TPC/AliTPCComparison.C

   1 /****************************************************************************
   2  *           Very important, delicate and rather obscure macro.             *
   3  *                                                                          *
   4  *               Creates list of "trackable" tracks,                        *
   5  *             calculates efficiency, resolutions etc.                      *
   6  *     There is a possibility to run this macro over several events.         *
   7  *                                                                          *
   8  *           Origin: I.Belikov, CERN, Jouri.Belikov@cern.ch                 *
   9  * with several nice improvements by: M.Ivanov, GSI, m.ivanov@gsi.de        *
  10  ****************************************************************************/
  11
  12 #if !defined(__CINT__) || defined(__MAKECINT__)
  13   #include <TMath.h>
  14   #include <TError.h>
  15   #include <Riostream.h>
  16   #include <TH1F.h>
  17   #include <TH2F.h>
  18   #include <TTree.h>
  19   #include <TParticle.h>
  20   #include <TCanvas.h>
  21   #include <TLine.h>
  22   #include <TText.h>
  23   #include <TBenchmark.h>
  24   #include <TStyle.h>
  25   #include <TKey.h>
  26   #include <TROOT.h>
  27
  28   #include "AliStack.h"
  29   #include "AliHeader.h"
  30   #include "AliTrackReference.h"
  31   #include "AliRunLoader.h"
  32   #include "AliRun.h"
  33   #include "AliESD.h"
  34
  35   #include "AliSimDigits.h"
  36   #include "AliTPC.h"
  37   #include "AliTPCParamSR.h"
  38   #include "AliTPCClustersArray.h"
  39   #include "AliTPCClustersRow.h"
  40   #include "AliTPCcluster.h"
  41   #include "AliTPCLoader.h"
  42 #endif
  43
  44 Int_t GoodTracksTPC(const Char_t *dir=".");
  45
  46 extern AliRun *gAlice;
  47 extern TBenchmark *gBenchmark;
  48 extern TROOT *gROOT;
  49
  50 static Int_t allgood=0;
  51 static Int_t allselected=0;
  52 static Int_t allfound=0;
  53
  54 Int_t AliTPCComparison
  55 (Float_t ptcutl=0.2, Float_t ptcuth=10., const Char_t *dir=".") {
  56    gBenchmark->Start("AliTPCComparison");
  57
  58    ::Info("AliTPCComparison.C","Doing comparison...");
  59
  60
  61
  62    TH1F *hp=(TH1F*)gROOT->FindObject("hp");
  63    if (!hp) hp=new TH1F("hp","PHI resolution",50,-20.,20.);
  64    hp->SetFillColor(4);
  65
  66    TH1F *hl=(TH1F*)gROOT->FindObject("hl");
  67    if (!hl) hl=new TH1F("hl","LAMBDA resolution",50,-20,20);
  68    hl->SetFillColor(4);
  69
  70    TH1F *hpt=(TH1F*)gROOT->FindObject("hpt");
  71    if (!hpt) hpt=new TH1F("hpt","Relative Pt resolution",30,-10.,10.);
  72    hpt->SetFillColor(2);
  73
  74    TH1F *hmpt=(TH1F*)gROOT->FindObject("hmpt");
  75    if (!hmpt)
  76       hmpt=new TH1F("hmpt","Relative Pt resolution (pt>4GeV/c)",30,-60,60);
  77    hmpt->SetFillColor(6);
  78
  79
  80
  81    TH1F *hgood=(TH1F*)gROOT->FindObject("hgood");
  82    if (!hgood) hgood=new TH1F("hgood","Good tracks",30,0.2,6.1);
  83
  84    TH1F *hfound=(TH1F*)gROOT->FindObject("hfound");
  85    if (!hfound) hfound=new TH1F("hfound","Found tracks",30,0.2,6.1);
  86
