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Effects of Endcap Staging/Descoping

Effects of Endcap Staging/Descoping. D.Acosta University of Florida. Effects of Endcap Staging/Descoping. Staged Muon scenarios: No ME 4/2 (CSC) No fourth CSC station for  < 1.8 No RPC for stations 2,3,4 No endcap RPC trigger, but station 1 there to cancel CSC ghosts if needed

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Effects of Endcap Staging/Descoping

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  1. Effects of Endcap Staging/Descoping D.Acosta University of Florida

  2. Effects of Endcap Staging/Descoping • Staged Muon scenarios: • No ME 4/2 (CSC) • No fourth CSC station for  < 1.8 • No RPC for stations 2,3,4 • No endcap RPC trigger, but station 1 there to cancel CSC ghosts if needed • ME1/1 strips put into “OR” • Reduce channel cost by not segmenting ME1/1 in  Darin Acosta

  3. ME4/2 Staging • With RPC trigger in place, CSC trigger runs in “loose” mode for high efficiency: • Only 2 CSC stations are required: one must be ME1 and one must be ME2 or ME3 (relax ME1 condition for DT/CSC overlap) • In principle, ME4 cannot affect efficiency or rate by design • But PT assignment is slightly better for 3-station tracks than for 2-station tracks, so might expect some changes to CSC rate and efficiency above certain PT threshold without ME4 • GMT requires match between CSC and RPC for low quality CSC muons, and optimizes the PT assignment, so any effect is reduced after GMT • Without RPC trigger in place, the CSC trigger must run in “tight” mode for improved rate reduction • Three CSC stations are required, including ME1 • No redundancy without ME4 means efficiency loss Darin Acosta

  4. ME4/2 Staging – Efficiency B.Scurlock Single muons: 3< PT<100 GeV “loose” (unchanged)  = 97% ME4/1 in/out “tight” ME4/2 in, =79% “tight”, ME4/2 out,  =73% h Darin Acosta

  5. ME4/2 Staging – Rates L=21033  5X L=1034 CSC loose, no ME4/2 U.Gasparini CSC loose CSC loose, no ME4/2 CSC tight CSC loose GMT is unchanged CSC tight without RPC achieves about same rate as CSC loose with RPC in GMT Darin Acosta

  6. ME4/1 Needed at High Eta L=21033 H.Sakulin • GMT as in ORCA 5.1.2 • rate at 20 GeV/c: 3.1 kHz • L1 efficiency(*): 96.6 % • re-tuned GMT selection: • Only three-station CSC tracks used without RPC confirmation • rate at 20 GeV/c: 1.4 kHz • L1 efficiency(*): 96.3 % • (*)efficiency to find muon of any pT in flat pT sample ORCA 5.1.2 Rate from unconfirmed 2-station CSC tracks, since no RPC coverage GMT single muon trigger rates (pT > 16 GeV/c) re-tuned GMT h Darin Acosta

  7. Mixed Mode CSC Trigger • Without RPC trigger and without ME 4/2, still allow “loose” CSC trigger for 1.2 <  < 1.8 (but “tight” everywhere else) • Gains efficiency here • Still want ME 4/1 at high  • DT/CSC overlap still a problem L=1034  ~ 85% loose Rate from “mixed-mode”close to that from “tight” Darin Acosta

  8. ME1/1 Staging • Recall that ME1/1 has split strips • Motivation was to reduce occupancy • Can we avoid it to reduce channel cost? • From muon TDR: • Charged particle occupancies in either half of ME1/1 are about 0.5%per chamber per BX • Neutron hit occupancies are no more than about 2%, but as they are uncorrelated through the chamber, a much smaller fraction actually give trigger primitives. • So these numbers are not large, and in fact are smaller by about 50% than the numbers for the other CSC chambers (ME2/1, ME3/1, and especially ME4/1) • In principle there should not be any problem if we can OR the strips from top to bottom of ME1/1 High Lumi: L=1034 Darin Acosta

  9. CSC LCT Rates in ORCA5 J.Mumford High Lumi: L=1034 min bias pile-up only no neutrons ME 1/1: 7 MHz ME 1/A: 10 MHz For 72 chambers of each type, occupancy per BX is: ME 1/A: 0.35% ME 1/1: 0.24% Darin Acosta

  10. CSC LCT Occupancy with Neutrons • Similar study performed with min bias pile-up and neutrons at L = 1034 using ORCA5 • Chamber LCT occupancies: Anode+Cathode Cathode only • ME 1/A: 0.46% ME 1/A: 0.61% • ME 1/1: 0.44% ME 1/1: 1.50% • ME 1/2: 0.05% ME 1/2: 0.10% • ME 1/3: 0.05% ME 1/3: 0.14% • ME 2/1: 0.29% • ME 2/2: 0.34% • ME 3/1: 0.21% • ME 3/2: 0.25% • ME 4/1: 0.25% ME 4/1: 0.81% • ME 4/2: 0.86% ME 4/2: 2.54% B.Scurlock Darin Acosta

  11. Discussion of ME 1/1 Strip “OR” • Combining the two halves of ME 1/1 can’t increase the trigger rate if the track segments come from real muons (i.e. correlated hits) • Extra trigger rate can only come from random combinations forming ghost track segments, which in turn form additional triggers • If the current LCT occupancies are dominated by real correlated hits, expect ME 1/1 and ME 1/A occupancies to add • If neutron-induced random hits dominate, expect occupancy to scale non-linearly • “Guestimate”: order of magnitude increase • How to tell without detailed simulation of strip OR? • Study dependence of occupancy with background level • ORCA4 study with pile-up and neutrons: Occupancy for L = 1034 L = 31034ME 1/A: 0.3% 0.9%ME 1/1: 0.3% 0.9% • Therefore, occupancies scale linearly Darin Acosta

  12. Summary • ME 4/2 staging • With RPC: No change in GMT rate or efficiency • Without RPC: Approximately no change in rate requiring 3 CSC stations, but 25% acceptance loss in endcaps for “tight” trigger (12% loss for mixed-mode trigger) • In any case, ME 4/1 is useful to reduce rate by factor of two if efficient triggering at >2.1 is desired • ME 1/1 Staging • At high luminosity, the ME 1/1 and ME 1/A track segment occupancies are about 0.5 – 1.0% per BX • Combining the two, the occupancies add and would be of order 1–2% • At low luminosity, occupancies would be 5X lower • Therefore, expect no change in efficiency or rate if strips in ME 1/1 and ME 1/A are put into an “OR” • Exactly how to do this is up to chamber designers • Different strip pitch in ME 1/1 and ME 1/A in current simulation • Perhaps it could be possible to segment HV so that high  wires can be turned off if occupancies turn out to be higher than expected (as is possible in other CSC chambers) • Complicated by wire tilt, however Darin Acosta

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