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a9a2d814 | 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 | // | |
19 | // Origin: Christian Kuhn, IReS, Strasbourg, christian.kuhn@ires.in2p3.fr | |
20 | //------------------------------------------------------------------------- | |
a9a2d814 | 21 | #include <TObjArray.h> |
116cbefd | 22 | #include <TTree.h> |
a9a2d814 | 23 | |
e23730c7 | 24 | #include "AliESD.h" |
25 | #include "AliESDv0.h" | |
26 | #include "AliESDcascade.h" | |
a9a2d814 | 27 | #include "AliCascadeVertex.h" |
28 | #include "AliCascadeVertexer.h" | |
a9a2d814 | 29 | #include "AliITStrackV2.h" |
116cbefd | 30 | #include "AliV0vertex.h" |
a9a2d814 | 31 | |
32 | ClassImp(AliCascadeVertexer) | |
33 | ||
e23730c7 | 34 | Int_t AliCascadeVertexer::V0sTracks2CascadeVertices(AliESD *event) { |
35 | //-------------------------------------------------------------------- | |
36 | // This function reconstructs cascade vertices | |
37 | // Adapted to the ESD by I.Belikov (Jouri.Belikov@cern.ch) | |
38 | //-------------------------------------------------------------------- | |
39 | ||
40 | Int_t nV0=(Int_t)event->GetNumberOfV0s(); | |
41 | TObjArray vtcs(nV0); | |
42 | Int_t i; | |
43 | for (i=0; i<nV0; i++) { | |
44 | const AliESDv0 *esdV0=event->GetV0(i); | |
45 | vtcs.AddLast(new AliV0vertex(*esdV0)); | |
46 | } | |
47 | ||
48 | ||
49 | Int_t ntr=(Int_t)event->GetNumberOfTracks(); | |
50 | TObjArray trks(ntr); | |
51 | for (i=0; i<ntr; i++) { | |
52 | AliESDtrack *esdtr=event->GetTrack(i); | |
53 | AliITStrackV2 *iotrack=new AliITStrackV2(*esdtr); | |
54 | iotrack->PropagateTo(3.,0.0023,65.19); iotrack->PropagateTo(2.5,0.,0.); | |
55 | trks.AddLast(iotrack); | |
56 | } | |
57 | ||
58 | Double_t massLambda=1.11568; | |
59 | Int_t ncasc=0; | |
60 | ||
61 | // Looking for the cascades... | |
62 | for (i=0; i<nV0; i++) { | |
63 | AliV0vertex *v=(AliV0vertex*)vtcs.UncheckedAt(i); | |
64 | v->ChangeMassHypothesis(kLambda0); // the v0 must be Lambda | |
65 | if (TMath::Abs(v->GetEffMass()-massLambda)>fMassWin) continue; | |
66 | if (v->GetD(0,0,0)<fDV0min) continue; | |
67 | for (Int_t j=0; j<ntr; j++) { | |
68 | AliITStrackV2 *b=(AliITStrackV2*)trks.UncheckedAt(j); | |
69 | ||
70 | if (TMath::Abs(b->GetD())<fDBachMin) continue; | |
71 | if (b->Get1Pt()<0.) continue; // bachelor's charge | |
72 | ||
73 | AliV0vertex v0(*v), *pv0=&v0; | |
74 | AliITStrackV2 bt(*b), *pbt=&bt; | |
75 | ||
76 | Double_t dca=PropagateToDCA(pv0,pbt); | |
77 | if (dca > fDCAmax) continue; | |
78 | ||
79 | AliCascadeVertex cascade(*pv0,*pbt); | |
80 | if (cascade.GetChi2() > fChi2max) continue; | |
81 | ||
82 | Double_t x,y,z; cascade.GetXYZ(x,y,z); | |
83 | Double_t r2=x*x + y*y; | |
84 | if (r2 > fRmax*fRmax) continue; // condition on fiducial zone | |
85 | if (r2 < fRmin*fRmin) continue; | |
86 | ||
87 | { | |
88 | Double_t x1,y1,z1; pv0->GetXYZ(x1,y1,z1); | |
89 | if (r2 > (x1*x1+y1*y1)) continue; | |
90 | if (z*z > z1*z1) continue; | |
91 | } | |
92 | ||
93 | Double_t px,py,pz; cascade.GetPxPyPz(px,py,pz); | |
94 | Double_t p2=px*px+py*py+pz*pz; | |
95 | Double_t cost=(x*px+y*py+z*pz)/TMath::Sqrt(p2*(r2+z*z)); | |
96 | ||
