ITS/AliCascadeComparison.C

   1 /****************************************************************************
   2  *           Very important, delicate and rather obscure macro.             *
   3  *                                                                          *
   4  *               Creates list of "findable" cascades,                       *
   5  *             calculates efficiency, resolutions etc.                      *
   6  *                                                                          *
   7  *  Origin: Christian Kuhn, IReS, Strasbourg, christian.kuhn@ires.in2p3.fr  *
   8  ****************************************************************************/
   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 <TTree.h>
  16   #include <TParticle.h>
  17   #include <TCanvas.h>
  18   #include <TLine.h>
  19   #include <TText.h>
  20   #include <TBenchmark.h>
  21   #include <TStyle.h>
  22   #include <TKey.h>
  23   #include <TROOT.h>
  24
  25   #include "AliStack.h"
  26   #include "AliHeader.h"
  27   #include "AliTrackReference.h"
  28   #include "AliRunLoader.h"
  29   #include "AliRun.h"
  30   #include "AliESD.h"
  31 #else
  32 const Int_t kXiMinus    = 3312;
  33 const Int_t kXiPlusBar  = -3312;
  34 const Int_t kOmegaMinus = 3334;
  35 const Int_t kOmegaPlusBar = -3334;
  36 #endif
  37
  38 Int_t GoodCascades(const Char_t *dir=".");
  39
  40 extern AliRun *gAlice;
  41 extern TBenchmark *gBenchmark;
  42 extern TROOT *gROOT;
  43
  44 static Int_t allgood=0;
  45 static Int_t allfound=0;
  46
  47 Int_t AliCascadeComparison(Int_t code=3312, const Char_t *dir=".") {
  48   //code= 3312; //kXiMinus
  49   //code=-3312; //kXiPlusBar
  50   //code= 3334; //kOmegaMinus
  51   //code=-3334; //kOmegaPlusBar
  52    gBenchmark->Start("AliCascadeComparison");
  53
  54    ::Info("AliCascadeComparison.C","Doing comparison...");
  55
  56    const Double_t cascadeWindow=0.05, cascadeWidth=0.015;
  57    Double_t ptncut=0.12, ptpcut=0.33, kine0cut=0.003;
  58    Double_t ptbcut=0.11, kinecut=0.002;
  59    Double_t cascadeMass=1.32131;
  60    switch (code) {
  61    case kXiMinus:
  62         break;
  63    case kXiPlusBar:
  64         ptncut=0.33; ptpcut=0.12;
  65         break;
  66    case kOmegaMinus:
  67         cascadeMass=1.67245;
  68         kine0cut=0.001;
  69         ptbcut=0.22; kinecut=0.006;
  70         break;
  71    case kOmegaPlusBar:
  72         cascadeMass=1.67245;
  73         kine0cut=0.001;
  74         ptncut=0.33; ptpcut=0.12;
  75         ptbcut=0.22; kinecut=0.006;
  76         break;
  77    default: cerr<<"Invalid PDG code !\n"; return 1;
  78    }
  79
  80
  81    TH1F *hp=(TH1F*)gROOT->FindObject("hp");
  82    if (!hp) hp=new TH1F("hp","Angular Resolution",30,-30.,30.);
