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7f6ddf58 | 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 V0 vertexer class | |
18 | // | |
19 | // Origin: Iouri Belikov, IReS, Strasbourg, Jouri.Belikov@cern.ch | |
20 | //------------------------------------------------------------------------- | |
116cbefd | 21 | #include <Riostream.h> |
7f6ddf58 | 22 | #include <TFile.h> |
116cbefd | 23 | #include <TPDGCode.h> |
7f6ddf58 | 24 | #include <TObjArray.h> |
116cbefd | 25 | #include <TTree.h> |
7f6ddf58 | 26 | |
116cbefd | 27 | #include "AliITStrackV2.h" |
7f6ddf58 | 28 | #include "AliV0vertex.h" |
29 | #include "AliV0vertexer.h" | |
7f6ddf58 | 30 | |
31 | ClassImp(AliV0vertexer) | |
32 | ||
33 | Int_t AliV0vertexer::Tracks2V0vertices(const TFile *inp, TFile *out) { | |
34 | //-------------------------------------------------------------------- | |
35 | //This function reconstructs V0 vertices | |
36 | //-------------------------------------------------------------------- | |
37 | TFile *in=(TFile*)inp; | |
38 | TDirectory *savedir=gDirectory; | |
39 | ||
40 | if (!in->IsOpen()) { | |
41 | cerr<<"AliV0vertexer::Tracks2V0vertices(): "; | |
42 | cerr<<"file with ITS tracks has not been open !\n"; | |
43 | return 1; | |
44 | } | |
45 | ||
46 | if (!out->IsOpen()) { | |
47 | cerr<<"AliV0vertexer::Tracks2V0vertices(): "; | |
48 | cerr<<"file for V0 vertices has not been open !\n"; | |
49 | return 2; | |
50 | } | |
51 | ||
52 | in->cd(); | |
53 | ||
5d390eda | 54 | Char_t name[100]; |
55 | sprintf(name,"TreeT_ITS_%d",fEventN); | |
56 | TTree *trkTree=(TTree*)in->Get(name); | |
7f6ddf58 | 57 | TBranch *branch=trkTree->GetBranch("tracks"); |
58 | Int_t nentr=(Int_t)trkTree->GetEntries(); | |
59 | ||
60 | TObjArray negtrks(nentr/2); | |
61 | TObjArray postrks(nentr/2); | |
62 | ||
63 | Int_t nneg=0, npos=0, nvtx=0; | |
64 | ||
65 | Int_t i; | |
66 | for (i=0; i<nentr; i++) { | |
67 | AliITStrackV2 *iotrack=new AliITStrackV2; | |
68 | branch->SetAddress(&iotrack); | |
69 | trkTree->GetEvent(i); | |
4ab260d6 | 70 | |
71 | iotrack->PropagateTo(3.,0.0023,65.19); iotrack->PropagateTo(2.5,0.,0.); | |
72 | ||
7f6ddf58 | 73 | if (iotrack->Get1Pt() > 0.) {nneg++; negtrks.AddLast(iotrack);} |
74 | else {npos++; postrks.AddLast(iotrack);} | |
75 | } | |
76 | ||
77 | ||
78 | out->cd(); | |
5d390eda | 79 | sprintf(name,"TreeV%d",fEventN); |
80 | TTree vtxTree(name,"Tree with V0 vertices"); | |
7f6ddf58 | 81 | AliV0vertex *ioVertex=0; |
82 | vtxTree.Branch("vertices","AliV0vertex",&ioVertex,32000,0); | |
83 | ||
84 | ||
85 | for (i=0; i<nneg; i++) { | |
86 | if (i%10==0) cerr<<nneg-i<<'\r'; | |
