Changes due to the new hit structure.
[u/mrichter/AliRoot.git] / TPC / AliTPCtracker.cxx
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73042f01 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$Log$
98ab53f4 18Revision 1.2 2000/06/30 12:07:50 kowal2
19Updated from the TPC-PreRelease branch
20
73042f01 21Revision 1.1.2.1 2000/06/25 08:53:55 kowal2
22Splitted from AliTPCtracking
23
24*/
25
26//-------------------------------------------------------
27// Implementation of the TPC tracker
28//
29// Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
30//-------------------------------------------------------
31
32#include "AliTPCtracker.h"
33#include "AliTPCcluster.h"
34#include <TObjArray.h>
35#include <TFile.h>
36#include "AliTPCClustersArray.h"
37#include "AliTPCClustersRow.h"
98ab53f4 38#include <TTree.h>
73042f01 39
40const AliTPCParam *AliTPCtracker::AliTPCSector::fgParam;
41
42//_____________________________________________________________________________
43Double_t SigmaY2(Double_t r, Double_t tgl, Double_t pt)
44{
45 //
46 // Parametrised error of the cluster reconstruction (pad direction)
47 //
48 // Sigma rphi
49 const Float_t kArphi=0.41818e-2;
50 const Float_t kBrphi=0.17460e-4;
51 const Float_t kCrphi=0.30993e-2;
52 const Float_t kDrphi=0.41061e-3;
53
54 pt=TMath::Abs(pt)*1000.;
55 Double_t x=r/pt;
56 tgl=TMath::Abs(tgl);
57 Double_t s=kArphi - kBrphi*r*tgl + kCrphi*x*x + kDrphi*x;
58 if (s<0.4e-3) s=0.4e-3;
59 s*=1.3; //Iouri Belikov
60
61 return s;
62}
63
64//_____________________________________________________________________________
65Double_t SigmaZ2(Double_t r, Double_t tgl)
66{
67 //
68 // Parametrised error of the cluster reconstruction (drift direction)
69 //
70 // Sigma z
71 const Float_t kAz=0.39614e-2;
72 const Float_t kBz=0.22443e-4;
73 const Float_t kCz=0.51504e-1;
74
75
76 tgl=TMath::Abs(tgl);
77 Double_t s=kAz - kBz*r*tgl + kCz*tgl*tgl;
78 if (s<0.4e-3) s=0.4e-3;
79 s*=1.3; //Iouri Belikov
80
81 return s;
82}
83
84//_____________________________________________________________________________
85inline Double_t f1(Double_t x1,Double_t y1,
86 Double_t x2,Double_t y2,
87 Double_t x3,Double_t y3)
88{
89 //-----------------------------------------------------------------
90 // Initial approximation of the track curvature
91 //-----------------------------------------------------------------
92 Double_t d=(x2-x1)*(y3-y2)-(x3-x2)*(y2-y1);
93 Double_t a=0.5*((y3-y2)*(y2*y2-y1*y1+x2*x2-x1*x1)-
94 (y2-y1)*(y3*y3-y2*y2+x3*x3-x2*x2));
95 Double_t b=0.5*((x2-x1)*(y3*y3-y2*y2+x3*x3-x2*x2)-
96 (x3-x2)*(y2*y2-y1*y1+x2*x2-x1*x1));
97
98 Double_t xr=TMath::Abs(d/(d*x1-a)), yr=d/(d*y1-b);
99
100 return -xr*yr/sqrt(xr*xr+yr*yr);
101}
102
103
104//_____________________________________________________________________________
105inline Double_t f2(Double_t x1,Double_t y1,
106 Double_t x2,Double_t y2,
107 Double_t x3,Double_t y3)
108{
109 //-----------------------------------------------------------------
110 // Initial approximation of the track curvature times center of curvature
111 //-----------------------------------------------------------------
112 Double_t d=(x2-x1)*(y3-y2)-(x3-x2)*(y2-y1);