  83    hp->SetXTitle("(mrad)"); hp->SetFillColor(2);
  84
  85    TH1F *hl=(TH1F*)gROOT->FindObject("hl");
  86    if (!hl) hl=new TH1F("hl","Lambda Resolution",30,-30,30);
  87    hl->SetXTitle("(mrad)"); hl->SetFillColor(1); hl->SetFillStyle(3013);
  88
  89    TH1F *hpt=(TH1F*)gROOT->FindObject("hpt");
  90    if (!hpt) hpt=new TH1F("hpt","Relative Pt Resolution",30,-10.,10.);
  91    hpt->SetXTitle("(%)"); hpt->SetFillColor(2);
  92
  93    TH1F *hx=(TH1F*)gROOT->FindObject("hx");
  94    if (!hx) hx=new TH1F("hx","Position Resolution (X,Y)",30,-3.,3.);
  95    hx->SetXTitle("(mm)"); hx->SetFillColor(6);
  96
  97    TH1F *hy=(TH1F*)gROOT->FindObject("hy");
  98    if (!hy) hy=new TH1F("hy","Position Resolution (Y)",30,-3.,3.);
  99    hy->SetXTitle("(mm)"); hy->SetFillColor(1); hy->SetFillStyle(3013);
 100
 101    TH1F *hz=(TH1F*)gROOT->FindObject("hz");
 102    if (!hz) hz=new TH1F("hz","Position Resolution (Z)",30,-3.,3.);
 103    hz->SetXTitle("(mm)"); hz->SetFillColor(6);
 104
 105
 106    Double_t pmin=0.2, pmax=4.2; Int_t nchan=20;
 107    TH1F *hgood=(TH1F*)gROOT->FindObject("hgood");
 108    if (!hgood) hgood=new TH1F("hgood","Good Cascades",nchan,pmin,pmax);
 109
 110    TH1F *hfound=(TH1F*)gROOT->FindObject("hfound");
 111    if (!hfound) hfound=new TH1F("hfound","Found Cascades",nchan,pmin,pmax);
 112
 113    TH1F *hfake=(TH1F*)gROOT->FindObject("hfake");
 114    if (!hfake) hfake=new TH1F("hfake","Fake Cascades",nchan,pmin,pmax);
 115
 116    TH1F *hg=(TH1F*)gROOT->FindObject("hg");
 117    if (!hg) hg=new TH1F("hg","Efficiency for Good Cascades",nchan,pmin,pmax);
 118    hg->SetLineColor(4); hg->SetLineWidth(2);
 119
 120    TH1F *hf=(TH1F*)gROOT->FindObject("hf");
 121    if (!hf) hf=new TH1F("hf","Probability of Fake Cascades",nchan,pmin,pmax);
 122    hf->SetFillColor(1); hf->SetFillStyle(3013); hf->SetLineWidth(2);
 123
 124
 125    Double_t mmin=cascadeMass-cascadeWindow, mmax=cascadeMass+cascadeWindow;
 126    TH1F *cs=(TH1F*)gROOT->FindObject("cs");
 127    if (!cs) cs=new TH1F("cs","Cascade Effective Mass",40, mmin, mmax);
 128    cs->SetXTitle("(GeV)"); cs->SetLineColor(4); cs->SetLineWidth(4);
 129
 130    TH1F *csf=(TH1F*)gROOT->FindObject("csf");
 131    if (!csf) csf=new TH1F("csf","Fake Cascade Effective Mass",40, mmin, mmax);
 132    csf->SetXTitle("(GeV)"); csf->SetFillColor(6);
 133
 134
 135    Char_t fname[100];
 136    sprintf(fname,"%s/GoodCascades.root",dir);
 137
 138    TFile *refFile=TFile::Open(fname,"old");
 139    if (!refFile || !refFile->IsOpen()) {
 140    ::Info("AliCascadeComparison.C","Marking good cascades (will take a while)...");
 141      if (GoodCascades(dir)) {
 142         ::Error("AliCascadesComparison.C","Can't generate the reference file !");
 143         return 1;
 144      }
 145    }
