ATLAS Experiment at the Large Hadron Collider

1. ATLAS Experimentat the Large Hadron Collider July 2003

2. Large Hadron Collider(LHC) • Located at the CERN, the European Laboratory for Particle Physics • Will be operational by 2007. • Colliding beam accelerator • Collides protons-on-protons(and can also do heavy ions-on-heavy ions). • Center-of-mass energy 14 TeV • High intensity(luminosity), more than 10x current proton-antiproton colliders.

3. Large Hadron Collider(LHC) Main CERN Site

4. LHC Layout and Parameters

5. LHC Magnets • Superconducting dipoles and other magnets guide and focus the proton beams and bring them into collision at multiple points around the ring. • Magnets are cooled by superfluid Helium at 1.9oK to achieve the highest possible magnetic field with the “standard” superconductor used.

6. LHC Technical Component Status • The status of LHC technical components may be seen at http://lhc-new-homepage.web.cern.ch/lhc-new-homepage/DashBoard/index.asp

7. ATLAS Collaboration (Status April 2003)Albany, Alberta, NIKHEF Amsterdam, Ankara, LAPP Annecy, Argonne NL, Arizona, UT Arlington, Athens, NTU Athens, Baku, IFAE Barcelona, Belgrade, Bergen, Berkeley LBL and UC, Bern, Birmingham, Bonn, Boston, Brandeis, Bratislava/SAS Kosice, Brookhaven NL, Bucharest, Cambridge, Carleton/CRPP, Casablanca/Rabat, CERN, Chinese Cluster, Chicago, Clermont-Ferrand, Columbia, NBI Copenhagen, Cosenza, INP Cracow, FPNT Cracow, Dortmund, JINR Dubna, Duke, Frascati, Freiburg, Geneva, Genoa, Glasgow, LPSC Grenoble, Technion Haifa, Hampton, Harvard, Heidelberg, Hiroshima, Hiroshima IT, Indiana, Innsbruck, Iowa SU, Irvine UC, Istanbul Bogazici, KEK, Kobe, Kyoto, Kyoto UE, Lancaster, Lecce, Lisbon LIP, Liverpool, Ljubljana, QMW London, RHBNC London, UC London, Lund, UA Madrid, Mainz, Manchester, Mannheim, CPPM Marseille, MIT, Melbourne, Michigan, Michigan SU, Milano, Minsk NAS, Minsk NCPHEP, Montreal, FIAN Moscow, ITEP Moscow, MEPhI Moscow, MSU Moscow, Munich LMU, MPI Munich, Nagasaki IAS, Naples, Naruto UE, New Mexico, Nijmegen, Northern Illinois, BINP Novosibirsk, Ohio SU, Okayama, Oklahoma, LAL Orsay, Oslo, Oxford, Paris VI and VII, Pavia, Pennsylvania, Pisa, Pittsburgh, CAS Prague, CU Prague, TU Prague, IHEP Protvino, Ritsumeikan, UFRJ Rio de Janeiro, Rochester, RomeI, Rome II, Rome III, Rutherford Appleton Laboratory, DAPNIA Saclay, Santa Cruz UC, Sheffield, Shinshu, Siegen, Simon Fraser Burnaby, Southern Methodist Dallas, NPI Petersburg, Stockholm, KTH Stockholm, Stony Brook, Sydney, AS Taipei, Tbilisi, Tel Aviv, Thessaloniki, Tokyo ICEPP, Tokyo MU, Tokyo UAT, Toronto, TRIUMF, Tsukuba, Tufts, Udine, Uppsala, Urbana UI, Valencia, UBC Vancouver, Victoria, Washington, Weizmann Rehovot, Wisconsin, Wuppertal, Yerevan(151 Institutions from 34 Countries) Total Scientific Authors 1600 Scientific Authors holding a PhD or equivalent 1310

8. International Collaboration

9. ATLAS at CERN http://atlas.web.cern.ch/Atlas/TCOORD/Activities/TcOffice/Scheduling/Installation/UX15webcams.html

10. ATLAS Detector Diameter 25 m Barrel toroid length 26 m End-cap end-wall chamber span 46 m Overall weight 7000 Tons

11. Detect Electrons Muons Taus(not so easy) Photons Jets(will explain) Original quark type(b,c,s) sometimes Neutrinos or other non-interacting particles How? Electromagnetic calorimetry/tracking Absorber/tracking Tracking/calorimeter Electromagnetic calorimetry/tracking Calorimeter/tracking Secondary vertices/tracking Calorimeter What Is Detected? Detection “Onion”

12. Basics of Particle Detection • Liberation and collection(sometimes also amplification) of charge(ionization) in • solid(eg. silicon) • gas(usually argon + other gases) • liquid(eg. liquid argon) • or creation of light by ionization(scintillation) that is converted to charge(eg. by photomultiplier tube) • Followed by amplification(if needed), storage, processing…in electronics elements. • Within ATLAS there are more than 108 individual electronics elements. • This is only possible by the extensive use of integrated circuit technology.

