7 | 105 | //Bo: if (bidx==v->GetNindex()) continue; //bachelor and v0's negative tracks must be different |
106 | if (bidx==v->GetIndex(0)) continue; //Bo: consistency 0 for neg | |
c7bafca9 | 107 | AliESDtrack *btrk=event->GetTrack(bidx); |
c7bafca9 | 108 | if (btrk->GetSign()>0) continue; // bachelor's charge |
109 | ||
c028b974 | 110 | AliESDv0 v0(*v), *pv0=&v0; |
c7bafca9 | 111 | AliExternalTrackParam bt(*btrk), *pbt=&bt; |
112 | ||
113 | Double_t dca=PropagateToDCA(pv0,pbt,b); | |
114 | if (dca > fDCAmax) continue; | |
115 | ||
c028b974 | 116 | AliESDcascade cascade(*pv0,*pbt,bidx);//constucts a cascade candidate |
f776b387 | 117 | //PH if (cascade.GetChi2Xi() > fChi2max) continue; |
c7bafca9 | 118 | |
85f0f56e | 119 | Double_t x,y,z; cascade.GetXYZcascade(x,y,z); // Bo: bug correction |
c7bafca9 | 120 | Double_t r2=x*x + y*y; |
121 | if (r2 > fRmax*fRmax) continue; // condition on fiducial zone | |
122 | if (r2 < fRmin*fRmin) continue; | |
123 | ||
c028b974 | 124 | Double_t pxV0,pyV0,pzV0; |
125 | pv0->GetPxPyPz(pxV0,pyV0,pzV0); | |
126 | if (x*pxV0+y*pyV0+z*pzV0 < 0) continue; //causality | |
127 | ||
c7bafca9 | 128 | Double_t x1,y1,z1; pv0->GetXYZ(x1,y1,z1); |
129 | if (r2 > (x1*x1+y1*y1)) continue; | |
c7bafca9 | 130 | |
81f174b6 | 131 | if (cascade.GetCascadeCosineOfPointingAngle(xPrimaryVertex,yPrimaryVertex,zPrimaryVertex) <fCPAmin) continue; //condition on the cascade pointing angle |
c028b974 | 132 | |
5c9c901e | 133 | cascade.SetDcaXiDaughters(dca); |
c028b974 | 134 | event->AddCascade(&cascade); |
c7bafca9 | 135 | ncasc++; |
c028b974 | 136 | } // end loop tracks |
137 | } // end loop V0s | |
c7bafca9 | 138 | |
139 | // Looking for the anti-cascades... | |
c028b974 | 140 | |
141 | for (i=0; i<nV0; i++) { //loop on V0s | |
c7bafca9 | 142 | AliESDv0 *v=(AliESDv0*)vtcs.UncheckedAt(i); |
143 | v->ChangeMassHypothesis(kLambda0Bar); //the v0 must be anti-Lambda | |
144 | if (TMath::Abs(v->GetEffMass()-massLambda)>fMassWin) continue; | |
c028b974 | 145 | |
146 | for (Int_t j=0; j<ntr; j++) {//loop on tracks | |
c7bafca9 | 147 | Int_t bidx=trk[j]; |
b75d63a7 | 148 | //Bo: if (bidx==v->GetPindex()) continue; //bachelor and v0's positive tracks must be different |
149 | if (bidx==v->GetIndex(1)) continue; //Bo: consistency 1 for pos | |
c7bafca9 | 150 | AliESDtrack *btrk=event->GetTrack(bidx); |
c7bafca9 | 151 | if (btrk->GetSign()<0) continue; // bachelor's charge |
152 | ||
153 | AliESDv0 v0(*v), *pv0=&v0; | |
154 | AliESDtrack bt(*btrk), *pbt=&bt; | |
155 | ||
156 | Double_t dca=PropagateToDCA(pv0,pbt,b); | |
157 | if (dca > fDCAmax) continue; | |
158 | ||
c028b974 | 159 | AliESDcascade cascade(*pv0,*pbt,bidx); //constucts a cascade candidate |
f776b387 | 160 | //PH if (cascade.GetChi2Xi() > fChi2max) continue; |
c7bafca9 | 161 | |
85f0f56e | 162 | Double_t x,y,z; cascade.GetXYZcascade(x,y,z); // Bo: bug correction |
c7bafca9 | 163 | Double_t r2=x*x + y*y; |
164 | if (r2 > fRmax*fRmax) continue; // condition on fiducial zone | |
165 | if (r2 < fRmin*fRmin) continue; | |
166 | ||
c028b974 | 167 | Double_t pxV0,pyV0,pzV0; |
168 | pv0->GetPxPyPz(pxV0,pyV0,pzV0); | |
169 | if (x*pxV0+y*pyV0+z*pzV0 < 0) continue; //causality | |
170 | ||
c7bafca9 | 171 | Double_t x1,y1,z1; pv0->GetXYZ(x1,y1,z1); |
172 | if (r2 > (x1*x1+y1*y1)) continue; | |