 146    refFile=TFile::Open(fname,"old");
 147    if (!refFile || !refFile->IsOpen()) {
 148      ::Error("AliCascadeComparison.C","Can't open the reference file !");
 149      return 1;
 150    }
 151
 152    TTree *csTree=(TTree*)refFile->Get("csTree");
 153    if (!csTree) {
 154      ::Error("AliCascadeComparison.C","Can't get the reference tree !");
 155      return 2;
 156    }
 157    TBranch *pbranch=csTree->GetBranch("positive");
 158    if (!pbranch) {
 159      ::Error("AliCascadeComparison.C","Can't get the positive daughter branch !");
 160      return 3;
 161    }
 162    TClonesArray dummy("AliTrackReference",1000), *prefs=&dummy;
 163    pbranch->SetAddress(&prefs);
 164
 165    TBranch *nbranch=csTree->GetBranch("negative");
 166    if (!nbranch) {
 167      ::Error("AliCascadeComparison.C","Can't get the negative daughter branch !");
 168      return 4;
 169    }
 170    TClonesArray dumm("AliTrackReference",1000), *nrefs=&dumm;
 171    nbranch->SetAddress(&nrefs);
 172
 173    TBranch *bbranch=csTree->GetBranch("bachelor");
 174    if (!nbranch) {
 175      ::Error("AliCascadeComparison.C","Can't get the bachelor branch !");
 176      return 4;
 177    }
 178    TClonesArray dum("AliTrackReference",1000), *brefs=&dum;
 179    bbranch->SetAddress(&brefs);
 180
 181
 182
 183    sprintf(fname,"%s/AliESDs.root",dir);
 184    TFile *ef=TFile::Open(fname);
 185    if ((!ef)||(!ef->IsOpen())) {
 186       sprintf(fname,"%s/AliESDcascade.root",dir);
 187       ef=TFile::Open(fname);
 188       if ((!ef)||(!ef->IsOpen())) {
 189          ::Error("AliCascadeComparison.C","Can't open AliESDcascade.root !");
 190          return 5;
 191       }
 192    }
 193    TKey *key=0;
 194    TIter next(ef->GetListOfKeys());
 195
 196
 197
 198    //******* Loop over events *********
 199    Int_t e=0;
 200    while ((key=(TKey*)next())!=0) {
 201       cout<<endl<<endl<<"********* Processing event number: "<<e<<"*******\n";
 202
 203       AliESD *event=(AliESD*)key->ReadObj();
 204
 205       Int_t nentr=event->GetNumberOfCascades();
 206       allfound+=nentr;
 207
 208
 209       if (csTree->GetEvent(e++)==0) {
 210          cerr<<"No reconstructable cascades !\n";
 211          continue;
 212       }
 213
 214       Int_t ngood=prefs->GetEntriesFast(),ng=0;
 215
 216       Double_t pxg=0.,pyg=0.,pzg=0.,ptg=0.;
 217       Int_t nlab=-1, plab=-1, blab=-1;
 218       Int_t i;
 219       for (i=0; i<nentr; i++) {
 220           AliESDcascade *cascade=event->GetCascade(i);
 221
 222           Int_t nidx=TMath::Abs(cascade->GetNindex());
 223           Int_t pidx=TMath::Abs(cascade->GetPindex());
 224           Int_t bidx=TMath::Abs(cascade->GetBindex());
 225
 226           AliESDtrack *ntrack=event->GetTrack(nidx);
 227           AliESDtrack *ptrack=event->GetTrack(pidx);
