1 / 14

Heavy Ion Physics with the CMS Experiment at the LHC

Heavy Ion Physics with the CMS Experiment at the LHC. G á bor Veres Eötvös Loránd University, Budapest, Hungary Massachusetts Institute of Technology, Cambridge, USA for the CMS Collaboration. Strangeness in Quark Matter ’06 UCLA, California, March 26, 2006.

scarlet-clemons
Download Presentation

Heavy Ion Physics with the CMS Experiment at the LHC

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Heavy Ion Physics with the CMS Experiment at the LHC Gábor Veres Eötvös Loránd University, Budapest, Hungary Massachusetts Institute of Technology, Cambridge, USA for the CMS Collaboration Strangeness in Quark Matter ’06 UCLA, California, March 26, 2006 CMS HI groups: Adana, Athens, Basel, Budapest, CERN, Demokritos, Dubna, Ioannina, Kiev, Krakow, Los Alamos, Lyon, MIT, Moscow, Mumbai, New Zealand, Protvino, PSI, Rice, Sofia, Strasbourg, U Kansas, Tbilisi, UC Davis, UC Riverside, UI Chicago, U Iowa, Yerevan, Warsaw, Zagreb Strangeness in Quark Matter ‘06, UCLA, March 26, 2006

  2. Physics opportunities at the LHC • LHC: a large increase in collision energy compared to existing accelerators: • Extended kinematical reach (y, pT) for p+p, p+A, A+A collisions • New properties of initial state, saturation even at mid-rapidity • A hotter and longer lived partonic phase • Increased cross sections of hard probes, heavy quarks • Last but not least: unknown territory/surprises? • New energy regime will open a new window on hot and dense matter physics: another large energy jump! Strangeness in Quark Matter ‘06, UCLA, March 26, 2006

  3. LHC RHIC  LHC RHIC J/ψ Heavy Ion Physics Topics at the LHC • High pT: modification by the medium • Copious production of high pT particles • Large jet production cross section • Different “melting” for the  family members, depending on binding energy • Large production cross section for the J/ψ and family • Correlations, scattering in medium • jets clearly identifiable, for the first time in heavy ion collisions Strangeness in Quark Matter ‘06, UCLA, March 26, 2006

  4. CMS, as a heavy ion experiment • Calorimeters: high resolution and segmentation • Hermetic coverage up to |h|<5 • (|h|<7 with the proposed CASTOR) • Zero Degree Calorimeter (approved) • Muon tracking: m from Z0, J/, • Wide rapidity coverage: |h|<2.4 • σm 50 MeV at the  mass in the barrel • Silicon Tracker • Good efficiency and purity for pT>1 GeV • Pixel occupancy: <2% at dNch/d  3500 • Dp/p  2% for pT<70 GeV CASTOR (5.32 < η < 6.86) • DAQ and Trigger • High rate capability for A+A, p+A, p+p • High Level Trigger: real time HI event reconstruction ZDC (z = 140 m) Functional at the highest expected multiplicities: studied in detail at dNch/dh3000-5000 and cross-checked at 7000-8000 Strangeness in Quark Matter ‘06, UCLA, March 26, 2006

  5. Lvl-1 HLT Data Acquisition and Trigger • Level 1 hardware trigger • Muon track segments • Calorimetric towers • No tracker data • Output rate (Pb+Pb): 1-2 kHz comparable to collision rate • High level trigger • Full event information available • Every event accepted by L1 sent to an online farm of 2000 PCs • Output rate (Pb+Pb): 40 Hz • Trigger algorithm: similar to offline reconstruction switch - Every event must pass the whole chain - Selectivity depends on available CPU power Strangeness in Quark Matter ‘06, UCLA, March 26, 2006

  6. Centrality and forward detectors Centrality (impact parameter) determination is needed for physics analysis Zero Degree Calorimeter Energy in the forward hadronic calorimeter Tungsten-quartz fibre structure electromagnetic section: 19X0 hadronic section 5.6λ0 Rad. hard to 20 Grad (AA, pp low lum.) Energy resolution: 10% at 2.75 TeV Position resolution: 2 mm (EM sect.) Pb+Pb ET [GeV] impact parameter [fm] Strangeness in Quark Matter ‘06, UCLA, March 26, 2006

