TPC/AliTPCComparison.C

   1 /// \file AliTPCComparison.C
   2 /// \brief Very important, delicate and rather obscure macro
   3 ///
   4 /// Creates list of "trackable" tracks, calculates efficiency, resolutions etc.
   5 ///
   6 /// There is a possibility to run this macro over several events.
   7 ///
   8 /// \author I.Belikov, CERN, Jouri.Belikov@cern.ch, M.Ivanov, GSI, m.ivanov@gsi.de
   9
  10 #if !defined(__CINT__) || defined(__MAKECINT__)
  11   #include <TMath.h>
  12   #include <TError.h>
  13   #include <Riostream.h>
  14   #include <TH1F.h>
  15   #include <TH2F.h>
  16   #include <TTree.h>
  17   #include <TParticle.h>
  18   #include <TCanvas.h>
  19   #include <TLine.h>
  20   #include <TText.h>
  21   #include <TBenchmark.h>
  22   #include <TStyle.h>
  23   #include <TFile.h>
  24   #include <TROOT.h>
  25
  26   #include "AliStack.h"
  27   #include "AliHeader.h"
  28   #include "AliTrackReference.h"
  29   #include "AliRunLoader.h"
  30   #include "AliRun.h"
  31   #include "AliESDEvent.h"
  32   #include "AliESDtrack.h"
  33
  34   #include "AliSimDigits.h"
  35   #include "AliTPC.h"
  36   #include "AliTPCParamSR.h"
  37   #include "AliTPCClustersArray.h"
  38   #include "AliTPCClustersRow.h"
  39   #include "AliTPCcluster.h"
  40   #include "AliTPCLoader.h"
  41
  42   #include "AliCDBManager.h"
  43   #include "AliTPCcalibDB.h"
  44 #endif
  45
  46 Int_t GoodTracksTPC(const Char_t *dir=".");
  47
  48 extern TBenchmark *gBenchmark;
  49 extern TROOT *gROOT;
  50
  51 static Int_t allgood=0;
  52 static Int_t allselected=0;
  53 static Int_t allfound=0;
  54
  55 Int_t AliTPCComparison
  56 (Float_t ptcutl=0.2, Float_t ptcuth=10., const Char_t *dir=".") {
  57    gBenchmark->Start("AliTPCComparison");
  58
  59    ::Info("AliTPCComparison.C","Doing comparison...");
  60
  61
  62
  63    TH1F *hp=(TH1F*)gROOT->FindObject("hp");
  64    if (!hp) hp=new TH1F("hp","PHI resolution",50,-20.,20.);
  65    hp->SetFillColor(4);
  66
  67    TH1F *hl=(TH1F*)gROOT->FindObject("hl");
  68    if (!hl) hl=new TH1F("hl","LAMBDA resolution",50,-20,20);
  69    hl->SetFillColor(4);
  70
  71    TH1F *hpt=(TH1F*)gROOT->FindObject("hpt");
  72    if (!hpt) hpt=new TH1F("hpt","Relative Pt resolution",30,-10.,10.);
  73    hpt->SetFillColor(2);
  74
  75    TH1F *hmpt=(TH1F*)gROOT->FindObject("hmpt");
  76    if (!hmpt)
  77       hmpt=new TH1F("hmpt","Relative Pt resolution (pt>4GeV/c)",30,-60,60);
  78    hmpt->SetFillColor(6);
  79
  80
  81
  82    TH1F *hgood=(TH1F*)gROOT->FindObject("hgood");
  83    if (!hgood) hgood=new TH1F("hgood","Good tracks",30,0.2,6.1);
  84