 228           AliESDtrack *btrack=event->GetTrack(bidx);
 229
 230           nlab=TMath::Abs(ntrack->GetLabel());
 231           plab=TMath::Abs(ptrack->GetLabel());
 232           blab=TMath::Abs(btrack->GetLabel());
 233
 234           /** Kinematical cuts **/
 235           Double_t pxn,pyn,pzn; cascade->GetNPxPyPz(pxn,pyn,pzn);
 236           Double_t ptn=TMath::Sqrt(pxn*pxn + pyn*pyn);
 237           if (ptn < ptncut) continue;
 238           Double_t pxp,pyp,pzp; cascade->GetPPxPyPz(pxp,pyp,pzp);
 239           Double_t ptp=TMath::Sqrt(pxp*pxp + pyp*pyp);
 240           if (ptp < ptpcut) continue;
 241           Double_t pxb,pyb,pzb; cascade->GetBPxPyPz(pxb,pyb,pzb);
 242           Double_t ptb=TMath::Sqrt(pxb*pxb + pyb*pyb);
 243           if (ptb < ptbcut) continue;
 244           Double_t kine0;
 245           Double_t kine=cascade->ChangeMassHypothesis(kine0,code);
 246           if (TMath::Abs(kine0)>kine0cut) continue;
 247           //if (TMath::Abs(kine)>kinecut) continue;
 248
 249           Double_t mass=cascade->GetEffMass();
 250           cs->Fill(mass);
 251           csf->Fill(mass);
 252
 253           AliTrackReference *nref=0, *pref=0, *bref=0;
 254           Int_t j;
 255           for (j=0; j<ngood; j++) {
 256               bref=(AliTrackReference*)brefs->UncheckedAt(j);
 257               nref=(AliTrackReference*)nrefs->UncheckedAt(j);
 258               pref=(AliTrackReference*)prefs->UncheckedAt(j);
 259               if (bref->Label() == blab)
 260               if (nref->Label() == nlab)
 261               if (pref->Label() == plab) break;
 262           }
 263
 264           if (TMath::Abs(mass-cascadeMass)>cascadeWidth) continue;
 265
 266           Double_t px,py,pz; cascade->GetPxPyPz(px,py,pz);
 267           Double_t pt=TMath::Sqrt(px*px+py*py);
 268
 269           if (j==ngood) {
 270              hfake->Fill(pt);
 271              cout<<"Fake cascade: ("<<nlab<<","<<plab<<","<<blab<<")\n";
 272              continue;
 273           }
 274           csf->Fill(mass,-1);
 275
 276           pxg=bref->Px()+nref->Px()+pref->Px();
 277           pyg=bref->Px()+nref->Py()+pref->Py();
 278           pzg=nref->Pz()+pref->Pz();
 279           ptg=TMath::Sqrt(pxg*pxg+pyg*pyg);
 280           Double_t phig=TMath::ATan2(pyg,pxg), phi=TMath::ATan2(py,px);
 281           Double_t lamg=TMath::ATan2(pzg,ptg), lam=TMath::ATan2(pz,pt);
 282           hp->Fill((phi - phig)*1000.);
 283           hl->Fill((lam - lamg)*1000.);
 284           hpt->Fill((1/pt - 1/ptg)/(1/ptg)*100.);
 285
 286           Double_t x,y,z; cascade->GetXYZ(x,y,z);
 287           hx->Fill((x-nref->X())*10);
 288           hy->Fill((y-nref->Y())*10);
 289           hz->Fill((z-nref->Z())*10);
 290
 291           hfound->Fill(ptg);
 292           nref->SetLabel(-1);