  7. ch Charged particle multiplicity Will be one of the first results, important for initial energy density, saturation, detector performance etc. • high granularity pixel detectors • pulse height measurement in each pixel reduces background • Very low pT reach, pT>26 MeV (counting hits) Simple extrapolation from RHIC data W. Busza, CMS Workshop, June 2004 Muon detection, tracking, jet finding performance checked up to dNch/dh5000 Strangeness in Quark Matter ‘06, UCLA, March 26, 2006

  8. 2.0<<2.5 -0.5<<0.5 2.0<<2.5 -0.5<<0.5 -0.5<<0.5 Track reconstruction Transverse Impact Parameter Resolution [cm] Momentum Resolution [%] Efficiency and fake rate [%] % efficiency fake rate (Event sample: dn/dy3000 + one 100GeV jet/event) • Excellent performance, even at the highest particle densities Strangeness in Quark Matter ‘06, UCLA, March 26, 2006

  9. Quarkonia in CMS Heavy Ions J/  family Mm+m-spectrum,  family sMY=50 MeV in the barrel Expected: 24000 J/y and ~ 18000/5000/3000 /’/’’ After one month of Pb+Pb running at L=1027cm-2s-1 with 50% efficiency J/ acceptance Online HLT farm improvesacceptance by 2.5 at high  and low pT Strangeness in Quark Matter ‘06, UCLA, March 26, 2006

  10. c a b d Jets – a new observable at LHC • Hard, perturbative scale: Q>>LQCD. Hard parton production unaffected by medium • Parton shower developmentaffected by the medium • At LHC in Pb+Pb collisions: • wider pT range for suppression, quenching studies • jet structure will likely be modified, compared to jets produced in p+p • comparison to p+p and p+A is essential • Observables: • High pT particles and particle correlations (similar to RHIC analyses) • Jet rates: single and multi-jets (quenching studies) • Jet fragmentation and shape: • Distance R to leading particle (in - space) • forward-backward correlation: (particle, jet axis) • Fragmentation function: F(z)=1/NjdNch/dz where z=pt/pjet • correlations with non-hadronic particles: jets+g, jets+Z • Jets originating from heavy quarks (b, c) Extensive theoretical and experimental preparatory work presently in progress Strangeness in Quark Matter ‘06, UCLA, March 26, 2006

  11. Jet reconstruction in the calorimeters efficiency efficiency 1.6<||<1.9 ||<0.3 1.6<||<1.9 ||<0.3 resolution resolution Strangeness in Quark Matter ‘06, UCLA, March 26, 2006

  12. Jet studies using the tracking Tracking is a very important capability for jet physics Azimuthal correlations (as studied at RHIC): Centrality dependence of pT specra can be studied: dN/dpT dN/d() Fragmentation functions: pT with respect to jet axis: 1/NjetsdNch/dz 1/NjetsdNch/dpTjet Strangeness in Quark Matter ‘06, UCLA, March 26, 2006

  13. Advantages of CMS over other HI experiments • Hermeticity, Resolution, Granularity • Central region: tracker, electromagnetic and hadronic calorimeters and muon detector • Forward coverage • calorimeters extend to Dh10 • Proposed CASTOR calorimeter to Dh14 • High data taking speed and trigger versatility • Two-level trigger • Ability to “inspect” every heavy ion event on the High Level Trigger computer farm (5.32 < η < 6.86) CASTOR TOTEM (z = 140 m) ZDC Strangeness in Quark Matter ‘06, UCLA, March 26, 2006

  14. CMS under construction… Solenoid superconducting, already at 4K Hadron Calorimeter Muon Absorber Electromagnetic Calorimeter DAQ Si tracker & Pixels Strangeness in Quark Matter ‘06, UCLA, March 26, 2006

More Related