  87    TH1F *hfake=(TH1F*)gROOT->FindObject("hfake");
  88    if (!hfake) hfake=new TH1F("hfake","Fake tracks",30,0.2,6.1);
  89
  90    TH1F *hg=(TH1F*)gROOT->FindObject("hg");
  91    if (!hg) hg=new TH1F("hg","Efficiency for good tracks",30,0.2,6.1);
  92    hg->SetLineColor(4); hg->SetLineWidth(2);
  93
  94    TH1F *hf=(TH1F*)gROOT->FindObject("hf");
  95    if (!hf) hf=new TH1F("hf","Efficiency for fake tracks",30,0.2,6.1);
  96    hf->SetFillColor(1); hf->SetFillStyle(3013); hf->SetLineWidth(2);
  97
  98    TH1F *he=(TH1F*)gROOT->FindObject("he");
  99    if (!he)
 100       he =new TH1F("he","dE/dX for pions with 0.4<p<0.5 GeV/c",50,0.,100.);
 101
 102    TH2F *hep=(TH2F*)gROOT->FindObject("hep");
 103    if (!hep) hep=new TH2F("hep","dE/dX vs momentum",50,0.,2.,50,0.,400.);
 104    hep->SetMarkerStyle(8);
 105    hep->SetMarkerSize(0.4);
 106
 107
 108    Char_t fname[100];
 109    sprintf(fname,"%s/GoodTracksTPC.root",dir);
 110
 111    TFile *refFile=TFile::Open(fname,"old");
 112    if (!refFile || !refFile->IsOpen()) {
 113      ::Info("AliTPCComparison.C","Marking good tracks (will take a while)...");
 114      if (GoodTracksTPC(dir)) {
 115         ::Error("AliTPCComparison.C","Can't generate the reference file !");
 116         return 1;
 117      }
 118    }
 119    refFile=TFile::Open(fname,"old");
 120    if (!refFile || !refFile->IsOpen()) {
 121      ::Error("AliTPCComparison.C","Can't open the reference file !");
 122      return 2;
 123    }
 124
 125    TTree *tpcTree=(TTree*)refFile->Get("tpcTree");
 126    if (!tpcTree) {
 127      ::Error("AliTPCComparison.C","Can't get the reference tree !");
 128      return 3;
 129    }
 130    TBranch *branch=tpcTree->GetBranch("TPC");
 131    if (!branch) {
 132      ::Error("AliTPCComparison.C","Can't get the TPC branch !");
 133      return 4;
 134    }
 135    TClonesArray dummy("AliTrackReference",1000), *refs=&dummy;
 136    branch->SetAddress(&refs);
 137
 138
 139    sprintf(fname,"%s/AliESDs.root",dir);
 140    TFile *ef=TFile::Open(fname);
 141    if ((!ef)||(!ef->IsOpen())) {
 142       sprintf(fname,"%s/AliESDtpc.root",dir);
 143       ef=TFile::Open(fname);
 144       if ((!ef)||(!ef->IsOpen())) {
 145          ::Error("AliTPCComparison.C","Can't open AliESDtpc.root !");
 146          return 5;
 147       }
 148    }
 149    TKey *key=0;
 150    TIter next(ef->GetListOfKeys());
 151
 152
 153    //******* Loop over events *********
 154    Int_t e=0;
 155    while ((key=(TKey*)next())!=0) {
 156       cout<<endl<<endl<<"********* Processing event number: "<<e<<"*******\n";
 157
 158       AliESD *event=(AliESD*)key->ReadObj();
 159
 160       Int_t nentr=event->GetNumberOfTracks();
 161       allfound+=nentr;
 162
 163       if (tpcTree->GetEvent(e++)==0) {
 164          cerr<<"No reconstructable tracks !\n";
 165          continue;
 166       }
 167
 168       Int_t ngood=refs->GetEntriesFast();
 169       allgood+=ngood;
 170
 171       const Int_t MAX=15000;
 172     //MI change
 173       Int_t track_notfound[MAX], itrack_notfound=0;
 174       Int_t track_fake[MAX], itrack_fake=0;
 175       Int_t track_multifound[MAX],track_multifound_n[MAX],itrack_multifound=0;
