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 <TFile.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 "AliESDEvent.h"
  34   #include "AliESDtrack.h"
  35
  36   #include "AliSimDigits.h"
  37   #include "AliTPC.h"
  38   #include "AliTPCParamSR.h"
  39   #include "AliTPCClustersArray.h"
  40   #include "AliTPCClustersRow.h"
  41   #include "AliTPCcluster.h"
  42   #include "AliTPCLoader.h"
  43 #endif
  44
  45 Int_t GoodTracksTPC(const Char_t *dir=".");
  46
  47 extern AliRun *gAlice;
  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    Int_t e=0;
 161    while (esdTree->GetEvent(e)) {
 162       cout<<endl<<endl<<"********* Processing event number: "<<e<<"*******\n";
 163
 164       Int_t nentr=event->GetNumberOfTracks();
 165       allfound+=nentr;
 166
 167       if (tpcTree->GetEvent(e++)==0) {
 168          cerr<<"No reconstructable tracks !\n";
 169          continue;
 170       }
 171
 172       Int_t ngood=refs->GetEntriesFast();
 173       allgood+=ngood;
 174
 175       const Int_t MAX=15000;
 176     //MI change
 177       Int_t track_notfound[MAX], itrack_notfound=0;
 178       Int_t track_fake[MAX], itrack_fake=0;
 179       Int_t track_multifound[MAX],track_multifound_n[MAX],itrack_multifound=0;
 180
 181       Int_t i;
 182       for (Int_t k=0; k<ngood; k++) {
 183         AliTrackReference *ref=(AliTrackReference*)refs->UncheckedAt(k);
 184         Int_t lab=ref->Label(), tlab=-1;
 185         Float_t ptg=TMath::Sqrt(ref->Px()*ref->Px() + ref->Py()*ref->Py());
 186
 187         if (ptg<1e-33) continue; // for those not crossing 0 pad row
 188
 189         if (ptg<ptcutl) continue;
 190         if (ptg>ptcuth) continue;
 191
 192         allselected++;
 193
 194         hgood->Fill(ptg);
 195
 196         AliESDtrack *track=0;
 197         for (i=0; i<nentr; i++) {
 198           track=event->GetTrack(i);
 199           tlab=track->GetTPCLabel();
 200           if (lab==TMath::Abs(tlab)) break;
 201         }
 202         if (i==nentr) {
 203            track_notfound[itrack_notfound++]=lab;
 204            continue;
 205         }
 206
 207         //MI change  - addition
 208         Int_t micount=0;
 209         Int_t mi;
 210         AliESDtrack * mitrack;
 211         for (mi=0; mi<nentr; mi++) {
 212           mitrack=event->GetTrack(mi);
 213           if (lab==TMath::Abs(mitrack->GetTPCLabel())) micount++;
 214         }
 215         if (micount>1) {
 216           track_multifound[itrack_multifound]=lab;
 217           track_multifound_n[itrack_multifound]=micount;
 218           itrack_multifound++;
 219         }
 220         if ((track->GetStatus()&AliESDtrack::kTPCrefit)==0) continue;
 221         if (lab==tlab) hfound->Fill(ptg);
 222         else {
 223           track_fake[itrack_fake++]=lab;
 224           hfake->Fill(ptg);
 225         }
 226
 227         Double_t pxpypz[3]; track->GetInnerPxPyPz(pxpypz);
 228         Float_t phi=TMath::ATan2(pxpypz[1],pxpypz[0]);
 229         if (phi<-TMath::Pi()) phi+=2*TMath::Pi();
 230         if (phi>=TMath::Pi()) phi-=2*TMath::Pi();
