Muon Calibration Difficulties

1
Muon Calibration Difficulties

• Calibration Shortcomings
• Angular Dependence
• Old Path Length Correction
• New Correction
• Results

2
Problems With Old Method

• Old Calibration Required Double Ended Hits
• Beam Muons Show Even/Odd Asymmetry

3
Angular Distribution

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

4
Angular Dependence of Pulse Height

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

5
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??

6
Old Path Length Correction

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

7
Simulation Results

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

8
New Path Length Correction

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

9
Results

• New Calibration Removes Some Of The Even Odd
  Asymmetry

• Still not an ideal calibration.

10
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

11
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.

12
More Front-Back Fun
13
New Tracker Working Well
14
Transverse Position Across Strip

• Pulse Height Depends on Transverse Position
  Across Strip.

15
Error On Determination Of Angle

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

16
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.