 176
 177       Int_t i;
 178       for (Int_t k=0; k<ngood; k++) {
 179         AliTrackReference *ref=(AliTrackReference*)refs->UncheckedAt(k);
 180         Int_t lab=ref->Label(), tlab=-1;
 181         Float_t ptg=TMath::Sqrt(ref->Px()*ref->Px() + ref->Py()*ref->Py());
 182
 183         if (ptg<1e-33) continue; // for those not crossing 0 pad row
 184
 185         if (ptg<ptcutl) continue;
 186         if (ptg>ptcuth) continue;
 187
 188         allselected++;
 189
 190         hgood->Fill(ptg);
 191
 192         AliESDtrack *track=0;
 193         for (i=0; i<nentr; i++) {
 194           track=event->GetTrack(i);
 195           tlab=track->GetTPCLabel();
 196           if (lab==TMath::Abs(tlab)) break;
 197         }
 198         if (i==nentr) {
 199            track_notfound[itrack_notfound++]=lab;
 200            continue;
 201         }
 202
 203         //MI change  - addition
 204         Int_t micount=0;
 205         Int_t mi;
 206         AliESDtrack * mitrack;
 207         for (mi=0; mi<nentr; mi++) {
 208           mitrack=event->GetTrack(mi);
 209           if (lab==TMath::Abs(mitrack->GetTPCLabel())) micount++;
 210         }
 211         if (micount>1) {
 212           track_multifound[itrack_multifound]=lab;
 213           track_multifound_n[itrack_multifound]=micount;
 214           itrack_multifound++;
 215         }
 216         if ((track->GetStatus()&AliESDtrack::kTPCrefit)==0) continue;
 217         if (lab==tlab) hfound->Fill(ptg);
 218         else {
 219           track_fake[itrack_fake++]=lab;
 220           hfake->Fill(ptg);
 221         }
 222
 223         Double_t pxpypz[3]; track->GetInnerPxPyPz(pxpypz);
 224         Float_t phi=TMath::ATan2(pxpypz[1],pxpypz[0]);
 225         if (phi<-TMath::Pi()) phi+=2*TMath::Pi();
 226         if (phi>=TMath::Pi()) phi-=2*TMath::Pi();
 227         Double_t pt=TMath::Sqrt(pxpypz[0]*pxpypz[0]+pxpypz[1]*pxpypz[1]);
 228         Float_t lam=TMath::ATan2(pxpypz[2],pt);
 229         Float_t pt_1=1/pt;
 230
 231         Int_t pdg=(Int_t)ref->GetLength();  //this is particle's PDG !
 232
 233         if (TMath::Abs(pdg)==11 && ptg>4.) {//high momentum electrons
 234            hmpt->Fill((pt_1 - 1/ptg)/(1/ptg)*100.);
 235         } else {
 236            Float_t phig=TMath::ATan2(ref->Py(),ref->Px());
 237            hp->Fill((phi - phig)*1000.);
 238
 239            Float_t lamg=TMath::ATan2(ref->Pz(),ptg);
 240            hl->Fill((lam - lamg)*1000.);
 241
 242            hpt->Fill((pt_1 - 1/ptg)/(1/ptg)*100.);
 243         }
 244
 245         Float_t mom=pt/TMath::Cos(lam);
 246         Float_t dedx=track->GetTPCsignal();
 247         hep->Fill(mom,dedx,1.);
 248         if (TMath::Abs(pdg)==211) //pions
 249            if (mom>0.4 && mom<0.5) {
 250               he->Fill(dedx,1.);
 251            }
 252       }
 253
 254       cout<<"\nList of Not found tracks :\n";
 255       for ( i = 0; i< itrack_notfound; i++){
 256         cout<<track_notfound[i]<<"\t";
 257         if ((i%5)==4) cout<<"\n";
 258       }
 259       cout<<"\nList of fake  tracks :\n";
 260       for ( i = 0; i< itrack_fake; i++){
 261         cout<<track_fake[i]<<"\t";
