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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/20071D. Froidevaux, CERN
Particle detection and reconstruction at the LHC (IV)
CERN-Fermilab Hadron Collider Physics Summer School, CERN, 200711th to 14th of August 2007 (D. Froidevaux, CERN)
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/20072D. Froidevaux, CERN
Particle detection and reconstruction at the LHC (and Tevatron)
Lecture 1 Historical introduction: from UA1/UA2 to ATLAS/CMS
Lecture 2 Experimental environment and main design choices of ATLAS and CMS
Lecture 3 Global performance overview, electrons and photons (and particle-ID in ALICE/LHCb)
Lecture 4 Muons and hadronic jets
Acknowledgments Material from HCP conferences (in particular for Tevatron) Special thanks to O. Kortner, M. Lefebvre, P. Loch and P. Sphicas
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/20073D. Froidevaux, CERN
Electron/photon ID in ATLAS and CMS will be a challenging and exciting task (harsher environment than at Tevatron, larger QCD backgrounds, more material in trackers)
But LHC detectors are better in many respects! Software is on its way to meet the challenge!
Huge effort in terms of understanding performance of detectors as installed ahead of us (calibration of calorimeters and alignment of trackers, material effects)
Electrons and photons in ATLAS/CMS: conclusions
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/20074D. Froidevaux, CERN
Remember which are primordial tasks of muon systems:1. Trigger on high-pT single
muons and muon pairs2. Identify muons 3. Measure muon momenta
independently of tracker
What is expected composition ofmuon L1 trigger at ~ 10 GeV?1. About 50% heavy flavours2. About 50% /K decays
Most muons are real but also non-isolated and embedded in jets with wide range of transverse energies
ATLAS/CMS: muon measurements and identification
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/20075D. Froidevaux, CERN
ATLAS/CMS: muon spectrometer parameters
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/20076D. Froidevaux, CERN
ATLAS/CMS: muon measurements and identification
• Limited impact on resolution from MS• B-field highly non-uniform and rapidly varying (has to be measured!)• Some difficult regions for acceptance (z = 0 and feet)• Transverse momentum resolution more or less uniform versus
• Resolution severely limited by MS• Very uniform B-field in central region
• Excellent geometrical acceptance
• Transverse momentum resolution degrades significantly at large
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/20077D. Froidevaux, CERN
CMS muon spectrometer• Superior combined momentum resolution in central region• Limited stand-alone resolution and trigger (at very high luminosities) due to multiple scattering in iron• Degraded overall resolution in the forward regions (|| > 2.0) where solenoid bending power becomes insufficient
CMS
ATLAS/CMS: muon measurements and identification
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/20078D. Froidevaux, CERN
ATLAS muon spectrometer• Excellent stand-alone capabilities and coverage in open geometry• Complicated geometry and field configuration (large fluctuations in acceptance and performance over full potential x coverage (|| < 2.7)
ATLAS
ATLAS/CMS: muon measurements and identification
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/20079D. Froidevaux, CERN
ATLAS/CMS: muon measurements and identification
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200710D. Froidevaux, CERN
ATLAS/CMS: low-pT muons
Requirements for muon identification and reconstruction at low pT
• Identify track stub in first layer of muon system• Check for minimum ionising signals in last layers of hadron calorimeter• Match as precisely as feasible (within limitations due to large MS and energy loss in calorimetry) measured track in inner detector with track stub in muon system
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200711D. Froidevaux, CERN
ATLAS/CMS: muon measurements and identification
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200712D. Froidevaux, CERN
ATLAS/CMS: muon measurements and identification
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200713D. Froidevaux, CERN
ATLAS/CMS: L1 trigger rates at L = 2 1033 A few words about trigger
L1 runs from calo and muons only (unlike CDF/D0!)
Jet trigger thresholds defined by luminosity and multiplicity
Muon and electron trigger thresholds defined by physics (heavy flavours and W/Z)
Hadronic and ETmiss trigger
thresholds defined by physics only when combined topologically with other trigger (e.g. x ET
miss for W to and lepton x for Z/H to
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200714D. Froidevaux, CERN
LHC environment: jet signatures
14 TeV
1.8 TeV
Inclusive jet cross-section
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200715D. Froidevaux, CERN
LHC environment: jet signatures
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200716D. Froidevaux, CERN
LHC environment: jet signatures
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200717D. Froidevaux, CERN
LHC environment: jet signatures
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200718D. Froidevaux, CERN
LHC environment: jet signaturesJet reconstruction and calibration strategy
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200719D. Froidevaux, CERN
LHC environment: underlying event
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200720D. Froidevaux, CERN
LHC environment: pile-up
Rm
s E
T (
GeV
)
Sqrt(area) in 0.1x0.1 cell units
ATLAS
BarrelEnd-cap
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200721D. Froidevaux, CERN
Jet reconstruction: hadronic showers
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200722D. Froidevaux, CERN
Jet reconstruction: hadronic showers
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200723D. Froidevaux, CERN
ATLAS/CMS: calorimeter response to pions
Huge effort in test-beams to measure performance of overall calorimetry with single particles and tune MC tools: not completed!
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200724D. Froidevaux, CERN
Jet reconstruction: noise (incoherent) in ATLAS
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200725D. Froidevaux, CERN
Jet reconstruction: noise (coherent) in ATLAS
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200726D. Froidevaux, CERN
Validation of G4 with test-beam data (ATLAS)Response to EM showers for LAr barrel EM and LAr hadronic end-cap
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200727D. Froidevaux, CERN
Validation of G4 with test-beam data (ATLAS)Response to pion showers for LAr hadronic end-cap
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200728D. Froidevaux, CERN
Validation of G4 with test-beam data (ATLAS)Response to pion showers for hadronic tile calorimeter (parallel to beam)
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200729D. Froidevaux, CERN
Jet reconstruction: dead material and cracks in ATLAS
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200730D. Froidevaux, CERN
Jet reconstruction: calibrated energy clusters in ATLAS
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200731D. Froidevaux, CERN
Jet reconstruction: calibrated energy clusters in ATLAS
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200732D. Froidevaux, CERN
Jet reconstruction: calibrated energy clusters in ATLAS
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200733D. Froidevaux, CERN
Jet reconstruction: calibrated energy clusters in ATLAS
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200734D. Froidevaux, CERN
Jet reconstruction: calibrated energy clusters in ATLAS
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200735D. Froidevaux, CERN
Jet reconstruction: calibrated energy clusters in ATLAS
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200736D. Froidevaux, CERN
Jet reconstruction: impact of new scheme in ATLAS
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200737D. Froidevaux, CERN
Jet reconstruction: impact of new scheme in ATLAS
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Hadron Collider Physics Summer School, CERN, 11/08/2007 to 14/08/200738D. Froidevaux, CERN
Jets are the most abundantly produced objects at the LHC and need therefore to be understood to the best of our ability for a variety of physics tasks on our to-do list over the next ten years:
• QCD processes are interesting per se
• QCD corrections to SM EW processes are very large and do not always converge for specific exclusive final states as one puts in more and more higher-order processes
• Jets (in particular b-jets) are often amongst the decay products of both SM (top) and new physics processes
Major and exciting effort in terms of understanding performance of calorimetry, software (energy-flow algorithms, optimisation of Etmiss calculations) ahead of us (calibration of calorimeters and alignment of trackers, material effects)
Jets in ATLAS/CMS: conclusions