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The BArreL MUON SYSTEM Of cms

The BArreL MUON SYSTEM Of cms. International Meeting on Fundamental Physics El Escorial April 5th 2006. Marcos Fern ández García Universidad Autónoma de Madrid. Length: 21.6 m Diameter: 14.6 m 12500 Tons Ready to close: 30th July 2007. CMS at a glance. Tracker @ -20ºC

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The BArreL MUON SYSTEM Of cms

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  1. The BArreL MUON SYSTEM Of cms International Meeting on Fundamental Physics El Escorial April 5th 2006 Marcos Fernández García Universidad Autónoma de Madrid

  2. Length: 21.6 m Diameter: 14.6 m 12500 Tons Ready to close: 30th July 2007 CMS at a glance Tracker@ -20ºC Pixel: =10(20) µm r (z) Strip Tracker: µstrips Silicon  TIB~20 µm,TOB~40 µm ECAL: PbWO4 crystals, short 0 and fast response, but low light yield Intrinsic gain photodetectors: Silicon APD barrel,VPT for EE Electrons: (E)/E~0.5-1%(E>20 GeV) Solenoid: Superconductor 4T L=13 m, 5.9 m Magnetic Field returns through iron yoke HCAL: Brass+plastic scint. tiles readout by WLS+CF Hadronization leaks after magnet caught by scint Hadron Outer (barrel) HCAL Energy resolution: Pions (E)/E~20%@50 GeV, ~15%(E>100 GeV) Trigger: Approx. 20 ev/bx @ L=1034/cm2s bx=40Mhz  109 ev/s L1 FPGAs,ASICs, 312 µs output rate 105 Hz Decision photon,e,µ,jets > pT cuts HLT output 100 ev/s Reduction info, farm CPUs Muon System: key for trigger. 250 DTs, 540 CSCs, 912 RPCs in 12 sectors Moderate pT resolution(comp. tracker) Barrel: <1.2, B< & uniform, R(µ) 1 Hz/cm2, R(n bkgd)=1-10 Hz/cm2 Endcaps: 0.9<<2.4, B upto 3.5T, R(µ)200 Hz/cm2,R(n bkgd)<1kHz/cm2 RPC:t~1 ns, identification bx

  3. CMS three years ago

  4. CMS now: MUONS YB-0 YB-1 Assembled on surface at point 5 in LHC ring YB+2 Barrel~50% installed YE+1 Forward HFCAL (cabled) CSCs all @ CERN (>80% cosmics comm.) YB+2 YE+1 CSCs

  5. CMS now: Magnet + HCAL Magnet closed Cooled down Coil powered May YB+0 Magnet outer case+SC HCAL on its transport structure Completed, 1st lowered HCAL slid inside magnet bore Transport structure (will be removed)

  6. =0 =1.5 Muon measurement Muons measured in 3 different ways (central muons with enough pT): 1) In the Inner Tracker 2) With the muon system 3) Inner Tracker+ Muon System Muons are measured at the tracker with higher resolution. Why using Muon Chambers anyway? Easier to find muon in the chambers than in the tracker. Once found in the barrel, the track is extrapolated backwards The L1 trigger (decision taken 128 bx after current event) can not wait for tracker reconstruction Tracker will not be fully aligned at the beggining of the experiment. Muons measured only using Muon System

  7. Øwire =50 µm Wire positioning error=100 µm Cell spatial resolution=250 µm = 1800 Vstrip Vwire Vbeams 5 electrostatic elements = 3600 =-1200 Why Ar/CO2 (85/15)%? Ar=monoatomic  e– undergo only elastic scattering with low energy loss Only Ar  excited atoms emit photons which induce new avalanches  discharges CO2 quencher required. Absorbs photons Time (ns) Avalanche Constant vd Muon chamber’s core: Drift cell Muon chambers Actually they are ionization gas detectors. They detect only muons, because these are the only (charged) particles reaching that far in CMS. Drift Cell: Muon ionises the gas Electrodes shape the field Constant drift velocity (roughly 50 µ/ns) TDC  µ crossing position known

  8. Muon Chamber, cabled on cosmic calibration bench Scintillator trigger panels R 150 µm   200 µm Angle=1 mrad Muon chambers Half cell staggering solves the left-right uncertainty A superLayer is just 4 layers of staggered cells (not scaled) 3 SLs  Muon Chamber 2  Honeycomb 1 RPC

  9. Muon Chambers in Level 1 trigger system On-chamber Local Trigger Logic 1 2 1 • Muon L1 Trigger based on custom electronics Local trigger (on-chamber): BTI: alignment in 4 layers, bx identification TRACO: Combines segments from the  SLs. TS: Selects best two segments/chamber Regional trigger (off-chamber) Track Finder: Connects segments of chambers in sector Assigns pT, angle and quality Regional Trigger

  10. Vincenzo INFN Bo J. Puerta CERN + Vittorio (INFN Bo), G. Fetchenhauer (Aa) (…) S. Di Vincezo CERN J.M. Ahijado CIEMAT A. Benvenuti INFN Bo M. Chamizo CIEMAT Chamber certification at the ISR lab ReceptionCertification Installation Commissioning Muon chamber storage and certification area at CERN uses the (dismantled) ISR facility Note: ISR was the world’s first pp collider (1971-1984), 62 GeV cdm, record L @ hadron collider till 2004 As of March 2006, 117 chambers pending for installation (133 already certified and installed) Currently 3 physicist, one engineer, 2-3 technicians devoted full time to this task Chamber certification process takes approx. 2 months. With current buffer of chambers, we certify 2-3 chambers/week After certification, chambers are installed at a rate of 2-4 chambers/day (depends on schedule) After installation chambers are commissioned in the wheels, approx. 5 chambers/week Work acknowledged to all those pictured below, as well as casual collaborators from institutes

  11. Survey Reception Unload Storage Gas MF HV Cables PADC Chamber dressing Chamber Certification @ ISR STEP I

  12. Intervention Intervention Currents time Cosmics Problem identification Chamber Certification @ ISR STEP II 2-3 interventions/chamber

  13. From ISR to SX5 Insertion Commissioning Insertion

  14. …and actually, everything works Commissioning of 2 sectors simultaneously Trigger logical AND of all 4 chambers (across 2 sectors!)

  15. …and Conclusions Perspectives CMS installation progressing on a daily basis Heavy lowering [July 2006-March 2007] The LHC time is already here First endcap wheel lowering by October 2006 Last DT chamber installed by Dec06-Jan07 CMS close to completion. Final detectors being installed: Magnet and HCAL … done Rest follow the path (and the schedule) 2007 LHC related dates: [Sept-Oct] Pilot Run First collisions: 1+1 bunches-43+43 bunches L1027  1030 cm-2s-1 Up to 10 pb-1, enough for subdetector calibrations Muon chambers key trigger detectors and very important for high pT muons Chambers certified prior to installation… and commissioned after installation So many tests ensure a performant µ system [Nov-Dec] First Physics Runs at 75 ns (936 bunches) and 25 ns (2808) L~ 1032 cm-2s-1 (75ns,936b)…21033 (25ns,2808) [Jan-Mar 08] Shutdown Installation of staged detectors Packed schedule from now on: Magnet test/Cosmic Challenge Final installation (surface and pit) First collisions … and last holidays! [Apr 08-…] Expected 7 months run

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