[Prex] [New Logentry] RC summary 08/27

[jonesdc at jlab.org]

Logentry Text:
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Since the accelerator was unable to deliver full current to both Halls A and C, Yves and Dennis worked on troubleshooting and finding a new solution that worked for both. In addition to this Hall B has been having increasing backgrounds from an unknown source. Large tails were found on the lasers which were creating issues. A temporary solution was found by increasing compression by adjusting the gang phase on 0L04 (https://logbooks.jlab.org/entry/3834985) and by tweaking the quad at 0L09 (https://logbooks.jlab.org/entry/3834962). Because of these adjustments in the machine, the optics in our beamline also had to be adjusted to match. Our final beam spot size was a bit larger than usual at ~300 microns. 

Ye checked that beam modulation was still operable although she said the amplitudes on coils 3, 5 and 7 had to be increased to accommodate for the increased 60 Hz noise. The new optics solution brought the Compton rates down very close to their high limit but we were able to start running again in late Swing. 

Cryomodule 2L25 was observed to have microphonics noise at 30Hz, 20Hz, and 10Hz (https://logbooks.jlab.org/entry/3834930). The source of this noise was not known at the 8AM meeting. A rough-in pump or something similar was suggested. This was causing instability and increased beam trips. The gradient was reduced to improve stability (https://logbooks.jlab.org/entry/3834821).

During Swing, Owl and this morning up until now we have accumulated about 4C of good production data. Data quality has been ok and efficiency around the 50% level. The new optics solution has increased the correlation between bpm12X and the 4X bpms. 

The plan is to continue production from now through the weekend. Monday Day through Thursday Owl we will be down for the Hall C 1 pass running. Restore is scheduled to happen during nextThursday Day. During this time Jessie has requested the hall be in Restricted access at least until day Wednesday. Jack and Alexandre also plan to get work done during this time. If you plan to be in the hall, please notify the RC and coordinate your work with Jessie.

We will have our usual daily RC meeting at 3:30 PM.
https://bluejeans.com/256205934

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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/3835668
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