Chester - Sept Russell Betts 1 Muon System

Chester - Sept Russell Betts 2 Barrel Muon System AACHEN(MB1) 59/70 end in Sept CIEMAT(MB2) 54/70 end in Sept LEGNARO(MB3) 56/70 end in Dec TORINO(MB4) 6/40 end in Apr. 06 Yoke wheel YB+2: 34 chambers installed

Chester - Sept Russell Betts 3 Endcap Muon System

Chester - Sept Russell Betts 4 Heavy Ion Physics with CMS Adana-Turkey, Athens, Basel, CERN, Demokritos, Dubna, Ioannina, Kent State, KFKI Budapest, Kiev, LANL*, Lyon, MIT, Moscow, Mumbai, N. Zealand, Ohio, Protvino, PSI, Rice, Sofia, Strasbourg, Tbilisi, UC Davis, UIC, U. Iowa, U Kansas, Warsaw, Yerevan

Chester - Sept Russell Betts 5 Detector Coverage Large Range of Hermetic Coverage in , x and Q 2 Unique Forward Capability Abundant High p T Probes, Jets, J/ , , Z 0

Chester - Sept Russell Betts 6 Tracker in HI Environment Tracker ECAL Central Pb+Pb Event dN/d  =5000 (HIJING+OSCAR+IGUANA) >50,000 Charged Particles – BUT Pixels are <2% Occupied (Key to Successful Tracking)

Chester - Sept Russell Betts 7 Charged Multiplicity Pixels have High Granularity, Located near Interaction Region (r 1 = 4 cm) Use Summed Pulse Height Measurement in Reconstructed Clusters to Remove Hits from Background Sources (Secondaries, Looping Tracks) Can Measure Very Low p T Particles

Chester - Sept Russell Betts 8 Track Reconstruction p T resolution (  p T /p T ) impact parameter |  | < 0.7 efficiency and fakes HIJING + GEANT + ORCA – C. Roland Track finder based on Kalman filtering method Algorithms exist for primary vertex finding, seed generation, track propagation, trajectory smoothing, and regional tracking High reconstruction efficiency and low fake rate even at high track density

Chester - Sept Russell Betts GeV Jet + Pb+Pb Event EM+Hadronic Energy Hijing GeV Jet Pair

Chester - Sept Russell Betts 10 HIJING (generator level, acceptance of HF and CASTOR) - C.Teplov Global Physics from Calorimeter HF ETET CASTOR E tot Impact Parameter Correlation with Calorimeter Flow from Azimuthal Asymmetry <Day 1 Measurement sQGP or wQGP ??

Chester - Sept Russell Betts 11 Jet Reconstruction  -Resolution Measured Energy  -Resolution Efficiency, Purity Energy resolution Sliding Jet Cone Algorithm Used for Background Subtraction Energy Resolution for 100 GeV Jets is  16% PYTHIA (100 GeV jet) + HIJING (PbPb, dN/d  =5000) + full GEANT - I. Vardanyan, O.Kodolova

Chester - Sept Russell Betts 12 Jet Fragmentation Longitudinal momentum fraction z along the thrust axis of a jet: p T relative to thrust axis: Using ECAL clusters~  0 in CMS Fragmentation function for 100 GeV Jets embedded in dN/dy ~5000 events. Use charged particles and electromagnetic clusters C. Roland P.Yepes

Chester - Sept Russell Betts 13 Balancing  or Z 0 vs Jets Estimated Event Samples in 1 month Pb+Pb at cm -2 s -1 , Z 0 jet

Chester - Sept Russell Betts 14 Quarkonia in CMS J/   family   = 60 MeV Pb+PbKr+KrAr+Ar L × J/  28.7k470k2200k ´´ 0.8k12k57k  22.6k320k1400k ´´ 12.4k180k770k  ´´ 7k100k440k Yield/month (with 50% duty factor)

Chester - Sept Russell Betts 15 DAQ and Trigger Two-level DAQ/Trigger architecture L1: Low-level hardware trigger Muon track segments Calorimetric towers No tracker info Output rate = few-10 kHz HLT: online farm Replaces traditional L2, L3, etc. Refit muon and calorimeter information, and add tracker info Output rate = 50 Hz Data rate approx. 2-5 MB/event (vs. 1 MB for pp)  MB/second written to tape TypicalCMS L1 HLT

Chester - Sept Russell Betts 16 High Level Trigger (HLT) Main Types of Trigger Required by Physics multiplicity/centrality:”min-bias”, “central-only” high p T probes: muons, jets, photons, quarkonia etc. High Occupancy but Low Luminosity many low level trigger objects may be present, but less isolated than in p+p. Level 1 may be difficult for high p T particles L1 in AA has larger backgrounds than in pp due to underlying event we can read most of the events up to High Level Trigger and do partial High Level Trigger can do a better job than L1 !

Chester - Sept Russell Betts 17 n Detection of low p T J/ψ requires efficient selection of low momentum, forward going muons. Simple hardware L1 dimuon trigger is not sufficient L1 trigger Two  60 Hz L2 triggerNone60 Hz L3 triggerNone60 Hz J/ψ p T >3 GeV/c L1 trigger Single  ~2 kHz L2 trigger Re-fit  70 Hz L3 triggerMatch tracker <40 Hz J/ψ p T >1 GeV/c Without online farm (HLT) With online farm (HLT) See CMS Analysis Note 2004/02  Online farm pTpT Improvement Acceptance x2.5 Power of HLT - Low p T J/ψ

Chester - Sept Russell Betts 18 Near Hermetic coverage (out to |η|<7 with CASTOR) Physics –Centrality –Nuclear PDFs - particularly gluon distributions –Momentum fractions x ~ – at scales of a few GeV 2 in pp –Diffractive processes (10-20% of total cross section at high energies) –Limiting Fragmentation –Peripheral and Ultra-Peripheral collisions –DCC, Centauros, Strangelets …… Forward Detectors: CASTOR and TOTEM CASTOR Coverage ZDC (z =  140 m) CASTOR

Chester - Sept Russell Betts cm of space available (9.6 x 12.5 x 100 cm) Quartz fiber/tungsten plates EM section segmented horizontally, HAD section longitudinally Luminosity detector in 2 nd 10 cm Improves resolution at large b Readout through HF electronics – signals available for L1 trigger b 2R ~ 15 fm Beam pipe splits ~140 m from IR Beams Spectators Participant Region HAD EM Lum Zero Degree Calorimetry

Chester - Sept Russell Betts 20 Summary and Outlook LHC will Extend Energy Range - in Particular High p T Reach - of HI Physics to Provide a New Window on QCD Matter CMS Detector offers Superb Capabilities l Full calorimeter coverage l Superior momentum resolution due to 4T magnetic field l High mass resolution for quarkonia l Centrality, multiplicity, spectra, energy flow to very low p T l No modification to detector hardware l New High Level Trigger (HLT) algorithms for HI l Zero Degree Calorimeter, CASTOR and TOTEM provide unique access to forward physics