87 | AliITStrackV2 *ntrk=(AliITStrackV2 *)negtrks.UncheckedAt(i); | |
a9a2d814 | 88 | |
5d390eda | 89 | if (TMath::Abs(ntrk->GetD(fX,fY))<fDPmin) continue; |
90 | if (TMath::Abs(ntrk->GetD(fX,fY))>fRmax) continue; | |
4ab260d6 | 91 | |
7f6ddf58 | 92 | for (Int_t k=0; k<npos; k++) { |
93 | AliITStrackV2 *ptrk=(AliITStrackV2 *)postrks.UncheckedAt(k); | |
94 | ||
5d390eda | 95 | if (TMath::Abs(ptrk->GetD(fX,fY))<fDPmin) continue; |
96 | if (TMath::Abs(ptrk->GetD(fX,fY))>fRmax) continue; | |
4ab260d6 | 97 | |
5d390eda | 98 | if (TMath::Abs(ntrk->GetD(fX,fY))<fDNmin) |
99 | if (TMath::Abs(ptrk->GetD(fX,fY))<fDNmin) continue; | |
4ab260d6 | 100 | |
7f6ddf58 | 101 | |
102 | AliITStrackV2 nt(*ntrk), pt(*ptrk), *pnt=&nt, *ppt=&pt; | |
103 | ||
104 | Double_t dca=PropagateToDCA(pnt,ppt); | |
105 | if (dca > fDCAmax) continue; | |
106 | ||
107 | AliV0vertex vertex(*pnt,*ppt); | |
108 | if (vertex.GetChi2() > fChi2max) continue; | |
109 | ||
110 | /* Think of something better here ! | |
111 | nt.PropagateToVertex(); if (TMath::Abs(nt.GetZ())<0.04) continue; | |
112 | pt.PropagateToVertex(); if (TMath::Abs(pt.GetZ())<0.04) continue; | |
113 | */ | |
114 | ||
115 | Double_t x,y,z; vertex.GetXYZ(x,y,z); | |
116 | Double_t r2=x*x + y*y; | |
117 | if (r2 > fRmax*fRmax) continue; | |
118 | if (r2 < fRmin*fRmin) continue; | |
119 | ||
120 | Double_t px,py,pz; vertex.GetPxPyPz(px,py,pz); | |
121 | Double_t p2=px*px+py*py+pz*pz; | |
5d390eda | 122 | Double_t cost=((x-fX)*px + (y-fY)*py + (z-fZ)*pz)/ |
123 | TMath::Sqrt(p2*((x-fX)*(x-fX) + (y-fY)*(y-fY) + (z-fZ)*(z-fZ))); | |
4ab260d6 | 124 | |
5d390eda | 125 | //if (cost < (5*fCPAmax-0.9-TMath::Sqrt(r2)*(fCPAmax-1))/4.1) continue; |
126 | if (cost < fCPAmax) continue; | |
7f6ddf58 | 127 | |
128 | //vertex.ChangeMassHypothesis(); //default is Lambda0 | |
129 | ||
130 | ioVertex=&vertex; vtxTree.Fill(); | |
131 | ||
132 | nvtx++; | |
133 | } | |
134 | } | |
135 | ||
136 | cerr<<"Number of reconstructed V0 vertices: "<<nvtx<<endl; | |
137 | ||
138 | vtxTree.Write(); | |
139 | ||
140 | negtrks.Delete(); | |
141 | postrks.Delete(); | |
142 | ||
143 | savedir->cd(); | |
144 | ||
145 | delete trkTree; | |
146 | ||
147 | return 0; | |
148 | } | |
149 | ||
150 | ||
151 | static void External2Helix(const AliITStrackV2 *t, Double_t helix[6]) { | |
152 | //-------------------------------------------------------------------- | |
153 | // External track parameters -> helix parameters | |
154 | //-------------------------------------------------------------------- | |
155 | Double_t alpha,x,cs,sn; | |
156 | t->GetExternalParameters(x,helix); alpha=t->GetAlpha(); | |
157 | ||
