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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); | |
a9459f9c | 53 | UInt_t status=esdtr->GetStatus(); |
e1cac29c | 54 | UInt_t flags=AliESDtrack::kITSin|AliESDtrack::kTPCin| |
55 | AliESDtrack::kTPCpid|AliESDtrack::kESDpid; | |
18856a77 | 56 | |
57 | if ((status&AliESDtrack::kITSrefit)==0) | |
e1cac29c | 58 | if (flags!=status) continue; |
18856a77 | 59 | |
e23730c7 | 60 | AliITStrackV2 *iotrack=new AliITStrackV2(*esdtr); |
df02fd67 | 61 | iotrack->SetLabel(i); // now it is the index in array of ESD tracks |
18856a77 | 62 | if ((status&AliESDtrack::kITSrefit)==0) //correction for the beam pipe |
df02fd67 | 63 | if (!iotrack->PropagateTo(3.,0.0023,65.19)) continue; |
64 | if (!iotrack->PropagateTo(2.5,0.,0.)) continue; | |
e23730c7 | 65 | trks.AddLast(iotrack); |
66 | } | |
df02fd67 | 67 | ntr=trks.GetEntriesFast(); |
e23730c7 | 68 | |
69 | Double_t massLambda=1.11568; | |
70 | Int_t ncasc=0; | |
71 | ||
72 | // Looking for the cascades... | |
73 | for (i=0; i<nV0; i++) { | |
74 | AliV0vertex *v=(AliV0vertex*)vtcs.UncheckedAt(i); | |
75 | v->ChangeMassHypothesis(kLambda0); // the v0 must be Lambda | |
76 | if (TMath::Abs(v->GetEffMass()-massLambda)>fMassWin) continue; | |
e1cac29c | 77 | if (v->GetD(fX,fY,fZ)<fDV0min) continue; |
e23730c7 | 78 | for (Int_t j=0; j<ntr; j++) { |
79 | AliITStrackV2 *b=(AliITStrackV2*)trks.UncheckedAt(j); | |
80 | ||
71bf84f0 | 81 | if (b->Get1Pt()>0.) continue; // bachelor's charge |
e1cac29c | 82 | if (TMath::Abs(b->GetD(fX,fY))<fDBachMin) continue; |
e23730c7 | 83 | |
84 | AliV0vertex v0(*v), *pv0=&v0; | |
85 | AliITStrackV2 bt(*b), *pbt=&bt; | |
86 | ||
87 | Double_t dca=PropagateToDCA(pv0,pbt); | |
88 | if (dca > fDCAmax) continue; | |
89 | ||
90 | AliCascadeVertex cascade(*pv0,*pbt); | |
91 | if (cascade.GetChi2() > fChi2max) continue; | |
92 | ||
93 | Double_t x,y,z; cascade.GetXYZ(x,y,z); | |
94 | Double_t r2=x*x + y*y; | |
95 | if (r2 > fRmax*fRmax) continue; // condition on fiducial zone | |
96 | if (r2 < fRmin*fRmin) continue; | |
97 | ||
98 | { | |
99 | Double_t x1,y1,z1; pv0->GetXYZ(x1,y1,z1); | |
100 | if (r2 > (x1*x1+y1*y1)) continue; | |
e1cac29c | 101 | //if ((z-fZ)*(z-fZ) > (z1-fZ)*(z1-fZ)) continue; |
e23730c7 | 102 | } |
103 | ||
104 | Double_t px,py,pz; cascade.GetPxPyPz(px,py,pz); | |
105 | Double_t p2=px*px+py*py+pz*pz; | |
e1cac29c | 106 | Double_t cost=((x-fX)*px + (y-fY)*py + (z-fZ)*pz)/ |
107 | TMath::Sqrt(p2*((x-fX)*(x-fX) + (y-fY)*(y-fY) + (z-fZ)*(z-fZ))); | |
108 | if (cost<fCPAmax) continue; //condition on the cascade pointing angle | |
e23730c7 | 109 | //cascade.ChangeMassHypothesis(); //default is Xi |
110 | ||
111 | event->AddCascade(&cascade); | |
112 | ||
113 | ncasc++; | |
114 | ||
115 | } | |
116 | } | |
117 | ||
118 | // Looking for the anti-cascades... | |
119 | for (i=0; i<nV0; i++) { | |
120 | AliV0vertex *v=(AliV0vertex*)vtcs.UncheckedAt(i); | |
121 | v->ChangeMassHypothesis(kLambda0Bar); //the v0 must be anti-Lambda | |
122 | if (TMath::Abs(v->GetEffMass()-massLambda)>fMassWin) continue; | |
e1cac29c | 123 | if (v->GetD(fX,fY,fZ)<fDV0min) continue; |
