status of atlas and preparation for the pb-pb run qm 2009, knoxville jiří dolejší charles...
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Status of ATLAS and preparation for the Pb-Pb runQM 2009, Knoxville
Jiří Dolejší Charles University Prague
for the ATLAS collaboration
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Performance & experience 2008
Single beam splash event on September 10th, 2008: particles from a beam hitting the collimator 140 m from ATLAS.
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Performance & experience 2008
Muon detectors
Calorimeters
Inner detector
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Inner detector2008: Cosmic run from September 14th:
Pixels: •Efficiency of about 98.4%•Optolinks tuned to 80Mbit/s
SCT: •99% of SCT Barrel and 97% of SCT EndCaps were operated•99% of all modules operational•99.8% strips alive
TRT:•97% of channels reading out•~99% of electronics working•2.9 M tracks collected in TRT
Repairs, prospects for 2009:•Cooling repairs & improvements•Restart during May 09
SCT
Pixels
TRT
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Inner detector – performance illustrations:
Display of cosmic ray event going through the SCT and pixel detector (notice low noise)
Alignment of upper and lower halves of cosmic tracks expressed in difference of d0 – distance to vertex. Tracks are selected to have pT > 2 GeV. Tracks are required to have a hit in the Pixel B layer, 3 Pixel hits and in total 7 Silicon hits.
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CalorimetersLiquid argon calorimeter:Successful operation in 2008: •97% power supplies OK•99.92% channels workingProspects for 2009:•Power supplies repaired, monitoring improved•Everything will be in place and ready to go by the end of AprilTile calorimeter:•Power supplies & controls: 99.2% OK•98.6% cells alive •Calibration ready or being commissioned, cell equalization within a few %. Tasks for 2009:•Further tuning of the 137Cs cell inter-calibration, monitoring of PMT stability, data quality monitoring.
Energy summed over 100 splash events in EM Presampler
ATLAS Preliminary
Liquid argon calorimeter- illustration of performance:
The 8-fold structure induced by the toroid endcap is clearly visible at large radius (layers S1, S2, S3).
The 16-fold structure is due to additional matter and shielding at low radius (Presampler PS).
The sum of 100 splash events from Sept. 10th
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up
down
ATLAS Preliminary
Tile calorimeter - illustration of performance:
This picture shows the 8-fold structure in of the beam splash events recorded on the 10th of September. The structure is due to the End Cap toroid material in front of TileCal for particles coming from the C-side. The up -down asymmetry is also due to the material in front of the detector.
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up
down
ATLAS Preliminary
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Tile calorimeter – test beam results: The response to electrons –
Tilecal EM scale factor (1.050±0.003 pC/GeV)
The energy resolution for pions impinging on the calorimeter at |η| =0.35, as a function of the beam energy. Data (full circles) are in reasonable agreement ‚with MC simulation results (open squares).
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)%2.07.5()%9.09.52(
beamEE
ATLAS Preliminary
ATLAS Preliminary
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Monitored Drift Tubes•98.5% chambers operational•98.3% channels working•Aim: 99.8% after shutdown
Muon system
MDT, CSC: precision tracking;
TGC, RPC: trigger, coordinate
Cosmic muon map reconstructed by off-line RPC standalone muon monitoring projected on surface (y=81m).
ATLAS Preliminary
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Forward detectors
LUCID (Luminosity CerenkovIntegrating Detector) at 17 m
2009: ZDC (Zero Degree Calorimeter ) at 140 m,
2010: ALFA (Absolute Lumi-nosity for ATLAS) at 240 m
LUCID is a running detector in advanced status of commissioning; nevertheless, some consolidation and repairs are ongoing during the shutdown period
LUCID signal, Sept. 10, 2008
Important for heavy ions, significant contribution from HI
group
Data acquisition – cosmic events
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ATLAS Preliminary
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Heavy Ion Physics with the ATLAS Detector at the LHC
Some selected results from the forthcoming Physics Performance Report
More in parallel talks:
•Jets by Nathan Grau•Quarkonia & Z0 by Marzia Rosati•Direct photons by Mark Baker
ATLAS calorimetry - full azimuthal acceptance
Tracking in 2T solenoid
MuonsPhotons
Jets
100 GeV jet depositing energy
Overview of ATLAS acceptance
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Tracking
Tracking efficiency and fake rate in || < 1 extracted from a sample of central(b=2 fm) HIJING events produced with quenching effects turned off in the ATLAS tracking system.Acceptable efficiency of about 70%, negligible fake rate above 1 GeV/c
Top: Tracking efficiency as a function of pseudorapidity for tracks with 3 < pT < 8 GeV extracted from the same central sample of events. Bottom: Fake rate as function of pseudo-rapidity for the same tracks as above.Negligible dependence on
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ATLAS Preliminary ATLAS Preliminary
Elliptic Flow
Transverse momentum dependence of the reconstructed v2: •from the event plane method (squares)•two-particle correlations (stars)•the Lee-Yang Zeros method (triangles)•input flow as extrapolated from RHIC data (line)Thanks to complete azimuthal coverage we can well reproduce the input, different methods offer sensitivity to non-flow effects
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ATLAS PreliminaryPb+Pb s = 5.5 TeV/A
b = 2.3 fm b=7.0 fm b=10.7 fm
Jets … elucidating the jet energy loss
Parallel talk by Nathan Grau
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Fragmentation function: D(z)
Reliable reconstruction of D(z):Reconstructed tracks with pT > 2 GeV matching calorimeter jets
The scale of possible modifications of fragmentation function – comparison of PYTHIA and PYQUENWe can measure jet quenching of the size simulated by PYQUEN
ATLAS PreliminaryATLAS Preliminary
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Dimuon Measurements … quarkonia, Z0
Parallel talk by Marzia Rosati
Background muons from open charm and beauty decays, from hadron in-flight decays before absorption in the calorimeter and from punch-through hadrons which can be reconstructed as muons.
Error bars show statistical errors only.
Di-muon invariant mass distribution as expected for one month of data, taking into account acceptance and efficiency, for decay muons in the barrel region only (|| < 1). 19 000 in one month running at nominal luminosity (0.5 nb-1)
ATLAS Preliminary
Mass Resolution 120 MeV, sufficient the separate states
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Direct Photons & Photon-Jet Correlations
Parallel talk by Mark D. Baker
The performance of the shower shape cuts and isolation cuts on PYTHIA di-jets embedded into b = 2 fm Pb+Pb events:
Background greatly suppressed!
ATLAS Preliminary
ATLAS Preliminary
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Summary
•ATLAS is fully operational, recorded several hundred million cosmic events
•Ongoing activities enable further detector improvements, calibration, refinement of monitoring, software tools
•Extensive preparations for Pb+Pb program show a promissing performance of ATLAS for heavy ion beams.
•We will participate in initial p+p data taking to get reference data for heavy ion program and to tune the analysis techniques.
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Sources of further information
ATLAS Public Results
https://twiki.cern.ch/twiki/bin/view/Atlas/AtlasResults
The ATLAS Experiment at the CERN Large Hadron Collider
The ATLAS Collaboration, G Aad et al 2008 JINST 3 S08003