97 | if (cost<fCPAmax) continue; //condition on the cascade pointing angle | |
98 | //cascade.ChangeMassHypothesis(); //default is Xi | |
99 | ||
100 | event->AddCascade(&cascade); | |
101 | ||
102 | ncasc++; | |
103 | ||
104 | } | |
105 | } | |
106 | ||
107 | // Looking for the anti-cascades... | |
108 | for (i=0; i<nV0; i++) { | |
109 | AliV0vertex *v=(AliV0vertex*)vtcs.UncheckedAt(i); | |
110 | v->ChangeMassHypothesis(kLambda0Bar); //the v0 must be anti-Lambda | |
111 | if (TMath::Abs(v->GetEffMass()-massLambda)>fMassWin) continue; | |
112 | if (v->GetD(0,0,0)<fDV0min) continue; | |
113 | for (Int_t j=0; j<ntr; j++) { | |
114 | AliITStrackV2 *b=(AliITStrackV2*)trks.UncheckedAt(j); | |
115 | ||
116 | if (TMath::Abs(b->GetD())<fDBachMin) continue; | |
117 | if (b->Get1Pt()>0.) continue; // bachelor's charge | |
118 | ||
119 | AliV0vertex v0(*v), *pv0=&v0; | |
120 | AliITStrackV2 bt(*b), *pbt=&bt; | |
121 | ||
122 | Double_t dca=PropagateToDCA(pv0,pbt); | |
123 | if (dca > fDCAmax) continue; | |
124 | ||
125 | AliCascadeVertex cascade(*pv0,*pbt); | |
126 | if (cascade.GetChi2() > fChi2max) continue; | |
127 | ||
128 | Double_t x,y,z; cascade.GetXYZ(x,y,z); | |
129 | Double_t r2=x*x + y*y; | |
130 | if (r2 > fRmax*fRmax) continue; // condition on fiducial zone | |
131 | if (r2 < fRmin*fRmin) continue; | |
132 | ||
133 | { | |
134 | Double_t x1,y1,z1; pv0->GetXYZ(x1,y1,z1); | |
135 | if (r2 > (x1*x1+y1*y1)) continue; | |
136 | if (z*z > z1*z1) continue; | |
137 | } | |
138 | ||
139 | Double_t px,py,pz; cascade.GetPxPyPz(px,py,pz); | |
140 | Double_t p2=px*px+py*py+pz*pz; | |
141 | Double_t cost=(x*px+y*py+z*pz)/TMath::Sqrt(p2*(r2+z*z)); | |
142 | ||
143 | if (cost<fCPAmax) continue; //condition on the cascade pointing angle | |
144 | //cascade.ChangeMassHypothesis(); //default is Xi | |
145 | ||
146 | event->AddCascade(&cascade); | |
147 | ||
148 | ncasc++; | |
149 | ||
150 | } | |
151 | } | |
152 | ||
153 | Info("V0sTracks2CascadeVertices","Number of reconstructed cascades: %d",ncasc); | |
154 | ||
155 | trks.Delete(); | |
156 | vtcs.Delete(); | |
157 | ||
158 | return 0; | |
159 | } | |
160 | ||
566abf75 | 161 | Int_t AliCascadeVertexer:: |
162 | V0sTracks2CascadeVertices(TTree *vTree,TTree *tTree, TTree *xTree) { | |
a9a2d814 | 163 | //-------------------------------------------------------------------- |
566abf75 | 164 | // This function reconstructs cascade vertices |
a9a2d814 | 165 | //-------------------------------------------------------------------- |
566abf75 | 166 | TBranch *branch=vTree->GetBranch("vertices"); |
167 | if (!branch) { | |
168 | Error("V0sTracks2CascadeVertices","Can't get the V0 branch !"); | |
169 | return 1; | |
170 | } | |
171 | Int_t nentrV0=(Int_t)vTree->GetEntries(); | |
a9a2d814 | 172 | |
173 | TObjArray vtxV0(nentrV0); | |
174 | ||
175 | // fill TObjArray vtxV0 with vertices | |
176 | ||
177 | Int_t i, nV0=0; | |
178 | for (i=0; i<nentrV0; i++) { | |
179 | ||
180 | AliV0vertex *ioVertex=new AliV0vertex; | |
181 | branch->SetAddress(&ioVertex); | |
566abf75 | 182 | vTree->GetEvent(i); |
a9a2d814 | 183 | nV0++; |
184 | vtxV0.AddLast(ioVertex); | |
185 | ||
186 | } | |
187 | ||
566abf75 | 188 | branch=tTree->GetBranch("tracks"); |
