Heavy Ion Physics with CMS

1. Heavy Ion Physics with CMS Russell Betts for the CMS Collaboration Heavy Ion Physics Institutions Athens, Auckland, Budapest, CERN, Chongbuk, Colorado, Cukurova, Iowa, Kansas, Korea, Los Alamos, Lyon, Maryland, Minnesota, MIT, Moscow, Mumbai, Rice, Seoul, Vanderbilt, UC Davis, UI Chicago, Yonsei, Zagreb Russell Betts Quark Matter 2006

2. Heavy Ion Physics at the LHC • Enormous increase in yields of hard probes • LHC Energy = 30 RHIC Energy • Gluon Saturation – even at h=0 Is the created matter the same as at RHIC? Yes – Possibility for detailed study of QCD matter discovered at RHIC No – A new challenge for models Russell Betts Quark Matter 2006

3. CMS Heavy Ion Physics Program • Comprehensive program with emphasis on hard probes • Program follows increasing luminosity • Pb+Pb for the first few years, expect other ions and p+Pb later Soft Physics and Global Event Characterization • Centrality and good Event Selection – Scaling with Npart, Ncoll • Charged Particle Multiplicity – Initial StateGluon Densities • Azimuthal Asymmetry (Flow) – Equation of State • Spectra + Correlations – Sources, Radial Flow, dE/dx and Quenching High pT Probes • High pT Particles and studies of Jet Fragmentation – Energy Loss and Modification of Fragmentation Functions. Flavor and Geometry Dependence. • Quarkonia (J/, ) and Heavy Quarks – Suppression and Recombination • High Energy Photons, Z0, Jet-, Jet-Z0, Multijet Events – Calibrated Measure of dE/dx Forward Physics • Limiting Fragmentation – Saturation, Color Glass Condensate • Ultra Peripheral Collisions – PDF in New Regions of x and Q2 • Exotica - Russell Betts Quark Matter 2006

4. Forward Detectors CASTOR (5.2 << 6.5) TOTEM Collar shielding (5.3 << 6.7) T2 ZDC (z = 140 m) EM HAD Beams The CMS Detector Russell Betts Quark Matter 2006

5. Particle Detection in CMS 4T Field Russell Betts Quark Matter 2006

6. Detector Specifications • Calorimetry • ECAL ~80,000 PbWO4 Crystals with APD Readout • HCAL Barrel and Endcap (Cu+Scint) Forward Calorimeter (Fe+Quartz) • Zero Degree Calorimeter EM & Hadronic Sections Luminosity Monitor Silicon Tracker • Pixel Detector Three Pixel (150*100 mm2) Layers with Energy Readout. Low Occupancy • Strip Detector Ten Barrel Layers Twelve Endcap Layers Muon System • Barrel Drift Chambers • Endcap Cathode Strips • Muon Trigger Resistive Plate Chambers Forward Detectors • CASTOR - Calorimeter • TOTEM - T2 Tracker • DAQ/Trigger • L0,L1 Hardware Trigger • High Level Trigger Event Builder and Switch Filter Farm (~1500 Servers) Russell Betts Quark Matter 2006

7. HF into the Collision Hall The Real CMS Russell Betts Quark Matter 2006

8. HCAL (Barrel+Endcap+Forward) Kinematics and Acceptance Large Range of Hermetic Coverage Russell Betts Quark Matter 2006

9. Pb+Pb event (dN/dy = 3500) with- Pb+Pb event display: Produced in full software framework (simulation, data structures, visualization) Heavy Ion Event in CMS m m Russell Betts Quark Matter 2006

10. Minimum Bias Trigger R Hollis, A Iordanova Russell Betts Quark Matter 2006

11. Pb+Pb ET [GeV] Event Selection Centrality (Impact Parameter) Determination is needed for Physics Analysis Zero Degree Calorimeter Energy in HF HF Correlate ZDC Signal with other Detectors M Murray - Poster Russell Betts Quark Matter 2006

12. CMS Trigger HLT provides - Centrality, Event Plane, Vertex Position, dN/dET, Ejet, Muon Tracks… Russell Betts Quark Matter 2006

13. Physics Enhancement with Strawman Trigger Table Production Rates in Pb+Pb Statistical Significance – 1 Year G Roland – Parallel Talk Russell Betts Quark Matter 2006

