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Status and Prospects of the CMS Experiment at the LHC

Status and Prospects of the CMS Experiment at the LHC. Darin Acosta University of Florida. Including LHC highlights. The CMS Collaboration.

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Status and Prospects of the CMS Experiment at the LHC

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  1. Status and Prospects of the CMS Experiment at the LHC Darin Acosta University of Florida Including LHC highlights

  2. The CMS Collaboration • 3000 scientists and engineers are involved in this huge project, coming from 183 institutes in 38 countries spanning Europe, Asia, the Americas and Australasia. • Southeast U.S. collaborating institutes on CMS: • Florida: • Florida International University, Florida Institute of Technology, Florida State University, University of Florida • Mississippi: • University of Mississippi • Tennessee: • Vanderbilt University • Virginia • University of Virginia The CMS Experiment - SESAPS08 - D.Acosta

  3. The Large Hadron Collider (LHC) • 7 TeV on 7 TeV proton-proton collider, 27km ring • 7 times higher energy than the Tevatron at Fermilab • Aim was for 5 TeV in 2008 • 100 times higher design luminosity than Tevatron (L=1034cm-2s-1) • 1232 superconducting 8.4T dipole magnets @ T=1.9ºK • Largest cryogenic structure, with 40 ktons of mass to cool • 4 experiments • Start Date:Sept. 10,2008 The CMS Experiment - SESAPS08 - D.Acosta

  4. Reasons for the LHC: Puzzles in Particle Physics • The precision of calculations in the Standard Model of particle physics depends on the Higgs mechanism in the theory, which generates mass for particles • But the associated Higgs boson has not yet been directly observed. • Need higher energy and higher luminosity to increase production yield • The Higgs mass must be fine-tuned to extremely high precision, as it receives radiative corrections to its mass in calculations • Protected by Supersymmetry ? • A symmetry sort of like antimatter, but with opposite spin rather than charge (bosons  fermions) • Not observed, so presumably at a higher energy scale • Protected by other new forces/particles? (Z’, W’, technicolor) • Protected by (compactified) extra dimensions? • Any unification of the fundamental forces? • What is the dark matter in the universe ? • Supersymmetry can lead to stable massive neutral particles The CMS Experiment - SESAPS08 - D.Acosta

  5. Clues • Nice consistency of direct mass measurements with indirect precision electroweak measurements  both point to a “light” Higgs • Light Higgs indicates new physics must come in for consistency of theory • Light Higgs (<135 GeV) can be accommodated by Supersymmetry Mass of W, carrier of weak force (radioactivity) Mass of the Higgs boson PDG, 11/2007 Mass of the top quark (heaviest) The CMS Experiment - SESAPS08 - D.Acosta

  6. LHC Start-up: Sept.10, 2008 Carlo Rubbia: Nobel laureate and former CERN director who launched the LHC Lyn Evans, LHC Project Leader

  7. A Brief Diary of LHC Events • Aug. 8 and Aug. 22 Weekends • “Synchronization tests” sent protons through the first arcs of the LHC in both directions, past ALICE and then LHCb experiments • By Aug.22, alternate injections of beam 1 and 2: “…pretty blooming amazing…” • Sun/Mon, 7-8 Sept. • Single shots of beam 1 onto a collimator 150m upstream of CMS. • Tues, 9-Sept • Additional single shots of beam 1 onto a collimator at CMS • Wed., 10 Sept. (Media Day!) • Beam 1 circulated in the morning, 3 turns by 10:40am (1 hour!) • Beam 2 circulated by 3:00pm • 300 turns of beam 2 by 11:15pm • Thurs., 11-Sep. • RF system captures beam at 10:30pm (millions of orbits) The CMS Experiment - SESAPS08 - D.Acosta

  8. Sept.10 – Big Media Day The CMS Experiment - SESAPS08 - D.Acosta

  9. Beams circulated at injection energy of 0.45 TeV on Sept.10 Separately, no collisions afternoon morning The CMS Experiment - SESAPS08 - D.Acosta

  10. Sept.10 orbits • 2 turns of clockwise beam: ~2x109 protons The CMS Experiment - SESAPS08 - D.Acosta

  11. Sept. 11 Beam Capture Wrong phase No RF orbit Time window Wrong frequency Captured! The CMS Experiment - SESAPS08 - D.Acosta

