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-- SaraKnaack - 10 Feb 2009

Update 2/11/2009

A fresh way of presenting the DeltaZ inconsistancy

  • The capture recoil pulses in the TPC, may or may not be observed in the TPC on the same anode. The capture recoil may be observed on an anode upstream or down stream from the actual muon stop (no more than 2 is allowed y the Z and X coincidence conditions.)
  • The capture time spectra showed serious inconsistencies for the events where the anode of the capture recoil varied from the anode of the muon stop.
  • In principle this is not expected, and it is believed to be artificially due to detector effects; not a physical result of the actual physics of the capture
  • This is independent of which anode was the stop anode of the muon.
  • The relative fraction of events which fall into any of the "DeltaZ" categories is time dependent, which is consistent with the strong variation with DeltaZ in the fit results to the time spectrum for these different finds of events.
  • It is possible to account for a gaussian smearing to the time spectrum analytically and take that into account in the fit function.
  • from [2]*(exp(-[0]*t)-exp(-[1]*t))+[3] to
  • [2]*(exp(-[0]*t+.5*[0]^2*[4]^2)-exp(-[1]*t+.5*[1]^2*[4]^2))+[3]
  • The constant background [3] was typically fixed to 0 for these purposes
  • In the scan below I've fixed the time constant at varying values between 0 and 500 ns, and the background to [3] parameter to 0.
  • In general this doesn't seem to adequately describe the important detector related response effects, and the fit consistency remains very poor for the different classes of events.
  • The fits were performed on time spectra using the minEH capture time definition, and with a 2,000 - 10,000 ns fit time-window

Previously shown fit scan over DeltaZ! and DeltaX!

  • The discrepancy vs DeltaZ is more severe than the DeltaX inconsistency and hence it's worth considering that a reasonable correction to the DeltaZ discrepancy in the data may trivially resolve any DeltaX inconsistencies
  • DeltaX is the analogous displacement of the recoil island of the capture event from the muon stop in the space of the TPC strips. Because of the nature of the TPC, this is a more ambiguous quantity to define. The thresholds on the strips and the geometry conspire to make the charge distribution of the pulses more extended over the strips as observed in the data, and makes the X coordinate a little less clear to define, and hence the displacement definition more ambiguous than in the Z coordinate/anode (DeltaZ) case.
  • Fixing the shorter, early-time diminating lambda_2 life time ([1] in the fit functions above) does not resolve the inconsistency of the fit results, and neither did changing the capture time definition.

Topic attachments
I Attachment History Action Size Date Who Comment
GIFgif Cx.gif r1 manage 9.1 K 2009-02-10 - 22:10 SaraKnaack  
GIFgif Cxth.gif r1 manage 7.8 K 2009-02-10 - 22:10 SaraKnaack  
GIFgif Cz.gif r1 manage 8.8 K 2009-02-10 - 22:11 SaraKnaack  
GIFgif Czth.gif r1 manage 7.7 K 2009-02-10 - 22:11 SaraKnaack  
GIFgif DelZFractionTotal.gif r1 manage 21.9 K 2009-02-10 - 22:08 SaraKnaack  
GIFgif DelZTimeResponseScan.gif r1 manage 29.3 K 2009-02-10 - 22:07 SaraKnaack  
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Topic revision: r1 - 2009-02-10 - SaraKnaack
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