 231         Double_t pt=TMath::Sqrt(pxpypz[0]*pxpypz[0]+pxpypz[1]*pxpypz[1]);
 232         Float_t lam=TMath::ATan2(pxpypz[2],pt);
 233         Float_t pt_1=1/pt;
 234
 235         Int_t pdg=(Int_t)ref->GetLength();  //this is particle's PDG !
 236
 237         if (TMath::Abs(pdg)==11 && ptg>4.) {//high momentum electrons
 238            hmpt->Fill((pt_1 - 1/ptg)/(1/ptg)*100.);
 239         } else {
 240            Float_t phig=TMath::ATan2(ref->Py(),ref->Px());
 241            hp->Fill((phi - phig)*1000.);
 242
 243            Float_t lamg=TMath::ATan2(ref->Pz(),ptg);
 244            hl->Fill((lam - lamg)*1000.);
 245
 246            hpt->Fill((pt_1 - 1/ptg)/(1/ptg)*100.);
 247         }
 248
 249         Float_t mom=pt/TMath::Cos(lam);
 250         Float_t dedx=track->GetTPCsignal();
 251         hep->Fill(mom,dedx,1.);
 252         if (TMath::Abs(pdg)==211) //pions
 253            if (mom>0.4 && mom<0.5) {
 254               he->Fill(dedx,1.);
 255            }
 256       }
 257
 258       cout<<"\nList of Not found tracks :\n";
 259       for ( i = 0; i< itrack_notfound; i++){
 260         cout<<track_notfound[i]<<"\t";
 261         if ((i%5)==4) cout<<"\n";
 262       }
 263       cout<<"\nList of fake  tracks :\n";
 264       for ( i = 0; i< itrack_fake; i++){
 265         cout<<track_fake[i]<<"\t";
 266         if ((i%5)==4) cout<<"\n";
 267       }
 268       cout<<"\nList of multiple found tracks :\n";
 269       for ( i=0; i<itrack_multifound; i++) {
 270           cout<<"id.   "<<track_multifound[i]
 271               <<"     found - "<<track_multifound_n[i]<<"times\n";
 272       }
 273
 274       cout<<"Number of found tracks ="<<nentr<<endl;
 275       cout<<"Number of \"good\" tracks ="<<ngood<<endl;
 276
 277       refs->Clear();
 278   }// ***** End of the loop over events
 279
 280    delete event;
 281    delete esdTree;
 282    ef->Close();
 283
 284    delete tpcTree;
 285    refFile->Close();
 286
 287    Stat_t ng=hgood->GetEntries(), nf=hfound->GetEntries();
 288    if (ng!=0) cout<<"\n\nIntegral efficiency is about "<<nf/ng*100.<<" %\n";
 289    cout<<"Total number selected of \"good\" tracks ="<<allselected<<endl<<endl;
 290    cout<<"Total number of found tracks ="<<allfound<<endl;
 291    cout<<"Total number of \"good\" tracks ="<<allgood<<endl;
 292    cout<<endl;
 293
 294    gStyle->SetOptStat(111110);
 295    gStyle->SetOptFit(1);
 296
 297    TCanvas *c1=new TCanvas("c1","",0,0,700,850);
 298
 299    Int_t minc=33;
 300
 301    TPad *p1=new TPad("p1","",0,0.3,.5,.6); p1->Draw();
 302    p1->cd(); p1->SetFillColor(42); p1->SetFrameFillColor(10);
 303    hp->SetFillColor(4);  hp->SetXTitle("(mrad)");
 304    if (hp->GetEntries()<minc) hp->Draw(); else hp->Fit("gaus"); c1->cd();
 305
 306    TPad *p2=new TPad("p2","",0.5,.3,1,.6); p2->Draw();
 307    p2->cd(); p2->SetFillColor(42); p2->SetFrameFillColor(10);
 308    hl->SetXTitle("(mrad)");
 309    if (hl->GetEntries()<minc) hl->Draw(); else hl->Fit("gaus"); c1->cd();
 310
 311    TPad *p3=new TPad("p3","",0,0,0.5,0.3); p3->Draw();
 312    p3->cd(); p3->SetFillColor(42); p3->SetFrameFillColor(10);
 313    hpt->SetXTitle("(%)");
 314    if (hpt->GetEntries()<minc) hpt->Draw(); else hpt->Fit("gaus"); c1->cd();
 315
 316    TPad *p4=new TPad("p4","",0.5,0,1,0.3); p4->Draw();
 317    p4->cd(); p4->SetFillColor(42); p4->SetFrameFillColor(10);
 318    hmpt->SetXTitle("(%)");
 319    if (hmpt->GetEntries()<minc) hmpt->Draw(); else hmpt->Fit("gaus"); c1->cd();
 320
 321    TPad *p5=new TPad("p5","",0,0.6,1,1); p5->Draw(); p5->cd();
