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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 | |
9fbe5c5c | 35 | AliCascadeVertexer::fgChi2max=33.; //maximal allowed chi2 |
5e4ff34d | 36 | Double_t |
9fbe5c5c | 37 | AliCascadeVertexer::fgDV0min=0.01; //min V0 impact parameter |
5e4ff34d | 38 | Double_t |
9fbe5c5c | 39 | AliCascadeVertexer::fgMassWin=0.008; //"window" around the Lambda mass |
5e4ff34d | 40 | Double_t |
9fbe5c5c | 41 | AliCascadeVertexer::fgDBachMin=0.01; //min bachelor impact parameter |
5e4ff34d | 42 | Double_t |
9fbe5c5c | 43 | AliCascadeVertexer::fgDCAmax=2.0; //max DCA between the V0 and the track |
5e4ff34d | 44 | Double_t |
9fbe5c5c | 45 | AliCascadeVertexer::fgCPAmin=0.98; //min cosine of the cascade pointing angle |
5e4ff34d | 46 | Double_t |
9fbe5c5c | 47 | AliCascadeVertexer::fgRmin=0.2; //min radius of the fiducial volume |
5e4ff34d | 48 | Double_t |
9fbe5c5c | 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); |
c71c41ac | 100 | AliESDv0 v0(*v); |
101 | v0.ChangeMassHypothesis(kLambda0); // the v0 must be Lambda | |
102 | if (TMath::Abs(v0.GetEffMass()-massLambda)>fMassWin) continue; | |
c028b974 | 103 | |
104 | for (Int_t j=0; j<ntr; j++) {//loop on tracks | |
c7bafca9 | 105 | Int_t bidx=trk[j]; |
b75d63a7 | 106 | //Bo: if (bidx==v->GetNindex()) continue; //bachelor and v0's negative tracks must be different |
c71c41ac | 107 | if (bidx==v0.GetIndex(0)) continue; //Bo: consistency 0 for neg |
c7bafca9 | 108 | AliESDtrack *btrk=event->GetTrack(bidx); |
c7bafca9 | 109 | if (btrk->GetSign()>0) continue; // bachelor's charge |
110 | ||
c71c41ac | 111 | AliESDv0 *pv0=&v0; |
c7bafca9 | 112 | AliExternalTrackParam bt(*btrk), *pbt=&bt; |
113 | ||
114 | Double_t dca=PropagateToDCA(pv0,pbt,b); | |
115 | if (dca > fDCAmax) continue; | |
116 | ||
c028b974 | 117 | AliESDcascade cascade(*pv0,*pbt,bidx);//constucts a cascade candidate |
f776b387 | 118 | //PH if (cascade.GetChi2Xi() > fChi2max) continue; |
c7bafca9 | 119 | |
85f0f56e | 120 | Double_t x,y,z; cascade.GetXYZcascade(x,y,z); // Bo: bug correction |
c7bafca9 | 121 | Double_t r2=x*x + y*y; |
122 | if (r2 > fRmax*fRmax) continue; // condition on fiducial zone | |
123 | if (r2 < fRmin*fRmin) continue; | |
124 | ||
c028b974 | 125 | Double_t pxV0,pyV0,pzV0; |
126 | pv0->GetPxPyPz(pxV0,pyV0,pzV0); | |
127 | if (x*pxV0+y*pyV0+z*pzV0 < 0) continue; //causality | |
128 | ||
c7bafca9 | 129 | Double_t x1,y1,z1; pv0->GetXYZ(x1,y1,z1); |
130 | if (r2 > (x1*x1+y1*y1)) continue; | |
c7bafca9 | 131 | |
81f174b6 | 132 | if (cascade.GetCascadeCosineOfPointingAngle(xPrimaryVertex,yPrimaryVertex,zPrimaryVertex) <fCPAmin) continue; //condition on the cascade pointing angle |
c028b974 | 133 | |
5c9c901e | 134 | cascade.SetDcaXiDaughters(dca); |
c028b974 | 135 | event->AddCascade(&cascade); |
c7bafca9 | 136 | ncasc++; |
c028b974 | 137 | } // end loop tracks |
138 | } // end loop V0s | |
c7bafca9 | 139 | |
140 | // Looking for the anti-cascades... | |
c028b974 | 141 | |
142 | for (i=0; i<nV0; i++) { //loop on V0s | |
c7bafca9 | 143 | AliESDv0 *v=(AliESDv0*)vtcs.UncheckedAt(i); |
c71c41ac | 144 | AliESDv0 v0(*v); |
145 | v0.ChangeMassHypothesis(kLambda0Bar); //the v0 must be anti-Lambda | |
146 | if (TMath::Abs(v0.GetEffMass()-massLambda)>fMassWin) continue; | |
c028b974 | 147 | |
148 | for (Int_t j=0; j<ntr; j++) {//loop on tracks | |
c7bafca9 | 149 | Int_t bidx=trk[j]; |
b75d63a7 | 150 | //Bo: if (bidx==v->GetPindex()) continue; //bachelor and v0's positive tracks must be different |
c71c41ac | 151 | if (bidx==v0.GetIndex(1)) continue; //Bo: consistency 1 for pos |
c7bafca9 | 152 | AliESDtrack *btrk=event->GetTrack(bidx); |
c7bafca9 | 153 | if (btrk->GetSign()<0) continue; // bachelor's charge |
154 | ||
c71c41ac | 155 | AliESDv0 *pv0=&v0; |
c7bafca9 | 156 | AliESDtrack bt(*btrk), *pbt=&bt; |
157 | ||
158 | Double_t dca=PropagateToDCA(pv0,pbt,b); | |
159 | if (dca > fDCAmax) continue; | |
160 | ||
