1. Russell Betts Quark Matter 2006 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

2. Russell Betts Quark Matter 2006 2 Heavy Ion Physics at the LHC Enormous increase in yields of hard probes 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 LHC Energy = 30  RHIC Energy Gluon Saturation – even at  =0

3. 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 N part, N coll Charged Particle Multiplicity – Initial State Gluon Densities Azimuthal Asymmetry (Flow) – Equation of State Spectra + Correlations – Sources, Radial Flow, dE/dx and Quenching High p T Probes High p T 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, Z 0, Jet- , Jet-Z 0, 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 Q 2 Exotica -

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

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

6. Russell Betts Quark Matter 2006 6 Detector Specifications Calorimetry n ECAL ~ 80,000 PbWO 4 Crystals with APD Readout n HCAL Barrel and Endcap (Cu+Scint) Forward Calorimeter (Fe+Quartz) n Zero Degree Calorimeter EM & Hadronic Sections Luminosity Monitor Silicon Tracker n Pixel Detector Three Pixel (150*100  m 2 ) Layers with Energy Readout. Low Occupancy n Strip Detector Ten Barrel Layers Twelve Endcap Layers Muon System n Barrel Drift Chambers n Endcap Cathode Strips n Muon Trigger Resistive Plate Chambers Forward Detectors n CASTOR - Calorimeter TOTEM - T2 Tracker DAQ/Trigger n L0,L1 Hardware Trigger n High Level Trigger Event Builder and Switch Filter Farm (~1500 Servers)

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

8. Russell Betts Quark Matter 2006 8 Kinematics and Acceptance HCAL (Barrel+Endcap+Forward) Large Range of Hermetic Coverage Silicon and  Tracker  ECAL  HCAL  CASTOR  ZDC Neutrals 

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

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

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

12. Russell Betts Quark Matter 2006 12 CMS Trigger HLT provides - Centrality, Event Plane, Vertex Position, dN/dE T, E jet, Muon Tracks…

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

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

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

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

17. 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

18. Russell Betts Quark Matter 2006 18 Tracking Performance at Low p T Pixel Tracking All Tracker Fitting Low p T Tracking Using Three Pixel Layers PID with dE/dx and Topology (V 0 ) Efficiency Fake Rate Sikler - Poster

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

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

21. Russell Betts Quark Matter 2006 21 Quarkonia () Quarkonia (J/  ) J/  Acceptance Kodolova, Bedjidian SPS Suppression ? Regeneration ? RHIC LHC Energy Density  = 35 MeV/c 2

22. Russell Betts Quark Matter 2006 22 Quarkonia () Quarkonia (  )  Acceptance Kodolova, Bedjidian C Loizides Thy. – Gunion and Vogt  ’/   = 54 MeV/c 2  ’’  ’’ Statistical Reach

23. Russell Betts Quark Matter 2006 23 High Mass Di Muons Z 0  reconstructed with high efficiency by design Dimuon continuum dominated by b decays High statistics Kvatadze Balance Energies of  */Z 0 and Jet Mironov - Poster

24. Russell Betts Quark Matter 2006 24 Forward Physics Quarkonia photoproduction Uses ZDC to trigger on forward emitted neutrons Measurement  ->  +  -, e + e - in the central detector Probes nuclear PDF in unexplored (x,Q 2 ) range D’Enterria - Parallel Talk

25. Russell Betts Quark Matter 2006 25 Summary CMS is a Superb and Versatile Detector for Heavy Ion Physics Excellent performance in high p T (E T ) region and for  pairs – by design Jet Physics Quarkonia Z 0 Surprising ability for global/soft physics Global Variables (N ch, E T ) over wide range of  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

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

27. Russell Betts Quark Matter 2006 27 Extra – Trigger Table