 322    p5->SetFillColor(41); p5->SetFrameFillColor(10);
 323    hfound->Sumw2(); hgood->Sumw2(); hfake->Sumw2();
 324    hg->Divide(hfound,hgood,1,1.,"b");
 325    hf->Divide(hfake,hgood,1,1.,"b");
 326    hg->SetMaximum(1.4);
 327    hg->SetYTitle("Tracking efficiency");
 328    hg->SetXTitle("Pt (GeV/c)");
 329    hg->Draw();
 330
 331    TLine *line1 = new TLine(0.1,1.0,6.1,1.0); line1->SetLineStyle(4);
 332    line1->Draw("same");
 333    TLine *line2 = new TLine(0.1,0.9,6.1,0.9); line2->SetLineStyle(4);
 334    line2->Draw("same");
 335
 336    hf->SetFillColor(1);
 337    hf->SetFillStyle(3013);
 338    hf->SetLineColor(2);
 339    hf->SetLineWidth(2);
 340    hf->Draw("histsame");
 341    TText *text = new TText(0.461176,0.248448,"Fake tracks");
 342    text->SetTextSize(0.05);
 343    text->Draw();
 344    text = new TText(0.453919,1.11408,"Good tracks");
 345    text->SetTextSize(0.05);
 346    text->Draw();
 347
 348
 349
 350    TCanvas *c2=new TCanvas("c2","",320,32,530,590);
 351
 352    TPad *p6=new TPad("p6","",0.,0.,1.,.5); p6->Draw();
 353    p6->cd(); p6->SetFillColor(42); p6->SetFrameFillColor(10);
 354    he->SetFillColor(2); he->SetFillStyle(3005);
 355    he->SetXTitle("Arbitrary Units");
 356    if (he->GetEntries()<minc) he->Draw(); else he->Fit("gaus"); c2->cd();
 357
 358    TPad *p7=new TPad("p7","",0.,0.5,1.,1.); p7->Draw();
 359    p7->cd(); p7->SetFillColor(42); p7->SetFrameFillColor(10);
 360    hep->SetXTitle("p (Gev/c)"); hep->SetYTitle("dE/dX (Arb. Units)");
 361    hep->Draw(); c1->cd();
 362
 363    TFile fc("AliTPCComparison.root","RECREATE");
 364    c1->Write();
 365    c2->Write();
 366    fc.Close();
 367
 368    gBenchmark->Stop("AliTPCComparison");
 369    gBenchmark->Show("AliTPCComparison");
 370
 371    return 0;
 372 }
 373
 374
 375 Int_t GoodTracksTPC(const Char_t *dir) {
 376    if (gAlice) {
 377        delete gAlice->GetRunLoader();
 378        delete gAlice;//if everything was OK here it is already NULL
 379        gAlice = 0x0;
 380    }
 381
 382    Char_t fname[100];
 383    sprintf(fname,"%s/galice.root",dir);
 384
 385    AliRunLoader *rl = AliRunLoader::Open(fname,"COMPARISON");
 386    if (!rl) {
 387       ::Error("GoodTracksTPC","Can't start session !");
 388       return 1;
 389    }
 390
 391    rl->LoadgAlice();
 392    rl->LoadHeader();
 393    rl->LoadKinematics();
 394    rl->LoadTrackRefs();
 395
 396    AliTPCLoader *tpcl = (AliTPCLoader *)rl->GetLoader("TPCLoader");
 397    if (tpcl == 0x0) {
 398       ::Error("GoodTracksTPC","Can not find TPCLoader !");
 399       delete rl;
 400       return 2;
 401    }
 402
 403    AliTPC *TPC=(AliTPC*)rl->GetAliRun()->GetDetector("TPC");
 404    Int_t ver = TPC->IsVersion();
 405    cout<<"TPC version "<<ver<<" has been found !\n";
 406    if (ver==1) tpcl->LoadRecPoints();
 407    else if (ver==2) tpcl->LoadDigits();
 408    else {
 409       ::Error("GoodTracksTPC","Wrong TPC version !");
 410       delete rl;
 411       return 3;
 412    }
 413
 414    rl->CdGAFile();
 415    AliTPCParamSR *digp=(AliTPCParamSR*)gDirectory->Get("75x40_100x60_150x60");
 416    if (!digp) {
 417      ::Error("AliTPCHits2Digits.C","TPC parameters have not been found !");
 418      delete rl;
 419      return 4;
 420    }
 421    TPC->SetParam(digp);
 422
 423    Int_t nrow_up=digp->GetNRowUp();
 424    Int_t nrows=digp->GetNRowLow()+nrow_up;
 425    Int_t zero=digp->GetZeroSup();
 426    Int_t gap=Int_t(0.125*nrows), shift=Int_t(0.5*gap);
 427    Int_t good_number=Int_t(0.4*nrows);
 428
 429    Int_t nev=rl->GetNumberOfEvents();