  85    TH1F *hfound=(TH1F*)gROOT->FindObject("hfound");
  86    if (!hfound) hfound=new TH1F("hfound","Found tracks",30,0.2,6.1);
  87
  88    TH1F *hfake=(TH1F*)gROOT->FindObject("hfake");
  89    if (!hfake) hfake=new TH1F("hfake","Fake tracks",30,0.2,6.1);
  90
  91    TH1F *hg=(TH1F*)gROOT->FindObject("hg");
  92    if (!hg) hg=new TH1F("hg","Efficiency for good tracks",30,0.2,6.1);
  93    hg->SetLineColor(4); hg->SetLineWidth(2);
  94
  95    TH1F *hf=(TH1F*)gROOT->FindObject("hf");
  96    if (!hf) hf=new TH1F("hf","Efficiency for fake tracks",30,0.2,6.1);
  97    hf->SetFillColor(1); hf->SetFillStyle(3013); hf->SetLineWidth(2);
  98
  99    TH1F *he=(TH1F*)gROOT->FindObject("he");
 100    if (!he)
 101       he =new TH1F("he","dE/dX for pions with 0.4<p<0.5 GeV/c",50,0.,100.);
 102
 103    TH2F *hep=(TH2F*)gROOT->FindObject("hep");
 104    if (!hep) hep=new TH2F("hep","dE/dX vs momentum",50,0.,2.,50,0.,400.);
 105    hep->SetMarkerStyle(8);
 106    hep->SetMarkerSize(0.4);
 107
 108
 109    Char_t fname[100];
 110    sprintf(fname,"%s/GoodTracksTPC.root",dir);
 111
 112    TFile *refFile=TFile::Open(fname,"old");
 113    if (!refFile || !refFile->IsOpen()) {
 114      ::Info("AliTPCComparison.C","Marking good tracks (will take a while)...");
 115      if (GoodTracksTPC(dir)) {
 116         ::Error("AliTPCComparison.C","Can't generate the reference file !");
 117         return 1;
 118      }
 119    }
 120    refFile=TFile::Open(fname,"old");
 121    if (!refFile || !refFile->IsOpen()) {
 122      ::Error("AliTPCComparison.C","Can't open the reference file !");
 123      return 2;
 124    }
 125
 126    TTree *tpcTree=(TTree*)refFile->Get("tpcTree");
 127    if (!tpcTree) {
 128      ::Error("AliTPCComparison.C","Can't get the reference tree !");
 129      return 3;
 130    }
 131    TBranch *branch=tpcTree->GetBranch("TPC");
 132    if (!branch) {
 133      ::Error("AliTPCComparison.C","Can't get the TPC branch !");
 134      return 4;
 135    }
 136    TClonesArray dummy("AliTrackReference",1000), *refs=&dummy;
 137    branch->SetAddress(&refs);
 138
 139
 140    sprintf(fname,"%s/AliESDs.root",dir);
 141    TFile *ef=TFile::Open(fname);
 142    if ((!ef)||(!ef->IsOpen())) {
 143       sprintf(fname,"%s/AliESDtpc.root",dir);
 144       ef=TFile::Open(fname);
 145       if ((!ef)||(!ef->IsOpen())) {
 146          ::Error("AliTPCComparison.C","Can't open AliESDtpc.root !");
 147          return 5;
 148       }
 149    }
 150    AliESDEvent* event = new AliESDEvent();
 151    TTree* esdTree = (TTree*) ef->Get("esdTree");
 152    if (!esdTree) {
 153       ::Error("AliTPCComparison.C", "no ESD tree found");
