Pol He3 Target Meeting November 23, 2020

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Start time: 1:30 p.m.

End time: 2:59 p.m.

Members present: Jian-ping, Arun, Bill, Murchhana, Mingyu, Melanie, Junhao, and Dave


  • Almost completed d2n calibration cross-check
  • When the info becomes available, be sure to update results with the final AFP loss for each cell/configuration, and proper PC and TC temperature values derived from the temperature tests
    • Junhao and Mingyu should make and update an appropriate database for this
  • Identify and separate "problematic" EPR measurements to discuss as a group, and to investigate the suspected issue (like obtaining necessary EPICs values for field instability, for example)


  • Working on deriving the target polarization per run. Need the following quantities:
    • NMR amplitude of last NMR measurement before the run
    • EPR correction based on the current field direction and magnets condition
    • Convection correction: target chamber polarization correction based on equilibrium condition
    • AFP loss on target chamber
    • pNMR loss on target chamber
    • polarization-evolution-based correction:
      • time: spin up time constant and observed polarization deterioration
      • charge: accumulated charge on target since the last NMR measurement
      • beam current
      • special conditions: laser status, QWP status, etc
  • AFP loss study done on longitudinal configuration with 6V convection heater; to get the true AFP loss, we need to also correct for the convection itself


  • Presented Field Mapping measurements done in September 2020
    • 11 and 14 degree settings weren’t done with everything on; only the 18 degree measurement was done with all the coils on, so is the only setting that can be compared to Murchhana's compass measurement
    • general trends are the same everywhere between both measurements
    • transverse and longitudinal orientations were equal to or less than 0.5 degree off from values found from the compass measurement
    • the takeaway is that we can trust the compass measurement results within 0.5 degrees; ideally would want to be within 0.1 degree confidence level