RC meeting and Run Plan, Friday Sept. 8, 2023

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RC Meeting Information

Time:at 3:30pm today

  • Location: Counting house conference room
  • ZoomGov Meeting Connection Information


Useful Links

Readiness for Beam

Accelerator readiness:

  • CG: beam restoration to hall A projected to start swing Tue Sept 12. We will need to have a shift crew starting on Wed Sept 13th.
  • SSG only has the Moller Target to check (everything else done).
  • ZR: plan to do checklist on Tue (everyone out of the hall by lunch)

Beamline readiness: beamline quads and harps, bcms, bpms, ion chambers (Ciprian Gal)

  • Daniel Moser: Beam plans for reviving the target protection systems (the position locks and ramp rate) in place (Bill will review).
    • Beam current limit: 45uA.

Subsystems Checklist

For each subsystem we ask that the responsible person go over the following points:

  1. The overall status of your subsystem
  2. Will your subsystem be ready well before Hall lock-up on Friday or at the latest by Monday morning?
  3. Does your system being ready depend on your team only or are outside resources required?


  • HCal (Jiwan Poudel)
    • ready
  • Bigbite (Arun Tadepalli)
    • Provakar: BBcal is working
  • Target cell status(Arun/Gordon)
    • Field measurements completed by 1pm today
    • Plan was to install the rest of the targets (reference cell on site)
    • over the weekend plan to do polarization checks
  • Target laser status (alignment, polarization, power etc)
    • last step remains to use the alignment laser to get the ladder set up (planned for Monday)
  • Counting House Alarms (Bill Henry)
    • Bill tested the alarms and instructions for shift crew response in the wiki (needs further revision?)
  • DAQ (Alex Camsonne)
    • fixed the SBS, LHRS crate
    • the rack for the TS tripped off -> will move the TS crate power to do further checks (today). Plan to leave the DAQ running over the weekend
    • Paul K checked the helicity and everything looks fine
  • GEMs (Holly Szumila-Vance)
    • Vimukthi: fixed issue with SBS and BB GEMs (LEMO cables was the culprit - logbook still needs to be made) => check on this
    • AC: from DAQ point of view it looks ok.
    • ChG: Ellen has a mass flow controller and needs to find some time to install it (not a show stopper - gas mixture changes from 79%Ar to 70%) => Chandan can also change the MFC
  • Target magnets and measurements (Bogdan W. and Bill Henry)
    • WH: done.
  • Moller polarimeter (Don Jones)
    • Target motion not working (Ellen looking into it)
    • we want to do at least one measurement at the beginning; all systems that could be checked now (besides the target) work as expected
    • magnet not cold; expect to get it there end of week (over the weekend)
  • SBS magnet and Bigbite magnets ramp and hold?
    • seems to work; acid flush rescheduled for the long down
  • Corrector magnets:
    • tested by Ellen and signed off on the HCO list
  • Hodoscopes:
    • AC: fixed the HV power supply so it should be fine to turn on; already took cosmics but didn't look at the data

Preliminary run plan

  1. First, bring the beam safely into the hall (Beam recovery procedure - Jiwan and William Henry https://sbs.jlab.org/wiki/index.php/HOW_TOs#Beam_Recovery_Procedure)

Q: At what stage is the SBS turned ON? WH: will post links to the corrector checkout

  1. BigBite/single foil location reconstruction (~20 mins?) - BigBite + HCAL detector experts on call consulting analysis experts like Andrew/Sean (magnet on)
  2. Target performance assessment by target group - Arun (Why hasn’t the target reached xx% polarization?), tell us when we will get there (Target group - Arun) and plan for those hours in between
  3. Take production data!

List of items in case target isn’t ready:

  1. Take data on reference cell at 10 atm H2 (portions that add up to 1 day)
  2. BigBite Sieve slit
    1. with 8 carbon foils and take optics for 1 hr at 40 uA (Sean/Andrew - confirm time)
    2. 1 hour for single foil (magnets off) => Chance BBcal HV setting to appropriate values
  3. Moller measurement depending on availability of people and results from Hall C


In person: Ciprian G, Alexandre C, Hanjie L, Mark J, Chandan G,

Online: Bogdan W, Jimmy C, Sanghwa P, Don J, Ole H, Jack J, Saru, Todd, Brian M, Xinzhan B, Gordon C