 262         if ((i%5)==4) cout<<"\n";
 263       }
 264       cout<<"\nList of multiple found tracks :\n";
 265       for ( i=0; i<itrack_multifound; i++) {
 266           cout<<"id.   "<<track_multifound[i]
 267               <<"     found - "<<track_multifound_n[i]<<"times\n";
 268       }
 269
 270       cout<<"Number of found tracks ="<<nentr<<endl;
 271       cout<<"Number of \"good\" tracks ="<<ngood<<endl;
 272
 273       refs->Clear();
 274       delete event;
 275   }// ***** End of the loop over events
 276
 277    ef->Close();
 278
 279    delete tpcTree;
 280    refFile->Close();
 281
 282    Stat_t ng=hgood->GetEntries(), nf=hfound->GetEntries();
 283    if (ng!=0) cout<<"\n\nIntegral efficiency is about "<<nf/ng*100.<<" %\n";
 284    cout<<"Total number selected of \"good\" tracks ="<<allselected<<endl<<endl;
 285    cout<<"Total number of found tracks ="<<allfound<<endl;
 286    cout<<"Total number of \"good\" tracks ="<<allgood<<endl;
 287    cout<<endl;
 288
 289    gStyle->SetOptStat(111110);
 290    gStyle->SetOptFit(1);
 291
 292    TCanvas *c1=new TCanvas("c1","",0,0,700,850);
 293
 294    Int_t minc=33;
 295
 296    TPad *p1=new TPad("p1","",0,0.3,.5,.6); p1->Draw();
 297    p1->cd(); p1->SetFillColor(42); p1->SetFrameFillColor(10);
 298    hp->SetFillColor(4);  hp->SetXTitle("(mrad)");
 299    if (hp->GetEntries()<minc) hp->Draw(); else hp->Fit("gaus"); c1->cd();
 300
 301    TPad *p2=new TPad("p2","",0.5,.3,1,.6); p2->Draw();
 302    p2->cd(); p2->SetFillColor(42); p2->SetFrameFillColor(10);
 303    hl->SetXTitle("(mrad)");
 304    if (hl->GetEntries()<minc) hl->Draw(); else hl->Fit("gaus"); c1->cd();
 305
 306    TPad *p3=new TPad("p3","",0,0,0.5,0.3); p3->Draw();
 307    p3->cd(); p3->SetFillColor(42); p3->SetFrameFillColor(10);
 308    hpt->SetXTitle("(%)");
 309    if (hpt->GetEntries()<minc) hpt->Draw(); else hpt->Fit("gaus"); c1->cd();
 310
 311    TPad *p4=new TPad("p4","",0.5,0,1,0.3); p4->Draw();
 312    p4->cd(); p4->SetFillColor(42); p4->SetFrameFillColor(10);
 313    hmpt->SetXTitle("(%)");
 314    if (hmpt->GetEntries()<minc) hmpt->Draw(); else hmpt->Fit("gaus"); c1->cd();
 315
 316    TPad *p5=new TPad("p5","",0,0.6,1,1); p5->Draw(); p5->cd();
 317    p5->SetFillColor(41); p5->SetFrameFillColor(10);
 318    hfound->Sumw2(); hgood->Sumw2(); hfake->Sumw2();
 319    hg->Divide(hfound,hgood,1,1.,"b");
 320    hf->Divide(hfake,hgood,1,1.,"b");
 321    hg->SetMaximum(1.4);
 322    hg->SetYTitle("Tracking efficiency");
 323    hg->SetXTitle("Pt (GeV/c)");
 324    hg->Draw();
 325
 326    TLine *line1 = new TLine(0.1,1.0,6.1,1.0); line1->SetLineStyle(4);
 327    line1->Draw("same");
 328    TLine *line2 = new TLine(0.1,0.9,6.1,0.9); line2->SetLineStyle(4);
 329    line2->Draw("same");
 330
 331    hf->SetFillColor(1);
 332    hf->SetFillStyle(3013);
 333    hf->SetLineColor(2);
 334    hf->SetLineWidth(2);
 335    hf->Draw("histsame");
 336    TText *text = new TText(0.461176,0.248448,"Fake tracks");
 337    text->SetTextSize(0.05);
 338    text->Draw();
 339    text = new TText(0.453919,1.11408,"Good tracks");
 340    text->SetTextSize(0.05);
 341    text->Draw();
 342
