Muon Calorimetry

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Muon Calorimetry

• Jeff Hartnell
• University of Oxford
• Rutherford Appleton Laboratory
• MINOS Week-in-the-Woods Collaboration Meeting,
  June 2004

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Talk Outline

• Whats the beam energy at CalDet?
• Muon Calorimetry Formula.
• New dEdx in Geant3.
• Muon calorimetry in MC.
• Preliminary results from CalDet data.
• Range Agreement with New dE/dx.
• Conclusions and Further Work.

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Whats the beam energy at CalDet?

• Particle responses are characterized in MEUs/GeV
  where GeV is the beam energy.
• The beam energy at CalDet is only known to /-
  2.
• This is a large (or largest?) contribution to the
  error on CalDet measurements.
• Muons are the best theoretically understood
  particles.
• Can use their range to estimate the beam energy
  but this is sensitive to reconstruction issues.
• Calorimetry measurements are largely
  reconstruction independent gives another handle.
• Can use the robust track-window technique to get
  a signal-to-energy conversion factor.

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Reminder Track-Window Method

• Designed to be inherently less sensitive to
  problems at the end of the track or beam issues.
• Procedure sum up the energy deposition in a
  window some distance from the end of the track.
• Define a Muon Energy Unit (MEU) to be the average
  energy deposited in the window by a perpendicular
  muon in one detector plane.
• Facilitates an accurate signal-to-energy
  conversion factor.

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Muon Calorimetry Formula

• Ebeam Csc Stotal Etotal / Esc
• Where
• Csc GeV per SigCor
  GeVInScintPerMEU / SigCorPerMEU
  (using window technique)
• Stotal Sum of signal (SigCor) in whole event.
• Esc/Etotal Ratio of energy deposited in
  scintillator to total particle energy.
• Esc/Etotal comes from MC as does the energy
  deposition in GeV per MEU.
• The SigCor per MEU is simply the number used for
  the relative calibration, which is obtained from
  stopping muons.

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New dEdx in GMINOS

• Mike Kordosky discovered that the dE/dx values in
  Geant3 were not consistent with the PDG/Groom
  tables. I have investigated the changes.
• The table below shows the effect on the muon
  calorimetry constants.

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Muon Calorimetry Constants

• Ensure that the same cuts are applied to data and
  MC when obtaining the SigCor to GeV conversion
  factor.
• Cut out muons that leave the detector when
  obtaining the Esc/Etotal number.
• Demonstrated insignificant energy dependence for
  Esc/Etotal (3 from 1-2 GeV).
• Note Muon energy resolution from calorimetry
  8/sqrt(E))

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Self-Consistency Works in MC

• New MC sample of monochromatic (0 smear) 1.8
  Gev/c muons.
• Calibrate MC determine MEU numbers and sum the
  total SigCor.
• Can see the range - energy correlation.

Beam energy from Calorimetry Make different cuts
on muons Planes 44-57 1.795 GeV Planes 50-52
1.802 GeV Plane 51 only 1.804 GeV Small
statistical errors (lt0.4)
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Data 1.8 GeV/c muons in T7

• Muons from the beam have a 1 smear but there
  are substantial tails in the distribution from
  off-momentum muons.
• Steeper slope in the energy range plot.

Beam energy from Calorimetry Make different cuts
on muons Planes 44-57 1.767 GeV Planes 50-52
1.799 GeV Plane 51 only 1.798 GeV Small
statistical errors (lt0.4)
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Muon Range with new dE/dx

• The new Geant3 dE/dx values make the agreement of
  muon range between MC and data much better.
• The peaks match well.
• The muon spectrum is clearly non-gaussian hence
  the need for the beamline simulation.

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Conclusions and Further Work

• Need to study the effect of the off-momentum
  muons using the beam simulation.
• Quantify the systematic errors of the MC
  constants dE/dx, scintillator thickness.
• Run over all possible runs and determine the beam
  energy.

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The End!