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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 | |
18856a77 | 18 | // Reads V0s and tracks, writes out cascade vertices |
19 | // Fills the ESD with the cascades | |
a9a2d814 | 20 | // Origin: Christian Kuhn, IReS, Strasbourg, christian.kuhn@ires.in2p3.fr |
21 | //------------------------------------------------------------------------- | |
a9a2d814 | 22 | #include <TObjArray.h> |
116cbefd | 23 | #include <TTree.h> |
a9a2d814 | 24 | |
e23730c7 | 25 | #include "AliESD.h" |
26 | #include "AliESDv0.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); | |
18856a77 | 53 | Int_t status=esdtr->GetStatus(); |
54 | ||
55 | if ((status&AliESDtrack::kITSrefit)==0) | |
56 | if ((status&AliESDtrack::kITSout)!=0 || (status&AliESDtrack::kITSin)==0) | |
57 | continue; | |
58 | ||
e23730c7 | 59 | AliITStrackV2 *iotrack=new AliITStrackV2(*esdtr); |
18856a77 | 60 | if ((status&AliESDtrack::kITSrefit)==0) //correction for the beam pipe |
61 | iotrack->PropagateTo(3.,0.0023,65.19); //material | |
62 | iotrack->PropagateTo(2.5,0.,0.); | |
e23730c7 | 63 | trks.AddLast(iotrack); |
64 | } | |
65 | ||
66 | Double_t massLambda=1.11568; | |
67 | Int_t ncasc=0; | |
68 | ||
69 | // Looking for the cascades... | |
70 | for (i=0; i<nV0; i++) { | |
71 | AliV0vertex *v=(AliV0vertex*)vtcs.UncheckedAt(i); | |
72 | v->ChangeMassHypothesis(kLambda0); // the v0 must be Lambda | |
73 | if (TMath::Abs(v->GetEffMass()-massLambda)>fMassWin) continue; | |
74 | if (v->GetD(0,0,0)<fDV0min) continue; | |
75 | for (Int_t j=0; j<ntr; j++) { | |
76 | AliITStrackV2 *b=(AliITStrackV2*)trks.UncheckedAt(j); | |
77 | ||
78 | if (TMath::Abs(b->GetD())<fDBachMin) continue; | |
79 | if (b->Get1Pt()<0.) continue; // bachelor's charge | |
80 | ||
81 | AliV0vertex v0(*v), *pv0=&v0; | |
82 | AliITStrackV2 bt(*b), *pbt=&bt; | |
83 | ||
84 | Double_t dca=PropagateToDCA(pv0,pbt); | |
85 | if (dca > fDCAmax) continue; | |
86 | ||
87 | AliCascadeVertex cascade(*pv0,*pbt); | |
88 | if (cascade.GetChi2() > fChi2max) continue; | |
89 | ||
90 | Double_t x,y,z; cascade.GetXYZ(x,y,z); | |
91 | Double_t r2=x*x + y*y; | |
92 | if (r2 > fRmax*fRmax) continue; // condition on fiducial zone | |
93 | if (r2 < fRmin*fRmin) continue; | |
94 | ||
95 | { | |
96 | Double_t x1,y1,z1; pv0->GetXYZ(x1,y1,z1); | |
97 | if (r2 > (x1*x1+y1*y1)) continue; | |
98 | if (z*z > z1*z1) continue; | |
99 | } | |
100 | ||
101 | Double_t px,py,pz; cascade.GetPxPyPz(px,py,pz); | |
102 | Double_t p2=px*px+py*py+pz*pz; | |
103 | Double_t cost=(x*px+y*py+z*pz)/TMath::Sqrt(p2*(r2+z*z)); | |
104 | ||
105 | if (cost<fCPAmax) continue; //condition on the cascade pointing angle | |
106 | //cascade.ChangeMassHypothesis(); //default is Xi | |
107 | ||
108 | event->AddCascade(&cascade); | |
109 | ||
110 | ncasc++; | |
111 | ||
112 | } | |
113 | } | |
114 | ||
115 | // Looking for the anti-cascades... | |
116 | for (i=0; i<nV0; i++) { | |
117 | AliV0vertex *v=(AliV0vertex*)vtcs.UncheckedAt(i); | |
118 | v->ChangeMassHypothesis(kLambda0Bar); //the v0 must be anti-Lambda | |
