<div dir="ltr"><div>Hi Nilanga,</div><div><br></div><div>This also happened on UV #0 in the past two days also, at least twice on that chamber as I noticed. For the xy GEM chambers, I've only seen it once (the one David posted). I am also concerned by this, since we already have APV saturations in every layer, I agree that we should back down on the HV by 50 V. I want to back down by 50 V for all GEM chambers, is that OK for everyone?</div><div><br></div><div>Best,</div><div><br></div><div>XInzhan<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Dec 6, 2021 at 3:37 PM Liyanage, Nilanga K (nl8n) <<a href="mailto:nl8n@virginia.edu">nl8n@virginia.edu</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">
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Hmmm, that is a bit worrying.</div>
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I think, until we understand this a bit more, we should back down the HV on just this one module by 50 V.</div>
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I expect the reduction of efficiency to be very small because of this change. So I think we should do this soon.</div>
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Best</div>
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Nilanga</div>
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<font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> Sbs_gems <<a href="mailto:sbs_gems-bounces@jlab.org" target="_blank">sbs_gems-bounces@jlab.org</a>> on behalf of <a href="mailto:flay@jlab.org" target="_blank">flay@jlab.org</a> <<a href="mailto:flay@jlab.org" target="_blank">flay@jlab.org</a>><br>
<b>Sent:</b> Monday, December 6, 2021 3:20 PM<br>
<b>To:</b> <a href="mailto:sbs_gems@jlab.org" target="_blank">sbs_gems@jlab.org</a> <<a href="mailto:sbs_gems@jlab.org" target="_blank">sbs_gems@jlab.org</a>><br>
<b>Subject:</b> [Sbs_gems] [New Logentry] Brief Voltage Spike on uva_xygem_2</font>
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<h1 style="font-size:1.6em"><a href="https://logbooks.jlab.org/entry/3957495" rel="bookmark" style="text-decoration:none" target="_blank">Brief Voltage Spike on uva_xygem_2
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<li><a href="https://logbooks.jlab.org/entry/3957495/edit?destination=email/send" style="text-decoration:none" target="_blank">Edit</a></li><li><a href="https://logbooks.jlab.org/entry/3957495/delete?destination=email/send" style="text-decoration:none" target="_blank">Delete</a></li></ul>
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Lognumber <a href="https://logbooks.jlab.org/entry/3957495" style="text-decoration:none" target="_blank">
3957495</a>. Submitted by <a href="https://logbooks.jlab.org/user/flay" style="text-decoration:none" target="_blank">
flay</a> on <a href="https://logbooks.jlab.org/entries?start_date=1638818252&end_date=1638825452&book=HALOG" style="text-decoration:none" target="_blank">Mon, 12/06/2021 - 15:17</a>.
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<a href="https://logbooks.jlab.org/book/halog" style="text-decoration:none" target="_blank">HALOG</a></td>
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flay</td>
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<p>Just catching up on this after the DAQ has settled back in and the HCAL HV was power cycled.
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<p>At around 13:50 we had a HV spike on uva_xygem_2, see attached.</p>
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<img alt="" src="https://logbooks.jlab.org/files/styles/plentybig/public/2021/12/3957495/uva_xygem_2_spike_12-06-21.png" width="960" height="316"></div>
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