Difference between revisions of "Wednesday, August 21, 2019, 11:00 am EDT"

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(Minutes)
 
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== Minutes ==
 
== Minutes ==
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* We discussed the possibility of flipping the laser helicity.  Dave’s model was based on significantly more data taken in this state so it was thought prudent to leave it in the more well known state.  We discussed taking Compton data to do a systematic check of laser polarization.
 +
** After the Wien flip, Dave et al will take data with the laser polarization set to an off-maximum value to compare the drop in asymmetry with the laser polarization model.  This should be about a shift on either side of the maximum polarization (current running).  If all goes well, this could be done on Friday.
 +
 +
* We discussed the Compton spectra.  The most recent target out run does not appear to be well fit by the simulation which makes the analyzing power uncertain.  We desire to center the beam on the collimator as soon as possible to decrease sensitivity.  We also discussed the idea of removing the collimator.
 +
** Amali will make some changes to fitting of spectra to investigate the disagreement.
 +
*** Fit only the high energy ~half of the Compton spectrum but plot the fit over the full range.  Do not include a pedestal offset in the fit.  (Already done see: https://hallaweb.jlab.org/dvcslog/compton/524)
 +
** Make an access at the earliest reasonable opportunity to lower the snapshot threshold to try and take a better target-out spectrum.
 +
 +
* We discussed accumulator 0 results.  There are non-statistical fluctuations in the minirun results.  The leading hypotheses was thought to be varying backgrounds which are not we accounted for in the current ~10 minute background subtraction procedure.
 +
** Juan Carlos will resurrect the cycle-wise analysis code and hand it off to Adam.  Now that we have a behaving laser this is a better analysis algorithm.
 +
** Adam will make plots of the asymmetry at various timescales: cycle-wise, run-wise, and slug-wise
 +
 +
* We briefly discussed accumulator 4.  Juan-Carlos said that he will look into this when he comes off RC.

Latest revision as of 13:38, 21 August 2019

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Agenda

Meeting room = 2nd floor Counting House

General

  • Compton measurements happening...

Laser

  • Laser update
    • New fiber amp performance
    • Laser helicity flip?

Photon Detector

  • Detector status (gain, etc.)

Analysis

  • Summary of data taken so far
  • ACC0 results
  • ACC4 results
  • Spectra (snapshots) - comparison with Monte Carlo

Minutes

  • We discussed the possibility of flipping the laser helicity. Dave’s model was based on significantly more data taken in this state so it was thought prudent to leave it in the more well known state. We discussed taking Compton data to do a systematic check of laser polarization.
    • After the Wien flip, Dave et al will take data with the laser polarization set to an off-maximum value to compare the drop in asymmetry with the laser polarization model. This should be about a shift on either side of the maximum polarization (current running). If all goes well, this could be done on Friday.
  • We discussed the Compton spectra. The most recent target out run does not appear to be well fit by the simulation which makes the analyzing power uncertain. We desire to center the beam on the collimator as soon as possible to decrease sensitivity. We also discussed the idea of removing the collimator.
    • Amali will make some changes to fitting of spectra to investigate the disagreement.
    • Make an access at the earliest reasonable opportunity to lower the snapshot threshold to try and take a better target-out spectrum.
  • We discussed accumulator 0 results. There are non-statistical fluctuations in the minirun results. The leading hypotheses was thought to be varying backgrounds which are not we accounted for in the current ~10 minute background subtraction procedure.
    • Juan Carlos will resurrect the cycle-wise analysis code and hand it off to Adam. Now that we have a behaving laser this is a better analysis algorithm.
    • Adam will make plots of the asymmetry at various timescales: cycle-wise, run-wise, and slug-wise
  • We briefly discussed accumulator 4. Juan-Carlos said that he will look into this when he comes off RC.