 343
 344
 345    TCanvas *c2=new TCanvas("c2","",320,32,530,590);
 346
 347    TPad *p6=new TPad("p6","",0.,0.,1.,.5); p6->Draw();
 348    p6->cd(); p6->SetFillColor(42); p6->SetFrameFillColor(10);
 349    he->SetFillColor(2); he->SetFillStyle(3005);
 350    he->SetXTitle("Arbitrary Units");
 351    if (he->GetEntries()<minc) he->Draw(); else he->Fit("gaus"); c2->cd();
 352
 353    TPad *p7=new TPad("p7","",0.,0.5,1.,1.); p7->Draw();
 354    p7->cd(); p7->SetFillColor(42); p7->SetFrameFillColor(10);
 355    hep->SetXTitle("p (Gev/c)"); hep->SetYTitle("dE/dX (Arb. Units)");
 356    hep->Draw(); c1->cd();
 357
 358    TFile fc("AliTPCComparison.root","RECREATE");
 359    c1->Write();
 360    c2->Write();
 361    fc.Close();
 362
 363    gBenchmark->Stop("AliTPCComparison");
 364    gBenchmark->Show("AliTPCComparison");
 365
 366    return 0;
 367 }
 368
 369
 370 Int_t GoodTracksTPC(const Char_t *dir) {
 371    if (gAlice) {
 372        delete gAlice->GetRunLoader();
 373        delete gAlice;//if everything was OK here it is already NULL
 374        gAlice = 0x0;
 375    }
 376
 377    Char_t fname[100];
 378    sprintf(fname,"%s/galice.root",dir);
 379
 380    AliRunLoader *rl = AliRunLoader::Open(fname,"COMPARISON");
 381    if (!rl) {
 382       ::Error("GoodTracksTPC","Can't start session !");
 383       return 1;
 384    }
 385
 386    rl->LoadgAlice();
 387    rl->LoadHeader();
 388    rl->LoadKinematics();
 389    rl->LoadTrackRefs();
 390
 391    AliTPCLoader *tpcl = (AliTPCLoader *)rl->GetLoader("TPCLoader");
 392    if (tpcl == 0x0) {
 393       ::Error("GoodTracksTPC","Can not find TPCLoader !");
 394       delete rl;
 395       return 2;
 396    }
 397
 398    AliTPC *TPC=(AliTPC*)rl->GetAliRun()->GetDetector("TPC");
 399    Int_t ver = TPC->IsVersion();
 400    cout<<"TPC version "<<ver<<" has been found !\n";
 401    if (ver==1) tpcl->LoadRecPoints();
 402    else if (ver==2) tpcl->LoadDigits();
 403    else {
 404       ::Error("GoodTracksTPC","Wrong TPC version !");
 405       delete rl;
 406       return 3;
 407    }
 408
 409    rl->CdGAFile();
 410    AliTPCParamSR *digp=(AliTPCParamSR*)gDirectory->Get("75x40_100x60_150x60");
 411    if (!digp) {
 412      ::Error("AliTPCHits2Digits.C","TPC parameters have not been found !");
 413      delete rl;
 414      return 4;
 415    }
 416    TPC->SetParam(digp);
 417
 418    Int_t nrow_up=digp->GetNRowUp();
 419    Int_t nrows=digp->GetNRowLow()+nrow_up;
 420    Int_t zero=digp->GetZeroSup();
 421    Int_t gap=Int_t(0.125*nrows), shift=Int_t(0.5*gap);
 422    Int_t good_number=Int_t(0.4*nrows);
 423
 424    Int_t nev=rl->GetNumberOfEvents();
 425    ::Info("GoodTracksTPC","Number of events : %d\n",nev);
 426
 427
 428    sprintf(fname,"%s/GoodTracksTPC.root",dir);
 429    TFile *file=TFile::Open(fname,"recreate");
 430
 431    TClonesArray dummy("AliTrackReference",1000), *refs=&dummy;
 432    TTree tpcTree("tpcTree","Tree with info about the reconstructable TPC tracks");
 433    tpcTree.Branch("TPC",&refs);
 434
 435    //********  Loop over generated events
 436    for (Int_t e=0; e<nev; e++) {
 437      Int_t nt=0;
 438      refs->Clear();
 439