 154       return 6;
 155    }
 156    event->ReadFromTree(esdTree);
 157
 158
 159   // ******* Loop over events *********
 160
 161    Int_t e=0;
 162    while (esdTree->GetEvent(e)) {
 163       cout<<endl<<endl<<"********* Processing event number: "<<e<<"*******\n";
 164
 165       Int_t nentr=event->GetNumberOfTracks();
 166       allfound+=nentr;
 167
 168       if (tpcTree->GetEvent(e++)==0) {
 169          cerr<<"No reconstructable tracks !\n";
 170          continue;
 171       }
 172
 173       Int_t ngood=refs->GetEntriesFast();
 174       allgood+=ngood;
 175
 176       const Int_t MAX=15000;
 177     //MI change
 178       Int_t track_notfound[MAX], itrack_notfound=0;
 179       Int_t track_fake[MAX], itrack_fake=0;
 180       Int_t track_multifound[MAX],track_multifound_n[MAX],itrack_multifound=0;
 181
 182       Int_t i;
 183       for (Int_t k=0; k<ngood; k++) {
 184         AliTrackReference *ref=(AliTrackReference*)refs->UncheckedAt(k);
 185         Int_t lab=ref->Label(), tlab=-1;
 186         Float_t ptg=TMath::Sqrt(ref->Px()*ref->Px() + ref->Py()*ref->Py());
 187
 188         if (ptg<1e-33) continue; // for those not crossing 0 pad row
 189
 190         if (ptg<ptcutl) continue;
 191         if (ptg>ptcuth) continue;
 192
 193         allselected++;
 194
 195         hgood->Fill(ptg);
 196
 197         AliESDtrack *track=0;
 198         for (i=0; i<nentr; i++) {
 199           track=event->GetTrack(i);
 200           tlab=track->GetTPCLabel();
 201           if (lab==TMath::Abs(tlab)) break;
 202         }
 203         if (i==nentr) {
 204            track_notfound[itrack_notfound++]=lab;
 205            continue;
 206         }
 207
 208         //MI change  - addition
 209         Int_t micount=0;
 210         Int_t mi;
 211         AliESDtrack * mitrack;
 212         for (mi=0; mi<nentr; mi++) {
 213           mitrack=event->GetTrack(mi);
 214           if (lab==TMath::Abs(mitrack->GetTPCLabel())) micount++;
 215         }
 216         if (micount>1) {
 217           track_multifound[itrack_multifound]=lab;
 218           track_multifound_n[itrack_multifound]=micount;
 219           itrack_multifound++;
 220         }
 221         if ((track->GetStatus()&AliESDtrack::kTPCrefit)==0) continue;
 222         if (lab==tlab) hfound->Fill(ptg);
 223         else {
 224           track_fake[itrack_fake++]=lab;
 225           hfake->Fill(ptg);
 226         }
 227
 228         Double_t pxpypz[3]; track->GetInnerPxPyPz(pxpypz);
 229         Float_t phi=TMath::ATan2(pxpypz[1],pxpypz[0]);
 230         if (phi<-TMath::Pi()) phi+=2*TMath::Pi();
 231         if (phi>=TMath::Pi()) phi-=2*TMath::Pi();