14. ch Global Physics Event by Event dn/dh and dE/dh Hit Counting and Tracklets in Pixels a la PHOBOS (Pulse Height in Pixels) Energy - h 5.2 (HF) 6.5 (CASTOR) C Smith Extrapolation from RHIC C Smith Russell Betts Quark Matter 2006

15. Elliptical Flow Krofcheck - Poster Will Hydro hold at LHC? Reaction Plane s = 0.12 rad S Petrushanko Russell Betts Quark Matter 2006

16. High pT Suppression/Tracking Inclusive pT Spectra vs Collision Centrality • Determine Nuclear Modification Factors RAA • Yield plus High Level Trigger will allow Measurement out to 200 GeV. I. Vitev and M. Gyulassy, Phys.Rev.Lett. 89 (2002) Momentum Resolution Efficiency/Fake-rate Track-Pointing Resolution 250 200 150 100 50 Resolution (%) • Efficiency • Fake Rate s(mm) (%) pT [GeV/c) pT [GeV/c) pT [GeV/c) C. Roland Russell Betts Quark Matter 2006

17. Jet Fragmentation and Correlations • Fragmentation function for 100GeV jets embedded in dN/dy ~5000 events. • Jet-jet correlations C Roland Russell Betts Quark Matter 2006

18. Tracking Performance at Low pT Efficiency All Tracker Fitting Fake Rate Pixel Tracking Low pT Tracking Using Three Pixel Layers PID with dE/dx and Topology (V0) Sikler - Poster Russell Betts Quark Matter 2006

19. 1. Subtract average pileup 2. Find jets with iterative cone algorithm 3. Recalculate pileup outside the cone 4. Recalculate jet energy Jet Energy Resolution Efficiency, Purity Measured Jet Energy Jet Reconstruction PILE-UP SUBTRACTION ALGORITHM Vardanyan Russell Betts Quark Matter 2006

20. Jet Quenching Statistical Significance – 1 Year High level trigger on high ET jets will extend physics reach. e.g RAA to 200 GeV C Roland, Veres - Poster Russell Betts Quark Matter 2006

21. Regeneration ? SPS RHIC LHC Suppression ? Energy Density Quarkonia (J/) Kodolova, Bedjidian J/ Acceptance s = 35 MeV/c2 Russell Betts Quark Matter 2006

22. Quarkonia () Kodolova, Bedjidian  s = 54 MeV/c2  Acceptance ’ ’’ ’/  C Loizides Thy. – Gunion and Vogt Statistical Reach Russell Betts Quark Matter 2006

23. High Mass Di Muons • Z0 reconstructed with high efficiency by design • Dimuon continuum dominated by b decays • High statistics Kvatadze Balance Energies of g*/Z0 and Jet Mironov - Poster Russell Betts Quark Matter 2006

24. Forward Physics • Quarkonia photoproduction • Uses ZDC to triggeron forward emitted neutrons • Measurement -> m+m-, e+e- in the central detector • Probes nuclear PDF in unexplored (x,Q2) range D’Enterria - Parallel Talk Russell Betts Quark Matter 2006

25. Summary • CMS is a Superb and Versatile Detector for Heavy Ion Physics • Excellent performance in high pT(ET) region and for m pairs – by design • Jet Physics • Quarkonia • Z0 • Surprising ability for global/soft physics • Global Variables (Nch, ET) over wide range of h • Event by event physics – flow etc etc • Unique forward physics capabilities - coverage • Sophisticated trigger will extend physics reach and allow us to focus on key physics issues Russell Betts Quark Matter 2006

26. Extra – CMS Detector Silicon Tracker • Pixel Detector • 3 barrel layers and 2 forward layers on each side • 100x150 m pixel size • Low occupancy: 2% for pixel L1 @ dN/d = 5000 • Strip Detector • 10 barrel layers of single- and double-sided silicon, 9 forwardlayers on each side • Muons • Wide rapidity range |h| < 2.4 • σm~ 50 MeV at • ECAL • Barrel • |h| 1.48 • DhxDf = 0.0175 x 0.0175 • Resolution: 0.027/E  0.0055 • Endcap • 1.48  |h|  3 • Preshower 1.652.6 • HCAL • Barrel+Endcap • |h|  3 • DhxDf = 0.087 x 0.087 • Resolution: 1.16/E  0.05 Russell Betts Quark Matter 2006

27. Extra – Trigger Table Russell Betts Quark Matter 2006