e23730c7 | 124 | for (Int_t j=0; j<ntr; j++) { |
125 | AliITStrackV2 *b=(AliITStrackV2*)trks.UncheckedAt(j); | |
126 | ||
e1cac29c | 127 | if (TMath::Abs(b->GetD(fX,fY))<fDBachMin) continue; |
71bf84f0 | 128 | if (b->Get1Pt()<0.) continue; // bachelor's charge |
e23730c7 | 129 | |
130 | AliV0vertex v0(*v), *pv0=&v0; | |
131 | AliITStrackV2 bt(*b), *pbt=&bt; | |
132 | ||
133 | Double_t dca=PropagateToDCA(pv0,pbt); | |
134 | if (dca > fDCAmax) continue; | |
135 | ||
136 | AliCascadeVertex cascade(*pv0,*pbt); | |
137 | if (cascade.GetChi2() > fChi2max) continue; | |
138 | ||
139 | Double_t x,y,z; cascade.GetXYZ(x,y,z); | |
140 | Double_t r2=x*x + y*y; | |
141 | if (r2 > fRmax*fRmax) continue; // condition on fiducial zone | |
142 | if (r2 < fRmin*fRmin) continue; | |
143 | ||
144 | { | |
145 | Double_t x1,y1,z1; pv0->GetXYZ(x1,y1,z1); | |
146 | if (r2 > (x1*x1+y1*y1)) continue; | |
147 | if (z*z > z1*z1) continue; | |
148 | } | |
149 | ||
150 | Double_t px,py,pz; cascade.GetPxPyPz(px,py,pz); | |
151 | Double_t p2=px*px+py*py+pz*pz; | |
e1cac29c | 152 | Double_t cost=((x-fX)*px + (y-fY)*py + (z-fZ)*pz)/ |
153 | TMath::Sqrt(p2*((x-fX)*(x-fX) + (y-fY)*(y-fY) + (z-fZ)*(z-fZ))); | |
e23730c7 | 154 | |
155 | if (cost<fCPAmax) continue; //condition on the cascade pointing angle | |
156 | //cascade.ChangeMassHypothesis(); //default is Xi | |
157 | ||
158 | event->AddCascade(&cascade); | |
159 | ||
160 | ncasc++; | |
161 | ||
162 | } | |
163 | } | |
164 | ||
165 | Info("V0sTracks2CascadeVertices","Number of reconstructed cascades: %d",ncasc); | |
166 | ||
167 | trks.Delete(); | |
168 | vtcs.Delete(); | |
169 | ||
170 | return 0; | |
171 | } | |
172 | ||
566abf75 | 173 | Int_t AliCascadeVertexer:: |
174 | V0sTracks2CascadeVertices(TTree *vTree,TTree *tTree, TTree *xTree) { | |
a9a2d814 | 175 | //-------------------------------------------------------------------- |
566abf75 | 176 | // This function reconstructs cascade vertices |
a9a2d814 | 177 | //-------------------------------------------------------------------- |
df02fd67 | 178 | Warning("V0sTracks2CascadeVertices(TTree*,TTree*,TTree*)", |
179 | "Will be removed soon ! Use V0sTracks2CascadeVertices(AliESD*) instead"); | |
180 | ||
566abf75 | 181 | TBranch *branch=vTree->GetBranch("vertices"); |
182 | if (!branch) { | |
183 | Error("V0sTracks2CascadeVertices","Can't get the V0 branch !"); | |
184 | return 1; | |
185 | } | |
186 | Int_t nentrV0=(Int_t)vTree->GetEntries(); | |
a9a2d814 | 187 | |
188 | TObjArray vtxV0(nentrV0); | |
189 | ||
190 | // fill TObjArray vtxV0 with vertices | |
191 | ||
192 | Int_t i, nV0=0; | |
193 | for (i=0; i<nentrV0; i++) { | |
194 | ||
195 | AliV0vertex *ioVertex=new AliV0vertex; | |
196 | branch->SetAddress(&ioVertex); | |
566abf75 | 197 | vTree->GetEvent(i); |
a9a2d814 | 198 | nV0++; |
199 | vtxV0.AddLast(ioVertex); | |
200 | ||
201 | } | |
202 | ||
566abf75 | 203 | branch=tTree->GetBranch("tracks"); |
204 | if (!branch) { | |
205 | Error("V0sTracks2CascadeVertices","Can't get the track branch !"); | |
206 | return 2; | |
207 | } | |
208 | Int_t nentr=(Int_t)tTree->GetEntries(); | |
a9a2d814 | 209 | |
210 | TObjArray trks(nentr); | |
211 | ||