 430    ::Info("GoodTracksTPC","Number of events : %d\n",nev);
 431
 432
 433    sprintf(fname,"%s/GoodTracksTPC.root",dir);
 434    TFile *file=TFile::Open(fname,"recreate");
 435
 436    TClonesArray dummy("AliTrackReference",1000), *refs=&dummy;
 437    TTree tpcTree("tpcTree","Tree with info about the reconstructable TPC tracks");
 438    tpcTree.Branch("TPC",&refs);
 439
 440    //********  Loop over generated events
 441    for (Int_t e=0; e<nev; e++) {
 442      Int_t nt=0;
 443      refs->Clear();
 444
 445      Int_t i;
 446
 447      rl->GetEvent(e);  file->cd();
 448
 449      Int_t np = rl->GetHeader()->GetNtrack();
 450      cout<<"Event "<<e<<" Number of particles: "<<np<<endl;
 451
 452      //******** Fill the "good" masks
 453      Int_t *good=new Int_t[np]; for (i=0; i<np; i++) good[i]=0;
 454      switch (ver) {
 455      case 1:
 456         {
 457         AliTPCClustersArray *pca=new AliTPCClustersArray, &ca=*pca;
 458         ca.Setup(digp);
 459         ca.SetClusterType("AliTPCcluster");
 460         ca.ConnectTree(tpcl->TreeR());
 461         Int_t nrows=Int_t(ca.GetTree()->GetEntries());
 462         for (Int_t n=0; n<nrows; n++) {
 463           AliSegmentID *s=ca.LoadEntry(n);
 464           Int_t sec,row;
 465           digp->AdjustSectorRow(s->GetID(),sec,row);
 466           AliTPCClustersRow &clrow = *ca.GetRow(sec,row);
 467           Int_t ncl=clrow.GetArray()->GetEntriesFast();
 468           while (ncl--) {
 469               AliTPCcluster *c=(AliTPCcluster*)clrow[ncl];
 470               Int_t lab=c->GetLabel(0);
 471               if (lab<0) continue; //noise cluster
 472               lab=TMath::Abs(lab);
 473
 474               if (sec>=digp->GetNInnerSector())
 475                  if (row==nrow_up-1) good[lab]|=0x4000;
 476               if (sec>=digp->GetNInnerSector())
 477                  if (row==nrow_up-1-gap) good[lab]|=0x1000;
 478
 479               if (sec>=digp->GetNInnerSector())
 480                  if (row==nrow_up-1-shift) good[lab]|=0x2000;
 481               if (sec>=digp->GetNInnerSector())
 482                  if (row==nrow_up-1-gap-shift) good[lab]|=0x800;
 483
 484               good[lab]++;
 485           }
 486           ca.ClearRow(sec,row);
 487         }
 488         delete pca;
 489         }
 490         break;
 491      case 2:
 492         {
 493         TTree *TD=tpcl->TreeD();
 494
 495         AliSimDigits da, *digits=&da;
 496         TD->GetBranch("Segment")->SetAddress(&digits);
 497
 498         Int_t *count = new Int_t[np];
 499         Int_t i;
 500         for (i=0; i<np; i++) count[i]=0;
 501
 502         Int_t sectors_by_rows=(Int_t)TD->GetEntries();
 503         for (i=0; i<sectors_by_rows; i++) {
 504           if (!TD->GetEvent(i)) continue;
 505           Int_t sec,row;
 506           digp->AdjustSectorRow(digits->GetID(),sec,row);
 507           //cerr<<sec<<' '<<row<<'\r';
 508           digits->First();
 509           do { //Many thanks to J.Chudoba who noticed this
 510               Int_t it=digits->CurrentRow(), ip=digits->CurrentColumn();
 511               Short_t dig = digits->GetDigit(it,ip);
 512               Int_t idx0=digits->GetTrackID(it,ip,0);
 513               Int_t idx1=digits->GetTrackID(it,ip,1);
 514               Int_t idx2=digits->GetTrackID(it,ip,2);
 515               if (idx0>=0 && dig>=zero && idx0<np) count[idx0]+=1;
 516               if (idx1>=0 && dig>=zero && idx1<np) count[idx1]+=1;
 517               if (idx2>=0 && dig>=zero && idx2<np) count[idx2]+=1;
 518           } while (digits->Next());