 293
 294       }
 295       for (i=0; i<ngood; i++) {
 296          AliTrackReference *bref=(AliTrackReference*)brefs->UncheckedAt(i);
 297          AliTrackReference *nref=(AliTrackReference*)nrefs->UncheckedAt(i);
 298          AliTrackReference *pref=(AliTrackReference*)prefs->UncheckedAt(i);
 299          Int_t pdg=(Int_t)nref->GetLength();  //this is the cascade's PDG !
 300          if (code!=pdg) continue;
 301          ng++;
 302          pxg=bref->Px()+nref->Px()+pref->Px();
 303          pyg=bref->Px()+nref->Py()+pref->Py();
 304          ptg=TMath::Sqrt(pxg*pxg+pyg*pyg);
 305          hgood->Fill(ptg);
 306          nlab=nref->Label(); plab=pref->Label(); blab=bref->Label();
 307          if (nlab < 0) continue;
 308          cout<<"Cascade ("<<nlab<<','<<plab<<","<<blab<<") has not been found !\n";
 309       }
 310       allgood+=ng;
 311
 312       cout<<"Number of found cascades : "<<nentr<<endl;
 313       cout<<"Number of \"good\" cascades : "<<ng<<endl;
 314
 315       brefs->Clear();
 316       prefs->Clear();
 317       nrefs->Clear();
 318       delete event;
 319
 320    } //**** End of the loop over events
 321
 322    ef->Close();
 323
 324    delete csTree;
 325    refFile->Close();
 326
 327    Stat_t ng=hgood->GetEntries(), nf=hfound->GetEntries();
 328    if (ng!=0) cout<<"Integral efficiency is about "<<nf/ng*100.<<" %\n";
 329    cout<<
 330    "Total number of found cascades: "<<allfound<<" ("<<nf<<" in the peak)\n";
 331    cout<<"Total number of \"good\" cascades: "<<allgood<<endl;
 332
 333
 334    gStyle->SetOptStat(111110);
 335    gStyle->SetOptFit(1);
 336
 337    TCanvas *c1=(TCanvas*)gROOT->FindObject("c1");
 338    if (!c1) {
 339       c1=new TCanvas("c1","",0,0,580,610);
 340       c1->Divide(2,2);
 341    }
 342
 343    Int_t minc=33;
 344
 345    c1->cd(1);
 346    gPad->SetFillColor(42); gPad->SetFrameFillColor(10);
 347    if (hp->GetEntries()<minc) hp->Draw(); else hp->Fit("gaus");
 348    hl->Draw("same"); c1->cd();
 349
 350    c1->cd(2);
 351    gPad->SetFillColor(42); gPad->SetFrameFillColor(10);
 352    if (hpt->GetEntries()<minc) hpt->Draw(); else hpt->Fit("gaus");
 353    c1->cd();
 354
 355    c1->cd(3);
 356    gPad->SetFillColor(42); gPad->SetFrameFillColor(10);
 357    if (hx->GetEntries()<minc) hx->Draw(); else hx->Fit("gaus");
 358    hy->Draw("same"); c1->cd();
 359
 360    c1->cd(4);
 361    gPad->SetFillColor(42); gPad->SetFrameFillColor(10);
 362    if (hz->GetEntries()<minc) hz->Draw(); else hz->Fit("gaus");
 363
 364    c1->Update();
 365
 366    TCanvas *c2=(TCanvas*)gROOT->FindObject("c2");
 367    if (!c2) {
 368       c2=new TCanvas("c2","",600,0,580,610);
 369       c2->Divide(1,2);
 370    }
 371
 372    c2->cd(1);
 373    gPad->SetFillColor(42); gPad->SetFrameFillColor(10);
 374    hfound->Sumw2(); hgood->Sumw2(); hfake->Sumw2();
 375    hg->Divide(hfound,hgood,1,1.,"b");
 376    hf->Divide(hfake,hgood,1,1.,"b");
 377    hg->SetMaximum(1.4);
 378    hg->SetYTitle("Cascade reconstruction efficiency");
 379    hg->SetXTitle("Pt (GeV/c)");
 380    hg->Draw();
 381
 382    TLine *line1 = new TLine(pmin,1.0,pmax,1.0); line1->SetLineStyle(4);
 383    line1->Draw("same");
 384    TLine *line2 = new TLine(pmin,0.9,pmax,0.9); line2->SetLineStyle(4);
 385    line2->Draw("same");
 386
 387    hf->SetFillColor(1);
 388    hf->SetFillStyle(3013);
 389    hf->SetLineColor(2);
 390    hf->SetLineWidth(2);
