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Muon SystemMuon System

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Barrel Muon SystemBarrel Muon SystemAACHEN(MB1) 59/70 end in SeptCIEMAT(MB2) 54/70 end in Sept

LEGNARO(MB3) 56/70 end in DecTORINO(MB4) 6/40 end in Apr. 06

Yoke wheel YB+2:

34 chambers installed

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Endcap Muon SystemEndcap Muon System

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Heavy Ion Physics with CMSHeavy 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

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Detector CoverageDetector CoverageLarge Range of Hermetic Coverage

in , x and Q2

Unique Forward Capability

Abundant High pT Probes, Jets, J/, , Z0

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Tracker in HI EnvironmentTracker in HI Environment

TrackerECAL

Central Pb+Pb Event dN/d=5000

(HIJING+OSCAR+IGUANA)

>50,000 Charged Particles –

BUT Pixels are <2% Occupied

(Key to Successful Tracking)

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Charged MultiplicityCharged Multiplicity•Pixels have High Granularity, Located near Interaction Region (r1 = 4 cm)

•Use Summed Pulse Height Measurement in Reconstructed Clusters to Remove

Hits from Background Sources (Secondaries, Looping Tracks)

•Can Measure Very Low pT Particles

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Track ReconstructionTrack ReconstructionpT resolution (pT/pT) impact parameter

|| < 0.7

efficiency and fakesHIJING + GEANT + ORCA – C. Roland

Track finder based on Kalman filteringTrack finder based on Kalman filteringmethodmethod

Algorithms exist for primary vertex finding,Algorithms exist for primary vertex finding,seed generation, track propagation, seed generation, track propagation, trajectory smoothing, and regional trackingtrajectory smoothing, and regional tracking

High reconstruction efficiency and low fakeHigh reconstruction efficiency and low fakerate even at high track densityrate even at high track density

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100 GeV Jet + Pb+Pb Event 100 GeV Jet + Pb+Pb Event

EM+Hadronic Energy

Hijing + 100 GeV Jet Pair

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HIJING (generator level, acceptance of HF and CASTOR) - C.Teplov

Global Physics from CalorimeterGlobal Physics from Calorimeter

HF

ET

CASTOR

Etot

Impact Parameter Correlation

with Calorimeter

Flow from Azimuthal Asymmetry

<Day 1 Measurement

sQGP or wQGP ??

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Jet ReconstructionJet Reconstruction

-Resolution

Measured Energy

-Resolution

Efficiency, Purity

Energy resolution

Sliding Jet Cone Algorithm Used for Background SubtractionSliding Jet Cone Algorithm Used for Background SubtractionEnergy Resolution for 100 GeV Jets is Energy Resolution for 100 GeV Jets is 16% 16%

PYTHIA (100 GeV jet) + HIJING (PbPb, dN/d=5000) +

full GEANT- I. Vardanyan, O.Kodolova

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Jet FragmentationJet FragmentationLongitudinal momentum fraction z along

the thrust axis of a jet: pT 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

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Balancing Balancing or Z or Z00 vs Jets vs Jets

Channel Barrel+endcap

Jet+jet 4.3 x 106

+jet 3.0 x 103

Z->+- + jet, ETet>50 GeV 4x102

# E

ven

ts/4

GeV

ET/0-ET

Jet (GeV)

<E>=8 GeV<E>=4 GeV<E>=0 GeV

Background

Isol. 0+jet

Estimated Event Samples in 1 month Pb+Pb at 1027cm-2s-1

, Z0

jet

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Quarkonia in CMSQuarkonia in CMS

J/ family

  = 60 MeV

Pb+Pb Kr+Kr Ar+Ar

L 1027 7×1028 1030

J/ 28.7k 470k 2200k

´ 0.8k 12k 57k

22.6k 320k 1400k

´ 12.4k 180k 770k

´´ 7k 100k 440k

Yield/monthYield/month(with 50% duty factor)(with 50% duty factor)

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DAQ and TriggerDAQ and TriggerTwo-level DAQ/Trigger architectureL1: Low-level hardware trigger

Muon track segmentsCalorimetric towersNo tracker infoOutput rate = few-10 kHz

HLT: online farmReplaces traditional L2, L3, etc.Refit muon and calorimeter information,

and add tracker infoOutput rate = 50 Hz

Data rateapprox. 2-5 MB/event (vs. 1 MB for pp) 100-200 MB/second written to tape

Typical CMS

L1

HLT

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High Level Trigger (HLT)High Level Trigger (HLT)

Main Types of Trigger Required by Physics multiplicity/centrality:”min-bias”, “central-only” high pT 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 pT 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 !High Level Trigger can do a better job than L1 !

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Detection of low pT 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 trigger None 60 Hz

L3 trigger None 60 Hz

J/ψ pT >3 GeV/c

L1 trigger Single ~2 kHz

L2 trigger Re-fit 70 Hz

L3 trigger Match tracker

<40 Hz

J/ψ pT >1 GeV/c

Without online farm (HLT) With online farm (HLT)

See CMS Analysis Note 2004/02

Online farm

pT

Online farmImprovement

Acceptance x2.5

Power of HLT - Low pPower of HLT - Low pTT J/ J/ψψ

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• Near Hermetic coverage (out to |η|<7 with CASTOR)

• Physics– Centrality

– Nuclear PDFs - particularly gluon distributions

– Momentum fractions x ~ 10-6 – 10-7 at scales of a few GeV2 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 Forward Detectors: CASTOR and TOTEMand TOTEM

CASTOR Coverage

ZDC

(z = 140 m)

TOTEM T2

BCM Sensor CarriageScintillators atz=10.5m

IP

TOTEM T1

BCM Sensors

CASTOR

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100 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 2nd 10 cm

Improves resolution at large b

Readout through HF electronics – signals available for L1 trigger

b2R ~ 15 fm

Beam pipe splits~140 m from IR

Beams

Spectators

Spectators

Participant Region

HADHAD

EMEM

LumLum

Zero Degree CalorimetryZero Degree Calorimetry

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Summary and OutlookSummary and OutlookLHC will Extend Energy Range - in Particular High

pT Reach - of HI Physics to Provide a New Window on QCD Matter

CMS Detector offers Superb Capabilities

Full calorimeter coverage Superior momentum resolution due to 4T magnetic field High mass resolution for quarkonia Centrality, multiplicity, spectra, energy flow to very low pT

No modification to detector hardware New High Level Trigger (HLT) algorithms for HI Zero Degree Calorimeter, CASTOR and TOTEM provide unique

access to forward physics