158 | cs=TMath::Cos(alpha); sn=TMath::Sin(alpha); | |
159 | helix[5]=x*cs - helix[0]*sn; // x0 | |
160 | helix[0]=x*sn + helix[0]*cs; // y0 | |
161 | //helix[1]= // z0 | |
162 | helix[2]=TMath::ASin(helix[2]) + alpha; // phi0 | |
163 | //helix[3]= // tgl | |
164 | helix[4]=helix[4]/t->GetConvConst(); // C | |
165 | } | |
166 | ||
167 | static void Evaluate(const Double_t *h, Double_t t, | |
168 | Double_t r[3], //radius vector | |
169 | Double_t g[3], //first defivatives | |
170 | Double_t gg[3]) //second derivatives | |
171 | { | |
172 | //-------------------------------------------------------------------- | |
173 | // Calculate position of a point on a track and some derivatives | |
174 | //-------------------------------------------------------------------- | |
175 | Double_t phase=h[4]*t+h[2]; | |
176 | Double_t sn=TMath::Sin(phase), cs=TMath::Cos(phase); | |
177 | ||
178 | r[0] = h[5] + (sn - h[6])/h[4]; | |
179 | r[1] = h[0] - (cs - h[7])/h[4]; | |
180 | r[2] = h[1] + h[3]*t; | |
181 | ||
182 | g[0] = cs; g[1]=sn; g[2]=h[3]; | |
183 | ||
184 | gg[0]=-h[4]*sn; gg[1]=h[4]*cs; gg[2]=0.; | |
185 | } | |
186 | ||
187 | Double_t AliV0vertexer::PropagateToDCA(AliITStrackV2 *n, AliITStrackV2 *p) { | |
188 | //-------------------------------------------------------------------- | |
189 | // This function returns the DCA between two tracks | |
190 | // The tracks will be moved to the point of DCA ! | |
191 | //-------------------------------------------------------------------- | |
a9a2d814 | 192 | Double_t dy2=n->GetSigmaY2() + p->GetSigmaY2(); |
193 | Double_t dz2=n->GetSigmaZ2() + p->GetSigmaZ2(); | |
194 | Double_t dx2=dy2; | |
195 | ||
196 | //dx2=dy2=dz2=1.; | |
197 | ||
7f6ddf58 | 198 | Double_t p1[8]; External2Helix(n,p1); |
199 | p1[6]=TMath::Sin(p1[2]); p1[7]=TMath::Cos(p1[2]); | |
200 | Double_t p2[8]; External2Helix(p,p2); | |
201 | p2[6]=TMath::Sin(p2[2]); p2[7]=TMath::Cos(p2[2]); | |
202 | ||
203 | ||
204 | Double_t r1[3],g1[3],gg1[3]; Double_t t1=0.; | |
205 | Evaluate(p1,t1,r1,g1,gg1); | |
206 | Double_t r2[3],g2[3],gg2[3]; Double_t t2=0.; | |
207 | Evaluate(p2,t2,r2,g2,gg2); | |
208 | ||
209 | Double_t dx=r2[0]-r1[0], dy=r2[1]-r1[1], dz=r2[2]-r1[2]; | |
a9a2d814 | 210 | Double_t dm=dx*dx/dx2 + dy*dy/dy2 + dz*dz/dz2; |
7f6ddf58 | 211 | |
212 | Int_t max=27; | |
213 | while (max--) { | |
a9a2d814 | 214 | Double_t gt1=-(dx*g1[0]/dx2 + dy*g1[1]/dy2 + dz*g1[2]/dz2); |
215 | Double_t gt2=+(dx*g2[0]/dx2 + dy*g2[1]/dy2 + dz*g2[2]/dz2); | |
216 | Double_t h11=(g1[0]*g1[0] - dx*gg1[0])/dx2 + | |
217 | (g1[1]*g1[1] - dy*gg1[1])/dy2 + | |
218 | (g1[2]*g1[2] - dz*gg1[2])/dz2; | |