212 | // fill TObjArray trks with tracks | |
213 | ||
214 | Int_t ntrack=0; | |
215 | ||
216 | for (i=0; i<nentr; i++) { | |
217 | ||
218 | AliITStrackV2 *iotrack=new AliITStrackV2; | |
219 | branch->SetAddress(&iotrack); | |
566abf75 | 220 | tTree->GetEvent(i); |
4ab260d6 | 221 | |
df02fd67 | 222 | if (!iotrack->PropagateTo(3.,0.0023,65.19)) continue; |
223 | if (!iotrack->PropagateTo(2.5,0.,0.)) continue; | |
4ab260d6 | 224 | |
a9a2d814 | 225 | ntrack++; trks.AddLast(iotrack); |
226 | ||
227 | } | |
228 | ||
566abf75 | 229 | AliCascadeVertex *ioCascade=0; |
230 | branch=xTree->GetBranch("cascades"); | |
231 | if (!branch) xTree->Branch("cascades","AliCascadeVertex",&ioCascade,32000,3); | |
232 | else branch->SetAddress(&ioCascade); | |
a9a2d814 | 233 | |
234 | // loop on all vertices | |
235 | ||
236 | Double_t massLambda=1.11568; | |
237 | Int_t ncasc=0; | |
238 | ||
239 | for (i=0; i<nV0; i++) { | |
240 | ||
93f82b23 | 241 | AliV0vertex *lV0ver=(AliV0vertex *)vtxV0.UncheckedAt(i); |
a9a2d814 | 242 | |
93f82b23 | 243 | lV0ver->ChangeMassHypothesis(kLambda0); //I.B. |
a9a2d814 | 244 | |
93f82b23 | 245 | if (lV0ver->GetEffMass()<massLambda-fMassWin || // condition of the V0 mass window (cut fMassWin) |
246 | lV0ver->GetEffMass()>massLambda+fMassWin) continue; | |
a9a2d814 | 247 | |
93f82b23 | 248 | if (lV0ver->GetD(0,0,0)<fDV0min) continue; // condition of minimum impact parameter of the V0 (cut fDV0min) |
a9a2d814 | 249 | // here why not cuting on pointing angle ??? |
250 | ||
251 | // for each vertex in the good mass range, loop on all tracks (= bachelor candidates) | |
252 | ||
253 | for (Int_t k=0; k<ntrack; k++) { | |
254 | ||
255 | AliITStrackV2 *bachtrk=(AliITStrackV2 *)trks.UncheckedAt(k); | |
256 | ||
257 | if (TMath::Abs(bachtrk->GetD())<fDBachMin) continue; // eliminate to small impact parameters | |
258 | ||
71bf84f0 | 259 | if (lV0ver->GetPdgCode()==kLambda0 && bachtrk->Get1Pt()>0.) continue; // condition on V0 label |
260 | if (lV0ver->GetPdgCode()==kLambda0Bar && bachtrk->Get1Pt()<0.) continue; // + good sign for bachelor | |
a9a2d814 | 261 | |
93f82b23 | 262 | AliV0vertex lV0(*lV0ver), *pV0=&lV0; |
a9a2d814 | 263 | AliITStrackV2 bt(*bachtrk), *pbt=&bt; |
264 | ||
265 | // calculation of the distance of closest approach between the V0 and the bachelor | |
266 | ||
267 | Double_t dca=PropagateToDCA(pV0,pbt); | |
268 | if (dca > fDCAmax) continue; // cut on dca | |
269 | ||
270 | // construction of a cascade object | |
271 | ||
272 | AliCascadeVertex cascade(*pV0,*pbt); | |
273 | if (cascade.GetChi2() > fChi2max) continue; | |
274 | ||
275 | // get cascade decay position (V0, bachelor) | |
276 | ||
277 | Double_t x,y,z; cascade.GetXYZ(x,y,z); | |
278 | Double_t r2=x*x + y*y; | |
279 | if (r2 > fRmax*fRmax) continue; // condition on fiducial zone | |
280 | if (r2 < fRmin*fRmin) continue; | |
281 | ||
4ab260d6 | 282 | { |
283 | //I.B. | |
93f82b23 | 284 | Double_t x1,y1,z1; lV0ver->GetXYZ(x1,y1,z1); |
4ab260d6 | 285 | if (r2 > (x1*x1+y1*y1)) continue; |
286 | if (z*z > z1*z1) continue; | |
287 | } | |
288 | ||
a9a2d814 | 289 | // get cascade momentum |
290 | ||