 232         Double_t pt=TMath::Sqrt(pxpypz[0]*pxpypz[0]+pxpypz[1]*pxpypz[1]);
 233         Float_t lam=TMath::ATan2(pxpypz[2],pt);
 234         Float_t pt_1=1/pt;
 235
 236         Int_t pdg=(Int_t)ref->GetLength();  //this is particle's PDG !
 237
 238         if (TMath::Abs(pdg)==11 && ptg>4.) {//high momentum electrons
 239            hmpt->Fill((pt_1 - 1/ptg)/(1/ptg)*100.);
 240         } else {
 241            Float_t phig=TMath::ATan2(ref->Py(),ref->Px());
 242            hp->Fill((phi - phig)*1000.);
 243
 244            Float_t lamg=TMath::ATan2(ref->Pz(),ptg);
 245            hl->Fill((lam - lamg)*1000.);
 246
 247            hpt->Fill((pt_1 - 1/ptg)/(1/ptg)*100.);
 248         }
 249
 250         Float_t mom=pt/TMath::Cos(lam);
 251         Float_t dedx=track->GetTPCsignal();
 252         hep->Fill(mom,dedx,1.);
 253         if (TMath::Abs(pdg)==211) //pions
 254            if (mom>0.4 && mom<0.5) {
 255               he->Fill(dedx,1.);
 256            }
 257       }
 258
 259       cout<<"\nList of Not found tracks :\n";
 260       for ( i = 0; i< itrack_notfound; i++){
 261         cout<<track_notfound[i]<<"\t";
 262         if ((i%5)==4) cout<<"\n";
 263       }
 264       cout<<"\nList of fake  tracks :\n";
 265       for ( i = 0; i< itrack_fake; i++){
 266         cout<<track_fake[i]<<"\t";
 267         if ((i%5)==4) cout<<"\n";
 268       }
 269       cout<<"\nList of multiple found tracks :\n";
 270       for ( i=0; i<itrack_multifound; i++) {
 271           cout<<"id.   "<<track_multifound[i]
 272               <<"     found - "<<track_multifound_n[i]<<"times\n";
 273       }
 274
 275       cout<<"Number of found tracks ="<<nentr<<endl;
 276       cout<<"Number of \"good\" tracks ="<<ngood<<endl;
 277
 278       refs->Clear();
 279   }// ***** End of the loop over events
 280
 281    delete event;
 282    delete esdTree;
 283    ef->Close();
 284
 285    delete tpcTree;
 286    refFile->Close();
 287
 288    Stat_t ng=hgood->GetEntries(), nf=hfound->GetEntries();
 289    if (ng!=0) cout<<"\n\nIntegral efficiency is about "<<nf/ng*100.<<" %\n";
 290    cout<<"Total number selected of \"good\" tracks ="<<allselected<<endl<<endl;
 291    cout<<"Total number of found tracks ="<<allfound<<endl;
 292    cout<<"Total number of \"good\" tracks ="<<allgood<<endl;
 293    cout<<endl;
 294
 295    gStyle->SetOptStat(111110);
 296    gStyle->SetOptFit(1);
 297
 298    TCanvas *c1=new TCanvas("c1","",0,0,700,850);
 299
 300    Int_t minc=33;
 301
 302    TPad *p1=new TPad("p1","",0,0.3,.5,.6); p1->Draw();
 303    p1->cd(); p1->SetFillColor(42); p1->SetFrameFillColor(10);
 304    hp->SetFillColor(4);  hp->SetXTitle("(mrad)");
 305    if (hp->GetEntries()<minc) hp->Draw(); else hp->Fit("gaus"); c1->cd();
 306
 307    TPad *p2=new TPad("p2","",0.5,.3,1,.6); p2->Draw();
 308    p2->cd(); p2->SetFillColor(42); p2->SetFrameFillColor(10);
 309    hl->SetXTitle("(mrad)");
 310    if (hl->GetEntries()<minc) hl->Draw(); else hl->Fit("gaus"); c1->cd();
 311
 312    TPad *p3=new TPad("p3","",0,0,0.5,0.3); p3->Draw();
 313    p3->cd(); p3->SetFillColor(42); p3->SetFrameFillColor(10);
 314    hpt->SetXTitle("(%)");
 315    if (hpt->GetEntries()<minc) hpt->Draw(); else hpt->Fit("gaus"); c1->cd();
 316
 317    TPad *p4=new TPad("p4","",0.5,0,1,0.3); p4->Draw();