113 Double_t a=0.5*((y3-y2)*(y2*y2-y1*y1+x2*x2-x1*x1)-
114 (y2-y1)*(y3*y3-y2*y2+x3*x3-x2*x2));
115 Double_t b=0.5*((x2-x1)*(y3*y3-y2*y2+x3*x3-x2*x2)-
116 (x3-x2)*(y2*y2-y1*y1+x2*x2-x1*x1));
117
118 Double_t xr=TMath::Abs(d/(d*x1-a)), yr=d/(d*y1-b);
119
120 return -a/(d*y1-b)*xr/sqrt(xr*xr+yr*yr);
121}
122
123//_____________________________________________________________________________
124inline Double_t f3(Double_t x1,Double_t y1,
125 Double_t x2,Double_t y2,
126 Double_t z1,Double_t z2)
127{
128 //-----------------------------------------------------------------
129 // Initial approximation of the tangent of the track dip angle
130 //-----------------------------------------------------------------
131 return (z1 - z2)/sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
132}
133
134//_____________________________________________________________________________
135Int_t AliTPCtracker::FindProlongation(AliTPCseed& t, const AliTPCSector *sec,
136Int_t s, Int_t rf)
137{
138 //-----------------------------------------------------------------
139 // This function tries to find a track prolongation.
140 //-----------------------------------------------------------------
141 const Int_t kSKIP=(t.GetNumberOfClusters()<10) ?
142 10 : Int_t(0.5*sec->GetNRows());
143 Int_t tryAgain=kSKIP;
144 Double_t alpha=sec->GetAlpha();
145 Int_t ns=Int_t(2*TMath::Pi()/alpha+0.5);
146
147 for (Int_t nr=sec->GetRowNumber(t.GetX())-1; nr>=rf; nr--) {
148 Double_t x=sec->GetX(nr), ymax=sec->GetMaxY(nr);
149 if (!t.PropagateTo(x)) return 0;
150
151 AliTPCcluster *cl=0;
152 UInt_t index=0;
153 Double_t maxchi2=12.;
154 const AliTPCRow &krow=sec[s][nr];
155 Double_t sy2=SigmaY2(t.GetX(),t.GetTgl(),t.GetPt());
156 Double_t sz2=SigmaZ2(t.GetX(),t.GetTgl());
157 Double_t road=4.*sqrt(t.GetSigmaY2() + sy2), y=t.GetY(), z=t.GetZ();
158
159 if (road>30) {
160 if (t.GetNumberOfClusters()>4)
161 cerr<<t.GetNumberOfClusters()
162 <<"FindProlongation warning: Too broad road !\n";
163 return 0;
164 }
165
166 if (krow) {
167 for (Int_t i=krow.Find(y-road); i<krow; i++) {
168 AliTPCcluster* c=(AliTPCcluster*)(krow[i]);
169 if (c->GetY() > y+road) break;
170 if (c->IsUsed()) continue;
171 if ((c->GetZ()-z)*(c->GetZ()-z) > 16.*(t.GetSigmaZ2()+sz2)) continue;
172 Double_t chi2=t.GetPredictedChi2(c);
173 if (chi2 > maxchi2) continue;
174 maxchi2=chi2;
175 cl=c;
176 index=krow.GetIndex(i);
177 }
178 }
179 if (cl) {
180 Float_t l=sec->GetPadPitchWidth();
181 t.SetSampledEdx(cl->GetQ()/l,t.GetNumberOfClusters());
182 t.Update(cl,maxchi2,index);
183 tryAgain=kSKIP;
184 } else {
185 if (tryAgain==0) break;
186 if (y > ymax) {
187 s = (s+1) % ns;
188 if (!t.Rotate(alpha)) return 0;
189 } else if (y <-ymax) {
190 s = (s-1+ns) % ns;
191 if (!t.Rotate(-alpha)) return 0;
192 }
193 tryAgain--;
194 }
195 }
196
197 return 1;
198
199}
200
201//_____________________________________________________________________________
202void
203AliTPCtracker::MakeSeeds(TObjArray& seeds,const AliTPCSector *sec, Int_t max,
204Int_t i1, Int_t i2)
205{
206 //-----------------------------------------------------------------
207 // This function creates track seeds.