291 | Double_t px,py,pz; cascade.GetPxPyPz(px,py,pz); | |
292 | Double_t p2=px*px+py*py+pz*pz; | |
293 | Double_t cost=(x*px+y*py+z*pz)/TMath::Sqrt(p2*(r2+z*z)); | |
294 | ||
295 | if (cost<fCPAmax) continue; // condition on the cascade pointing angle | |
296 | ||
297 | //cascade.ChangeMassHypothesis(); //default is Xi | |
298 | ||
299 | ||
566abf75 | 300 | ioCascade=&cascade; xTree->Fill(); |
a9a2d814 | 301 | |
302 | ncasc++; | |
303 | ||
304 | } | |
305 | } | |
306 | ||
e23730c7 | 307 | Info("V0sTracks2CascadeVertices","Number of reconstructed cascades: %d",ncasc); |
a9a2d814 | 308 | |
a9a2d814 | 309 | trks.Delete(); |
310 | vtxV0.Delete(); | |
311 | ||
a9a2d814 | 312 | return 0; |
313 | } | |
314 | ||
315 | inline Double_t det(Double_t a00, Double_t a01, Double_t a10, Double_t a11){ | |
316 | // determinant 2x2 | |
317 | return a00*a11 - a01*a10; | |
318 | } | |
319 | ||
320 | inline Double_t det (Double_t a00,Double_t a01,Double_t a02, | |
321 | Double_t a10,Double_t a11,Double_t a12, | |
322 | Double_t a20,Double_t a21,Double_t a22) { | |
323 | // determinant 3x3 | |
324 | return | |
325 | a00*det(a11,a12,a21,a22)-a01*det(a10,a12,a20,a22)+a02*det(a10,a11,a20,a21); | |
326 | } | |
327 | ||
328 | ||
329 | ||
330 | ||
331 | Double_t | |
332 | AliCascadeVertexer::PropagateToDCA(AliV0vertex *v, AliITStrackV2 *t) { | |
333 | //-------------------------------------------------------------------- | |
334 | // This function returns the DCA between the V0 and the track | |
335 | //-------------------------------------------------------------------- | |
336 | ||
337 | Double_t phi, x, par[5]; | |
338 | Double_t alpha, cs1, sn1; | |
339 | ||
340 | t->GetExternalParameters(x,par); alpha=t->GetAlpha(); | |
341 | phi=TMath::ASin(par[2]) + alpha; | |
342 | Double_t px1=TMath::Cos(phi), py1=TMath::Sin(phi), pz1=par[3]; | |
343 | ||
344 | ||
345 | cs1=TMath::Cos(alpha); sn1=TMath::Sin(alpha); | |
346 | Double_t x1=x*cs1 - par[0]*sn1; | |
347 | Double_t y1=x*sn1 + par[0]*cs1; | |
348 | Double_t z1=par[1]; | |
349 | ||
350 | ||
351 | Double_t x2,y2,z2; // position and momentum of V0 | |
352 | Double_t px2,py2,pz2; | |
353 | ||
354 | v->GetXYZ(x2,y2,z2); | |
355 | v->GetPxPyPz(px2,py2,pz2); | |
356 | ||
357 | // calculation dca | |
358 | ||
359 | Double_t dd= det(x2-x1,y2-y1,z2-z1,px1,py1,pz1,px2,py2,pz2); | |
360 | Double_t ax= det(py1,pz1,py2,pz2); | |
361 | Double_t ay=-det(px1,pz1,px2,pz2); | |
362 | Double_t az= det(px1,py1,px2,py2); | |
363 | ||
364 | Double_t dca=TMath::Abs(dd)/TMath::Sqrt(ax*ax + ay*ay + az*az); | |
365 | ||
366 | //points of the DCA | |
367 | Double_t t1 = det(x2-x1,y2-y1,z2-z1,px2,py2,pz2,ax,ay,az)/ | |
368 | det(px1,py1,pz1,px2,py2,pz2,ax,ay,az); | |
369 | ||
370 | x1 += px1*t1; y1 += py1*t1; //z1 += pz1*t1; | |
371 | ||
372 | ||
373 | //propagate track to the points of DCA | |
374 | ||
375 | x1=x1*cs1 + y1*sn1; | |
376 | if (!t->PropagateTo(x1,0.,0.)) { | |
e23730c7 | 377 | Error("PropagateToDCA","Propagation failed !"); |
a9a2d814 | 378 | return 1.e+33; |
379 | } | |
380 | ||
381 | return dca; | |
382 | } | |
383 | ||
384 | ||
385 | ||
386 | ||
387 | ||
388 | ||
389 | ||
390 | ||
391 | ||
392 | ||
393 |