 318    p4->cd(); p4->SetFillColor(42); p4->SetFrameFillColor(10);
 319    hmpt->SetXTitle("(%)");
 320    if (hmpt->GetEntries()<minc) hmpt->Draw(); else hmpt->Fit("gaus"); c1->cd();
 321
 322    TPad *p5=new TPad("p5","",0,0.6,1,1); p5->Draw(); p5->cd();
 323    p5->SetFillColor(41); p5->SetFrameFillColor(10);
 324    hfound->Sumw2(); hgood->Sumw2(); hfake->Sumw2();
 325    hg->Divide(hfound,hgood,1,1.,"b");
 326    hf->Divide(hfake,hgood,1,1.,"b");
 327    hg->SetMaximum(1.4);
 328    hg->SetYTitle("Tracking efficiency");
 329    hg->SetXTitle("Pt (GeV/c)");
 330    hg->Draw();
 331
 332    TLine *line1 = new TLine(0.1,1.0,6.1,1.0); line1->SetLineStyle(4);
 333    line1->Draw("same");
 334    TLine *line2 = new TLine(0.1,0.9,6.1,0.9); line2->SetLineStyle(4);
 335    line2->Draw("same");
 336
 337    hf->SetFillColor(1);
 338    hf->SetFillStyle(3013);
 339    hf->SetLineColor(2);
 340    hf->SetLineWidth(2);
 341    hf->Draw("histsame");
 342    TText *text = new TText(0.461176,0.248448,"Fake tracks");
 343    text->SetTextSize(0.05);
 344    text->Draw();
 345    text = new TText(0.453919,1.11408,"Good tracks");
 346    text->SetTextSize(0.05);
 347    text->Draw();
 348
 349
 350
 351    TCanvas *c2=new TCanvas("c2","",320,32,530,590);
 352
 353    TPad *p6=new TPad("p6","",0.,0.,1.,.5); p6->Draw();
 354    p6->cd(); p6->SetFillColor(42); p6->SetFrameFillColor(10);
 355    he->SetFillColor(2); he->SetFillStyle(3005);
 356    he->SetXTitle("Arbitrary Units");
 357    if (he->GetEntries()<minc) he->Draw(); else he->Fit("gaus"); c2->cd();
 358
 359    TPad *p7=new TPad("p7","",0.,0.5,1.,1.); p7->Draw();
 360    p7->cd(); p7->SetFillColor(42); p7->SetFrameFillColor(10);
 361    hep->SetXTitle("p (Gev/c)"); hep->SetYTitle("dE/dX (Arb. Units)");
 362    hep->Draw(); c1->cd();
 363
 364    TFile fc("AliTPCComparison.root","RECREATE");
 365    c1->Write();
 366    c2->Write();
 367    fc.Close();
 368
 369    gBenchmark->Stop("AliTPCComparison");
 370    gBenchmark->Show("AliTPCComparison");
 371
 372    return 0;
 373 }
 374
 375
 376 Int_t GoodTracksTPC(const Char_t *dir) {
 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
 410    AliCDBManager *man=AliCDBManager::Instance();
 411    man->SetDefaultStorage("local://$ALICE_ROOT/OCDB");
 412    man->SetRun(0);
 413    AliTPCParamSR *digp=
 414    (AliTPCParamSR*)(AliTPCcalibDB::Instance()->GetParameters());
 415    if (!digp) {
 416      ::Error("AliTPCComparison.C","TPC parameters have not been found !");
 417      delete rl;
 418      return 4;
 419    }
 420
 421    Int_t nrow_up=digp->GetNRowUp();
 422    Int_t nrows=digp->GetNRowLow()+nrow_up;
 423    Int_t zero=digp->GetZeroSup();
 424    Int_t gap=Int_t(0.125*nrows), shift=Int_t(0.5*gap);
 425    Int_t good_number=Int_t(0.4*nrows);
 426
 427    Int_t nev=rl->GetNumberOfEvents();
 428    ::Info("GoodTracksTPC","Number of events : %d\n",nev);
 429
 430
 431    sprintf(fname,"%s/GoodTracksTPC.root",dir);
 432    TFile *file=TFile::Open(fname,"recreate");
 433
 434    TClonesArray dummy("AliTrackReference",1000), *refs=&dummy;
 435    TTree tpcTree("tpcTree","Tree with info about the reconstructable TPC tracks");
 436    tpcTree.Branch("TPC",&refs);
 437
 438    //********  Loop over generated events
 439    for (Int_t e=0; e<nev; e++) {
 440      Int_t nt=0;
 441      refs->Clear();
 442
 443      Int_t i;
