<div dir="ltr"><div>Hi All,</div><div><br></div><div>After some more work we have decided that the HV channel is probably broken. So we will need to make an access to the hall to fix this. It is not critical for GEn so we will leave these two SBS GEMs off and wait for the next hall access.</div><div><br></div><div>Best,</div><div>Sean<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Feb 15, 2023 at 3:20 PM jeffas--- via Sbs_gems <<a href="mailto:sbs_gems@jlab.org">sbs_gems@jlab.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div class="msg-3106370261556187865">
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<a href="https://logbooks.jlab.org/entry/4131946" rel="bookmark" target="_blank">SBS GEM HV Issue</a>
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Lognumber <a href="https://logbooks.jlab.org/entry/4131946" target="_blank">4131946</a>. Submitted by <a href="https://logbooks.jlab.org/user/jeffas" target="_blank">jeffas</a> on <a href="https://logbooks.jlab.org/entries?start_date=1676487169&end_date=1676494369&book=HALOG" target="_blank">Wed, 02/15/2023 - 14:52</a>. </p>
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Last updated on Wed, 02/15/2023 - 15:17</p>
<table><tbody><tr><th>Logbooks: </th><td><a href="https://logbooks.jlab.org/book/halog" target="_blank">HALOG</a></td></tr><tr><th>Backlinks: </th><td><a href="https://logbooks.jlab.org/entry/4131957" target="_blank">UVa SBS GEMs on except L2 M0 & M1</a></td></tr></tbody></table></div>
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<p>I noticed that two SBS GEM voltages started drifting. See the attached plots below. These two GEMs are physically next to each other on the HV power supply and on the detector stack. You can see that M0 drifts down while M1 drifts up. At some point M1 trips. Then I try to turn it back on and it goes back to drifting upward again. Then I try turning off HV on both modules, and M1 turns off but M0 refuses to turn off and continues drifting. I turned all of SBS GEMs off and you can see in run 4173 that M0 is clearly still on, <a href="https://logbooks.jlab.org/entry/4131954" target="_blank">https://logbooks.jlab.org/entry/4131954</a> (also look at the plot below. For now I will leave M0 and M1 off ad keep all other SBS GEMs on.</p>
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<div><img src="https://logbooks.jlab.org/files/styles/plentybig/public/2023/02/4131946/Screenshot+from+2023-02-15+14-36-09.png" alt="" width="960" height="519"></div> <div><img src="https://logbooks.jlab.org/files/styles/plentybig/public/2023/02/4131946/Screenshot+from+2023-02-15+14-28-51.png" alt="" width="884" height="722"></div> <div><img src="https://logbooks.jlab.org/files/styles/plentybig/public/2023/02/4131946/Screenshot+at+2023-02-15+15-16-19.png" alt="" width="936" height="728"></div> </div>
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