189 | if (!branch) { | |
190 | Error("V0sTracks2CascadeVertices","Can't get the track branch !"); | |
191 | return 2; | |
192 | } | |
193 | Int_t nentr=(Int_t)tTree->GetEntries(); | |
a9a2d814 | 194 | |
195 | TObjArray trks(nentr); | |
196 | ||
197 | // fill TObjArray trks with tracks | |
198 | ||
199 | Int_t ntrack=0; | |
200 | ||
201 | for (i=0; i<nentr; i++) { | |
202 | ||
203 | AliITStrackV2 *iotrack=new AliITStrackV2; | |
204 | branch->SetAddress(&iotrack); | |
566abf75 | 205 | tTree->GetEvent(i); |
4ab260d6 | 206 | |
207 | iotrack->PropagateTo(3.,0.0023,65.19); iotrack->PropagateTo(2.5,0.,0.); | |
208 | ||
a9a2d814 | 209 | ntrack++; trks.AddLast(iotrack); |
210 | ||
211 | } | |
212 | ||
566abf75 | 213 | AliCascadeVertex *ioCascade=0; |
214 | branch=xTree->GetBranch("cascades"); | |
215 | if (!branch) xTree->Branch("cascades","AliCascadeVertex",&ioCascade,32000,3); | |
216 | else branch->SetAddress(&ioCascade); | |
a9a2d814 | 217 | |
218 | // loop on all vertices | |
219 | ||
220 | Double_t massLambda=1.11568; | |
221 | Int_t ncasc=0; | |
222 | ||
223 | for (i=0; i<nV0; i++) { | |
224 | ||
225 | AliV0vertex *V0ver=(AliV0vertex *)vtxV0.UncheckedAt(i); | |
226 | ||
227 | V0ver->ChangeMassHypothesis(kLambda0); //I.B. | |
228 | ||
229 | if (V0ver->GetEffMass()<massLambda-fMassWin || // condition of the V0 mass window (cut fMassWin) | |
230 | V0ver->GetEffMass()>massLambda+fMassWin) continue; | |
231 | ||
232 | if (V0ver->GetD(0,0,0)<fDV0min) continue; // condition of minimum impact parameter of the V0 (cut fDV0min) | |
233 | // here why not cuting on pointing angle ??? | |
234 | ||
235 | // for each vertex in the good mass range, loop on all tracks (= bachelor candidates) | |
236 | ||
237 | for (Int_t k=0; k<ntrack; k++) { | |
238 | ||
239 | AliITStrackV2 *bachtrk=(AliITStrackV2 *)trks.UncheckedAt(k); | |
240 | ||
241 | if (TMath::Abs(bachtrk->GetD())<fDBachMin) continue; // eliminate to small impact parameters | |
242 | ||
243 | if (V0ver->GetPdgCode()==kLambda0 && bachtrk->Get1Pt()<0.) continue; // condition on V0 label | |
244 | if (V0ver->GetPdgCode()==kLambda0Bar && bachtrk->Get1Pt()>0.) continue; // + good sign for bachelor | |
245 | ||
246 | AliV0vertex V0(*V0ver), *pV0=&V0; | |
247 | AliITStrackV2 bt(*bachtrk), *pbt=&bt; | |
248 | ||
249 | // calculation of the distance of closest approach between the V0 and the bachelor | |
250 | ||
251 | Double_t dca=PropagateToDCA(pV0,pbt); | |
252 | if (dca > fDCAmax) continue; // cut on dca | |
253 | ||
254 | // construction of a cascade object | |
255 | ||
256 | AliCascadeVertex cascade(*pV0,*pbt); | |
257 | if (cascade.GetChi2() > fChi2max) continue; | |
258 | ||
259 | // get cascade decay position (V0, bachelor) | |
260 | ||
261 | Double_t x,y,z; cascade.GetXYZ(x,y,z); | |
262 | Double_t r2=x*x + y*y; | |
263 | if (r2 > fRmax*fRmax) continue; // condition on fiducial zone | |
264 | if (r2 < fRmin*fRmin) continue; | |
265 | ||
4ab260d6 | 266 | { |
267 | //I.B. | |
268 | Double_t x1,y1,z1; V0ver->GetXYZ(x1,y1,z1); | |
269 | if (r2 > (x1*x1+y1*y1)) continue; | |
270 | if (z*z > z1*z1) continue; | |
271 | } | |
272 | ||
a9a2d814 | 273 | // get cascade momentum |
274 | ||