 444
 445      rl->GetEvent(e);  file->cd();
 446
 447      Int_t np = rl->GetHeader()->GetNtrack();
 448      cout<<"Event "<<e<<" Number of particles: "<<np<<endl;
 449
 450      //******** Fill the "good" masks
 451      Int_t *good=new Int_t[np]; for (i=0; i<np; i++) good[i]=0;
 452      switch (ver) {
 453      case 1:
 454         {
 455         AliTPCClustersArray *pca=new AliTPCClustersArray, &ca=*pca;
 456         ca.Setup(digp);
 457         ca.SetClusterType("AliTPCcluster");
 458         ca.ConnectTree(tpcl->TreeR());
 459         Int_t nrows=Int_t(ca.GetTree()->GetEntries());
 460         for (Int_t n=0; n<nrows; n++) {
 461           AliSegmentID *s=ca.LoadEntry(n);
 462           Int_t sec,row;
 463           digp->AdjustSectorRow(s->GetID(),sec,row);
 464           AliTPCClustersRow &clrow = *ca.GetRow(sec,row);
 465           Int_t ncl=clrow.GetArray()->GetEntriesFast();
 466           while (ncl--) {
 467               AliTPCcluster *c=(AliTPCcluster*)clrow[ncl];
 468               Int_t lab=c->GetLabel(0);
 469               if (lab<0) continue; //noise cluster
 470               lab=TMath::Abs(lab);
 471
 472               if (sec>=digp->GetNInnerSector())
 473                  if (row==nrow_up-1) good[lab]|=0x4000;
 474               if (sec>=digp->GetNInnerSector())
 475                  if (row==nrow_up-1-gap) good[lab]|=0x1000;
 476
 477               if (sec>=digp->GetNInnerSector())
 478                  if (row==nrow_up-1-shift) good[lab]|=0x2000;
 479               if (sec>=digp->GetNInnerSector())
 480                  if (row==nrow_up-1-gap-shift) good[lab]|=0x800;
 481
 482               good[lab]++;
 483           }
 484           ca.ClearRow(sec,row);
 485         }
 486         delete pca;
 487         }
 488         break;
 489      case 2:
 490         {
 491         TTree *TD=tpcl->TreeD();
 492
 493         AliSimDigits da, *digits=&da;
 494         TD->GetBranch("Segment")->SetAddress(&digits);
 495
 496         Int_t *count = new Int_t[np];
 497         Int_t i;
 498         for (i=0; i<np; i++) count[i]=0;
 499
 500         Int_t sectors_by_rows=(Int_t)TD->GetEntries();
 501         for (i=0; i<sectors_by_rows; i++) {
 502           if (!TD->GetEvent(i)) continue;
 503           Int_t sec,row;
 504           digp->AdjustSectorRow(digits->GetID(),sec,row);
 505           //cerr<<sec<<' '<<row<<'\r';
 506           digits->First();
 507           do { //Many thanks to J.Chudoba who noticed this
 508               Int_t it=digits->CurrentRow(), ip=digits->CurrentColumn();
 509               Short_t dig = digits->GetDigit(it,ip);
 510               Int_t idx0=digits->GetTrackID(it,ip,0);
 511               Int_t idx1=digits->GetTrackID(it,ip,1);
 512               Int_t idx2=digits->GetTrackID(it,ip,2);
 513               if (idx0>=0 && dig>=zero && idx0<np) count[idx0]+=1;
 514               if (idx1>=0 && dig>=zero && idx1<np) count[idx1]+=1;
 515               if (idx2>=0 && dig>=zero && idx2<np) count[idx2]+=1;
 516           } while (digits->Next());
 517           for (Int_t j=0; j<np; j++) {
 518               if (count[j]>1) {
 519                  if (sec>=digp->GetNInnerSector())
 520                    if (row==nrow_up-1    ) good[j]|=0x4000;
 521                  if (sec>=digp->GetNInnerSector())
