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ATLAS detector commissioning with cosmics and first beam

ATLAS detector commissioning with cosmics and first beam. Alessandro Cerri on behalf of the ATLAS collaboration. Talk Outline. Introduction Status of ATLAS Commissioning of the detector with cosmic rays First beam …plans? Please see later at this conference:

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ATLAS detector commissioning with cosmics and first beam

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  1. ATLAS detector commissioning with cosmics and first beam Alessandro Cerri on behalf of the ATLAS collaboration

  2. Talk Outline • Introduction • Status of ATLAS • Commissioning of the detector with cosmic rays • First beam • …plans? Please see later at this conference: • D. Sampsonidis: “early ATLAS physics” • WeinaJi: “B hadron properties @ LHC” • A. Dewhurst: BsJ/ψϕ with ATLAS and CMS • S. Chouridou: “expected performance of the ATLAS inner detector”

  3. Talk presentedonbehalfoftheATLAS Collaboration 37 Countries 169 Institutions ~2800 Scientific Authors (~800 PhD students) Cambridge, Carleton, Casablanca/Rabat, CERN, Chinese Cluster, Chicago, Chile, Clermont-Ferrand, Columbia, NBI Copenhagen, Cosenza, AGH UST Cracow, IFJ PAN Cracow, UT Dallas, DESY, Dortmund, TU Dresden, JINR Dubna, Duke, Frascati, Freiburg, Geneva, Genoa, Giessen, Glasgow, Göttingen, Albany, Alberta, NIKHEF Amsterdam, Ankara, LAPP Annecy, Argonne NL, Arizona, UT Arlington, Athens, NTU Athens, Baku, IFAE Barcelona, Belgrade, Bergen, Berkeley LBL and UC, HU Berlin, Bern, Birmingham, UAN Bogota, Bologna, Bonn, Boston, Brandeis, Bratislava/SAS Kosice, Brookhaven NL, Buenos Aires, Bucharest, LPSC Grenoble, Technion Haifa, Hampton, Harvard, Heidelberg, Hiroshima, Hiroshima IT, Indiana, Innsbruck, Iowa SU, Irvine UC, Istanbul Bogazici, KEK, Kobe, Kyoto, Kyoto UE, Lancaster, UN La Plata, Lecce, Lisbon LIP, Liverpool, Ljubljana, QMW London, RHBNC London, UC London, Lund, UA Madrid, Mainz, Manchester, CPPM Marseille, Massachusetts, MIT, Melbourne, Michigan, Michigan SU, Milano, Minsk NAS, Minsk NCPHEP, Montreal, McGill Montreal, FIAN Moscow, ITEP Moscow, MEPhI Moscow, MSU Moscow, Munich LMU, MPI Munich, Nagasaki IAS, Nagoya, Naples, New Mexico, New York, Nijmegen, BINP Novosibirsk, Ohio SU, Okayama, Oklahoma, Oklahoma SU, Olomouc, Oregon, LAL Orsay, Osaka, Oslo, Oxford, Paris VI and VII, Pavia, Pennsylvania, Pisa, Pittsburgh, CAS Prague, CU Prague, TU Prague, IHEP Protvino, Regina, Ritsumeikan, UFRJ Rio de Janeiro, Rome I, Rome II, Rome III, Rutherford Appleton Laboratory, DAPNIA Saclay, Santa Cruz UC, Sheffield, Shinshu, Siegen, Simon Fraser Burnaby, SLAC, Southern Methodist Dallas, NPI Petersburg, Stockholm, KTH Stockholm, Stony Brook, Sydney, AS Taipei, Tbilisi, Tel Aviv, Thessaloniki, Tokyo ICEPP, Tokyo MU, Toronto, TRIUMF, Tsukuba, Tufts, Udine/ICTP, Uppsala, Urbana UI, Valencia, UBC Vancouver, Victoria, Washington, Weizmann Rehovot, FH Wiener Neustadt, Wisconsin, Wuppertal, Würzburg, Yale, Yerevan

  4. The ATLAS Detector The ATLAS Collaboration, G. Aad et al., The ATLAS Experiment at the CERN Large Hadron Collider, JINST 3 (2008) S08003

  5. The ATLAS Inner Detector Tracking ||<2.5 B=2T Pixel Silicon pixels(Pixel) : 80 106 channels Silicon strips(SCT) : 6.3 106 channels Transition Radiation Tracker(TRT) : straw tubes (Xe), 3.5 105 channels e/separation Resolutions:/pT ~ 1.5%  3.4x10-4pT(GeV) d0 ~ 10  140 / Pt (GeV) μm TRT SCT