c7bafca9 | 173 | |
81f174b6 | 174 | if (cascade.GetCascadeCosineOfPointingAngle(xPrimaryVertex,yPrimaryVertex,zPrimaryVertex) < fCPAmin) continue; //condition on the cascade pointing angle |
5c9c901e | 175 | |
176 | cascade.SetDcaXiDaughters(dca); | |
c028b974 | 177 | event->AddCascade(&cascade); |
c7bafca9 | 178 | ncasc++; |
179 | ||
c028b974 | 180 | } // end loop tracks |
181 | } // end loop V0s | |
c7bafca9 | 182 | |
183 | Info("V0sTracks2CascadeVertices","Number of reconstructed cascades: %d",ncasc); | |
184 | ||
185 | return 0; | |
186 | } | |
187 | ||
188 | ||
97135b34 | 189 | Double_t AliCascadeVertexer::Det(Double_t a00, Double_t a01, Double_t a10, Double_t a11) const { |
190 | //-------------------------------------------------------------------- | |
191 | // This function calculates locally a 2x2 determinant | |
192 | //-------------------------------------------------------------------- | |
c7bafca9 | 193 | return a00*a11 - a01*a10; |
194 | } | |
195 | ||
97135b34 | 196 | Double_t AliCascadeVertexer::Det(Double_t a00,Double_t a01,Double_t a02, |
197 | Double_t a10,Double_t a11,Double_t a12, | |
198 | Double_t a20,Double_t a21,Double_t a22) const { | |
199 | //-------------------------------------------------------------------- | |
200 | // This function calculates locally a 3x3 determinant | |
201 | //-------------------------------------------------------------------- | |
202 | return a00*Det(a11,a12,a21,a22)-a01*Det(a10,a12,a20,a22)+a02*Det(a10,a11,a20,a21); | |
c7bafca9 | 203 | } |
204 | ||
205 | ||
206 | ||
207 | ||
97135b34 | 208 | Double_t AliCascadeVertexer::PropagateToDCA(AliESDv0 *v, AliExternalTrackParam *t, Double_t b) { |
c7bafca9 | 209 | //-------------------------------------------------------------------- |
210 | // This function returns the DCA between the V0 and the track | |
211 | //-------------------------------------------------------------------- | |
212 | Double_t alpha=t->GetAlpha(), cs1=TMath::Cos(alpha), sn1=TMath::Sin(alpha); | |
213 | Double_t r[3]; t->GetXYZ(r); | |
214 | Double_t x1=r[0], y1=r[1], z1=r[2]; | |
215 | Double_t p[3]; t->GetPxPyPz(p); | |
216 | Double_t px1=p[0], py1=p[1], pz1=p[2]; | |
217 | ||
218 | Double_t x2,y2,z2; // position and momentum of V0 | |
219 | Double_t px2,py2,pz2; | |
220 | ||
221 | v->GetXYZ(x2,y2,z2); | |
222 | v->GetPxPyPz(px2,py2,pz2); | |
223 | ||
224 | // calculation dca | |
225 | ||
97135b34 | 226 | Double_t dd= Det(x2-x1,y2-y1,z2-z1,px1,py1,pz1,px2,py2,pz2); |
227 | Double_t ax= Det(py1,pz1,py2,pz2); | |
228 | Double_t ay=-Det(px1,pz1,px2,pz2); | |
229 | Double_t az= Det(px1,py1,px2,py2); | |
c7bafca9 | 230 | |
231 | Double_t dca=TMath::Abs(dd)/TMath::Sqrt(ax*ax + ay*ay + az*az); | |
232 | ||
233 | //points of the DCA | |
97135b34 | 234 | Double_t t1 = Det(x2-x1,y2-y1,z2-z1,px2,py2,pz2,ax,ay,az)/ |
235 | Det(px1,py1,pz1,px2,py2,pz2,ax,ay,az); | |
c7bafca9 | 236 | |
237 | x1 += px1*t1; y1 += py1*t1; //z1 += pz1*t1; | |
238 | ||
239 | ||
240 | //propagate track to the points of DCA | |
241 | ||
242 | x1=x1*cs1 + y1*sn1; | |
243 | if (!t->PropagateTo(x1,b)) { | |
244 | Error("PropagateToDCA","Propagation failed !"); | |
245 | return 1.e+33; | |
246 | } | |
247 | ||
248 | return dca; | |
249 | } | |
250 | ||
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260 |