 440      Int_t i;
 441
 442      rl->GetEvent(e);  file->cd();
 443
 444      Int_t np = rl->GetHeader()->GetNtrack();
 445      cout<<"Event "<<e<<" Number of particles: "<<np<<endl;
 446
 447      //******** Fill the "good" masks
 448      Int_t *good=new Int_t[np]; for (i=0; i<np; i++) good[i]=0;
 449      switch (ver) {
 450      case 1:
 451         {
 452         AliTPCClustersArray *pca=new AliTPCClustersArray, &ca=*pca;
 453         ca.Setup(digp);
 454         ca.SetClusterType("AliTPCcluster");
 455         ca.ConnectTree(tpcl->TreeR());
 456         Int_t nrows=Int_t(ca.GetTree()->GetEntries());
 457         for (Int_t n=0; n<nrows; n++) {
 458           AliSegmentID *s=ca.LoadEntry(n);
 459           Int_t sec,row;
 460           digp->AdjustSectorRow(s->GetID(),sec,row);
 461           AliTPCClustersRow &clrow = *ca.GetRow(sec,row);
 462           Int_t ncl=clrow.GetArray()->GetEntriesFast();
 463           while (ncl--) {
 464               AliTPCcluster *c=(AliTPCcluster*)clrow[ncl];
 465               Int_t lab=c->GetLabel(0);
 466               if (lab<0) continue; //noise cluster
 467               lab=TMath::Abs(lab);
 468
 469               if (sec>=digp->GetNInnerSector())
 470                  if (row==nrow_up-1) good[lab]|=0x4000;
 471               if (sec>=digp->GetNInnerSector())
 472                  if (row==nrow_up-1-gap) good[lab]|=0x1000;
 473
 474               if (sec>=digp->GetNInnerSector())
 475                  if (row==nrow_up-1-shift) good[lab]|=0x2000;
 476               if (sec>=digp->GetNInnerSector())
 477                  if (row==nrow_up-1-gap-shift) good[lab]|=0x800;
 478
 479               good[lab]++;
 480           }
 481           ca.ClearRow(sec,row);
 482         }
 483         delete pca;
 484         }
 485         break;
 486      case 2:
 487         {
 488         TTree *TD=tpcl->TreeD();
 489
 490         AliSimDigits da, *digits=&da;
 491         TD->GetBranch("Segment")->SetAddress(&digits);
 492
 493         Int_t *count = new Int_t[np];
 494         Int_t i;
 495         for (i=0; i<np; i++) count[i]=0;
 496
 497         Int_t sectors_by_rows=(Int_t)TD->GetEntries();
 498         for (i=0; i<sectors_by_rows; i++) {
 499           if (!TD->GetEvent(i)) continue;
 500           Int_t sec,row;
 501           digp->AdjustSectorRow(digits->GetID(),sec,row);
 502           //cerr<<sec<<' '<<row<<'\r';
 503           digits->First();
 504           do { //Many thanks to J.Chudoba who noticed this
 505               Int_t it=digits->CurrentRow(), ip=digits->CurrentColumn();
 506               Short_t dig = digits->GetDigit(it,ip);
 507               Int_t idx0=digits->GetTrackID(it,ip,0);
 508               Int_t idx1=digits->GetTrackID(it,ip,1);
 509               Int_t idx2=digits->GetTrackID(it,ip,2);
 510               if (idx0>=0 && dig>=zero && idx0<np) count[idx0]+=1;
 511               if (idx1>=0 && dig>=zero && idx1<np) count[idx1]+=1;
 512               if (idx2>=0 && dig>=zero && idx2<np) count[idx2]+=1;
 513           } while (digits->Next());
 514           for (Int_t j=0; j<np; j++) {
 515               if (count[j]>1) {
