Effects of Endcap Staging/Descoping

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 ? lt 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 ?

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

4
ME4/2 Staging Efficiency
B.Scurlock
Single muons 3lt PTlt100 GeV
loose (unchanged) ? 97
ME4/1 in/out
tight ME4/2 in, ?79
tight, ME4/2 out, ? 73
h
5
ME4/2 Staging Rates
L2?1033 ? 5X
L1034
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
6
ME4/1 Needed at High Eta
H.Sakulin
L2?1033
ORCA 5.1.2

• 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

Rate from unconfirmed 2-station CSC tracks,
since no RPC coverage
GMT single muon trigger rates (pT gt 16 GeV/c)
re-tuned GMT
h
7
Mixed Mode CSC Trigger

• Without RPC trigger and without ME 4/2, still
  allow loose CSC trigger for 1.2 lt ? lt 1.8 (but
  tight everywhere else)
• Gains efficiency here
• Still want ME 4/1 at high ?
• DT/CSC overlap still a problem

L1034
? 85
loose
Rate from mixed-modeclose to that from tight
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 L1034
9
CSC LCT Rates in ORCA5
J.Mumford
High Lumi L1034 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
10
CSC LCT Occupancy with Neutrons
B.Scurlock

• Similar study performed with min bias pile-up and
  neutrons at L 1034 using ORCA5
• Chamber LCT occupancies
• AnodeCathode 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

11
Discussion of ME 1/1 Strip OR

• Combining the two halves of ME 1/1 cant
  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?1034 ME
  1/A 0.3 0.9 ME 1/1 0.3 0.9
• Therefore, occupancies scale linearly

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 ?gt2.1 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 12
• 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