  6. The ATLAS barrel tracker goes in place (August 2006)

  7. Muons in ATLAS MDT Stand-alone momentum resolution Δpt/pt < 10% up to Eμ ~ 1 TeV 2-6 Tm ||<1.3 4-8 Tm 1.6<||<2.7 Barrel:~650MDT (Monitored Drift Tubes) precision chambers for track reconstruction,~550RPC (Resitive Plate Chambers) for trigger Barrelchambers

  8. Forward Muon Detectors September 2007 Big wheels (and end-wall wheels): ~500 MDT precision chambers and ~3600 TGC (Thin Gap Chambers) trigger chambers Small wheels: 32 CSC (Cathode Strip Chambers) precision chambers + ~80 MDT February 2008

  9. October 2005: full barrel toroid is in place 8 superconducting coils, 25 m long, 100 ton each, I=20.5 kA, T=4.5 K ATLAS Magnets System Since August 2008, the full magnet system (barrel toroid, end-cap toroids and central solenoid) has been operated at full current for long periods June-July 2009 Planned short runs, not quenches!

  10. Calorimetry ||<5 Barrel em HadronicEndcap Electromagnetic Calorimeter Barrel, Endcap:Pb-LAr E~10%/√E for e/γ 170000 channels: longitudinal segmentation HadronCalorimeter Barrel:Iron-Tile EC/Fwd:Cu/W-LAr (~19000 channels) /E ~ 50%/E  0.03 (~10 ) Trigger and measurements for e/γ, jets, Missing ET Tile

  11. The ATLAS Trigger/DAQ infrastructure Level-1 Trigger Calorimeter Muon System Hardware based Coarse granularity Front End Electronics Readout Drivers Level-2 Trigger RoI e/γ, , jet, .. Full granularity in RoI ~ 500 PC (multi-core) Readout SystemCustom built buffers in PC farm High Level Trigger (HLT) Event Filter ~1800 PC (multi-core) High bandwidth Data Network Event Building More PC farms on Data Network 300 MByte/s to Computer Center ~3 Pbytes stored / year DAQ software Control, configuration, monitoring on Control Network

  12. In total about 300 racks with electronics in the underground counting rooms Today: 850 HLT PCs installed (35% of what we plan for high luminosity) The ATLAS Trigger and DAQ systems have been extensively exercised since early 2008 running simulated data through the DAQ chain, as well as with several periods of cosmic rays data taking! Level-1 Trigger racks

  13. Computing! ATLAS world-wide computing: ~ 70 sites (including CERN Tier0, 10 Tier-1s, ~ 40 Tier-2 federations) • Amazingoperational challenges: • ~ 50 PB of data to be moved across the world every year • 109raw events per year to be processed and reprocessed • Complex Computing Model • Operation and computing models havebeen stress-tested and refined over the last years through functional tests and data challenges of increasing functionality, size and realism.

  14. ATLAS was ready for LHC data-taking in August 2008 • August-October 2008: global cosmics runs (with full detector operational) • (~ 500 M events collected, 1.2 PB of raw data) • September 2008:single-beam events recorded • October 2008: detector opened formaintenance, consolidation, a few repairs • June 2009: closed again • End June 2009:global cosmics runs restarted(100 M events collected) On June 16th 2008 the last piece of the LHC beam pipe ring is put in place, in the ATLAS cavern

  15. 10 September 2008, ~10h am: waiting for first beams

  16. tertiary collimators 140 m Beam pick-ups (BPTX) (175 m) 10 September 2008, 10:19h am: first ATLAS ‘beam splash’ event recorded Beam bunches (2x109 protons at 450 GeV) stopped by (closed) collimators upstream of experiments  “splash” events in the detectors (debris are mainly muons) ~ 100 TeV in the detector !

