RC meeting and Run Plan, Friday October 21st

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RC Meeting Information

Time: Daily at 3:00pm

  • Location: Counting house conference room

Useful Links

Current Status

  • Went into controlled access yesterday for target related work: [[1]]
  • EPR RF amplifier was surveyed and moved upstairs and can now make EPR measurements without needing access: [[2]]
  • EPR calibration with SBS and BB magnets odd: [[3]]
  • Calibration constant with SBS and BB magnets on----> ~1.4
  • Target polarization is closer to ~30%!: [4]
  • Arun adjusted the 3 variacs from 60% to 70%: [5]
  • Polarization is high enough that the decision was to proceed with production running on polarized helium-3 (as opposed to taking optics data during Friday DAY shift)
  • Beam line + raster checkout: [6],[7]
  • Hall C performed a high current BCM calibration. We were limited to 35 uA during SWING and OWL shifts
  • Began production running ~ 03:30 AM. The beam trip rate was high and a stable beam current of 25 uA was found: [8]
  • Beam stability has been an issue during day. We worked with MCC to try and increase the current in 5uA increments. Currently stable at 30 uA 
[ https://logbooks.jlab.org/entry/4064903]
  • Compromise with Hall C in regards to beam current? Hall C has high current and low current targets
  • While we are at ~30 uA ---- Update prescales
  • Work with GEM experts to set reasonable trip threshold limits
  • Recent NMR measurement 30.7% with 30 uA current on target: [9]
  • Configuration and pass change moved to Monday (10/31/2022): [10]
  • Additional Moller measurement before pass change?

Current Run Plan

For Friday SWING to MONDAY OWL we will be focusing on polarized helium-3 production.

  • Question for target group: How long would you like to continue taking NMR measurements every ~2 hours?

Run Plan 1.) He-3 runs, at 45uA (or whatever MCC can deliver) of beam current. Use ps1==8, ps3==0, all others -1. Take two runs that should each last for one hour. 2.) Move the target to the pickup coil position, and the TO should run an NMR sweep to measure the polarization. 3.) Return to step 1.)

Bringing Beam Back to Hall After Extended Down Time If beam is down due to tuning for our line or for a long down, move to the "no target" position, and follow this procedure to verify the spot size: https://sbs.jlab.org/wiki/index.php/HOW_TOs#If_beam_has_been_down_due_to...

After doing the spot size check, you will need to restore the raster before putting the He-3 cell back into the beam; ask OPS for the raster to be set with Generator 1 Vertical equal to 1.3409, and Generator 1 Horizontal equal to 1.2068. The settings are shown in the last figure of https://logbooks.jlab.org/entry/4062516. (Older procedure described in https://sbs.jlab.org/wiki/index.php/HOW_TOs#How_to_ask_MCC_to_set_the_de...). 1) Restore beam on the "no target" position. Turn off the raster, and check the intrinsic spot with harp swipes with 5uA of tune beam at 1H04A and 1H04B, if the spot is still good, turn the raster back on. If not, ask OPS to adjust the spot size and recheck, like in the procedure https://sbs.jlab.org/wiki/index.php/HOW_TOs#If_beam_has_been_down_due_to.. 1A) Did you turn the raster back on? 2) Put in the He-3 target then ramp to 30 uA. Shift leaders should watch the "TS1-BBHI" rate when we ramp up, and compare to the rates versus current as shown in https://logbooks.jlab.org/entry/4062308. Also watch the ion chamber values and compare to https://logbooks.jlab.org/entry/4060717. 3) He-3 runs, at 45uA (or whatever MCC can deliver) of beam current. Use ps1==8, ps3==0, all others -1. Take two runs that should each last for one hour. 4) Move the target to the pickup coil position, and the TO should run an NMR sweep to measure the polarization.


Notices in Effect for Shift Crew

Current Issues

  • Shift Openings
  • Raster GUI was updated over OWL to include a field for size in mm
  • Need communication before such changes are made to avoid confusion (new procedure clearly states


Planned Accesses to the Hall

Special Requests

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