208 //-----------------------------------------------------------------
209 Double_t x[5], c[15];
210
211 Double_t alpha=sec->GetAlpha(), shift=sec->GetAlphaShift();
212 Double_t cs=cos(alpha), sn=sin(alpha);
213
214 Double_t x1 =sec->GetX(i1);
215 Double_t xx2=sec->GetX(i2);
216
217 for (Int_t ns=0; ns<max; ns++) {
218 Int_t nl=sec[(ns-1+max)%max][i2];
219 Int_t nm=sec[ns][i2];
220 Int_t nu=sec[(ns+1)%max][i2];
221 const AliTPCRow& kr1=sec[ns][i1];
222 for (Int_t is=0; is < kr1; is++) {
223 Double_t y1=kr1[is]->GetY(), z1=kr1[is]->GetZ();
224 for (Int_t js=0; js < nl+nm+nu; js++) {
225 const AliTPCcluster *kcl;
226 Double_t x2, y2, z2;
227 Double_t x3=0.,y3=0.;
228
229 if (js<nl) {
230 const AliTPCRow& kr2=sec[(ns-1+max)%max][i2];
231 kcl=kr2[js];
232 y2=kcl->GetY(); z2=kcl->GetZ();
233 x2= xx2*cs+y2*sn;
234 y2=-xx2*sn+y2*cs;
235 } else
236 if (js<nl+nm) {
237 const AliTPCRow& kr2=sec[ns][i2];
238 kcl=kr2[js-nl];
239 x2=xx2; y2=kcl->GetY(); z2=kcl->GetZ();
240 } else {
241 const AliTPCRow& kr2=sec[(ns+1)%max][i2];
242 kcl=kr2[js-nl-nm];
243 y2=kcl->GetY(); z2=kcl->GetZ();
244 x2=xx2*cs-y2*sn;
245 y2=xx2*sn+y2*cs;
246 }
247
248 Double_t zz=z1 - z1/x1*(x1-x2);
249 if (TMath::Abs(zz-z2)>5.) continue;
250
251 Double_t d=(x2-x1)*(0.-y2)-(0.-x2)*(y2-y1);
252 if (d==0.) {cerr<<"MakeSeeds warning: Straight seed !\n"; continue;}
253
254 x[0]=y1;
255 x[1]=z1;
256 x[2]=f1(x1,y1,x2,y2,x3,y3);
257 if (TMath::Abs(x[2]) >= 0.0066) continue;
258 x[3]=f2(x1,y1,x2,y2,x3,y3);
259 //if (TMath::Abs(x[2]*x1-x[3]) >= 0.99999) continue;
260 x[4]=f3(x1,y1,x2,y2,z1,z2);
261 if (TMath::Abs(x[4]) > 1.2) continue;
262 Double_t a=asin(x[3]);
263 Double_t zv=z1 - x[4]/x[2]*(a+asin(x[2]*x1-x[3]));
264 if (TMath::Abs(zv)>10.) continue;
265
266 Double_t sy1=kr1[is]->GetSigmaY2(), sz1=kr1[is]->GetSigmaZ2();
267 Double_t sy2=kcl->GetSigmaY2(), sz2=kcl->GetSigmaZ2();
268 Double_t sy3=100*0.025, sy=0.1, sz=0.1;
269
270 Double_t f20=(f1(x1,y1+sy,x2,y2,x3,y3)-x[2])/sy;
271 Double_t f22=(f1(x1,y1,x2,y2+sy,x3,y3)-x[2])/sy;
272 Double_t f24=(f1(x1,y1,x2,y2,x3,y3+sy)-x[2])/sy;
273 Double_t f30=(f2(x1,y1+sy,x2,y2,x3,y3)-x[3])/sy;
274 Double_t f32=(f2(x1,y1,x2,y2+sy,x3,y3)-x[3])/sy;
275 Double_t f34=(f2(x1,y1,x2,y2,x3,y3+sy)-x[3])/sy;
276 Double_t f40=(f3(x1,y1+sy,x2,y2,z1,z2)-x[4])/sy;
277 Double_t f41=(f3(x1,y1,x2,y2,z1+sz,z2)-x[4])/sz;
278 Double_t f42=(f3(x1,y1,x2,y2+sy,z1,z2)-x[4])/sy;
279 Double_t f43=(f3(x1,y1,x2,y2,z1,z2+sz)-x[4])/sz;
280
281 c[0]=sy1;
282 c[1]=0.; c[2]=sz1;
283 c[3]=f20*sy1; c[4]=0.; c[5]=f20*sy1*f20+f22*sy2*f22+f24*sy3*f24;