13. Magnets • All are superconducting. • Solenoid magnet(relatively conventional) provides 2 Tesla field for charge particle tracking with high granularity, radiation resistant tracking detectors. • Very large toroids provide field up to about 4 Tesla outside the calorimetry for muon triggering and momentum measurements. • This is the first time superconducting toroids have been used on this scale for high energy physics experiments.

14. Central Solenoid • Field of 2 Tesla. • Fully tested. • Ready at CERN for integration in common cryostat with the Liquid Argon calorimeter by the end of this year.

15. Barrel Toroid • 25.3 m length • 20.1 m outer diameter • 8 coils • 1.08 GJ stored energy • 370 tons cold mass • 830 tons weight • 118 T on superconductor • 56 km Al/NbTi conductor • 20.5 kA @ 4 T nominal current • 4.5 K working point

16. Cold mass #3ready for impregnation Next coil (#4) in preparation Barrel Coil Status First coil test expected to start by August this year.

17. Barrel Toroid Installation Jan ‘04 May ‘04

18. Endcap Toroids First cold mass will be delivered to CERN Oct. 2003 Parameters • 1.65 m bore • 10.7 m diameter • 5m length • 8 coils • 250 MJ stored energy • 160 tons cold mass • 239 tons weight • 4.1 T on superconductor • 26 km Al/NbTi conductor • 65 kA @ 5 T critical current • 20.5 kA @ 4.1 T operating current

19. Endcap Toroid Installation Nov ‘05

20. Calorimeters Tiles HAD LAr EM LAr HAD LAr Forward

21. Hadron Tiles Hadron LAr EM LAr Endcap cryostat Solenoid Forward LAr Barrel cryostat Calorimetry Overview • Ionization created by electromagnetic(EM) showers(in lead mostly) is detected in liquid argon. Electromagnetic Shower

22. Barrel Hadronic Calorimetry Photomultiplier Tube Preassembly on surface well advanced Scintillating Fiber Scintillating Tile Steel

23. EM Calorimetry Photon Resolution

24. EM Barrel Assembly LAr EM half barrel after insertion into the cryostat LAr EM barrel assembly

25. h=1.9 a = 10.35%0.05 b = 0.27%0.02  E/E (%)  E/E (%) h=0.3375 a = 9.24%0.10 b = 0.23%0.04 E beam (GeV) E beam (GeV) EM Energy Resolution • Test beam results End-cap Barrel

26. Liquid Argon Hadronic Endcap • Planar electrode geometry. • Copper absorber Assembly of a HEC wheel (horizontal) Assembled wheels in insertion stand (vertical)

27. Forward Calorimeters • Liquid argon with rod electrodes in metal matrix.

28. Barrel Calorimeter Installation • Underground installation will be well into full operation by about a year from now. May ‘04 Sep ‘04

29. Muon System • Trigger chambers: • 1136 RPCs in the barrel • 3574 TGCs in the end-caps barrel chambers (MDT, RPC) 17% assembled small wheel (MDT, TGC, CSC) 57% assembled • Precision chambers: • 1165MDTsin the barrel and end-caps • 32 CSCs at large  in the innermost end-cap stations 55% assembled EO fixed wheel (MDT) 18% assembled 4 big wheels (MDT, TGC)

30. Muon Detection • Muon penetrate material(calorimetry) • Detector outside the calorimeter • Measure momentum • Extrapolate back to use tracking inside solenoid.