  17. First beam: trigger timing 10 September 12 September • Remember: ATLAS is 6 LHC bunch crossings (25 ns each) across!!! • Various systems aligned in time using beam pick-ups (BPTX) as reference • Signal times of various triggers adjusted to match the BPTX reference • Few splash events meant a jump in quality with respect to cosmic rays for detector timing! Note different scale RPC not adjusted

  18. ATLAS Commissioning with Cosmics Cosmic events collected from mid September to end October 2008

  19. A “typical” cosmic ray seen by ATLAS • Commissioning • with cosmics: • Debug the • experiment • fix problems • First calibration • and alignment • studies • Gain global • operation • experience in • situ Cosmics rate in ATLAS: 1-700 Hz(varies withsub-detector size and location) Achieved precisions far better than expectations at this stage

  20. Commissioning with cosmics: plenty of results!

  21. Extrapolation to the surface of cosmic muon tracks 18m 12m (from RPC trigger chambers) Access shafts Lifts Full calo readout LVL1 calo trigger Muon (shower) energy measured with full calorimeter readout vs energy measured in trigger towers (x=0.1x0.1) by level-1calorimeter trigger. [Initial calibration: final one will reduce spread LVL1 trigger towers

  22. Trigger on cosmics Efficiency of the track trigger at level-two vs track impact parameter ~ 5 M cosmics events selected by this trigger ATLAS L1 and HLT triggers have reliably collected, selected and rejected 100s of millions of events! Curves reflect the different geometrical acceptance of the various sub-detectors Radial impact parameter d0 (mm) • Difference in η between the Event Filtermuon and the offline reconstructed muon • Good agreement, width of fitted Gaussian = 0.007 • Tails understood, due to slightly different configuration online vs offline η difference: event filter - offline

  23. ID alignment and B-field measurement Solenoid B-field mapping campaign 2006: precision of 2x10-4 (4 Gauss) achieved Pixel detector alignment with cosmics data MC (perfect detector) residuals after alignment Both are essential ingredients for precise measurements of tracks and knowledge of absolute momentum scale to << 0.1% (e.g. for W-mass measurement) residuals before alignment Distance (mm) between fitted track and hits in the individual layers 250 000 points measured (5 currents) • Pixels, SCT: achieved with cosmics: • alignment precision: ~ 20 m (ultimate goal 5-10 m) • alignment stability Oct-2008-June-2009: few microns • layer hit efficiency: > 99% ; pixel occupancy: 10-10

  24. ID track reconstruction • Cosmic rays allow direct measurement of track resolutions: • Cosmic tracks cross both the upper and lower hemisphere of the ID • Splitin the center and refit tracks separately Impact parameter resolution Momentum resolution Already close to ideal detector performance!

  25. Muon Spectrometer Alignment Cosmics data, field off • Muon spectrometer is basically another tracking system! • Alignment needed to achieve nominal performance • Study unbiased residuals at different alignment stages • Alignment procedure successfully tested on cosmic ray tracks Combination of segments on outer layers

  26. ID and Muon Spectrometer Correlation Muon coordinate Muon Spectrometer Inner Detector Difference between the muon momentum measured in the ID and in the MS for tracks in the bottom part of the detector (energy lost in the calorimeter: ~ 3 GeV as expected) ΔMuon momentum (ID-MS) [GeV/c]

  27. ATLAS Detector Status Overall data taking efficiency: already ~ 83% during the latest cosmic weeks [6-14 hour long simulated LHC stores in July 2009]

  28. Expectations with 100 pb-1 Note: expect up to 200 pb-1 after first physics run at high energy few pb-1 Goals in 2010: 1)Commission and calibrate the detector in situ using well-known physics samples e.g. - Z ee,  tracker, ECAL, Muon chamber calibration and alignment, etc. - ttblbjjjet scale from W jj, b-tag performance, etc. 2)“Rediscover” and measure Standard Model at LHC:W, Z, tt, QCD jets … (also because omnipresent backgrounds to New Physics) 3) Early discoveries ? Potentially accessible: Z’, SUSY, …. surprises ? 50 pb-1 100 pb-1 ….

  29. ATLAS performance on Day 1

  30. Pending Issues • Calibrations, alignments etc. (previous slide) • Finalization of trigger timing • needs beam events • Concerns: long term reliability of • Low Voltage power supplies • LAr readout optical links • Inner detector cooling Back-up solutions are being prepared for future shut-down periods

  31. Conclusion • ATLAS in excellent shape • O(10-3) non-working channels!!! • 0.5B cosmic and “few” single beam events: • Detector performance above expectations • Procedures and people trained to operate the detector • Software and computing ready to simulate, analyze and distribute data! Ready for the challenge of LHC collisions!

  32. Backup

  33. The Transition Radiation Tracker Transition radiation intensity is proportional to particle g-factor. The onset at high g( E~100 GeV for muons) is observed with cosmic muons as compared to test beam results.

  34. Performance on Day 1

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