 391    hf->Draw("histsame");
 392    TText *text = new TText(0.461176,0.248448,"Fake cascades");
 393    text->SetTextSize(0.05);
 394    text->Draw();
 395    text = new TText(0.453919,1.11408,"Good cascades");
 396    text->SetTextSize(0.05);
 397    text->Draw();
 398
 399
 400    c2->cd(2);
 401    gPad->SetFillColor(42); gPad->SetFrameFillColor(10);
 402    if (cs->GetEntries()<minc) cs->Draw();
 403    else cs->Fit("gaus","","",cascadeMass-cascadeWidth,cascadeMass+cascadeWidth);
 404    csf->Draw("same");
 405    Double_t max=cs->GetMaximum();
 406    TLine *line3 =
 407       new TLine(cascadeMass-cascadeWidth,0.,cascadeMass-cascadeWidth,max);
 408    line3->Draw("same");
 409    TLine *line4 =
 410       new TLine(cascadeMass+cascadeWidth,0.,cascadeMass+cascadeWidth,max);
 411    line4->Draw("same");
 412
 413    c2->Update();
 414
 415    TFile fc("AliCascadeComparison.root","RECREATE");
 416    c1->Write();
 417    c2->Write();
 418    fc.Close();
 419
 420    gBenchmark->Stop("AliCascadeComparison");
 421    gBenchmark->Show("AliCascadeComparison");
 422
 423
 424    return 0;
 425 }
 426
 427
 428 Int_t GoodCascades(const Char_t *dir) {
 429    if (gAlice) {
 430       delete gAlice->GetRunLoader();
 431       delete gAlice;
 432       gAlice=0;
 433    }
 434
 435    Char_t fname[100];
 436    sprintf(fname,"%s/galice.root",dir);
 437
 438    AliRunLoader *rl = AliRunLoader::Open(fname,"COMPARISON");
 439    if (!rl) {
 440        ::Error("GoodCascades","Can't start session !");
 441        return 1;
 442    }
 443
 444    rl->LoadgAlice();
 445    rl->LoadHeader();
 446    rl->LoadKinematics();
 447
 448
 449    Int_t nev=rl->GetNumberOfEvents();
 450    ::Info("GoodCascades","Number of events : %d\n",nev);
 451
 452
 453    sprintf(fname,"%s/GoodTracksITS.root",dir);
 454    TFile *itsFile=TFile::Open(fname);
 455    if ((!itsFile)||(!itsFile->IsOpen())) {
 456        ::Error("GoodCAscades","Can't open the GoodTracksITS.root !");
 457        delete rl;
 458        return 5;
 459    }
 460    TClonesArray dm("AliTrackReference",1000), *itsRefs=&dm;
 461    TTree *itsTree=(TTree*)itsFile->Get("itsTree");
 462    if (!itsTree) {
 463        ::Error("GoodCascades","Can't get the ITS reference tree !");
 464        delete rl;
 465        return 6;
 466    }
 467    TBranch *itsBranch=itsTree->GetBranch("ITS");
 468    if (!itsBranch) {
 469       ::Error("GoodCascades","Can't get the ITS reference branch !");
 470       delete rl;
 471       return 7;
 472    }
 473    itsBranch->SetAddress(&itsRefs);
 474
 475
 476    sprintf(fname,"%s/GoodCascades.root",dir);
 477    TFile *csFile=TFile::Open(fname,"recreate");
 478    TClonesArray dummy("AliTrackReference",1000), *nrefs=&dummy;
 479    TClonesArray dumm("AliTrackReference",1000), *prefs=&dumm;
 480    TClonesArray dum("AliTrackReference",1000), *brefs=&dum;
 481    TTree csTree("csTree","Tree with info about the reconstructable cascades");
 482    csTree.Branch("negative",&nrefs);
 483    csTree.Branch("positive",&prefs);
 484    csTree.Branch("bachelor",&brefs);
 485
 486
 487    // *** Get information about the cuts ***
 488    Double_t r2min=0.9*0.9;
 489    Double_t r2max=2.9*2.9;
 490
 491
 492    //********  Loop over generated events
 493    for (Int_t e=0; e<nev; e++) {
 494       rl->GetEvent(e);  csFile->cd();
 495
 496       Int_t np = rl->GetHeader()->GetNtrack();
