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Muon Detection & Measurement @ SLHC

This workshop in 2003 discussed critical issues in muon detection and measurement for SLHC experiments such as rate demand, occupancy, trigger PT resolution, stability, and technological advancements in chambers and electronics. Various types of gaseous detectors like DTs, CSCs, and RPCs were explored for their precision tracking capabilities in both the ATLAS and CMS systems. The event highlighted the challenges in tracking technologies, neutron and photon flux effects, rate handling, trigger resolutions, and advancements in thin gap chambers like TGCs.

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Muon Detection & Measurement @ SLHC

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  1. Muon Detection & Measurement @ SLHC CMS ATLAS Frank Taylor MIT Int’nl Workshop on Future Hadron Colliders FNAL October 16-18, 2003

  2. Critical Issues • Rate demand on tracking & trigger technologies • Occupancy vs. pattern recognition • Ghost tracks & Track Matching between ID & Muons • Trigger PT – resolution & Rate • Stability of chamber parameters under rate • Space charge effects, R-T relation affected • Spatial resolution vs. rate • Beam crossing timing • Longevity • Chambers & Electronics (Rad Hard & SE Upsets) • Shielding size & activation • Thick enough • Personnel access F.E. Taylor

  3. SLHC Environment ~ 600 @ RHIC F.E. Taylor

  4. CMS Muon System • Three types of gaseous detectors: • Drift Tubes in Barrel (DTs) • Cathode Strip Chambers in Endcaps (CSCs) • Resistive Plate Chambers (RPCs) in both barrel and endcaps • Coverage: || < 2.4 F.E. Taylor

  5. ATLAS Muon System • Muon Spectrometer: • Toroidal magnetic field: <B> = 0.4 T • Air-core coils • 3 detector stations • - cylindrical in barrel • -wheels for endcaps • Coverage: || < 2.7 • Technologies: • Fast trigger chambers: TGC,RPC • High resolution tracking detectors: MDT,CSC F.E. Taylor

  6. CMS Barrel Drift Tube Chambers Drift time ~ 320 to 400 ns F.E. Taylor

  7. Monitored Drift Tube Chambers (MDT) Barrel • 6 / 8 drift tube layers,arranged in • 2 multilayersglued to a spacer frame • Length: 1 – 6 m, width: 1 – 2 m • Gas: Ar:CO2 (93:7) @ 3 bar • Maximum drift time ~ 600 ns End Cap F.E. Taylor

  8. CMS CSC Endcap • 468 CSCs of 7 different types/sizes • > 2,000,000 wires (50 mm) • 6,000 m2 sensitive area • 1 kHz/cm2 rates • 2 mm and 4 ns resolution/CSC (L1-trigger) • 100 m resolution/CSC (offline) Charge integration time ~ 400 ns F.E. Taylor

  9. CMS f precision coordinate Drift Tubes (DT) In barrel 0<|h|<1 40 mm x 13 mm cell 2nd coordinate Beam crossing time t ~ 400 ns Cathode Strip Chambers (CSC) in endcap 1<|h|<2.4 2-D readout f strips 3 to 16 mm ATLAS q precision coordinate Monitored Drift Tubes (MDT) in Barrel & Endcap 0<|h|<2.7 except 1st layer 30 mm dia. cell t ~ 600 ns 2nd Coordinate RPC in barrel & TGC in endcap CSC inner endcap layer 2.0<|h|<2.7 2-D readout q strips 3 mm f strips ~ 10 mm Gas Detectors-Tracking Technologies F.E. Taylor

  10. ATLAS l vs. h Design Criterion m-rate dominated by prompt & decays in inner tracker volume CMS 10 to 15 l in front of M1 station F.E. Taylor

  11. Neutron Flux – ATLAS @ 1034 cm-2 s-1 2-10 mSv/h in access 4 20 100 • (MDT) ~ 5x10-4 e (CSC) ~ 2x10-4 • (RPC) ~ 5x10-4 e(TGC) ~ 10-3 N neutrons (kHz/cm2) @ 300 keV but strongly energy dependent F.E. Taylor