119 | if (TMath::Abs(v->GetEffMass()-massLambda)>fMassWin) continue; | |
120 | if (v->GetD(0,0,0)<fDV0min) continue; | |
121 | for (Int_t j=0; j<ntr; j++) { | |
122 | AliITStrackV2 *b=(AliITStrackV2*)trks.UncheckedAt(j); | |
123 | ||
124 | if (TMath::Abs(b->GetD())<fDBachMin) continue; | |
125 | if (b->Get1Pt()>0.) continue; // bachelor's charge | |
126 | ||
127 | AliV0vertex v0(*v), *pv0=&v0; | |
128 | AliITStrackV2 bt(*b), *pbt=&bt; | |
129 | ||
130 | Double_t dca=PropagateToDCA(pv0,pbt); | |
131 | if (dca > fDCAmax) continue; | |
132 | ||
133 | AliCascadeVertex cascade(*pv0,*pbt); | |
134 | if (cascade.GetChi2() > fChi2max) continue; | |
135 | ||
136 | Double_t x,y,z; cascade.GetXYZ(x,y,z); | |
137 | Double_t r2=x*x + y*y; | |
138 | if (r2 > fRmax*fRmax) continue; // condition on fiducial zone | |
139 | if (r2 < fRmin*fRmin) continue; | |
140 | ||
141 | { | |
142 | Double_t x1,y1,z1; pv0->GetXYZ(x1,y1,z1); | |
143 | if (r2 > (x1*x1+y1*y1)) continue; | |
144 | if (z*z > z1*z1) continue; | |
145 | } | |
146 | ||
147 | Double_t px,py,pz; cascade.GetPxPyPz(px,py,pz); | |
148 | Double_t p2=px*px+py*py+pz*pz; | |
149 | Double_t cost=(x*px+y*py+z*pz)/TMath::Sqrt(p2*(r2+z*z)); | |
150 | ||
151 | if (cost<fCPAmax) continue; //condition on the cascade pointing angle | |
152 | //cascade.ChangeMassHypothesis(); //default is Xi | |
153 | ||
154 | event->AddCascade(&cascade); | |
155 | ||
156 | ncasc++; | |
157 | ||
158 | } | |
159 | } | |
160 | ||
161 | Info("V0sTracks2CascadeVertices","Number of reconstructed cascades: %d",ncasc); | |
162 | ||
163 | trks.Delete(); | |
164 | vtcs.Delete(); | |
165 | ||
166 | return 0; | |
167 | } | |
168 | ||
566abf75 | 169 | Int_t AliCascadeVertexer:: |
170 | V0sTracks2CascadeVertices(TTree *vTree,TTree *tTree, TTree *xTree) { | |
a9a2d814 | 171 | //-------------------------------------------------------------------- |
566abf75 | 172 | // This function reconstructs cascade vertices |
a9a2d814 | 173 | //-------------------------------------------------------------------- |
566abf75 | 174 | TBranch *branch=vTree->GetBranch("vertices"); |
175 | if (!branch) { | |
176 | Error("V0sTracks2CascadeVertices","Can't get the V0 branch !"); | |
177 | return 1; | |
178 | } | |
179 | Int_t nentrV0=(Int_t)vTree->GetEntries(); | |
a9a2d814 | 180 | |
181 | TObjArray vtxV0(nentrV0); | |
182 | ||
183 | // fill TObjArray vtxV0 with vertices | |
184 | ||
185 | Int_t i, nV0=0; | |
186 | for (i=0; i<nentrV0; i++) { | |
187 | ||
188 | AliV0vertex *ioVertex=new AliV0vertex; | |
189 | branch->SetAddress(&ioVertex); | |
566abf75 | 190 | vTree->GetEvent(i); |
a9a2d814 | 191 | nV0++; |
192 | vtxV0.AddLast(ioVertex); | |
193 | ||
194 | } | |
195 | ||
566abf75 | 196 | branch=tTree->GetBranch("tracks"); |
197 | if (!branch) { | |
198 | Error("V0sTracks2CascadeVertices","Can't get the track branch !"); | |
199 | return 2; | |
200 | } | |
201 | Int_t nentr=(Int_t)tTree->GetEntries(); | |
a9a2d814 | 202 | |
203 | TObjArray trks(nentr); | |
204 | ||
205 | // fill TObjArray trks with tracks | |
206 | ||
207 | Int_t ntrack=0; | |
208 | ||
