STEER/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 <TFile.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    AliESD* event = new AliESD;
 194    TTree* esdTree = (TTree*) ef->Get("esdTree");
 195    if (!esdTree) {
 196       ::Error("AliCascadeComparison.C", "no ESD tree found");
 197       return 6;
 198    }
 199    esdTree->SetBranchAddress("ESD", &event);
 200
 201
 202    //******* Loop over events *********
 203    Int_t e=0;
 204    while (esdTree->GetEvent(e)) {
 205       cout<<endl<<endl<<"********* Processing event number: "<<e<<"*******\n";
 206
 207       Int_t nentr=event->GetNumberOfCascades();
 208       allfound+=nentr;
 209
 210
 211       if (csTree->GetEvent(e++)==0) {
 212          cerr<<"No reconstructable cascades !\n";
 213          continue;
 214       }
 215
 216       Int_t ngood=prefs->GetEntriesFast(),ng=0;
 217
 218       Double_t pxg=0.,pyg=0.,pzg=0.,ptg=0.;
 219       Int_t nlab=-1, plab=-1, blab=-1;
 220       Int_t i;
 221       for (i=0; i<nentr; i++) {
 222           AliESDcascade *cascade=event->GetCascade(i);
 223
 224           Int_t nidx=TMath::Abs(cascade->GetNindex());
 225           Int_t pidx=TMath::Abs(cascade->GetPindex());
 226           Int_t bidx=TMath::Abs(cascade->GetBindex());
 227
 228           AliESDtrack *ntrack=event->GetTrack(nidx);
 229           AliESDtrack *ptrack=event->GetTrack(pidx);
 230           AliESDtrack *btrack=event->GetTrack(bidx);
 231
 232           nlab=TMath::Abs(ntrack->GetLabel());
 233           plab=TMath::Abs(ptrack->GetLabel());
 234           blab=TMath::Abs(btrack->GetLabel());
 235
 236           /** Kinematical cuts **/
 237           Double_t pxn,pyn,pzn; cascade->GetNPxPyPz(pxn,pyn,pzn);
 238           Double_t ptn=TMath::Sqrt(pxn*pxn + pyn*pyn);
 239           if (ptn < ptncut) continue;
 240           Double_t pxp,pyp,pzp; cascade->GetPPxPyPz(pxp,pyp,pzp);
 241           Double_t ptp=TMath::Sqrt(pxp*pxp + pyp*pyp);
 242           if (ptp < ptpcut) continue;
 243           Double_t pxb,pyb,pzb; cascade->GetBPxPyPz(pxb,pyb,pzb);
 244           Double_t ptb=TMath::Sqrt(pxb*pxb + pyb*pyb);
 245           if (ptb < ptbcut) continue;
 246           Double_t kine0;
 247           Double_t kine=cascade->ChangeMassHypothesis(kine0,code);
 248           if (TMath::Abs(kine0)>kine0cut) continue;
 249           //if (TMath::Abs(kine)>kinecut) continue;
 250
 251           Double_t mass=cascade->GetEffMass();
 252           cs->Fill(mass);
 253           csf->Fill(mass);
 254
 255           AliTrackReference *nref=0, *pref=0, *bref=0;
 256           Int_t j;
 257           for (j=0; j<ngood; j++) {
 258               bref=(AliTrackReference*)brefs->UncheckedAt(j);
 259               nref=(AliTrackReference*)nrefs->UncheckedAt(j);
 260               pref=(AliTrackReference*)prefs->UncheckedAt(j);
 261               if (bref->Label() == blab)
 262               if (nref->Label() == nlab)
 263               if (pref->Label() == plab) break;
 264           }
 265
 266           if (TMath::Abs(mass-cascadeMass)>cascadeWidth) continue;
 267
 268           Double_t px,py,pz; cascade->GetPxPyPz(px,py,pz);
 269           Double_t pt=TMath::Sqrt(px*px+py*py);
 270
 271           if (j==ngood) {
 272              hfake->Fill(pt);
 273              cout<<"Fake cascade: ("<<nlab<<","<<plab<<","<<blab<<")\n";
 274              continue;
 275           }
 276           csf->Fill(mass,-1);
 277
 278           pxg=bref->Px()+nref->Px()+pref->Px();
 279           pyg=bref->Px()+nref->Py()+pref->Py();
 280           pzg=nref->Pz()+pref->Pz();
 281           ptg=TMath::Sqrt(pxg*pxg+pyg*pyg);
 282           Double_t phig=TMath::ATan2(pyg,pxg), phi=TMath::ATan2(py,px);
 283           Double_t lamg=TMath::ATan2(pzg,ptg), lam=TMath::ATan2(pz,pt);
 284           hp->Fill((phi - phig)*1000.);
 285           hl->Fill((lam - lamg)*1000.);
 286           hpt->Fill((1/pt - 1/ptg)/(1/ptg)*100.);
 287
 288           Double_t x,y,z; cascade->GetXYZ(x,y,z);
 289           hx->Fill((x-nref->X())*10);
 290           hy->Fill((y-nref->Y())*10);
 291           hz->Fill((z-nref->Z())*10);
 292
 293           hfound->Fill(ptg);
 294           nref->SetLabel(-1);
