Observables in heavy-ion collisions at CMS
Haidong Liu
2009-10-21
outline
• The CMS detector
• Review of the ‘golden’ observables
• Other interesting observables for me
• LHC schedule (latest version)
CMS detectors
– Silicon pixel detector– Silicon microstrip tracker– Electromagnetic Calorimeter– Hadronic Calorimeter– Superconducting Solenoid– Muon detectors
• Drift Tubes (barrel)• Cathode Strip Chambers (endcaps)• Resistive Plate Chambers (barrel+endcap
s)
– CASTOR Calorimeter (forward)– Zero Degree Calorimeter (forward) (Jet with cone size R=0.5)
Low pT PID spectra for Pb+Pb @ 5.5 TeV
Event plane resolutionb=9fm of Pb+Pb collisions --the expected resolution is 0.37 rad with ECAL
NA49 Phys. Rev. C 68 034903 PHOBOS nucl-ex/0610037PHOBOS Nucl. Phys. A 774 523–26 STAR AIP Conf. Proc. 870 691–4Voloshin S A and Poskanzer A M Phys. Lett. B 474 27–32Kolb P F, Sollfrank J and Heinz U W ,Phys. Rev. C 62 054909Teaney D, Lauret J and Shuryak E V nucl-th/0110037
Φsimu-Φreco
J. Phys. G: Nucl. Part. Phys. 34 (2007) 2307-2455
high pT charged particle spectra
Expected reach (0.5 nb-1): pT~ 300 GeV/c (inclusive hadrons)
Jet
Jet ET reco resolution Jet ET distributions for 1 month data
Expected quarkonia signalsin one month data (di-muon) Assuming no quarkonia suppression
Solid line: Both μ |η|<2.4 dashed line: Both μ |η|<0.8
Acceptance
J. Phys. G: Nucl. Part. Phys. 34 (2007) 2307-2455
Stat. errors of Y’/Y ratios(a
rbitr
ary
)
Curves are calculations for different initial conditions and different assumption of Tdiss
Z0 μμ signal
1 month data: ~11000 (Z μμ)
J. Phys. G: Nucl. Part. Phys. 34 (2007) 2307-2455
Tagged Jet
An ideal way to measure parton energy loss in the medium
Other interesting observables
• Open charm & bottom– DK+π
– DK+μ+νμ (K μ correlations)
– B+J/psi K+ (BR~0.001)– B0J/psi K0 (BR~0.001)– X-section and flow are both very interesting
• Z boson reconstruction– Ze+e- (BR 3.4%)– ZJets
For B and D reconstruction
pion efficiencies in pp and PbPb collisions
Ks in ppPixel+tracker
1. Low pt track efficiency is not bad2. Ks can be reconstructed nicely3. dEdx can help on PID
DK+e+νe (K e correlations at STAR)
3<pT(e)<6 GeV/c 3<pT(e)<6 GeV/c
Φ<36 degree
PYthia simulation at 200 GeV
DK+e+νe (K e correlations at STAR)
Run5 & Run6 pp data
Z boson reconstruction
• Ze+e- (BR 3.4%)– Large energy electrons (>50 GeV) identificatio
n should be easy
• ZJets– Huge background– Depends on the study of the jet reco algorithm
LHC schedule
• Preparing for mid-November start of beam operations– A few weeks for first collisions from then– First 7 TeV collisions in week before Christmas
break
• Initial operations at 7 TeV (3.5+3.5)– “Energy scan” (0.9, 7, 8-10TeV)
• Pb+Pb run still scheduled at the end of p+p run– Now foreseen to start Nov 1 2010
Thank you
CMS detectors
– Silicon pixel detector– Silicon microstrip tracker– Electromagnetic Calorimeter– Hadronic Calorimeter– Superconducting Solenoid– Muon detectors
• Drift Tubes (barrel)• Cathode Strip Chambers (endcaps)• Resistive Plate Chambers (barrel+en
dcaps)
– CASTOR Calorimeter– Zero Degree Calorimeter
pp@14TeV L~1034cm-2s-1 [email protected] L~1027cm-2s-1
(Jet with cone R=0.5)
Photon tagged jets
Isolated photon+
away side jet
CMS NOTE HIN-07-002
Unquenched FF Quenched FF
models used in this analysisPYQUEN: selected QCD channels w/ jet quenchingPYTHIA: selected QCD channels w/o jet quenchingHYDJET: underlying corresponding Pb+Pb events
Ratio of quenchedand unquenched FF
Detailed quantitative studies of medium-induced parton energy-loss possible.