284 c[6]=f30*sy1; c[7]=0.; c[8]=f30*sy1*f20+f32*sy2*f22+f34*sy3*f24;
285 c[9]=f30*sy1*f30+f32*sy2*f32+f34*sy3*f34;
286 c[10]=f40*sy1; c[11]=f41*sz1; c[12]=f40*sy1*f20+f42*sy2*f22;
287 c[13]=f40*sy1*f30+f42*sy2*f32;
288 c[14]=f40*sy1*f40+f41*sz1*f41+f42*sy2*f42+f43*sz2*f43;
289
290 UInt_t index=kr1.GetIndex(is);
291 AliTPCseed *track=new AliTPCseed(index, x, c, x1, ns*alpha+shift);
292 Float_t l=sec->GetPadPitchWidth();
293 track->SetSampledEdx(kr1[is]->GetQ()/l,0);
294
295 Int_t rc=FindProlongation(*track,sec,ns,i2);
296 if (rc<0 || track->GetNumberOfClusters()<(i1-i2)/2) delete track;
297 else seeds.AddLast(track);
298 }
299 }
300 }
301}
302
303//_____________________________________________________________________________
304void AliTPCtracker::Clusters2Tracks(const AliTPCParam *par, TFile *of) {
305 //-----------------------------------------------------------------
306 // This is a track finder.
307 //-----------------------------------------------------------------
308 TDirectory *savedir=gDirectory;
309
310 if (!of->IsOpen()) {
311 cerr<<"AliTPC::Clusters2Tracks(): output file not open !\n";
312 return;
313 }
314
315 AliTPCClustersArray carray;
316 carray.Setup(par);
317 carray.SetClusterType("AliTPCcluster");
318 carray.ConnectTree("Segment Tree");
319
320 of->cd();
321 TTree tracktree("TreeT","Tree with TPC tracks");
322 AliTPCtrack *iotrack=0;
323 tracktree.Branch("tracks","AliTPCtrack",&iotrack,32000,0);
324
325 AliTPCSector::SetParam(par);
326
327 const Int_t kNIS=par->GetNInnerSector()/2;
328 AliTPCSSector *ssec=new AliTPCSSector[kNIS];
329 Int_t nlow=ssec->GetNRows();
330
331 const Int_t kNOS=par->GetNOuterSector()/2;
332 AliTPCLSector *lsec=new AliTPCLSector[kNOS];
333 Int_t nup=lsec->GetNRows();
334
335 //Load outer sectors
336 UInt_t index;
337 Int_t i,j;
338
339 j=Int_t(carray.GetTree()->GetEntries());
340 for (i=0; i<j; i++) {
341 AliSegmentID *s=carray.LoadEntry(i);
342 Int_t sec,row;
343 par->AdjustSectorRow(s->GetID(),sec,row);
344 if (sec<kNIS*2) continue;
345 AliTPCClustersRow *clrow=carray.GetRow(sec,row);
346 Int_t ncl=clrow->GetArray()->GetEntriesFast();
347 while (ncl--) {
348 AliTPCcluster *c=(AliTPCcluster*)(*clrow)[ncl];
349 index=(((sec<<8)+row)<<16)+ncl;
350 lsec[(sec-kNIS*2)%kNOS][row].InsertCluster(c,index);
351 }
352 }
353
354 //find track seeds
355 TObjArray seeds(20000);
356 Int_t nrows=nlow+nup;
357 Int_t gap=Int_t(0.125*nrows), shift=Int_t(0.5*gap);
358 MakeSeeds(seeds, lsec, kNOS, nup-1, nup-1-gap);
359 MakeSeeds(seeds, lsec, kNOS, nup-1-shift, nup-1-shift-gap);
360 seeds.Sort();
361