 295
 296       }
 297       for (i=0; i<ngood; i++) {
 298          AliTrackReference *bref=(AliTrackReference*)brefs->UncheckedAt(i);
 299          AliTrackReference *nref=(AliTrackReference*)nrefs->UncheckedAt(i);
 300          AliTrackReference *pref=(AliTrackReference*)prefs->UncheckedAt(i);
 301          Int_t pdg=(Int_t)nref->GetLength();  //this is the cascade's PDG !
 302          if (code!=pdg) continue;
 303          ng++;
 304          pxg=bref->Px()+nref->Px()+pref->Px();
 305          pyg=bref->Px()+nref->Py()+pref->Py();
 306          ptg=TMath::Sqrt(pxg*pxg+pyg*pyg);
 307          hgood->Fill(ptg);
 308          nlab=nref->Label(); plab=pref->Label(); blab=bref->Label();
 309          if (nlab < 0) continue;
 310          cout<<"Cascade ("<<nlab<<','<<plab<<","<<blab<<") has not been found !\n";
 311       }
 312       allgood+=ng;
 313
 314       cout<<"Number of found cascades : "<<nentr<<endl;
 315       cout<<"Number of \"good\" cascades : "<<ng<<endl;
 316
 317       brefs->Clear();
 318       prefs->Clear();
 319       nrefs->Clear();
 320
 321    } //**** End of the loop over events
 322
 323    delete event;
 324    ef->Close();
 325
 326    delete csTree;
 327    refFile->Close();
 328
 329    Stat_t ng=hgood->GetEntries(), nf=hfound->GetEntries();
 330    if (ng!=0) cout<<"Integral efficiency is about "<<nf/ng*100.<<" %\n";
 331    cout<<
 332    "Total number of found cascades: "<<allfound<<" ("<<nf<<" in the peak)\n";
 333    cout<<"Total number of \"good\" cascades: "<<allgood<<endl;
 334
 335
 336    gStyle->SetOptStat(111110);
 337    gStyle->SetOptFit(1);
 338
 339    TCanvas *c1=(TCanvas*)gROOT->FindObject("c1");
 340    if (!c1) {
 341       c1=new TCanvas("c1","",0,0,580,610);
 342       c1->Divide(2,2);
 343    }
 344
 345    Int_t minc=33;
 346
 347    c1->cd(1);
 348    gPad->SetFillColor(42); gPad->SetFrameFillColor(10);
 349    if (hp->GetEntries()<minc) hp->Draw(); else hp->Fit("gaus");
 350    hl->Draw("same"); c1->cd();
 351
 352    c1->cd(2);
 353    gPad->SetFillColor(42); gPad->SetFrameFillColor(10);
 354    if (hpt->GetEntries()<minc) hpt->Draw(); else hpt->Fit("gaus");
 355    c1->cd();
 356
 357    c1->cd(3);
 358    gPad->SetFillColor(42); gPad->SetFrameFillColor(10);
 359    if (hx->GetEntries()<minc) hx->Draw(); else hx->Fit("gaus");
 360    hy->Draw("same"); c1->cd();
 361
 362    c1->cd(4);
 363    gPad->SetFillColor(42); gPad->SetFrameFillColor(10);
 364    if (hz->GetEntries()<minc) hz->Draw(); else hz->Fit("gaus");
 365
 366    c1->Update();
 367
 368    TCanvas *c2=(TCanvas*)gROOT->FindObject("c2");
 369    if (!c2) {
 370       c2=new TCanvas("c2","",600,0,580,610);
 371       c2->Divide(1,2);
 372    }
 373
 374    c2->cd(1);
 375    gPad->SetFillColor(42); gPad->SetFrameFillColor(10);
 376    hfound->Sumw2(); hgood->Sumw2(); hfake->Sumw2();
 377    hg->Divide(hfound,hgood,1,1.,"b");
 378    hf->Divide(hfake,hgood,1,1.,"b");
 379    hg->SetMaximum(1.4);
 380    hg->SetYTitle("Cascade reconstruction efficiency");
 381    hg->SetXTitle("Pt (GeV/c)");
 382    hg->Draw();
 383
 384    TLine *line1 = new TLine(pmin,1.0,pmax,1.0); line1->SetLineStyle(4);
 385    line1->Draw("same");
 386    TLine *line2 = new TLine(pmin,0.9,pmax,0.9); line2->SetLineStyle(4);
 387    line2->Draw("same");
 388
 389    hf->SetFillColor(1);
 390    hf->SetFillStyle(3013);
 391    hf->SetLineColor(2);
 392    hf->SetLineWidth(2);