275 | Double_t px,py,pz; cascade.GetPxPyPz(px,py,pz); | |
276 | Double_t p2=px*px+py*py+pz*pz; | |
277 | Double_t cost=(x*px+y*py+z*pz)/TMath::Sqrt(p2*(r2+z*z)); | |
278 | ||
279 | if (cost<fCPAmax) continue; // condition on the cascade pointing angle | |
280 | ||
281 | //cascade.ChangeMassHypothesis(); //default is Xi | |
282 | ||
283 | ||
566abf75 | 284 | ioCascade=&cascade; xTree->Fill(); |
a9a2d814 | 285 | |
286 | ncasc++; | |
287 | ||
288 | } | |
289 | } | |
290 | ||
e23730c7 | 291 | Info("V0sTracks2CascadeVertices","Number of reconstructed cascades: %d",ncasc); |
a9a2d814 | 292 | |
a9a2d814 | 293 | trks.Delete(); |
294 | vtxV0.Delete(); | |
295 | ||
a9a2d814 | 296 | return 0; |
297 | } | |
298 | ||
299 | inline Double_t det(Double_t a00, Double_t a01, Double_t a10, Double_t a11){ | |
300 | // determinant 2x2 | |
301 | return a00*a11 - a01*a10; | |
302 | } | |
303 | ||
304 | inline Double_t det (Double_t a00,Double_t a01,Double_t a02, | |
305 | Double_t a10,Double_t a11,Double_t a12, | |
306 | Double_t a20,Double_t a21,Double_t a22) { | |
307 | // determinant 3x3 | |
308 | return | |
309 | a00*det(a11,a12,a21,a22)-a01*det(a10,a12,a20,a22)+a02*det(a10,a11,a20,a21); | |
310 | } | |
311 | ||
312 | ||
313 | ||
314 | ||
315 | Double_t | |
316 | AliCascadeVertexer::PropagateToDCA(AliV0vertex *v, AliITStrackV2 *t) { | |
317 | //-------------------------------------------------------------------- | |
318 | // This function returns the DCA between the V0 and the track | |
319 | //-------------------------------------------------------------------- | |
320 | ||
321 | Double_t phi, x, par[5]; | |
322 | Double_t alpha, cs1, sn1; | |
323 | ||
324 | t->GetExternalParameters(x,par); alpha=t->GetAlpha(); | |
325 | phi=TMath::ASin(par[2]) + alpha; | |
326 | Double_t px1=TMath::Cos(phi), py1=TMath::Sin(phi), pz1=par[3]; | |
327 | ||
328 | ||
329 | cs1=TMath::Cos(alpha); sn1=TMath::Sin(alpha); | |
330 | Double_t x1=x*cs1 - par[0]*sn1; | |
331 | Double_t y1=x*sn1 + par[0]*cs1; | |
332 | Double_t z1=par[1]; | |
333 | ||
334 | ||
335 | Double_t x2,y2,z2; // position and momentum of V0 | |
336 | Double_t px2,py2,pz2; | |
337 | ||
338 | v->GetXYZ(x2,y2,z2); | |
339 | v->GetPxPyPz(px2,py2,pz2); | |
340 | ||
341 | // calculation dca | |
342 | ||
343 | Double_t dd= det(x2-x1,y2-y1,z2-z1,px1,py1,pz1,px2,py2,pz2); | |
344 | Double_t ax= det(py1,pz1,py2,pz2); | |
345 | Double_t ay=-det(px1,pz1,px2,pz2); | |
346 | Double_t az= det(px1,py1,px2,py2); | |
347 | ||
348 | Double_t dca=TMath::Abs(dd)/TMath::Sqrt(ax*ax + ay*ay + az*az); | |
349 | ||
350 | //points of the DCA | |
351 | Double_t t1 = det(x2-x1,y2-y1,z2-z1,px2,py2,pz2,ax,ay,az)/ | |
352 | det(px1,py1,pz1,px2,py2,pz2,ax,ay,az); | |
353 | ||
354 | x1 += px1*t1; y1 += py1*t1; //z1 += pz1*t1; | |
355 | ||
356 | ||
357 | //propagate track to the points of DCA | |
358 | ||
359 | x1=x1*cs1 + y1*sn1; | |
360 | if (!t->PropagateTo(x1,0.,0.)) { | |
e23730c7 | 361 | Error("PropagateToDCA","Propagation failed !"); |
a9a2d814 | 362 | return 1.e+33; |
363 | } | |
364 | ||
365 | return dca; | |
366 | } | |
367 | ||
368 | ||
369 | ||
370 | ||
371 | ||
372 | ||
373 | ||
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375 | ||
376 | ||
377 |