c028b974 | 161 | AliESDcascade cascade(*pv0,*pbt,bidx); //constucts a cascade candidate |
f776b387 | 162 | //PH if (cascade.GetChi2Xi() > fChi2max) continue; |
c7bafca9 | 163 | |
85f0f56e | 164 | Double_t x,y,z; cascade.GetXYZcascade(x,y,z); // Bo: bug correction |
c7bafca9 | 165 | Double_t r2=x*x + y*y; |
166 | if (r2 > fRmax*fRmax) continue; // condition on fiducial zone | |
167 | if (r2 < fRmin*fRmin) continue; | |
168 | ||
c028b974 | 169 | Double_t pxV0,pyV0,pzV0; |
170 | pv0->GetPxPyPz(pxV0,pyV0,pzV0); | |
171 | if (x*pxV0+y*pyV0+z*pzV0 < 0) continue; //causality | |
172 | ||
c7bafca9 | 173 | Double_t x1,y1,z1; pv0->GetXYZ(x1,y1,z1); |
174 | if (r2 > (x1*x1+y1*y1)) continue; | |
c7bafca9 | 175 | |
81f174b6 | 176 | if (cascade.GetCascadeCosineOfPointingAngle(xPrimaryVertex,yPrimaryVertex,zPrimaryVertex) < fCPAmin) continue; //condition on the cascade pointing angle |
5c9c901e | 177 | |
178 | cascade.SetDcaXiDaughters(dca); | |
c028b974 | 179 | event->AddCascade(&cascade); |
c7bafca9 | 180 | ncasc++; |
181 | ||
c028b974 | 182 | } // end loop tracks |
183 | } // end loop V0s | |
c7bafca9 | 184 | |
185 | Info("V0sTracks2CascadeVertices","Number of reconstructed cascades: %d",ncasc); | |
186 | ||
187 | return 0; | |
188 | } | |
189 | ||
190 | ||
97135b34 | 191 | Double_t AliCascadeVertexer::Det(Double_t a00, Double_t a01, Double_t a10, Double_t a11) const { |
192 | //-------------------------------------------------------------------- | |
193 | // This function calculates locally a 2x2 determinant | |
194 | //-------------------------------------------------------------------- | |
c7bafca9 | 195 | return a00*a11 - a01*a10; |
196 | } | |
197 | ||
97135b34 | 198 | Double_t AliCascadeVertexer::Det(Double_t a00,Double_t a01,Double_t a02, |
199 | Double_t a10,Double_t a11,Double_t a12, | |
200 | Double_t a20,Double_t a21,Double_t a22) const { | |
201 | //-------------------------------------------------------------------- | |
202 | // This function calculates locally a 3x3 determinant | |
203 | //-------------------------------------------------------------------- | |
204 | return a00*Det(a11,a12,a21,a22)-a01*Det(a10,a12,a20,a22)+a02*Det(a10,a11,a20,a21); | |
c7bafca9 | 205 | } |
206 | ||
207 | ||
208 | ||
209 | ||
97135b34 | 210 | Double_t AliCascadeVertexer::PropagateToDCA(AliESDv0 *v, AliExternalTrackParam *t, Double_t b) { |
c7bafca9 | 211 | //-------------------------------------------------------------------- |
212 | // This function returns the DCA between the V0 and the track | |
213 | //-------------------------------------------------------------------- | |
214 | Double_t alpha=t->GetAlpha(), cs1=TMath::Cos(alpha), sn1=TMath::Sin(alpha); | |
215 | Double_t r[3]; t->GetXYZ(r); | |
216 | Double_t x1=r[0], y1=r[1], z1=r[2]; | |
217 | Double_t p[3]; t->GetPxPyPz(p); | |
218 | Double_t px1=p[0], py1=p[1], pz1=p[2]; | |
219 | ||
220 | Double_t x2,y2,z2; // position and momentum of V0 | |
221 | Double_t px2,py2,pz2; | |
222 | ||
223 | v->GetXYZ(x2,y2,z2); | |
224 | v->GetPxPyPz(px2,py2,pz2); | |
225 | ||
226 | // calculation dca | |
227 | ||
97135b34 | 228 | Double_t dd= Det(x2-x1,y2-y1,z2-z1,px1,py1,pz1,px2,py2,pz2); |
229 | Double_t ax= Det(py1,pz1,py2,pz2); | |
230 | Double_t ay=-Det(px1,pz1,px2,pz2); | |
231 | Double_t az= Det(px1,py1,px2,py2); | |
c7bafca9 | 232 | |
233 | Double_t dca=TMath::Abs(dd)/TMath::Sqrt(ax*ax + ay*ay + az*az); | |
234 | ||
235 | //points of the DCA | |
97135b34 | 236 | Double_t t1 = Det(x2-x1,y2-y1,z2-z1,px2,py2,pz2,ax,ay,az)/ |
237 | Det(px1,py1,pz1,px2,py2,pz2,ax,ay,az); | |
c7bafca9 | 238 | |
239 | x1 += px1*t1; y1 += py1*t1; //z1 += pz1*t1; | |
240 | ||
241 | ||
242 | //propagate track to the points of DCA | |
243 | ||
244 | x1=x1*cs1 + y1*sn1; | |
245 | if (!t->PropagateTo(x1,b)) { | |
246 | Error("PropagateToDCA","Propagation failed !"); | |
247 | return 1.e+33; | |
248 | } | |
249 | ||
250 | return dca; | |
251 | } | |
252 | ||
253 | ||
254 | ||
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