  12. Photon Flux – ATLAS @ 1034 cm-2 s-1 2 4 20 • (MDT) ~ 8x10-3 e (CSC) ~ 5x10-3 • (RPC) ~ 5x10-3 e(TGC) ~ 5x10-3 N photons (kHz/cm2) F.E. Taylor

  13. Rate ‘Cross section’ vs. PT - ATLAS m m m mb/GeV F.E. Taylor

  14. Muon Chamber Counting Rate – ATLAS @ 1034 gsare dominate component @ 1035 -> max rate ~ 10 kHz/cm2 MDT ~ 0.5 C/cm-yr Calorimeter Electronics “Chimney” TDR now smaller F.E. Taylor

  15. Muon Track in ATLAS 5 X Bkg. @ 1034 Occup. ~ 10 % F.E. Taylor

  16. Precision Tracking Chamber Occupancy L ~ 5x1034 cm-2 s-1 MDT & CSC 2X larger ~ acceptable 10X larger very uncomfortable and something has to done Occupancy (%) F.E. Taylor

  17. MDT Performance under Rate single tube resolution vs. drift radius , Ar:CO2(93:7), 3 bar Degradation due to space charge fluctuations F.E. Taylor

  18. Luminosity effects HZZ  ee event with MH= 300 GeV for different luminosities 1032 cm-2s-1 1033 cm-2s-1 Praha July 2003 1034 cm-2s-1 1035 cm-2s-1 F.E. Taylor SLHC prospects Albert De Roeck (CERN)

  19. Pattern Recognition to be Studied • Track matching between ID & Muon System • Spatial matching • 1/P matching • Second Coordinate & Ghost tracks • Muon Track Isolation • Decay ms from b, c, p, K • Dominate Bkg from H -> ZZ* -> mmmm is tt and Zbb • Isolation cut DR = (Dh2 + Df2)1/2 < Rmax F.E. Taylor

  20. Trigger Issues • Resolution • Sharpness of Pt turn-on • Rate • Reals & Accidentals • Possible to raise threshold ? • Resolution & Accidentals permitting F.E. Taylor

  21. CMS Trigger primitive developed from track curvature in muon system of DT, CSC, RPC F.E. Taylor

  22. ATLAS Muon Trigger Primitives F.E. Taylor

  23. RPC – used in both CMS & ATLAS 3 mm gap • Intrinsically fast response ~ 3 ns • R&D effort to understand long term characteristics • Rate handling depends on electrode resistivity • r observed to increase by 2 orders of magnitude F.E. Taylor

  24. Thin Gap Chambers (TGC) in ATLAS Not to scale • Small drift distance & close wire spacing t ~ 25 ns • 1.8 mm wire spacing, 1.4 mm anode - cathode • Has to use a heavily quenched gas F.E. Taylor

  25. TGC Timing TGC inefficient for 12.5 ns beam crossing interval F.E. Taylor

  26. Trigger PT Resolution e@ turn-on important F.E. Taylor

  27. Trigger Resolution & Rate Accidentals X 10 Accidentals 6 GeV @ 1035 (100 nb-1 s-1 ) Trig Rate ~ 104 Hz & mostly ‘real’ if accidental rate nominal – higher thresholds ~ larger fraction of accidentals 20 GeV 20 GeV 6 GeV F.E. Taylor

  28. Conclusions • R&D Program • Experience with LHC running • Calibration of shielding & Backgrounds • Identify the ‘real’ problems • Detector issues clear at this time (2003) • Faster & More Rad-Hard trigger technology needed • RPCs (present design) will not survive @ 1035 • TGCs need to be faster … perhaps possible • Gaseous detectors only practical way to cover large area of muon system (DT, MDT & CSC) Area ~ 104 m2 • Better test data needed on resol’n vs. rate • Bkg. g and neutron efficiencies • Search for faster gas => smaller drift time • Drive technologies to 1035 conditions • Technologies DT, MDT & CSC not precluded F.E. Taylor

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