 519           for (Int_t j=0; j<np; j++) {
 520               if (count[j]>1) {
 521                  if (sec>=digp->GetNInnerSector())
 522                    if (row==nrow_up-1    ) good[j]|=0x4000;
 523                  if (sec>=digp->GetNInnerSector())
 524                    if (row==nrow_up-1-gap) good[j]|=0x1000;
 525
 526                  if (sec>=digp->GetNInnerSector())
 527                    if (row==nrow_up-1-shift) good[j]|=0x2000;
 528                  if (sec>=digp->GetNInnerSector())
 529                    if (row==nrow_up-1-gap-shift) good[j]|=0x800;
 530                  good[j]++;
 531               }
 532               count[j]=0;
 533           }
 534         }
 535         delete[] count;
 536         }
 537         break;
 538      }
 539
 540
 541      //****** select tracks which are "good" enough
 542      AliStack* stack = rl->Stack();
 543      for (i=0; i<np; i++) {
 544         if ((good[i]&0x5000) != 0x5000)
 545         if ((good[i]&0x2800) != 0x2800) continue;
 546         if ((good[i]&0x7FF ) < good_number) continue;
 547
 548         TParticle *p = (TParticle*)stack->Particle(i);
 549         if (p == 0x0) {
 550          cerr<<"Can not get particle "<<i<<endl;
 551          continue;
 552         }
 553         if (p->Pt()<0.100) continue;
 554         if (TMath::Abs(p->Pz()/p->Pt())>0.999) continue;
 555
 556         Double_t vx=p->Vx(),vy=p->Vy();
 557         if (TMath::Sqrt(vx*vx+vy*vy)>3.5) continue;
 558
 559         AliTrackReference *ref=new((*refs)[nt]) AliTrackReference();
 560
 561         ref->SetLabel(i);
 562         Int_t pdg=p->GetPdgCode();
 563         ref->SetLength(pdg);  //This will the particle's PDG !
 564         ref->SetMomentum(0.,0.,0.);
 565         ref->SetPosition(0.,0.,0.);
 566
 567         nt++;
 568      }
 569
 570      //**** check if there is also information at the entrance of the TPC
 571      TTree *TR=rl->TreeTR();
 572      TBranch *branch=TR->GetBranch("TrackReferences");
 573      if (branch==0) {
 574         ::Error("GoodTracksTPC","No track references !");
 575         delete rl;
 576         return 5;
 577      }
 578      TClonesArray tpcdummy("AliTrackReference",1000), *tpcRefs=&tpcdummy;
 579      branch->SetAddress(&tpcRefs);
 580      Int_t nr=(Int_t)TR->GetEntries();
 581      for (Int_t r=0; r<nr; r++) {
 582          //cerr<<r<<' '<<nr<<'\r';
 583          TR->GetEvent(r);
 584
 585          Int_t nref = tpcRefs->GetEntriesFast();
 586          if (!nref) continue;
 587          AliTrackReference *tpcRef= 0x0;
 588          for (Int_t iref=0; iref<nref; ++iref) {
 589            tpcRef = (AliTrackReference*)tpcRefs->UncheckedAt(iref);
 590            if (tpcRef->DetectorId() == AliTrackReference::kTPC) break;
 591            tpcRef = 0x0;
 592          }
 593
 594          if (!tpcRef) continue;
 595
 596          Int_t j;
 597          AliTrackReference *ref=0;
 598          for (j=0; j<nt; j++) {
 599            ref=(AliTrackReference *)refs->UncheckedAt(j);
 600            if (ref->Label()==tpcRef->Label()) break;
 601            ref=0;
 602          }
 603          if (ref==0) continue;
 604
 605          ref->SetMomentum(tpcRef->Px(),tpcRef->Py(),tpcRef->Pz());
 606          ref->SetPosition(tpcRef->LocalX(),tpcRef->LocalY(),tpcRef->Z());
 607
 608          tpcRefs->Clear();
 609      }
 610
 611      tpcTree.Fill();
 612
 613      delete[] good;
 614    } //****** end of the loop over generated events
 615
 616
 617    tpcTree.Write();
 618    file->Close();
 619
 620    delete rl;
 621    return 0;
 622 }