[Alert_collaboration] [New Logentry] RC Summary July 29 - July 30 Owl

[schmidta at jlab.org]

Logentry Text:
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This is the RC summary for Day Shift July 29 through Owl shift July 30.

Yesterday, we ran production (325 nA on He-4) up until 10:10 AM, when beam was taken away for the RF Separator test. At that time, Zeyu began the change from the He-4 to hydrogen targets, including 10 fill/purge cycles. Beam delivery resumed at 10:45 AM, at which point the shift crew conducted two Moller runs, one with each Helmholtz polarity. The results were:
- Positive polarity: 86.766 +/- 1.492   (see: https://logbooks.jlab.org/entry/4429832)
- Negative polarity: -84.959 +/- 1.357 (see: https://logbooks.jlab.org/entry/4429847)

The target was ready at 13:40, and we prepared for production running on hydrogen. We collected data at 100 nA, the maximum current allowable under the current operational restrictions. Because fifth pass running on hydrogen is not covered in the RSAD, there is no way to increase that limit. (For upcoming third pass running, this limit will increase to 350 nA.) 

We collected production data smoothly until owl shift when, at 02:10, the solenoid and then the torus experienced a fast ramp down (see: https://logbooks.jlab.org/entry/4430379, https://logbooks.jlab.org/entry/4430350). Denny and Krister (engineering on-call) were notified and began investigating the cause. Detector HV was ramped down as a precaution. The work to understand what happened and to prepare the magnets to be ramped up is still on going.

At approx. 08:00, the accelerator turned off for the maintenance day. Radcon surveyed the hall so that we can move to Restricted for today's work. 

- 7/29 day shift summary: https://logbooks.jlab.org/entry/4429713
- 7/29 swing shift summary: https://logbooks.jlab.org/entry/4430007
- 7/30 owl shift summary: https://logbooks.jlab.org/entry/4430267

ABU for last 24h

- 12.3h of ABUs ~ 51% efficiency,

- Total ABUs since April 5th: 1254.3+12.3=1266.6 --> 1266.6 / (75.5 * 24) = 69.9%

- Day 116 of 151 scheduled: 116/151= 76.8%

- BANU: 6.1h due to target change, magnet ramp down, HV trips, DAQ resets

Plan for today:
Today is a maintenance day, and the Hall is in Restricted. Today's work includes
* Figure out what happened to the magnets, and get them ramped back up
* Investigate water leak on the third floor of the forward carriage (See https://logbooks.jlab.org/entry/4428339)
When we are ready to resume production, 
* Take two Moller runs, one with each Helmholtz setting, now with HWP-in
* continue running 100 nA on hydrogen until the pass change tomorrow morning. 

RC meeting:

We will meet as usual today at 11:30 (EST) in CH Room 200C and online via Zoom
Zoom meeting ID: 160 570 5819
Zoom Link: https://jlab-org.zoomgov.com/j/1605705819

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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/4430609
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