A Consideration on Muon System

1
A Consideration on Muon System

• Y.Sugimoto
• KEK
• 2005.11.22

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Muon ID in a Jet

• How to identify muon track in the TPC?
• Conventional method
• Extrapolate TPC track and find a matching track
  segment in the Muon Tracker within a rage of
  expected spread by multiple scattering
• For muons inside jets (small ptjet), background
  is large
• Pion punch-through
• Decay of shower pion
• Pion sail-through (Irreducible, but very small
  for GLDgt7l)
• Pion decay-in-flight (Irreducible)
• Kaon decay-in-flight (reducible by dE/dx and
  kink)
• If there are two near-by tracks in TPC, both can
  be the muon candidate, or mismatching due to M.S.
  can happen
• At ILC, we have to study more collimated jets and
  the matching using spatial information only may
  not be sufficient

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Muon ID in a Jet
CAL
Solenoid
Muon System
Jet
Pion decay-in-flight Pion sail-through Pion
punch-through Decay of shower particle
Independent momentum measurement by the Muon
System may help matching of Muon track and TPC
track by checking the consistency of the
momentum measurements
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P measurement by Muon Sys.

• Low momentum (lt 5GeV) Muon range
• dp/p6 from range struggling (?) (CHORUS)
• Energy loss of a muon track in one Fe plate dE
  should be dE/E0/sqrt(12)lt6 (E0 E before energy
  loss)
• Incident angle to the octagonal Fe can be very
  shallow for low momentum tracks.
• Inner layers should be thinner than outer layers
• Dodecagonal shape is preferable

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• Incident angle of the same momentum tracks
  deviates by 45 degrees for the octagonal shape
  muon system
• Muon path length in a Fe plate has a large f
  dependence
• ? Dodecagon shape is more preferable than octagon

6
P measurement by Muon Sys.

• High momentum (gt 5GeV) Track curvature
• With L2.3m, BFe2T, Nmeas5, smeas1cm,
• Measurement term is comparable with M.S. term at
  5GeV
• So, smeas better than 1cm is preferable
• Vertex constraint and Kalman filter would improve
  the resolution significantly

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Summary

• My personal guess
• The muon system should be designed so that it can
  measure the muon momentum independently
• For a muon which stops inside the muon system,
  the momentum can be measured by its range and Fe
  thickness and the number of layers should be
  optimized for it
• For higher momentum muons, the momentum
  resolution with vertex constraint and Kalman
  filter should be studied together with the
  required detector resolution