Pol He3 Target Meeting May 4, 2020

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Begin time: 1:30 p.m. End time: 2:40 p.m.

Members present: Jian-ping, Todd, Brad, Mingyu, Melanie, Junhao, Xiaochao, Arun, Bill, and Christopher Jantzi


  • Building on polarimetry runlist
    • want to learn how the beam current affects the target polarizations (depolarization)
      • use (total charge/beam on time) to calculate the average current per run
      • the average current is located in the report file, but won’t be the most useful for us since the average current uses beam-off time (which can be a significant amount of time)
      • Brad: FYI: Mya (EPICS archiver) records the beam current at all times. Can do time correlations to look at region of interest. Info is also stored in CODA files for run-by-run information
  • Need to find out the target tests done (polarization loss, temperature tests, etc.) on Feb. 10th before Dutch was swapped out for Big Brother


  • Show explicitly how the errors were calculated in the frequency fits in the EPR analyses
    • been using the midpoint in the event of a non-straight line (usually due to field instability, which is the biggest systematic affect). this might not be the best way to go – instead implement some correlation between how much each fit deviates from each other
  • NMR signal fit was different in January on Dutch – use Junhao’s treatment of the NMR signal instead of the latest fit for the calibrations


  • Used a "tiled" and "non-tilted" line to fit Compass data instead of the previously-used ellipse to calculate the uncertainties
    • non-tilted produced a +/- 0.02 degree contribution
    • tilted fit produced a +/- 0.06 degree contribution
  • Since the tilted fit has the lower chai-squared value, perhaps use this fit (although there is reason to believe no x-y correlation should be present...but the error contribution is similar enough to one another that it shouldn't matter much)

Xiaochao says Jixie claims to have ~ 75% of his report on the field measurements completed

Next week, we expect presentations from Junhao and Melanie