### 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);}
```

Topic attachments
I Attachment History Action Size Date Who Comment
gif Fwd_HF.gif r1 manage 16.3 K 2007-09-07 - 10:18 SertacOzturk Correlation Between Energy Flow & Energy Deposition in HF
gif HF_energy_deposition.gif r1 manage 14.4 K 2007-09-07 - 10:16 SertacOzturk Energy Deposition in HF
gif HF_energy_dist.gif r1 manage 13.8 K 2007-09-07 - 10:19 SertacOzturk Energy Deposition in HF for All Events
gif HF_particles_energy.gif r1 manage 15.8 K 2007-09-06 - 13:05 SertacOzturk Particles Energy Flow
gif HF_particles_trvs_energy.gif r1 manage 16.0 K 2007-09-06 - 13:11 SertacOzturk Particles Transverse Energy Flow
doc QM08-fulltext.doc r1 manage 2809.5 K 2007-11-23 - 09:46 SertacOzturk
gif dist_b1.gif r1 manage 12.1 K 2007-09-07 - 13:20 SertacOzturk b distribution (103,5>E>100) TeV
gif dist_b2.gif r1 manage 12.3 K 2007-09-07 - 13:21 SertacOzturk b distribution (73,5>E>70) TeV
gif dist_b3.gif r1 manage 12.3 K 2007-09-07 - 13:21 SertacOzturk b distribution (33,5>E>30) TeV
gif dist_b4.gif r1 manage 12.9 K 2007-09-07 - 13:22 SertacOzturk b distribution (3,5>E>0) TeV
gif eHF1_eHF2.gif r1 manage 17.6 K 2007-09-07 - 09:40 SertacOzturk Energy Flow Correlation Between HF1 & HF2
gif etHF1_etHF2.gif r1 manage 17.3 K 2007-09-07 - 09:41 SertacOzturk Transverse Energy Flow Correlation Between HF1 & HF2
gif ratio_EEt.gif r1 manage 15.3 K 2007-09-06 - 13:35 SertacOzturk Ratio Between Energy and Transverse Energy
Topic revision: r7 - 2007-11-23 - SertacOzturk

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