Muon Calibration Difficulties

1
Muon Calibration Difficulties

• Calibration Shortcomings
• Angular Effects
• Old Path Length Correction
• New Correction
• Other Matters
• Results

Ryan Nichol and Chris Smith
2
Problems With Old Method

• Old Calibration Required Double Ended Hits.
• To Remove Crosstalk.
• Beam Muons Show Even/Odd Asymmetry.

3
New Tracker Working Well
4
Corner Clippers

• New Tracker Enabled Lifting Of Double Ended Hit
  Requirement.
• This Led To Inclusion Of More Corner Clipping
  Muons.
• Decided To Remove Corner Clipping Hits From
  Sample.

5
Angular Distribution

• Large Angular Asymmetry at CalDet.
• Due To Orientation of Planes.

6
Error On Determination Of Angle

• Bands Correspond To Muon Track Length.
• Accuracy Limited By Strip Resolution.

7
Angular Dependence of Pulse Height

• Corner Clippers Removed.
• Two Views Have Similar Dependence.
• Strange Bimodal Shape.

8
Path Length Factors

• Angular Dependence.
• Finite Strip Width.
• Affects Two Orientations Differently.
• Minimum Path Length In Strip.
• Path Length In Neighbouring Strips.
• Transverse Position Across Strip Width.
• Other Effects??

9
Geometrical Constraints

• Path Length Constrained By
• Finite Strip Width
• Minimum PL in Strip.
• Maximum PL in neighbouring strips.
• These extrema are determined by light output.

10
Transverse Position Across Strip

• Pulse Height Depends on Transverse Position
  Across Strip.

11
Old Path Length Correction

• Tries To Account For
• Angle
• Finite Strip Width
• Minimum Path Length
• Doesnt Succeed.
• Introduces Even/Odd Bias.

12
Simulation Results

• Simulated Muons In CalDet With Measured Angular
  Distribution.
• Calculated Path Length Differs From True Path
  Length.

13
New Path Length Correction

• The Solution
• 92
• Only Accounts For Angles.
• Corrects to 2 level.

14
Results

• New Calibration Removes Some Of The Even Odd
  Asymmetry

• Still not an ideal calibration.

15
Forwards-Backwards Asymmetry

• Seemingly More Energy Deposited By Cosmics
  Traveling Backwards Through The Detector.
• Steel-Scintillator-Air or Steel-Air-Scintillator?
• Groove Position?
• Needs Further MC Investigation.

16
More Front-Back Fun
17
Summary

• Large Angular Asymmetry Between Views.
• Due To Orientation Of Planes.
• Complicated Pulse Height Dependence.
• Old (Current) Path Length Correction Wrong.
• Best Results From A Fudge Factor