The Status of the ATLAS Experiment Dr Alan Watson University of Birmingham on behalf of the ATLAS Collaboration

Alan Watson DIS 2009, 26/03/09 2 The Large Hadron Collider ATLAS CMS ALICE LHCb Design parameters  s = 14 TeV L = cm -2 s MHz bunch-crossing rate Initial operation  s = 10 TeV L =  cm -2 s  40 MHz bunch- crossing rate

Alan Watson DIS 2009, 26/03/09 3 LHC Point 1

Alan Watson DIS 2009, 26/03/09 4 ATLAS

Alan Watson DIS 2009, 26/03/09 5 ATLAS Installation

Alan Watson DIS 2009, 26/03/09 6 Commissioning started in 2005, in parallel with installation Test channel mappings and timing Identify dead and noisy channels, and fix where possible Verify stability of hardware during operation Gain experience in detector operation and control, data acquisition, reconstruction and analysis Develop and test monitoring tools Understand and improve detector performance  Detector alignment  Initial calibrations Commissioning Commissioning data Pedestal and calibration runs Cosmic ray events Single beams and “beam splash” events pp collisions  2009 Most cosmic data were taken in Autumn 2008

Alan Watson DIS 2009, 26/03/09 7 Combined Cosmic Running Alignment across different detectors Hit efficiency measurements Wide energy range E T spectrum from cosmic events – Sum of all cells with |E| > 2  –MC normalised to data in range GeV –Excess at highest E T possibly due to air showers (not included in simulation)

Alan Watson DIS 2009, 26/03/09 8 The Inner Detector

Alan Watson DIS 2009, 26/03/09 9 Inner Detector Components SCT (Semiconductor tracker) 4 double layers of strips in barrel. 9 in endcaps modules, 80  m strips, 6M channels. resolution 17  m  580  m >99% of barrel & >97 % of endcap modules operational Hit efficiency > 99%, noise occupancy  TRT (Transition Radiation Tracker) 4mm straw tubes with 35  m anode wires Transition radiation gives e-p separation between 0.5 < E < 150 GeV 73 barrel layers, axial straws 2  160 layers of radial straws in forward region, arranged in 20 discs 98% of channels operationa. Pixels 3 layers in barrel & endcap pixel size 50  m  400  m resolution 10  m  110  m 80 M channels, > 95% operational Hit efficiency > 98%, Noise occupancy 5  10 -9

Alan Watson DIS 2009, 26/03/09 10 Cosmic Tracking

Alan Watson DIS 2009, 26/03/09 11 Cosmic Track Statistics

Alan Watson DIS 2009, 26/03/09 12 TRT Commissioning Cosmic shower in TRT, showing “bubble-chamber like” tracking Measurement of turn-on of transition radiation for cosmic ray muons.  Good agreement with test beam results confirms detector working properly

Alan Watson DIS 2009, 26/03/09 13 SCT Commissioning Track residuals with preliminary aligned geometry Similar efficiencies are measured in endcaps SCT Barrel layer hit efficiencies

Alan Watson DIS 2009, 26/03/09 14 Pixel Commissioning Measurement of Lorentz angle  Important for reaching ultimate precision  MC prediction ~224 mrad

Alan Watson DIS 2009, 26/03/09 15 Calorimeters

Alan Watson DIS 2009, 26/03/09 16 ATLAS Calorimeters LAr Electromagnetic (|  | < 3.2) Pb-LAr accordion structure 3 longitudinal samples |  | < 2.5 presampler |  | < 1.8 LAr Endcap Hadronic (1.5 < |  | < 3.2) Cu-LAr structure, 4 longitudinal samples LAr Forward W/Cu rods & matrix, thin LAr gaps. 3 longitudinal samples. Tile Hadronic (|  | < 1.7) Fe-scintillating tile structure 3 longitudinal samples EM energy resolution  (E)/E = 10%/  E  0.7 % Hadronic energy resolution (jets)  (E)/E = 50%/  E  3 % (|  | < 3.2)  (E)/E = 100%/  E  10 % (|  | > 3.2) Status LAr: 0.02% dead channels (+ 0.9% recoverable). ~0.003% noisy channels Tile: ~1.4% dead channels, being repaired during shutdown

