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<p class="MsoNormal">Hello all, </p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I wish I could bring you better news. In light of yesterday’s cell rupture event, it is clear we will not be bringing beam back into Hall A before the holiday shutdown. I am canceling all remaining shifts until the holiday shutdown.
</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">RC update: </p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">At approximately 16:42 during swing shift yesterday (Dec 14), the shift crew noticed a “massive HV trip” of all of the BigBite GEMs and also the GRINCH:
</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><a href="https://logbooks.jlab.org/entry/4101677">https://logbooks.jlab.org/entry/4101677</a>
</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">At the time, Gordon and Hunter were in the CH. While assessing the situation, Hunter saw a target chamber temperature spike similar to what was seen during the previous cell rupture event in November, correlated in time with the detector
HV trips. An NMR was performed on the pumping chamber, and no signal was seen, confirming that target cell Hunter had ruptured. Zooming in on the time of the event, we found that a large (~9 mm!) BPM Y (vertical) position excursion happened without tripping
off the beam for nearly 5 seconds: </p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><a href="https://logbooks.jlab.org/entry/4101739">https://logbooks.jlab.org/entry/4101739</a>
</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">This was also associated with a large spike in radiation in the Hall:
</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><a href="https://logbooks.jlab.org/entry/4102088">https://logbooks.jlab.org/entry/4102088</a>
</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Around this time, there were also some vacuum issues developing in the upstream beamline. Failure of the upstream Be window is suspected, but not yet confirmed.
</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Once the situation was understood, we powered down all detectors and spectrometer magnets, turned off and locked out the target lasers and the target oven, sent the swing shift crew home, and immediately canceled owl and day shifts for
12/15. This morning it is clear that there will be no more beam before the holiday shutdown. Your RC is working to get RadCon support for cleanup of the target enclosure (the tech on call has been notified), and the spokespeople are discussing what work can
still be accomplished before the holiday shutdown to keep the existing plans and preparation for Kin. 4 on schedule.
</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">We will hold an RC meeting today at the usual time of 3:30 PM today to continue the discussion:
</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Location: Counting house conference room<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal">Join ZoomGov Meeting<o:p></o:p></p>
<p class="MsoNormal"><a href="https://jlab-org.zoomgov.com/j/1619032184?pwd=aWhTVWxya1ZZQzA1K2ZPSTd2ZXZ2QT09">https://jlab-org.zoomgov.com/j/1619032184?pwd=aWhTVWxya1ZZQzA1K2ZPSTd2ZXZ2QT09</a><o:p></o:p></p>
<p class="MsoNormal">Meeting ID: 161 903 2184<o:p></o:p></p>
<p class="MsoNormal">Passcode: 260715<o:p></o:p></p>
<p class="MsoNormal">Dial by your location<o:p></o:p></p>
<p class="MsoNormal"> +1 669 254 5252 US (San Jose)<o:p></o:p></p>
<p class="MsoNormal"> +1 646 828 7666 US (New York)<o:p></o:p></p>
<p class="MsoNormal"> +1 551 285 1373 US<o:p></o:p></p>
<p class="MsoNormal"> +1 669 216 1590 US (San Jose)<o:p></o:p></p>
<p class="MsoNormal"> 833 568 8864 US Toll-free<o:p></o:p></p>
<p class="MsoNormal">Find your local number: <a href="https://jlab-org.zoomgov.com/u/acj3pTicMx">
https://jlab-org.zoomgov.com/u/acj3pTicMx</a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Sincerely,</p>
<p class="MsoNormal">Andrew</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-family:"Century",serif;color:black">Andrew Puckett<br>
Associate Professor, Physics Department<br>
University of Connecticut<br>
196 Auditorium Road, Unit 3046<br>
Storrs, CT 06269-3046<br>
Office phone: (860) 486-7137<br>
</span><a href="https://puckett.physics.uconn.edu/" title="https://puckett.physics.uconn.edu/"><span style="font-family:"Century",serif;color:#00006A">https://puckett.physics.uconn.edu</span></a><span style="font-family:"Century",serif;color:black"><br>
</span><a href="mailto:puckett@jlab.org" title="mailto:puckett@jlab.org"><span style="font-family:"Century",serif;color:#000064">puckett@jlab.org</span></a></p>
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