31. Muon Tracking/Triggering • Very large area. Rates(including backgrounds) depend strongly on  => different technologies at small and large . • MDT – Monitored Drift Tubes(5500 m2) • Aluminium tubes of 30 mm diameter and 400 mm wall thickness, with a 50 mm diameter central W–Re wire. The tubes are operated at 3 bar absolute pressure and have a single-wire resolution of ~80 mm. • CSC – Cathode Strip Chamber(25 m2) • Multiwire proportional chambers with cathode strip readout. The precision coordinate is obtained by measuring the charge induced on the segmented cathode and is ~60 mm. • RPC – Resistive Plate Chambers(3600 m2) • Gaseous detector providing a typical space–time resolution of 1 cm ´ 1 ns with digital readout. The basic RPC unit is a narrow gas gap formed by two parallel resistive bakelite plates, separated by insulating spacers. • TGC – Thin Gap Chambers(2900 m2) • Similar in design to multiwire proportional chambers. Signals from the anode • wires, arranged parallel to the MDT wires, provide the trigger information together with readoutstrips arranged orthogonal to the wires. Note that areas are module areas, not individual plane areas.

32. Monitored Drift Tubes • Tubes arrayed with high precision and glued together to form large modules. • In-situ module alignment is monitored by optical system. • About 1000 B-field probes Axial lines (RASNIK) Projective lines (RASNIK)

33. CSC, RPC and TGC • Muon components well into production • Storage, reception and surface integration underway at CERN. RPC chamber production CSC chamber production TGC chamber production

34. Muon Reconstruction Higgs ->4

35. Interleaved with installation of other subelements. Very many parts to be installed underground! Services for rest of detector pass through muon system. Like a complicated building. Muon Installation Dec ‘04

36. Inner Tracking Detector • Straw-tube tracking with Transition Radiation(TRT) • Silicon strip detector(SCT) • Silicon pixel detector(PIX) End view of simulated event

37. Initial Inner Tracking • Combined technologies to allow tracking a 1034. Transition Radiation Tracker Silicon Strip Detector Pixel Detector

38. End-cap Straws Radiator End-cap Radiator Straws Transition Radiation Tracker • 4mm straws • Small drift tubes • Combined tracking and sensitivity to transition radiation X-rays for e-hadron identification

39. Silicon Strip Detector • About 6x106 channels. • 60m2 of silicon. • Radiation hardness up to 10 MRad • About 4000 modules. • Integration of modules on to mechanical structures later this year. • LBNL is building modules.

40. Silicon Pixel Detector • LHC radiation levels at 1034cm-2sec-1 prevent long-term operation of silicon strip detectors for R< 25 cm. • Pixel size 50x400 • About 108 channels • About 1,200 modules LBNL is building large part of Pixel Detector

41. Pigtail (beyond) Sensor ASICs Flex Hybrid Bumps Wirebonds Schematic Cross Section (through here) Silicon Pixel Detector

42. Pixels are separate unit integrated with beam pipe and lowered in April ‘06 Barrel and two endcap sections are integrated on the surface. Lowered and installed as units. Inner Detector Installation Sep ‘05

43. ATLAS Channels Muon system Calorimetry Inner detector Trigger

44. 120 GB/s ~3+3 GB/s ~ 300 MB/s Trigger/Data Acquisition • LEVEL 1 TRIGGER • Hardware-Based (FPGAs ASICs) • Coarse granularity from calorimeter & muon systems • 2 s latency (2.5 s pipelines) 40 MHz 75 kHz 2 kHz 200 Hz • LEVEL 2 TRIGGER • Regions-of-Interest “seeds” • Full granularity for all subdetector systems • Fast Rejection “steering” • O(10 ms) latency • EVENT FILTER • “Seeded” by Level 2 result • Potential full event access • Offline-like Algorithms • O(1 s) latency High Level Trigger

45. Example of High Level Triggers

46. Underground Assembly Components Construction Systems Integration on Surface ATLAS Schedule commissioning USA15 UX15 97 99 01 03 05 07

47. Software and Computing • Deserves a talk by itself – complex organization(see next page) • Development of software and implementation of computing resources driven by mock-data challenges (DC) up to turn-on of LHC. • DC0 and part of DC1 complete • DC2: mid-2004, like DC1 in scale • Computing Technical Design Report by mid-2005 • DC3: end 2005. • Physics Readiness Report by mid-2006

48. ATLAS Computing Organization New organization since last year LBNL

49. Education and Outreach M. Barnett from LBNL coordinates these activities for ATLAS

50. Where Are We Today? • Completion of the detector components is proceeding well, many components already at CERN. • Installation underground has just started and will continue for about three more years. • Significant data challenges have been completed to begin to use and validate the simulation and analysis software. Very substantial work ahead. • The focus of the collaboration has started to turn to how to commission the detector and how to extract early physics results.