Alan Watson DIS 2009, 26/03/09 17 LAr Cosmic Commissioning

Alan Watson DIS 2009, 26/03/09 18 LAr Noise & Stability

Alan Watson DIS 2009, 26/03/09 19 Tile Calorimeters Tile Cell Noise vs eta  Variation due to power distribution Muon dE/dx from single beam data  Horizontal muons provide test of tile module intercalibration

Alan Watson DIS 2009, 26/03/09 20 Muon Spectrometer

Alan Watson DIS 2009, 26/03/09 21 Muon Spectrometer Spectrometer performance  Bdl = TM (|  |<1.4)  Bdl = TM (|  |>1.6) Standalone resolution:  p T /p T < 10% up to 1 TeV Precision Chambers (  2.5) Monitored Drift Tubes (MDT)  1088 chambers, 330k channels  99.8% of chambers operational  0.1% dead channels (+ 1% recoverable) Cathode Strip Chambers (CSC)  32 chambers, 31k channels. 2d readout  100% chambers operational  <0.1% dead channels Spatial resolution  m Optical alignment system: sensors Trigger Chambers (  2.4) Resistive Plate Chambers (RPC)  544 chambers, 359k channels  70% operational (goal 99.5% 2009)  < 2% dead strips Thin Gap Chambers (TCG)  3588 chambers, 318k channels  99.8% operational, <0.01 % dead channels 2d readout. Spatial resolution 5-10 mm, time resolution < 10 ns

Alan Watson DIS 2009, 26/03/09 22 Trigger and Precision Chambers Hit correlation between barrel precision and trigger chambers Correlation between tracks from endcap trigger and precision chambers

Alan Watson DIS 2009, 26/03/09 23 Cosmic Muon Tracks RPC tracks projected onto cavern surface  Access and lift shafts visible Momentum difference between ID and lower muon spectrometer  Measures energy loss in calorimeters

Alan Watson DIS 2009, 26/03/09 24 Trigger and DAQ Level-1 Trigger Completely installed Rate tests to 40 kHz, improve to nominal 75 kHz in 2009 Fine timing of triggers in progress High-Level Triggers (Level-2 & Event Filter) Current configuration  850 PCs in 27 racks (can be used as L2 or EF)  Capable of 60 kHz sustained rate Final configuration  500 PCs for L2, 1800 PCs for EF (PC: 8 cores, 2.5 GHz, 2 GB RAM per core)  17 Level-2 racks, 67 EF racks (28 racks configurable)  Finalisation will be luminosity-driven HLT tracking algorithms used to enrich cosmic samples for inner detector studies.

Alan Watson DIS 2009, 26/03/09 25 Trigger Commissioning Energy correlation between L1 calo trigger and precision readout  Random phase of cosmics broadens trigger resolution Muon trigger time from beam data –Difference in endcaps due to ToF –Narrow peaks mean timing otherwise good at ~1 BC level.

Alan Watson DIS 2009, 26/03/09 26 Beam Splash Events Tertiary 140 m Beam 175 m Minimum Bias Trigger Scintillators

Alan Watson DIS 2009, 26/03/09 27 Beam Splash Events Many TeV of energy deposited

Alan Watson DIS 2009, 26/03/09 28 Trigger Timing with Single Beams L1 trigger timing distribution, Sep 10 th BPTX trigger for stable time reference wrt LHC (BC 0) Poor beam quality – large numbers of muon and calorimeter triggers Two-peak structure in TGC (endcap muon) trigger due to time of flight of muons  length of ATLAS ~5 bunch crossings! L1 trigger timing distribution, Sep 12 th Triggered by MBTS (BC 0), which had been timed in relative to BPTX  good overlap between these triggers Few other triggers – indication of improved beam quality. RPC (barrel muon) trigger had not been timed in prior to this run.

Alan Watson DIS 2009, 26/03/09 29 Calorimeter Timing with Beam Tile signal timing Time dispersion within partitions ~2ns Differences between partitions < 1 BC Raw timingTOF corrected Horizontal muons from halo & splash provide checks on timing LAr physics vs calibration pulse timing Measure time from pulse profile + TOF Predict timing from calibration pulses + cables Most agree < 2ns

Alan Watson DIS 2009, 26/03/09 30 Status of the ATLAS Experiment Commissioning of the ATLAS detector started more than 3 years ago Large numbers of cosmic events taken with full detector in 2008 ATLAS successfully took beam data in 2008 Cosmic and beam data very useful for commissioning, calibration, timing and alignment Detector studies continue through the shutdown ATLAS was ready for collisions in 2008 … … we will be in better shape in 2009