 522                    if (row==nrow_up-1-gap) good[j]|=0x1000;
 523
 524                  if (sec>=digp->GetNInnerSector())
 525                    if (row==nrow_up-1-shift) good[j]|=0x2000;
 526                  if (sec>=digp->GetNInnerSector())
 527                    if (row==nrow_up-1-gap-shift) good[j]|=0x800;
 528                  good[j]++;
 529               }
 530               count[j]=0;
 531           }
 532         }
 533         delete[] count;
 534         }
 535         break;
 536      }
 537
 538
 539      //****** select tracks which are "good" enough
 540      AliStack* stack = rl->Stack();
 541      for (i=0; i<np; i++) {
 542         if ((good[i]&0x5000) != 0x5000)
 543         if ((good[i]&0x2800) != 0x2800) continue;
 544         if ((good[i]&0x7FF ) < good_number) continue;
 545
 546         TParticle *p = (TParticle*)stack->Particle(i);
 547         if (p == 0x0) {
 548          cerr<<"Can not get particle "<<i<<endl;
 549          continue;
 550         }
 551         if (p->Pt()<0.100) continue;
 552         if (TMath::Abs(p->Pz()/p->Pt())>0.999) continue;
 553
 554         Double_t vx=p->Vx(),vy=p->Vy(),vz=p->Vz();
 555         if (TMath::Sqrt(vx*vx+vy*vy)>3.5) continue;
 556         if (TMath::Abs(vz) > 50.) continue;
 557
 558         AliTrackReference *ref=new((*refs)[nt]) AliTrackReference();
 559
 560         ref->SetLabel(i);
 561         Int_t pdg=p->GetPdgCode();
 562         ref->SetLength(pdg);  //This will the particle's PDG !
 563         ref->SetMomentum(0.,0.,0.);
 564         ref->SetPosition(0.,0.,0.);
 565
 566         nt++;
 567      }
 568
 569      //**** check if there is also information at the entrance of the TPC
 570      TTree *TR=rl->TreeTR();
 571      TBranch *branch=TR->GetBranch("TrackReferences");
 572      if (branch==0) {
 573         ::Error("GoodTracksTPC","No track references !");
 574         delete rl;
 575         return 5;
 576      }
 577      TClonesArray tpcdummy("AliTrackReference",1000), *tpcRefs=&tpcdummy;
 578      branch->SetAddress(&tpcRefs);
 579      Int_t nr=(Int_t)TR->GetEntries();
 580      for (Int_t r=0; r<nr; r++) {
 581          //cerr<<r<<' '<<nr<<'\r';
 582          TR->GetEvent(r);
 583
 584          Int_t nref = tpcRefs->GetEntriesFast();
 585          if (!nref) continue;
 586          AliTrackReference *tpcRef= 0x0;
 587          for (Int_t iref=0; iref<nref; ++iref) {
 588            tpcRef = (AliTrackReference*)tpcRefs->UncheckedAt(iref);
 589            if (tpcRef->DetectorId() == AliTrackReference::kTPC) break;
 590            tpcRef = 0x0;
 591          }
 592
 593          if (!tpcRef) continue;
 594
 595          Int_t j;
 596          AliTrackReference *ref=0;
 597          for (j=0; j<nt; j++) {
 598            ref=(AliTrackReference *)refs->UncheckedAt(j);
 599            if (ref->Label()==tpcRef->Label()) break;
 600            ref=0;
 601          }
 602          if (ref==0) continue;
 603
 604          ref->SetMomentum(tpcRef->Px(),tpcRef->Py(),tpcRef->Pz());
 605          ref->SetPosition(tpcRef->LocalX(),tpcRef->LocalY(),tpcRef->Z());
 606
 607          tpcRefs->Clear();
 608      }
 609
 610      tpcTree.Fill();
 611
 612      delete[] good;
 613    } //****** end of the loop over generated events
 614
 615
 616    tpcTree.Write();
 617    file->Close();
 618
 619    delete rl;
 620    return 0;
 621 }