209 | for (i=0; i<nentr; i++) { | |
210 | ||
211 | AliITStrackV2 *iotrack=new AliITStrackV2; | |
212 | branch->SetAddress(&iotrack); | |
566abf75 | 213 | tTree->GetEvent(i); |
4ab260d6 | 214 | |
215 | iotrack->PropagateTo(3.,0.0023,65.19); iotrack->PropagateTo(2.5,0.,0.); | |
216 | ||
a9a2d814 | 217 | ntrack++; trks.AddLast(iotrack); |
218 | ||
219 | } | |
220 | ||
566abf75 | 221 | AliCascadeVertex *ioCascade=0; |
222 | branch=xTree->GetBranch("cascades"); | |
223 | if (!branch) xTree->Branch("cascades","AliCascadeVertex",&ioCascade,32000,3); | |
224 | else branch->SetAddress(&ioCascade); | |
a9a2d814 | 225 | |
226 | // loop on all vertices | |
227 | ||
228 | Double_t massLambda=1.11568; | |
229 | Int_t ncasc=0; | |
230 | ||
231 | for (i=0; i<nV0; i++) { | |
232 | ||
93f82b23 | 233 | AliV0vertex *lV0ver=(AliV0vertex *)vtxV0.UncheckedAt(i); |
a9a2d814 | 234 | |
93f82b23 | 235 | lV0ver->ChangeMassHypothesis(kLambda0); //I.B. |
a9a2d814 | 236 | |
93f82b23 | 237 | if (lV0ver->GetEffMass()<massLambda-fMassWin || // condition of the V0 mass window (cut fMassWin) |
238 | lV0ver->GetEffMass()>massLambda+fMassWin) continue; | |
a9a2d814 | 239 | |
93f82b23 | 240 | if (lV0ver->GetD(0,0,0)<fDV0min) continue; // condition of minimum impact parameter of the V0 (cut fDV0min) |
a9a2d814 | 241 | // here why not cuting on pointing angle ??? |
242 | ||
243 | // for each vertex in the good mass range, loop on all tracks (= bachelor candidates) | |
244 | ||
245 | for (Int_t k=0; k<ntrack; k++) { | |
246 | ||
247 | AliITStrackV2 *bachtrk=(AliITStrackV2 *)trks.UncheckedAt(k); | |
248 | ||
249 | if (TMath::Abs(bachtrk->GetD())<fDBachMin) continue; // eliminate to small impact parameters | |
250 | ||
93f82b23 | 251 | if (lV0ver->GetPdgCode()==kLambda0 && bachtrk->Get1Pt()<0.) continue; // condition on V0 label |
252 | if (lV0ver->GetPdgCode()==kLambda0Bar && bachtrk->Get1Pt()>0.) continue; // + good sign for bachelor | |
a9a2d814 | 253 | |
93f82b23 | 254 | AliV0vertex lV0(*lV0ver), *pV0=&lV0; |
a9a2d814 | 255 | AliITStrackV2 bt(*bachtrk), *pbt=&bt; |
256 | ||
257 | // calculation of the distance of closest approach between the V0 and the bachelor | |
258 | ||
259 | Double_t dca=PropagateToDCA(pV0,pbt); | |
260 | if (dca > fDCAmax) continue; // cut on dca | |
261 | ||
262 | // construction of a cascade object | |
263 | ||
264 | AliCascadeVertex cascade(*pV0,*pbt); | |
265 | if (cascade.GetChi2() > fChi2max) continue; | |
266 | ||
267 | // get cascade decay position (V0, bachelor) | |
268 | ||
269 | Double_t x,y,z; cascade.GetXYZ(x,y,z); | |
270 | Double_t r2=x*x + y*y; | |
271 | if (r2 > fRmax*fRmax) continue; // condition on fiducial zone | |
272 | if (r2 < fRmin*fRmin) continue; | |
273 | ||
4ab260d6 | 274 | { |
275 | //I.B. | |
93f82b23 | 276 | Double_t x1,y1,z1; lV0ver->GetXYZ(x1,y1,z1); |
4ab260d6 | 277 | if (r2 > (x1*x1+y1*y1)) continue; |
278 | if (z*z > z1*z1) continue; | |
279 | } | |
280 | ||
a9a2d814 | 281 | // get cascade momentum |
282 | ||
283 | Double_t px,py,pz; cascade.GetPxPyPz(px,py,pz); | |
284 | Double_t p2=px*px+py*py+pz*pz; | |