219 | Double_t h22=(g2[0]*g2[0] + dx*gg2[0])/dx2 + | |
220 | (g2[1]*g2[1] + dy*gg2[1])/dy2 + | |
221 | (g2[2]*g2[2] + dz*gg2[2])/dz2; | |
222 | Double_t h12=-(g1[0]*g2[0]/dx2 + g1[1]*g2[1]/dy2 + g1[2]*g2[2]/dz2); | |
7f6ddf58 | 223 | |
224 | Double_t det=h11*h22-h12*h12; | |
225 | ||
226 | Double_t dt1,dt2; | |
227 | if (TMath::Abs(det)<1.e-33) { | |
228 | //(quasi)singular Hessian | |
229 | dt1=-gt1; dt2=-gt2; | |
230 | } else { | |
231 | dt1=-(gt1*h22 - gt2*h12)/det; | |
232 | dt2=-(h11*gt2 - h12*gt1)/det; | |
233 | } | |
234 | ||
235 | if ((dt1*gt1+dt2*gt2)>0) {dt1=-dt1; dt2=-dt2;} | |
236 | ||
237 | //check delta(phase1) ? | |
238 | //check delta(phase2) ? | |
239 | ||
240 | if (TMath::Abs(dt1)/(TMath::Abs(t1)+1.e-3) < 1.e-4) | |
241 | if (TMath::Abs(dt2)/(TMath::Abs(t2)+1.e-3) < 1.e-4) { | |
a9a2d814 | 242 | if ((gt1*gt1+gt2*gt2) > 1.e-4/dy2/dy2) |
7f6ddf58 | 243 | cerr<<"AliV0vertexer::PropagateToDCA:" |
244 | " stopped at not a stationary point !\n"; | |
245 | Double_t lmb=h11+h22; lmb=lmb-TMath::Sqrt(lmb*lmb-4*det); | |
246 | if (lmb < 0.) | |
247 | cerr<<"AliV0vertexer::PropagateToDCA:" | |
248 | " stopped at not a minimum !\n"; | |
249 | break; | |
250 | } | |
251 | ||
252 | Double_t dd=dm; | |
253 | for (Int_t div=1 ; ; div*=2) { | |
254 | Evaluate(p1,t1+dt1,r1,g1,gg1); | |
255 | Evaluate(p2,t2+dt2,r2,g2,gg2); | |
256 | dx=r2[0]-r1[0]; dy=r2[1]-r1[1]; dz=r2[2]-r1[2]; | |
a9a2d814 | 257 | dd=dx*dx/dx2 + dy*dy/dy2 + dz*dz/dz2; |
7f6ddf58 | 258 | if (dd<dm) break; |
259 | dt1*=0.5; dt2*=0.5; | |
260 | if (div>512) { | |
261 | cerr<<"AliV0vertexer::PropagateToDCA: overshoot !\n"; break; | |
262 | } | |
263 | } | |
264 | dm=dd; | |
265 | ||
266 | t1+=dt1; | |
267 | t2+=dt2; | |
268 | ||
269 | } | |
270 | ||
271 | if (max<=0) cerr<<"AliV0vertexer::PropagateToDCA: too many iterations !\n"; | |
272 | ||
273 | //propagate tracks to the points of DCA | |
274 | Double_t cs=TMath::Cos(n->GetAlpha()); | |
275 | Double_t sn=TMath::Sin(n->GetAlpha()); | |
276 | Double_t x=r1[0]*cs + r1[1]*sn; | |
277 | if (!n->PropagateTo(x,0.,0.)) { | |
278 | //cerr<<"AliV0vertexer::PropagateToDCA: propagation failed !\n"; | |
279 | return 1.e+33; | |
280 | } | |
281 | ||
282 | cs=TMath::Cos(p->GetAlpha()); | |
283 | sn=TMath::Sin(p->GetAlpha()); | |
284 | x=r2[0]*cs + r2[1]*sn; | |
285 | if (!p->PropagateTo(x,0.,0.)) { | |
286 | //cerr<<"AliV0vertexer::PropagateToDCA: propagation failed !\n"; | |
287 | return 1.e+33; | |
288 | } | |
289 | ||
4ab260d6 | 290 | return TMath::Sqrt(dm*TMath::Sqrt(dy2*dz2)); |
291 | //return TMath::Sqrt(dx*dx + dy*dy + dz*dz); | |
7f6ddf58 | 292 | } |
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