1 /**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
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 **************************************************************************/
18 Revision 1.2 2000/06/30 12:07:50 kowal2
19 Updated from the TPC-PreRelease branch
21 Revision 1.1.2.1 2000/06/25 08:53:55 kowal2
22 Splitted from AliTPCtracking
26 //-------------------------------------------------------
27 // Implementation of the TPC tracker
29 // Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
30 //-------------------------------------------------------
32 #include "AliTPCtracker.h"
33 #include "AliTPCcluster.h"
34 #include <TObjArray.h>
36 #include "AliTPCClustersArray.h"
37 #include "AliTPCClustersRow.h"
40 const AliTPCParam *AliTPCtracker::AliTPCSector::fgParam;
42 //_____________________________________________________________________________
43 Double_t SigmaY2(Double_t r, Double_t tgl, Double_t pt)
46 // Parametrised error of the cluster reconstruction (pad direction)
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;
54 pt=TMath::Abs(pt)*1000.;
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
64 //_____________________________________________________________________________
65 Double_t SigmaZ2(Double_t r, Double_t tgl)
68 // Parametrised error of the cluster reconstruction (drift direction)
71 const Float_t kAz=0.39614e-2;
72 const Float_t kBz=0.22443e-4;
73 const Float_t kCz=0.51504e-1;
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
84 //_____________________________________________________________________________
85 inline Double_t f1(Double_t x1,Double_t y1,
86 Double_t x2,Double_t y2,
87 Double_t x3,Double_t y3)
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));
98 Double_t xr=TMath::Abs(d/(d*x1-a)), yr=d/(d*y1-b);
100 return -xr*yr/sqrt(xr*xr+yr*yr);
104 //_____________________________________________________________________________
105 inline Double_t f2(Double_t x1,Double_t y1,
106 Double_t x2,Double_t y2,
107 Double_t x3,Double_t y3)
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));
118 Double_t xr=TMath::Abs(d/(d*x1-a)), yr=d/(d*y1-b);
120 return -a/(d*y1-b)*xr/sqrt(xr*xr+yr*yr);
123 //_____________________________________________________________________________
124 inline Double_t f3(Double_t x1,Double_t y1,
125 Double_t x2,Double_t y2,
126 Double_t z1,Double_t z2)
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));
134 //_____________________________________________________________________________
135 Int_t AliTPCtracker::FindProlongation(AliTPCseed& t, const AliTPCSector *sec,
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);
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;
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();
160 if (t.GetNumberOfClusters()>4)
161 cerr<<t.GetNumberOfClusters()
162 <<"FindProlongation warning: Too broad road !\n";
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;
176 index=krow.GetIndex(i);
180 Float_t l=sec->GetPadPitchWidth();
181 t.SetSampledEdx(cl->GetQ()/l,t.GetNumberOfClusters());
182 t.Update(cl,maxchi2,index);
185 if (tryAgain==0) break;
188 if (!t.Rotate(alpha)) return 0;
189 } else if (y <-ymax) {
191 if (!t.Rotate(-alpha)) return 0;
201 //_____________________________________________________________________________
203 AliTPCtracker::MakeSeeds(TObjArray& seeds,const AliTPCSector *sec, Int_t max,
206 //-----------------------------------------------------------------
207 // This function creates track seeds.
208 //-----------------------------------------------------------------
209 Double_t x[5], c[15];
211 Double_t alpha=sec->GetAlpha(), shift=sec->GetAlphaShift();
212 Double_t cs=cos(alpha), sn=sin(alpha);
214 Double_t x1 =sec->GetX(i1);
215 Double_t xx2=sec->GetX(i2);
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;
227 Double_t x3=0.,y3=0.;
230 const AliTPCRow& kr2=sec[(ns-1+max)%max][i2];
232 y2=kcl->GetY(); z2=kcl->GetZ();
237 const AliTPCRow& kr2=sec[ns][i2];
239 x2=xx2; y2=kcl->GetY(); z2=kcl->GetZ();
241 const AliTPCRow& kr2=sec[(ns+1)%max][i2];
243 y2=kcl->GetY(); z2=kcl->GetZ();
248 Double_t zz=z1 - z1/x1*(x1-x2);
249 if (TMath::Abs(zz-z2)>5.) continue;
251 Double_t d=(x2-x1)*(0.-y2)-(0.-x2)*(y2-y1);
252 if (d==0.) {cerr<<"MakeSeeds warning: Straight seed !\n"; continue;}
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;
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;
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;
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;
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);
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);
303 //_____________________________________________________________________________
304 void AliTPCtracker::Clusters2Tracks(const AliTPCParam *par, TFile *of) {
305 //-----------------------------------------------------------------
306 // This is a track finder.