  12. Setback: Friday, Sept.19 • An incident occurred during a powering test of one LHC sector for commissioning beam operation to 5 TeV • Massive helium loss in one arc of the tunnel (2 tons initially), cryogenics and vacuum lost • The cause of the incident was determined to be a faulty electrical connection (“bus bar”) between a dipole and a quadrupole • Mechanical damage occurred • Need to extract and repair dipole and quadrupole magnets in the region • Not enough time to make repairs before winter shutdown Aim to restart LHC operations mid-2009 The CMS Experiment - SESAPS08 - D.Acosta

  13. Components of a Collider Detector • Surround the collision point with instruments in order to identify the types of particles and their energy or momentum to reconstruct collisions Tracking detectors Magnet Calorimeters Muon detectors The CMS Experiment - SESAPS08 - D.Acosta

  14. The Compact Muon Solenoid Experiment Conceived 1992 4T solenoid Muon chambers Forward calorimeter Silicon Strip & Pixel Tracker PbWO4 Crystals Hadronic calorimeterBrass/Scintillator The CMS Experiment - SESAPS08 - D.Acosta

  15. And in reality… muon detectors Hadron calorimeter being inserted (for energy measurements) magnet March 2007 The CMS Experiment - SESAPS08 - D.Acosta

  16. Preassembled muon detector structures lowered into the cavern (1000-2000 ton structures!) Endcap disks:January 2007 to January 2008 Barrel wheels:Jan. – Oct. 2007 The CMS Experiment - SESAPS08 - D.Acosta

  17. CMS Electromagnetic Crystal Calorimeter 76K PbWO4 crystals for fine electron/photon energy measurements More crystals (in volume or number) than in all previous HEP experiments combined Barrel production and installation completed 27 July 2007 Endcap production complete and inserted 1 August 2008  The CMS Experiment - SESAPS08 - D.Acosta

  18. Silicon Strip Tracker, Dec 2007 Cabling completed March 2008 200 m2 of sensor coverage, 11M strips (Charged particle tracking) 10 times more coverage than CDF silicon detector The CMS Experiment - SESAPS08 - D.Acosta

  19. Installation of the Pixel System, August 2008 • A 66 megapixel “camera” ! • Makes precise measurements of charged particle impact parameters to tag particles with a small but finite lifetime The CMS Experiment - SESAPS08 - D.Acosta

  20. CMS Completed!August 25, 2008 – 16 years after its Letter of Intent Ready for the LHC The CMS Experiment - SESAPS08 - D.Acosta 20

  21. Detector Commissioning Exercises • In Fall 2006 we had the first magnet test and data-taking with a slice of the experiment for about 2 months • Since May 2007, periodic exercises of 3-10 days have been devoted to global commissioning exercises with installed detectors and electronics underground, ultimately using final power/cooling in the underground experiment cavern and the service cavern • Balancing the need to continue installation and local commissioning activities with the need for global system tests • The incremental goals from one run to the next focus on increased complexity and increased scale. • Frequency of runs increased as we headed to LHC start-up, where CMS ultimately became a 24/7 running experiment ready for beam The CMS Experiment - SESAPS08 - D.Acosta

  22. Fraction of CMS Systems in Global Runs Pixel system and ECAL endcaps installed Muon Cabling complete, final power & cooling become available Cooling ready for Strip Tracker The CMS Experiment - SESAPS08 - D.Acosta

  23. Cosmic ray muons used as probe of detector performance during Global Runs (no beam!) Total rate is about 350 Hz at 100m depth (about 1% of rate on surface of Earth) The CMS Experiment - SESAPS08 - D.Acosta

  24. Global Detector Readout • Muon signals traced through • muon system • Strip Tracker (and pixels when close to beam pipe) • ECAL • HCAL • Requires synchronization of all electronic signals • Global track fit can be used for alignment and detector performance studies Muon System ECAL Tracker HCAL The CMS Experiment - SESAPS08 - D.Acosta 24

  25. Tracks crossing the pixel tracking system • Rate < 0.1 Hz • Need a LOT of data to align sensors • But tracks going through the small pixel detector resemble those from collisions First cosmic tracks with Pixels The CMS Experiment - SESAPS08 - D.Acosta 25

  26. The Excitement of the First LHC Beam Measurements at CMS! (September 2008) The CMS Experiment - SESAPS08 - D.Acosta

  27. Beam Splash Events • Beam with 2x109 protons dumped onto a target (collimator)150m upstream of CMS • Sept. 7,9,10,18 • Leads to a “tsunami” wave of O(100K) muons coming down the tunnel! • A far cry from the single cosmic muon events… • CMS was ready for this challenge given its extensive commissioning program beforehand • Electronic triggers and data acquisition worked well TCTH TCTV TCLP TAN MBRC debris CMS p 146 m The CMS Experiment - SESAPS08 - D.Acosta