 516                  if (sec>=digp->GetNInnerSector())
 517                    if (row==nrow_up-1    ) good[j]|=0x4000;
 518                  if (sec>=digp->GetNInnerSector())
 519                    if (row==nrow_up-1-gap) good[j]|=0x1000;
 520
 521                  if (sec>=digp->GetNInnerSector())
 522                    if (row==nrow_up-1-shift) good[j]|=0x2000;
 523                  if (sec>=digp->GetNInnerSector())
 524                    if (row==nrow_up-1-gap-shift) good[j]|=0x800;
 525                  good[j]++;
 526               }
 527               count[j]=0;
 528           }
 529         }
 530         delete[] count;
 531         }
 532         break;
 533      }
 534
 535
 536      //****** select tracks which are "good" enough
 537      AliStack* stack = rl->Stack();
 538      for (i=0; i<np; i++) {
 539         if ((good[i]&0x5000) != 0x5000)
 540         if ((good[i]&0x2800) != 0x2800) continue;
 541         if ((good[i]&0x7FF ) < good_number) continue;
 542
 543         TParticle *p = (TParticle*)stack->Particle(i);
 544         if (p == 0x0) {
 545          cerr<<"Can not get particle "<<i<<endl;
 546          continue;
 547         }
 548         if (p->Pt()<0.100) continue;
 549         if (TMath::Abs(p->Pz()/p->Pt())>0.999) continue;
 550
 551         Double_t vx=p->Vx(),vy=p->Vy();
 552         if (TMath::Sqrt(vx*vx+vy*vy)>3.5) continue;
 553
 554         AliTrackReference *ref=new((*refs)[nt]) AliTrackReference();
 555
 556         ref->SetLabel(i);
 557         Int_t pdg=p->GetPdgCode();
 558         ref->SetLength(pdg);  //This will the particle's PDG !
 559         ref->SetMomentum(0.,0.,0.);
 560         ref->SetPosition(0.,0.,0.);
 561
 562         nt++;
 563      }
 564
 565      //**** check if there is also information at the entrance of the TPC
 566      TTree *TR=rl->TreeTR();
 567      TBranch *branch=TR->GetBranch("TPC");
 568      if (branch==0) {
 569         ::Error("GoodTracksTPC","No track references !");
 570         delete rl;
 571         return 5;
 572      }
 573      TClonesArray tpcdummy("AliTrackReference",1000), *tpcRefs=&tpcdummy;
 574      branch->SetAddress(&tpcRefs);
 575      Int_t nr=(Int_t)TR->GetEntries();
 576      for (Int_t r=0; r<nr; r++) {
 577          //cerr<<r<<' '<<nr<<'\r';
 578          TR->GetEvent(r);
 579          if (tpcRefs->GetEntriesFast()==0) continue;
 580          AliTrackReference *tpcRef=(AliTrackReference*)tpcRefs->UncheckedAt(0);
 581          Int_t j;
 582          AliTrackReference *ref=0;
 583          for (j=0; j<nt; j++) {
 584            ref=(AliTrackReference *)refs->UncheckedAt(j);
 585            if (ref->Label()==tpcRef->Label()) break;
 586            ref=0;
 587          }
 588          if (ref==0) continue;
 589
 590          ref->SetMomentum(tpcRef->Px(),tpcRef->Py(),tpcRef->Pz());
 591          ref->SetPosition(tpcRef->LocalX(),tpcRef->LocalY(),tpcRef->Z());
 592
 593          tpcRefs->Clear();
 594      }
 595
 596      tpcTree.Fill();
 597
 598      delete[] good;
 599    } //****** end of the loop over generated events
 600
 601
 602    tpcTree.Write();
 603    file->Close();
 604
 605    delete rl;
 606    return 0;
 607 }