Centrality Measurement in HF for Heavy Ion Collisions

The goal of this study is to show how the measurable variables change with impact parameter (b) in HF rapidity region. CMSSW_1_5_1 was used for this study. The events that were used can be found in "dcache:/pnfs/cmsaf.mit.edu/hibat/cms/users/yetkin/reco/hf/" folder. My presentation can also be found http://indico.cern.ch/conferenceDisplay.py?confId=15751

Total Energy and Transverse Energy Flow in HF Rapidity Region

• Particles energy flow in HF region for different impact parameters
  

• Particles transverse energy flow in HF region for different impact parameters
  

• Ratio between particles energy and transverse energy in HF region for different impact parameters
  

• Particles energy flow correlation between HF1 & HF2

• Particles transverse energy flow correlation between HF1 & HF2

For these histograms, my code is:

/////// Energy Calculation /////////

Handle<CandidateCollection> genParticles;
        iEvent.getByLabel("genParticleCandidates", genParticles);
        for(size_t ipar = 0; ipar < genParticles->size(); ++ ipar) {
           const Candidate & p = (*genParticles)[ ipar ];

        eta = p.eta();
        energy = p.energy();
        et = p.et();

     if(p.numberOfDaughters() == 0){
        
    if((eta*eta<25.) && (eta*eta>9.)){

        eFwd = eFwd + p.energy();
        etFwd = etFwd + p.et();
        r = eFwd / etFwd; }

///////////// HF1 & HF2 //////////////////

        if(eta<5. && eta>3.){
                   eHF1 = eHF1 + p.energy();
                   etHF1 = etHF1 + p.et(); }

        if(eta<-3. && eta>-5.){
                   eHF2 = eHF2 + p.energy();
                   etHF2 = etHF2 + p.et(); }
                                                         }  

Particles energy flow in different rapidity regions can be seen here

Energy Deposition in HF

• Energy deposition in HF for different impact parameters
  

• Correlation between particles energy flow in HF region & energy deposition in HF
  

• Energy deposition distribution in HF for all events
  

For energy deposition in HF, my code is:

 Handle<HFRecHitCollection> hits;
           iEvent.getByLabel("hfreco",hits);
        for(size_t ihit = 0; ihit<hits->size(); ++ ihit){
           const HFRecHit & rechit = (*hits)[ ihit ];
        eHF = eHF + rechit.energy();
        }

Distribution of Impact Parameter (b) at Fixed HF Energy Deposition

• Impact parameter distribution at (103,5>E>100) TeV
  

• Impact parameter distribution at (73,5>E>70) TeV
  

• Impact parameter distribution at (33,5>E>30) TeV
  

• Impact parameter distribution at (3,5>E>0) TeV
  

For this study, my code is:

Handle<HFRecHitCollection> hits;
           iEvent.getByLabel("hfreco",hits);
        for(size_t ihit = 0; ihit<hits->size(); ++ ihit){
           const HFRecHit & rechit = (*hits)[ ihit ];
        eHF = eHF + rechit.energy();
        }

        if(eHF<=103500. && eHF>=100000.){
        eHistDistb->Fill(b); }

        if(eHF<=73500. && eHF>=70000.){
        eHistDistb1->Fill(b); }

        if(eHF<=33500. && eHF>=30000.){
        eHistDistb2->Fill(b); }

        if(eHF<=3500. && eHF>=0.){
        eHistDistb3->Fill(b);}   

• QM08-fulltext.doc: QM08-fulltext.doc