Chester - Sept 12-17 2005 Russell Betts 1 Muon System.
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Transcript of Chester - Sept 12-17 2005 Russell Betts 1 Muon System.
Chester - Sept 12-17 2005 Russell Betts 2
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
Chester - Sept 12-17 2005 Russell Betts 4
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
Chester - Sept 12-17 2005 Russell Betts 5
Detector CoverageDetector CoverageLarge Range of Hermetic Coverage
in , x and Q2
Unique Forward Capability
Abundant High pT Probes, Jets, J/, , Z0
Chester - Sept 12-17 2005 Russell Betts 6
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)
Chester - Sept 12-17 2005 Russell Betts 7
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
Chester - Sept 12-17 2005 Russell Betts 8
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
Chester - Sept 12-17 2005 Russell Betts 9
100 GeV Jet + Pb+Pb Event 100 GeV Jet + Pb+Pb Event
EM+Hadronic Energy
Hijing + 100 GeV Jet Pair
Chester - Sept 12-17 2005 Russell Betts 10
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 ??
Chester - Sept 12-17 2005 Russell Betts 11
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
Chester - Sept 12-17 2005 Russell Betts 12
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
Chester - Sept 12-17 2005 Russell Betts 13
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
Chester - Sept 12-17 2005 Russell Betts 14
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)
Chester - Sept 12-17 2005 Russell Betts 15
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
Chester - Sept 12-17 2005 Russell Betts 16
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 !
Chester - Sept 12-17 2005 Russell Betts 17
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
Chester - Sept 12-17 2005 Russell Betts 18
• 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
Chester - Sept 12-17 2005 Russell Betts 19
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
Chester - Sept 12-17 2005 Russell Betts 20
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