 393    hf->Draw("histsame");
 394    TText *text = new TText(0.461176,0.248448,"Fake cascades");
 395    text->SetTextSize(0.05);
 396    text->Draw();
 397    text = new TText(0.453919,1.11408,"Good cascades");
 398    text->SetTextSize(0.05);
 399    text->Draw();
 400
 401
 402    c2->cd(2);
 403    gPad->SetFillColor(42); gPad->SetFrameFillColor(10);
 404    if (cs->GetEntries()<minc) cs->Draw();
 405    else cs->Fit("gaus","","",cascadeMass-cascadeWidth,cascadeMass+cascadeWidth);
 406    csf->Draw("same");
 407    Double_t max=cs->GetMaximum();
 408    TLine *line3 =
 409       new TLine(cascadeMass-cascadeWidth,0.,cascadeMass-cascadeWidth,max);
 410    line3->Draw("same");
 411    TLine *line4 =
 412       new TLine(cascadeMass+cascadeWidth,0.,cascadeMass+cascadeWidth,max);
 413    line4->Draw("same");
 414
 415    c2->Update();
 416
 417    TFile fc("AliCascadeComparison.root","RECREATE");
 418    c1->Write();
 419    c2->Write();
 420    fc.Close();
 421
 422    gBenchmark->Stop("AliCascadeComparison");
 423    gBenchmark->Show("AliCascadeComparison");
 424
 425
 426    return 0;
 427 }
 428
 429
 430 Int_t GoodCascades(const Char_t *dir) {
 431    if (gAlice) {
 432       delete gAlice->GetRunLoader();
 433       delete gAlice;
 434       gAlice=0;
 435    }
 436
 437    Char_t fname[100];
 438    sprintf(fname,"%s/galice.root",dir);
 439
 440    AliRunLoader *rl = AliRunLoader::Open(fname,"COMPARISON");
 441    if (!rl) {
 442        ::Error("GoodCascades","Can't start session !");
 443        return 1;
 444    }
 445
 446    rl->LoadgAlice();
 447    rl->LoadHeader();
 448    rl->LoadKinematics();
 449
 450
 451    Int_t nev=rl->GetNumberOfEvents();
 452    ::Info("GoodCascades","Number of events : %d\n",nev);
 453
 454
 455    sprintf(fname,"%s/GoodTracksITS.root",dir);
 456    TFile *itsFile=TFile::Open(fname);
 457    if ((!itsFile)||(!itsFile->IsOpen())) {
 458        ::Error("GoodCAscades","Can't open the GoodTracksITS.root !");
 459        delete rl;
 460        return 5;
 461    }
 462    TClonesArray dm("AliTrackReference",1000), *itsRefs=&dm;
 463    TTree *itsTree=(TTree*)itsFile->Get("itsTree");
 464    if (!itsTree) {
 465        ::Error("GoodCascades","Can't get the ITS reference tree !");
 466        delete rl;
 467        return 6;
 468    }
 469    TBranch *itsBranch=itsTree->GetBranch("ITS");
 470    if (!itsBranch) {
 471       ::Error("GoodCascades","Can't get the ITS reference branch !");
 472       delete rl;
 473       return 7;
 474    }
 475    itsBranch->SetAddress(&itsRefs);
 476
 477
 478    sprintf(fname,"%s/GoodCascades.root",dir);
 479    TFile *csFile=TFile::Open(fname,"recreate");
 480    TClonesArray dummy("AliTrackReference",1000), *nrefs=&dummy;
 481    TClonesArray dumm("AliTrackReference",1000), *prefs=&dumm;
 482    TClonesArray dum("AliTrackReference",1000), *brefs=&dum;
 483    TTree csTree("csTree","Tree with info about the reconstructable cascades");
 484    csTree.Branch("negative",&nrefs);
 485    csTree.Branch("positive",&prefs);
 486    csTree.Branch("bachelor",&brefs);
 487
 488
 489    // *** Get information about the cuts ***
 490    Double_t r2min=0.9*0.9;
 491    Double_t r2max=2.9*2.9;
 492
 493
 494    //********  Loop over generated events
 495    for (Int_t e=0; e<nev; e++) {
 496       rl->GetEvent(e);  csFile->cd();
 497
 498       Int_t np = rl->GetHeader()->GetNtrack();
 499       cout<<"Event "<<e<<" Number of particles: "<<np<<endl;
