[Hallc_running] [New Logentry] RC Update (12/03/2022)

[mnycz at jlab.org]

Logentry Text:
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Good Morning,

First, a BIG thank you to Dave Meekins, Walter Kellner,  Jeremey Nines, and Stanley Madlock for their hard work yesterday, addressing the downstream vacuum issue (that prevented the experiment from running on Wednesday), and getting getting the experiment back up and running.
They worked during the DAY and SWING shifts yesterday and the vacuum is now stable/acceptable and we are able to begin running on target ladder 2.
After working on the vacuum, Dave Meekins then worked on the cryotargets, setting everything up so that we would be able to run on both Helium-3 and Helium-4. Due to some limitations with cryo, we need to park one of the cryotargets while the other is in use. He provided a procedure that we must follow:
https://logbooks.jlab.org/entry/4094507
Zeke added some additional information and screenshots he made when following Dave's procedure yesterday that could be helpful for future TOs:
https://logbooks.jlab.org/entry/4094547
Starting back up, we first preformed harp scans and checked the beam position on the aluminum hole. The beam position for target ladder 2 is nearly the same as it was for ladder 1: https://logbooks.jlab.org/entry/4094405
Currently, the beam current is limited to 40 uA for the cryotargets, so we next slowly ramped up to 40 uA to make sure we stayed within the target parameters/limits.
At 30 uA, MCC did new Ion chamber calibrations for both He-3 and He-4 cryotargets.
https://logbooks.jlab.org/entry/4094454 ---- Helium-3
https://logbooks.jlab.org/entry/4094576 ---- Helium-4

When running on the 10 cm dummy target with 40 uA, the target vacuum became poor. We scaled back to 5 uA and after speaking with Dave Meekins, found that this was expected and we proceeded to "burn off" the target with increasing currents until the vacuum recovered.
https://logbooks.jlab.org/entry/4094529

During OWL, we continued with the solid targets : Li-6 and Li-7. We are currently finishing up Li-7
The first 1-2 runs on both Lithium targets were to also "burn off" any remaining mineral oil residue. While running, Casey monitored the invariant mass distribution add did not notice any size able elastic peak. They also did not notice any large changes in the target vacuum.

Below is the Kinematic setting which we are currently at for target ladder 2
3.3.1 : Setting 1
HMS: 20 degrees (-6.6 GeV)
SHMS: 8.0 degrees (-9.2 GeV)

After finishing the Li-7 target, we still have 12C, 27Al, 63Cu, and 197 Au before moving to the next setting.

I would suggest skipping the RC meeting today. Everyone have a great weekend!
Best Regards, 
Mike Nycz, Hall C RC

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This is a plain text email for clients that cannot display HTML.  The full logentry can be found online at https://logbooks.jlab.org/entry/4094832
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