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</style><article id="node-1204983" class="node node-logentry contextual-links-region article ia-n clearfix" role="article"><header class="node-header"><h1 class="node-title">
<a href="https://logbooks.jlab.org/entry/4131946" rel="bookmark">SBS GEM HV Issue</a>
</h1>
</header><div class="contextual-links-wrapper"><ul class="contextual-links"><li><a href="https://logbooks.jlab.org/entry/4131946/edit?destination=email/send">Edit</a></li><li><a href="https://logbooks.jlab.org/entry/4131946/delete?destination=email/send">Delete</a></li></ul></div>
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<p class="author-datetime">
Lognumber <a href="https://logbooks.jlab.org/entry/4131946" class="lognumber" data-lognumber="4131946">4131946</a>. Submitted by <a href="https://logbooks.jlab.org/user/jeffas">jeffas</a> on <time datetime="2023-02-15T14:52:49-0500" pubdate="pubdate"><a href="https://logbooks.jlab.org/entries?start_date=1676487169&end_date=1676494369&book=HALOG">Wed, 02/15/2023 - 14:52</a></time>. </p>
<p class="last-update">
Last updated on <time datetime="2023-02-15T15:17:13-0500" pubdate="pubdate">Wed, 02/15/2023 - 15:17</time></p>
<table class="field-vitals"><tr><th>Logbooks: </th><td><a href="https://logbooks.jlab.org/book/halog">HALOG</a></td></tr><tr><th>Backlinks: </th><td><a href="https://logbooks.jlab.org/entry/4131957">UVa SBS GEMs on except L2 M0 & M1</a></td></tr></table></div>
<div class="logentry node-content">
<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">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 class="image-wrapper"><img view_mode="elog_email" class="image-style-plentybig" src="https://logbooks.jlab.org/files/styles/plentybig/public/2023/02/4131946/Screenshot from 2023-02-15 14-36-09.png" width="960" height="519" alt="" /></div> <div class="image-wrapper"><img view_mode="elog_email" class="image-style-plentybig" src="https://logbooks.jlab.org/files/styles/plentybig/public/2023/02/4131946/Screenshot from 2023-02-15 14-28-51.png" width="884" height="722" alt="" /></div> <div class="image-wrapper"><img view_mode="elog_email" class="image-style-plentybig" src="https://logbooks.jlab.org/files/styles/plentybig/public/2023/02/4131946/Screenshot at 2023-02-15 15-16-19.png" width="936" height="728" alt="" /></div> </div>
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