 500
 501       itsTree->GetEvent(e);
 502       Int_t nk=itsRefs->GetEntriesFast();
 503
 504       AliStack *stack=rl->Stack();
 505
 506       AliTrackReference *nref=0, *pref=0, *bref=0;
 507
 508       Int_t nc=0;
 509       while (np--) {
 510          //cerr<<np<<'\r';
 511          TParticle *cp=stack->Particle(np);
 512
 513          // *** only these cascades are "good" ***
 514          Int_t code=cp->GetPdgCode();
 515          if (code!=kXiMinus)    if (code!=kXiPlusBar)
 516          if (code!=kOmegaMinus) if (code!=kOmegaPlusBar) continue;
 517
 518          // *** daughter tracks must be "good" ***
 519          Int_t v0lab=cp->GetFirstDaughter(), blab=cp->GetLastDaughter();
 520          if (v0lab==blab) continue;
 521          if (v0lab<0) continue;
 522          if (blab<0) continue;
 523
 524          TParticle *p0=stack->Particle(v0lab);
 525          TParticle *bp=stack->Particle(blab);
 526          Int_t i;
 527          if ((p0->GetPdgCode()!=kLambda0) && (p0->GetPdgCode()!=kLambda0Bar)) {
 528             TParticle *p=p0; p0=bp; bp=p;
 529             i=v0lab; v0lab=blab; blab=i;
 530             if ((p0->GetPdgCode()!=kLambda0)&&(p0->GetPdgCode()!=kLambda0Bar))
 531                                                                    continue;
 532          }
 533
 534          // ** is the bachelor "good" ? **
 535          for (i=0; i<nk; i++) {
 536              bref=(AliTrackReference*)itsRefs->UncheckedAt(i);
 537              if (bref->Label()==blab) break;
 538          }
 539          if (i==nk) continue;
 540
 541          // ** is the V0 "good" ? **
 542          Int_t plab=p0->GetFirstDaughter(), nlab=p0->GetLastDaughter();
 543          if (nlab==plab) continue;
 544          if (nlab<0) continue;
 545          if (plab<0) continue;
 546          if (stack->Particle(plab)->GetPDG()->Charge() < 0.) {
 547             i=plab; plab=nlab; nlab=i;
 548          }
 549          for (i=0; i<nk; i++) {
 550              nref=(AliTrackReference*)itsRefs->UncheckedAt(i);
 551              if (nref->Label()==nlab) break;
 552          }
 553          if (i==nk) continue;
 554          for (i=0; i<nk; i++) {
 555              pref=(AliTrackReference*)itsRefs->UncheckedAt(i);
 556              if (pref->Label()==plab) break;
 557          }
 558          if (i==nk) continue;
 559
 560
 561          // *** fiducial volume ***
 562          Double_t x=bp->Vx(), y=bp->Vy(), r2=x*x+y*y; //bachelor
 563          if (r2<r2min) continue;
 564          if (r2>r2max) continue;
 565          TParticle *pp=stack->Particle(plab);
 566          x=pp->Vx(); y=pp->Vy(); r2=x*x+y*y;          //V0
 567          if (r2<r2min) continue;
 568          if (r2>r2max) continue;
 569
 570          Int_t pdg=cp->GetPdgCode();
 571          nref->SetLength(pdg);  //This will the cascade's PDG !
 572
 573          new((*nrefs)[nc]) AliTrackReference(*nref);
 574          new((*prefs)[nc]) AliTrackReference(*pref);
 575          new((*brefs)[nc]) AliTrackReference(*bref);
 576
 577          nc++;
 578       }
 579       itsRefs->Clear();
 580
 581       csTree.Fill();
 582       nrefs->Clear(); prefs->Clear(); brefs->Clear();
 583
 584    } //**** end of the loop over generated events
 585
 586    csTree.Write();
 587    csFile->Close();
 588
 589    delete itsTree;
 590    itsFile->Close();
 591
 592    delete rl;
 593    return 0;
 594 }