 497       cout<<"Event "<<e<<" Number of particles: "<<np<<endl;
 498
 499       itsTree->GetEvent(e);
 500       Int_t nk=itsRefs->GetEntriesFast();
 501
 502       AliStack *stack=rl->Stack();
 503
 504       AliTrackReference *nref=0, *pref=0, *bref=0;
 505
 506       Int_t nc=0;
 507       while (np--) {
 508          //cerr<<np<<'\r';
 509          TParticle *cp=stack->Particle(np);
 510
 511          // *** only these cascades are "good" ***
 512          Int_t code=cp->GetPdgCode();
 513          if (code!=kXiMinus)    if (code!=kXiPlusBar)
 514          if (code!=kOmegaMinus) if (code!=kOmegaPlusBar) continue;
 515
 516          // *** daughter tracks must be "good" ***
 517          Int_t v0lab=cp->GetFirstDaughter(), blab=cp->GetLastDaughter();
 518          if (v0lab==blab) continue;
 519          if (v0lab<0) continue;
 520          if (blab<0) continue;
 521
 522          TParticle *p0=stack->Particle(v0lab);
 523          TParticle *bp=stack->Particle(blab);
 524          Int_t i;
 525          if ((p0->GetPdgCode()!=kLambda0) && (p0->GetPdgCode()!=kLambda0Bar)) {
 526             TParticle *p=p0; p0=bp; bp=p;
 527             i=v0lab; v0lab=blab; blab=i;
 528             if ((p0->GetPdgCode()!=kLambda0)&&(p0->GetPdgCode()!=kLambda0Bar))
 529                                                                    continue;
 530          }
 531
 532          // ** is the bachelor "good" ? **
 533          for (i=0; i<nk; i++) {
 534              bref=(AliTrackReference*)itsRefs->UncheckedAt(i);
 535              if (bref->Label()==blab) break;
 536          }
 537          if (i==nk) continue;
 538
 539          // ** is the V0 "good" ? **
 540          Int_t plab=p0->GetFirstDaughter(), nlab=p0->GetLastDaughter();
 541          if (nlab==plab) continue;
 542          if (nlab<0) continue;
 543          if (plab<0) continue;
 544          if (stack->Particle(plab)->GetPDG()->Charge() < 0.) {
 545             i=plab; plab=nlab; nlab=i;
 546          }
 547          for (i=0; i<nk; i++) {
 548              nref=(AliTrackReference*)itsRefs->UncheckedAt(i);
 549              if (nref->Label()==nlab) break;
 550          }
 551          if (i==nk) continue;
 552          for (i=0; i<nk; i++) {
 553              pref=(AliTrackReference*)itsRefs->UncheckedAt(i);
 554              if (pref->Label()==plab) break;
 555          }
 556          if (i==nk) continue;
 557
 558
 559          // *** fiducial volume ***
 560          Double_t x=bp->Vx(), y=bp->Vy(), r2=x*x+y*y; //bachelor
 561          if (r2<r2min) continue;
 562          if (r2>r2max) continue;
 563          TParticle *pp=stack->Particle(plab);
 564          x=pp->Vx(); y=pp->Vy(); r2=x*x+y*y;          //V0
 565          if (r2<r2min) continue;
 566          if (r2>r2max) continue;
 567
 568          Int_t pdg=cp->GetPdgCode();
 569          nref->SetLength(pdg);  //This will the cascade's PDG !
 570
 571          new((*nrefs)[nc]) AliTrackReference(*nref);
 572          new((*prefs)[nc]) AliTrackReference(*pref);
 573          new((*brefs)[nc]) AliTrackReference(*bref);
 574
 575          nc++;
 576       }
 577       itsRefs->Clear();
 578
 579       csTree.Fill();
 580       nrefs->Clear(); prefs->Clear(); brefs->Clear();
 581
 582    } //**** end of the loop over generated events
 583
 584    csTree.Write();
 585    csFile->Close();
 586
 587    delete itsTree;
 588    itsFile->Close();
 589
 590    delete rl;
 591    return 0;
 592 }