362 //tracking in outer sectors
363 Int_t nseed=seeds.GetEntriesFast();
364 for (i=0; i<nseed; i++) {
365 AliTPCseed *pt=(AliTPCseed*)seeds.UncheckedAt(i), &t=*pt;
366 Double_t alpha=t.GetAlpha();
367 if (alpha > 2.*TMath::Pi()) alpha -= 2.*TMath::Pi();
368 if (alpha < 0. ) alpha += 2.*TMath::Pi();
369 Int_t ns=Int_t(alpha/lsec->GetAlpha())%kNOS;
370
371 if (FindProlongation(t,lsec,ns)) {
372 t.UseClusters(&carray);
373 continue;
374 }
375 delete seeds.RemoveAt(i);
376 }
377
378 //unload outer sectors
379 for (i=0; i<kNOS; i++) {
380 for (j=0; j<nup; j++) {
381 if (carray.GetRow(i+kNIS*2,j)) carray.ClearRow(i+kNIS*2,j);
382 if (carray.GetRow(i+kNIS*2+kNOS,j)) carray.ClearRow(i+kNIS*2+kNOS,j);
383 }
384 }
385
386 //load inner sectors
387 j=Int_t(carray.GetTree()->GetEntries());
388 for (i=0; i<j; i++) {
389 AliSegmentID *s=carray.LoadEntry(i);
390 Int_t sec,row;
391 par->AdjustSectorRow(s->GetID(),sec,row);
392 if (sec>=kNIS*2) continue;
393 AliTPCClustersRow *clrow=carray.GetRow(sec,row);
394 Int_t ncl=clrow->GetArray()->GetEntriesFast();
395 while (ncl--) {
396 AliTPCcluster *c=(AliTPCcluster*)(*clrow)[ncl];
397 index=(((sec<<8)+row)<<16)+ncl;
398 ssec[sec%kNIS][row].InsertCluster(c,index);
399 }
400 }
401
402 //tracking in inner sectors
403 Int_t found=0;
404 for (i=0; i<nseed; i++) {
405 AliTPCseed *pt=(AliTPCseed*)seeds.UncheckedAt(i), &t=*pt;
406 if (!pt) continue;
407 Int_t nc=t.GetNumberOfClusters();
408
409 Double_t alpha=t.GetAlpha() - ssec->GetAlphaShift();
410 if (alpha > 2.*TMath::Pi()) alpha -= 2.*TMath::Pi();
411 if (alpha < 0. ) alpha += 2.*TMath::Pi();
412 Int_t ns=Int_t(alpha/ssec->GetAlpha())%kNIS;
413
414 alpha=ns*ssec->GetAlpha() + ssec->GetAlphaShift() - t.GetAlpha();
415
416 if (t.Rotate(alpha)) {
417 if (FindProlongation(t,ssec,ns)) {
418 if (t.GetNumberOfClusters() >= Int_t(0.4*nrows)) {
419 t.CookdEdx();
420 //t.CookLabel(&carray);
421 iotrack=pt;
422 tracktree.Fill();
423 t.UseClusters(&carray,nc);
424 cerr<<found++<<'\r';
425 }
426 }
427 }
428 delete seeds.RemoveAt(i);
429 }
430 tracktree.Write();
431
432 //unload inner sectors
433 for (i=0; i<kNIS; i++) {
434 for (j=0; j<nlow; j++) {
435 if (carray.GetRow(i,j)) carray.ClearRow(i,j);
436 if (carray.GetRow(i+kNIS,j)) carray.ClearRow(i+kNIS,j);
437 }
438 }
439
440 cerr<<"Number of found tracks : "<<found<<endl;
441
442 delete[] ssec;
443 delete[] lsec;
444
445 savedir->cd();
446}
447
448//_________________________________________________________________________
449void
450AliTPCtracker::AliTPCRow::InsertCluster(const AliTPCcluster* c, UInt_t index) {
