Possibility to calculate the DCA between two ESD track. The V0 and cascade vertexes...
[u/mrichter/AliRoot.git] / 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 }