reviews galore

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UCLA meeting, 2012 Hauser 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 2 nd day under development (Loveless) Meanwhile: ARC review for Z+jets at 7 TeV

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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 - PowerPoint PPT Presentation

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Page 1: Reviews galore

UCLA meeting, 2012 Hauser 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

Page 2: Reviews galore

UCLA meeting, 2012 Hauser 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

Df(CSC-GEM)~ 3 mradDx ~6 mm

pT=20 GeV

pT=5 GeV

Full Geant Simulation

Page 3: Reviews galore

• 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

FORWARD TRIGGER RATE

New CSCTF: rate reduction factor

CMS DAQ TDR

Page 4: Reviews galore

POTENTIAL SOLUTIONS• 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 mm or better trigger resolution to effectively discriminate 5-10 GeV muons from 20+ GeV ones

YE-1/1 pT=5 GeV pT=20 GeVDxDz=30 cm 3±1mm 12±3mm

View from the top of CMS down

Page 5: Reviews galore

BENDING ANGLE: SIMULATION

• 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

Df(CSC-GEM)~ 4 mradDx ~8 mm

pT=20 GeVpT=5 GeV

“Close” chamber pairs “Far” chamber pairs

Page 6: Reviews galore

• 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

EFFECT ON THE TRIGGER RATE

Super Preliminary

Super Preliminary

Page 7: Reviews galore

UCLA meeting, 2012 Hauser 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