307 //-----------------------------------------------------------------
308 TDirectory *savedir=gDirectory;
311 cerr<<"AliTPC::Clusters2Tracks(): output file not open !\n";
315 AliTPCClustersArray carray;
317 carray.SetClusterType("AliTPCcluster");
318 carray.ConnectTree("Segment Tree");
321 TTree tracktree("TreeT","Tree with TPC tracks");
322 AliTPCtrack *iotrack=0;
323 tracktree.Branch("tracks","AliTPCtrack",&iotrack,32000,0);
325 AliTPCSector::SetParam(par);
327 const Int_t kNIS=par->GetNInnerSector()/2;
328 AliTPCSSector *ssec=new AliTPCSSector[kNIS];
329 Int_t nlow=ssec->GetNRows();
331 const Int_t kNOS=par->GetNOuterSector()/2;
332 AliTPCLSector *lsec=new AliTPCLSector[kNOS];
333 Int_t nup=lsec->GetNRows();
339 j=Int_t(carray.GetTree()->GetEntries());
340 for (i=0; i<j; i++) {
341 AliSegmentID *s=carray.LoadEntry(i);
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();
348 AliTPCcluster *c=(AliTPCcluster*)(*clrow)[ncl];
349 index=(((sec<<8)+row)<<16)+ncl;
350 lsec[(sec-kNIS*2)%kNOS][row].InsertCluster(c,index);
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);
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;
371 if (FindProlongation(t,lsec,ns)) {
372 t.UseClusters(&carray);
375 delete seeds.RemoveAt(i);
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);
387 j=Int_t(carray.GetTree()->GetEntries());
388 for (i=0; i<j; i++) {
389 AliSegmentID *s=carray.LoadEntry(i);
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();
396 AliTPCcluster *c=(AliTPCcluster*)(*clrow)[ncl];
397 index=(((sec<<8)+row)<<16)+ncl;
398 ssec[sec%kNIS][row].InsertCluster(c,index);
402 //tracking in inner sectors
404 for (i=0; i<nseed; i++) {
405 AliTPCseed *pt=(AliTPCseed*)seeds.UncheckedAt(i), &t=*pt;
407 Int_t nc=t.GetNumberOfClusters();
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;
414 alpha=ns*ssec->GetAlpha() + ssec->GetAlphaShift() - t.GetAlpha();
416 if (t.Rotate(alpha)) {
417 if (FindProlongation(t,ssec,ns)) {
418 if (t.GetNumberOfClusters() >= Int_t(0.4*nrows)) {
420 //t.CookLabel(&carray);
423 t.UseClusters(&carray,nc);
428 delete seeds.RemoveAt(i);
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);
440 cerr<<"Number of found tracks : "<<found<<endl;
448 //_________________________________________________________________________
450 AliTPCtracker::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;
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++;
464 //___________________________________________________________________
465 Int_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;
479 //_____________________________________________________________________________
480 void AliTPCtracker::AliTPCseed::CookdEdx(Double_t low, Double_t up) {
481 //-----------------------------------------------------------------
482 // This funtion calculates dE/dX within the "low" and "up" cuts.
483 //-----------------------------------------------------------------
486 Int_t swap;//stupid sorting
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;
496 Int_t nl=Int_t(low*fN), nu=Int_t(up*fN);
498 for (i=nl; i<=nu; i++) dedx += fdEdx[i];
503 //_____________________________________________________________________________
504 void AliTPCtracker::AliTPCseed::UseClusters(AliTPCClustersArray *ca, Int_t n) {
505 //-----------------------------------------------------------------
506 // This function marks clusters associated with this track.
507 //-----------------------------------------------------------------
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];