Muon dE/dx Fitting

1
Muon dE/dx Fitting
In CalDet...... and beyond?

• Mike Kordosky
• UCL
• Ely, 2005

2
dE/dX fitting

• Does the observed muon-signal/plane agree with
  our expectations based on
• Muon Energy?
• Detector Composition?
• Beam Energy?
• Can we relate the observed signal to
• energy deposited in scint?
• energy lost in scint?

3
Data

• Histograms from Jeff H. analysis
• CalDet stopping muons 1.4-2.0 GeV/c
• signal/plane as a function of distance from
  stopping position
• signals corrected for track angle

4
Method

• Assume muon exits last scintillator plane with
  some momentum plast
• Integrate backwards along the track, calculating
  energy gained via Bethe-Bloch

Form a c2 using the calculated energy loss, mean
signal and uncertainty in each plane
5
Examples
Plast (GeV/c)
C (sigcor/GeV)
6
Energy Deposited vs. Lost

• Extract, from MC, true energy deposited per
  plane.
• Do same fit, now C is the amount of energy
  deposited per unit energy lost.
• Fit C0.916

7
Fit Summary

• Fit results for 3 CalDet running periods
• Points weighted by fit errors
• Differences between periods expected due to
  recommissioning of detector

8
MeV / Jeff-MEU

• Jeff H Track-window technique employed to define
  MEU constant
• This fitting method complementary
• Combination yields definition of MEU in MeV

?
MEU 2.00 /- 0.01 MeV (lost) 1.83
/- 0.01 MeV (dep)
Energy Lost
9
Summary and Conclusions

• Bethe-Bloch fitting technique developed on CalDet
  stopping muons
• Data well described by fits.
• Jeff MEU 2.00 /- 0.01 MeV muon energy loss
• Fitter only works on CalDet muons
• Near Far more difficult due to track angle,
  curvature
• Algorithm would need to be rewritten... worth it?