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Reviews galore

Reviews galore. Yesterday: GEM proposal review (more later) Mon-Tues Feb 25&26: Workshop #2 on CSC Planning for LS1 Created agenda at https:// indico.cern.ch/conferenceDisplay.py?confId=236792 Weds-Thurs Feb 27&28: CERN review of ME1/1 and ME4/2 projects

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Reviews galore

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  1. Reviews galore • Yesterday: GEM proposal review (more later) • Mon-Tues Feb 25&26: Workshop #2 on CSC Planning for LS1 • Created agenda at https://indico.cern.ch/conferenceDisplay.py?confId=236792 • Weds-Thurs Feb 27&28: CERN review of ME1/1 and ME4/2 projects • Agenda for first day at https://indico.cern.ch/conferenceDisplay.py?confId=235558 • Agenda for 2nd day under development (Loveless) • Meanwhile: ARC review for Z+jets at 7 TeV

  2. GEM review: motivation • From 2 weeks ago •  Lever arm in 1/1 station increased 2.5-5.0x •  Resolution allowed by current 16:1 ganging for trigger is ~8 mrad, need at least 4x finer (see below) for trigger Full Geant Simulation Df(CSC-GEM)~ 3 mrad Dx ~6 mm pT=20 GeV pT=5 GeV

  3. Forward trigger RATE • Muon momentum from stub positions • DfXY=f(ME-X)-f(ME-Y) • Measurement driven by Df12 • ME-1/1 defines the accuracy • Least scattering and B field • “Flattening”: mismeasured soft muons • Soft muons scattering in the absorber can occasionally have stubs align like for a high pt muon • Rare but there are lots of them! • Tails in L1 momentum resolution • A fundamental issue with no solution • At some point you just hit the wall • Likely the last improvement, as the new TF has likely reached that wall CMS DAQ TDR New CSCTF: rate reduction factor

  4. Potential solutions View from the top of CMS down • Removing tails in L1 muon momentum resolution to control trigger rate cannot be done without a second detector: • Match to inner tracker tracks at L1 • Great but unavailable until LS3 • Can a second muon system improve momentum resolution? • It could if we can measure and use the “bending angle” • Used in the Barrel; CSCs are too thin to see the bend on its own • A new detector in YE-1/1 (the least affected by scattering and largest magnetic field) • Increase “lever arm” & have enough spatial resolution to measure bending angle • Physical constraints allow a maximum lever arm of Dz=30-50 cm in YE-1/1 • The new detector needs ~2-3 mmor better trigger resolution to effectively discriminate 5-10 GeVmuons from 20+ GeV ones

  5. Bending angle: simulation Df(CSC-GEM)~ 4 mrad Dx ~8 mm “Close” chamber pairs “Far” chamber pairs pT=20 GeV pT=5 GeV • GEM-CSC bending angle measurement using GEANT simulation: • Muons with PT=5 and PT=20 GeV • Digi level (full GEM granularity) – this is what HLT Level-2 can do • Slight deterioration due to discretization and resolution effects, but still strong discrimination

  6. Effect on the trigger rate • Extremely preliminary • Accounts for some but not all CSC TF improvements • An explicit cut on the CSC-GEM bending angle to be ~100% efficient at and above 20 GeV • In real case we will send “bending angle pattern” • Dramatic decrease in ratio towards low pt due to that cut • Ratio will flatten once bending patterns for pT ranges are defined • The plot is less than 24 hours old, so take it as a promise that the final plot is on the way Super Preliminary Super Preliminary

  7. Implementation • Use 4 of 5 unused fibers in ME1/1 bundle of 12 • Feeds directly into TMB • GEM group proposed to put 2 chambers in place during LS1 • Front-end electronics not final • Trigger 4-16x worse segmentation than final electronics • Readout system cobbled together • DAQ electronics effort thin • New suggestion: • Put a “slice test” with 3, 6, or 9 GEM chambers in during long YETS between 2016-2017 (when new pixels installed). • Could use final electronics • (Time to develop good TMB firmware) • Transparencies for front end at https://www.dropbox.com/s/6hfyzy935sr0jy1/Aspell_LS2_Electronics.pdf and FPGA/DAQ at https://www.dropbox.com/s/sftbtist9oxgky8/Gilles_2013-02-GEM-Review.pdf

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