451 //-----------------------------------------------------------------------
452 // Insert a cluster into this pad row in accordence with its y-coordinate
453 //-----------------------------------------------------------------------
454 if (fN==kMAXCLUSTER) {
455 cerr<<"AliTPCRow::InsertCluster(): Too many clusters !\n"; return;
456 }
457 if (fN==0) {fIndex[0]=index; fClusters[fN++]=c; return;}
458 Int_t i=Find(c->GetY());
459 memmove(fClusters+i+1 ,fClusters+i,(fN-i)*sizeof(AliTPCcluster*));
460 memmove(fIndex +i+1 ,fIndex +i,(fN-i)*sizeof(UInt_t));
461 fIndex[i]=index; fClusters[i]=c; fN++;
462}
463
464//___________________________________________________________________
465Int_t AliTPCtracker::AliTPCRow::Find(Double_t y) const {
466 //-----------------------------------------------------------------------
467 // Return the index of the nearest cluster
468 //-----------------------------------------------------------------------
469 if (y <= fClusters[0]->GetY()) return 0;
470 if (y > fClusters[fN-1]->GetY()) return fN;
471 Int_t b=0, e=fN-1, m=(b+e)/2;
472 for (; b<e; m=(b+e)/2) {
473 if (y > fClusters[m]->GetY()) b=m+1;
474 else e=m;
475 }
476 return m;
477}
478
479//_____________________________________________________________________________
480void AliTPCtracker::AliTPCseed::CookdEdx(Double_t low, Double_t up) {
481 //-----------------------------------------------------------------
482 // This funtion calculates dE/dX within the "low" and "up" cuts.
483 //-----------------------------------------------------------------
484 Int_t i;
485
486 Int_t swap;//stupid sorting
487 do {
488 swap=0;
489 for (i=0; i<fN-1; i++) {
490 if (fdEdx[i]<=fdEdx[i+1]) continue;
491 Float_t tmp=fdEdx[i]; fdEdx[i]=fdEdx[i+1]; fdEdx[i+1]=tmp;
492 swap++;
493 }
494 } while (swap);
495
496 Int_t nl=Int_t(low*fN), nu=Int_t(up*fN);
497 Float_t dedx=0;
498 for (i=nl; i<=nu; i++) dedx += fdEdx[i];
499 dedx /= (nu-nl+1);
500 SetdEdx(dedx);
501}
502
503//_____________________________________________________________________________
504void AliTPCtracker::AliTPCseed::UseClusters(AliTPCClustersArray *ca, Int_t n) {
505 //-----------------------------------------------------------------
506 // This function marks clusters associated with this track.
507 //-----------------------------------------------------------------
508 Int_t sec,row,ncl;
509 for (Int_t i=n; i<fN; i++) {
510 GetCluster(i,sec,row,ncl);
511 AliTPCClustersRow *clrow=ca->GetRow(sec,row);
512 AliTPCcluster *c=(AliTPCcluster*)(*clrow)[ncl];
513 c->Use();
514 }
515}
516
517