  28. Different projections of a “splash” event HCAL energy ECAL energy particle debris Longitudinal views DT muon chamber hits Transverse views Inner silicon tracking systems kept OFF The CMS Experiment - SESAPS08 - D.Acosta

  29. ME1 ME2 ME3 ME4 Note shape of tunnel Halo Muons(from proton beams passing through CMS) Muons associated with beam (but outside beam pipe) arising from the decays of pions created when off-axis protons scrape collimators or other elements along beamline A useful tool for detector alignment and time synchronization  More details on triggering on these muons, and their rates, in presentation by J.Gartner The CMS Experiment - SESAPS08 - D.Acosta

  30. Now: Cosmic Run at Four Tesla (CRAFT) • In the rush to install the last components of CMS and to close the experiment, CMS did not manage to re-commission its magnet to 3.8T underground, nor record a significant amount of data at full field before LHC start-up • Magnet was commissioned in 2006 while experiment was in the surface assembly hall • Only short tests up to 3T underground took place • Now without the LHC for the rest of 2008, CMS continues its program with a month-long exercise to collect cosmic muons with B=3.8 T • Aim for 300M cosmic events for analysis, equaling the sample size we have collected at zero field • Run 24/7 for 1 month to refine operations even without beams to improve readiness for LHC next year The CMS Experiment - SESAPS08 - D.Acosta

  31. CRAFT Statistics, Oct.16 – 29 • In 2 weeks surpassed 150M events, 50% of our goal • Reached 100% data-taking efficiency over 24h [average 55%] This week: 24h run Tue-Wed 16h runSat-Sun The CMS Experiment - SESAPS08 - D.Acosta

  32. F=q(v×B) From which p = qBr The CMS Experiment - SESAPS08 - D.Acosta

  33. Cosmic Charge Ratio Measurement CMS NOTE-2008/016DT Muon system measurement Aim to improve upon 2006 measurement using CRAFT data and full detector The CMS Experiment - SESAPS08 - D.Acosta

  34. Physics Preparation: Calibration and Alignment • Alignment • Need the strip tracker modules aligned to about 20m precision, whereas the placement precision for structures is about 1mm • Significant progress using cosmic muons to align components • Better than 50m precision for about half of central Tracker • Will improve with CRAFT data and with LHC collision data • Energy calibration: • Hadron calorimeter: 5% precision confirmed with cosmic rays • Electromagnetic calorimeter (Central region): • 0.3% precision for 1/4 of barrel (dedicated beam tests) • 1.5 - 2.5% on remaining 3/4 from cosmic rays • Methods to cross-check or improve precision using first LHC collisions • Isolated charged particles with momentum measured by Tracker • Average energy flow • “Resonances” (particles decaying to photons, electrons) • Expect sufficient precision for LHC startup physics ! The CMS Experiment - SESAPS08 - D.Acosta

  35. ? Possible reach for 2009 ? Glimpse of Discovery Physics: Z′→ee, µµ New force search simulated Tevatron reach The CMS Experiment - SESAPS08 - D.Acosta

  36. Glimpse of Discovery Physics: Supersymmetry • Large missing momentum from escaping invisible particles • Classic signature of minimal supersymmetric models with a dark matter candidate • Energetic “jets” from supersymmetric particle decays • Similarly extend reach well past the Tevatron simulated The CMS Experiment - SESAPS08 - D.Acosta

  37. Summary of Discovery Prospects in SUSY • Squark and gluino masses up to about 2 TeV with 10 fb-1, 2.5 TeV ultimately at LHC Various search topologies 2009 reach ? ? Tevatron reach The CMS Experiment - SESAPS08 - D.Acosta

  38. Summary & Outlook • The CMS experiment was completed and ready in time for the LHC this year • Definitely a non-trivial accomplishment! • Already made maximum use of the limited time with LHC beams • The LHC setback is disappointing, but not surprising given the complexity and scale • The rapid pace of LHC start-up commissioning bodes well for next year! • CMS is focused on collecting a large cosmic dataset with its magnet at full strength (3.8T) for the next month • Continue exercising experimental procedures to improve readiness for 2009 • Refine knowledge of detector performance in preparation for physics studies • Even more eagerly awaiting to launch the LHC, and studying physics at the TeV frontier! The CMS Experiment - SESAPS08 - D.Acosta

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