285 | Double_t cost=(x*px+y*py+z*pz)/TMath::Sqrt(p2*(r2+z*z)); | |
286 | ||
287 | if (cost<fCPAmax) continue; // condition on the cascade pointing angle | |
288 | ||
289 | //cascade.ChangeMassHypothesis(); //default is Xi | |
290 | ||
291 | ||
566abf75 | 292 | ioCascade=&cascade; xTree->Fill(); |
a9a2d814 | 293 | |
294 | ncasc++; | |
295 | ||
296 | } | |
297 | } | |
298 | ||
e23730c7 | 299 | Info("V0sTracks2CascadeVertices","Number of reconstructed cascades: %d",ncasc); |
a9a2d814 | 300 | |
a9a2d814 | 301 | trks.Delete(); |
302 | vtxV0.Delete(); | |
303 | ||
a9a2d814 | 304 | return 0; |
305 | } | |
306 | ||
307 | inline Double_t det(Double_t a00, Double_t a01, Double_t a10, Double_t a11){ | |
308 | // determinant 2x2 | |
309 | return a00*a11 - a01*a10; | |
310 | } | |
311 | ||
312 | inline Double_t det (Double_t a00,Double_t a01,Double_t a02, | |
313 | Double_t a10,Double_t a11,Double_t a12, | |
314 | Double_t a20,Double_t a21,Double_t a22) { | |
315 | // determinant 3x3 | |
316 | return | |
317 | a00*det(a11,a12,a21,a22)-a01*det(a10,a12,a20,a22)+a02*det(a10,a11,a20,a21); | |
318 | } | |
319 | ||
320 | ||
321 | ||
322 | ||
323 | Double_t | |
324 | AliCascadeVertexer::PropagateToDCA(AliV0vertex *v, AliITStrackV2 *t) { | |
325 | //-------------------------------------------------------------------- | |
326 | // This function returns the DCA between the V0 and the track | |
327 | //-------------------------------------------------------------------- | |
328 | ||
329 | Double_t phi, x, par[5]; | |
330 | Double_t alpha, cs1, sn1; | |
331 | ||
332 | t->GetExternalParameters(x,par); alpha=t->GetAlpha(); | |
333 | phi=TMath::ASin(par[2]) + alpha; | |
334 | Double_t px1=TMath::Cos(phi), py1=TMath::Sin(phi), pz1=par[3]; | |
335 | ||
336 | ||
337 | cs1=TMath::Cos(alpha); sn1=TMath::Sin(alpha); | |
338 | Double_t x1=x*cs1 - par[0]*sn1; | |
339 | Double_t y1=x*sn1 + par[0]*cs1; | |
340 | Double_t z1=par[1]; | |
341 | ||
342 | ||
343 | Double_t x2,y2,z2; // position and momentum of V0 | |
344 | Double_t px2,py2,pz2; | |
345 | ||
346 | v->GetXYZ(x2,y2,z2); | |
347 | v->GetPxPyPz(px2,py2,pz2); | |
348 | ||
349 | // calculation dca | |
350 | ||
351 | Double_t dd= det(x2-x1,y2-y1,z2-z1,px1,py1,pz1,px2,py2,pz2); | |
352 | Double_t ax= det(py1,pz1,py2,pz2); | |
353 | Double_t ay=-det(px1,pz1,px2,pz2); | |
354 | Double_t az= det(px1,py1,px2,py2); | |
355 | ||
356 | Double_t dca=TMath::Abs(dd)/TMath::Sqrt(ax*ax + ay*ay + az*az); | |
357 | ||
358 | //points of the DCA | |
359 | Double_t t1 = det(x2-x1,y2-y1,z2-z1,px2,py2,pz2,ax,ay,az)/ | |
360 | det(px1,py1,pz1,px2,py2,pz2,ax,ay,az); | |
361 | ||
362 | x1 += px1*t1; y1 += py1*t1; //z1 += pz1*t1; | |
363 | ||
364 | ||
365 | //propagate track to the points of DCA | |
366 | ||
367 | x1=x1*cs1 + y1*sn1; | |
368 | if (!t->PropagateTo(x1,0.,0.)) { | |
e23730c7 | 369 | Error("PropagateToDCA","Propagation failed !"); |
a9a2d814 | 370 | return 1.e+33; |
371 | } | |
372 | ||
373 | return dca; | |
374 | } | |
375 | ||
376 | ||
377 | ||
378 | ||
379 | ||
380 | ||
381 | ||
382 | ||
383 | ||
384 | ||
385 |