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Outline

Outline. Establishing a platform for SLHC muon trigger studies Understanding defficiencies of CSC stub-finding algorithm in muon finding for SLHC Ways to solve them Likely implications on the scope of electronics upgrade. Example Efficiency. Low PU and high PU efficiency vs eta

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Outline

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Presentation Transcript

  1. Outline • Establishing a platform for SLHC muon trigger studies • Understanding defficiencies of CSC stub-finding algorithm in muon finding for SLHC • Ways to solve them • Likely implications on the scope of electronics upgrade

  2. Example Efficiency • Low PU and high PU efficiency vs eta • Clearly large inefficiencies: • Medium-high eta range: ME1/1b • Occupancies? • High eta range • ME1/1a not in the trigger (but could be) • Separate topic, also related to ganging of strips in ME1/1a

  3. CSC Muon Trigger • Trigger logic step-by-step: • Reconstruct CLCT • Up to 2 per chamber • Deadtime of 6BXs if found any CLCT in a chamber • Reconstruct ALCT • Up to 2 per chamber • Match CLCT to ALCT to produce LCT • Up to 2 per chamber • MPC: pass best LCTs to CSC TF • Up to 3 LCTs per sector of 60 degrees (30 degrees in ME1) per BX • Builds track in CSC TF using segments in stations • Stub in ME1 is critical to reliable tracking

  4. Sources of Efficiency Losses • Found several inconsistencies in default emulator with actual trigger implementation: • Turns out many were intentional to allow debugging while having no impact at low luminosity • Took a lot of time to figure out thanks to heroic effort by Vadim and help from Slava, Jay, Rick, Tim, Oana

  5. Trigger Efficiency Step-by-Step

  6. Restoring Trigger Efficiency I • LCT not found • Caused by deadtime in CLCT: • Currently 6 BX • Use brute force to make it 1 BX • Source is high occupancy in previous BXs • Either reduce occupancy by tightening CLCT definition or do matching by CFEB (deadtime will stay the same but will be per portion of a chamber)

  7. Restoring Efficiency II • ALCT not being found • Turns out to be not due to ALCT reconstruction but due to a junk ALCT from previous BX • Our good CLCT got matched with that junk ALCT from previous BX and shipped to CSC TF in the previous event • For events passing CLCT but not ALCT stage: • Plot BX vs BX of ALCT and CLCT matched into LCT • Solutions: • Improve CLCT timing (tighten DBX) • Improve ALCT quality (reduce occurrences) • Send CLCT twice with both ALCTs

  8. Bottlenecks: TMB • Keep no more than 2 LCTs per chamber • Only 2 LCTs per chamber are stored in the event, so can’t see how often we get 3 or more

  9. Bottlenecks: MPC • Keep no more than 3 LCTs per sector • Plot number of LCTs in the same BX – can it be more than 3? How often?

  10. LCT Quality and Pattern • Pattern plots and quality plots for signal and background

  11. CLCT Timing • Plot BX for digis by layer: • Can’t do now, requires re-running samples (will have to do later)

  12. ME-1/1a Stubs • Occupancies vs wire group number and strip number. • TMB – separate upper and lower parts, treat as separate things • Possibly send 1/1a in 2nd BX if 1st BX is taken • If ME1/1a is turned on “as is”, it contributes towards the 2-LCT limit, but is not reported to MPC • This would be nuts!

  13. Hardware Discussion

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