<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="Generator" content="Microsoft Word 15 (filtered medium)">
<!--[if !mso]><style>v\:* {behavior:url(#default#VML);}
o\:* {behavior:url(#default#VML);}
w\:* {behavior:url(#default#VML);}
.shape {behavior:url(#default#VML);}
</style><![endif]--><style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:"Trebuchet MS";
panose-1:2 11 6 3 2 2 2 2 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
h1
{mso-style-priority:9;
mso-style-link:"Heading 1 Char";
mso-margin-top-alt:auto;
margin-right:0in;
mso-margin-bottom-alt:auto;
margin-left:0in;
font-size:24.0pt;
font-family:"Calibri",sans-serif;
font-weight:bold;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
p.MsoListParagraph, li.MsoListParagraph, div.MsoListParagraph
{mso-style-priority:34;
margin-top:0in;
margin-right:0in;
margin-bottom:0in;
margin-left:.5in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
p.gmail-m-6284437974280400217msolistparagraph, li.gmail-m-6284437974280400217msolistparagraph, div.gmail-m-6284437974280400217msolistparagraph
{mso-style-name:gmail-m_-6284437974280400217msolistparagraph;
mso-margin-top-alt:auto;
margin-right:0in;
mso-margin-bottom-alt:auto;
margin-left:0in;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
span.Heading1Char
{mso-style-name:"Heading 1 Char";
mso-style-priority:9;
mso-style-link:"Heading 1";
font-family:"Calibri Light",sans-serif;
color:#2F5496;}
p.gmail-m-6284437974280400217xxauthor-datetime, li.gmail-m-6284437974280400217xxauthor-datetime, div.gmail-m-6284437974280400217xxauthor-datetime
{mso-style-name:gmail-m_-6284437974280400217xxauthor-datetime;
mso-margin-top-alt:auto;
margin-right:0in;
mso-margin-bottom-alt:auto;
margin-left:0in;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
.MsoChpDefault
{mso-style-type:export-only;
font-family:"Calibri",sans-serif;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
/* List Definitions */
@list l0
{mso-list-id:91095183;
mso-list-template-ids:1152271786;}
@list l0:level1
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:.5in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l0:level2
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:1.0in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l0:level3
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:1.5in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l0:level4
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:2.0in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l0:level5
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:2.5in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l0:level6
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:3.0in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l0:level7
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:3.5in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l0:level8
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:4.0in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l0:level9
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:4.5in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l1
{mso-list-id:698313790;
mso-list-template-ids:-2021986524;}
@list l1:level1
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:.5in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l1:level2
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:1.0in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l1:level3
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:1.5in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l1:level4
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:2.0in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l1:level5
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:2.5in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l1:level6
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:3.0in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l1:level7
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:3.5in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l1:level8
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:4.0in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l1:level9
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:4.5in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l2
{mso-list-id:788549686;
mso-list-type:hybrid;
mso-list-template-ids:-2135147742 1148634424 67698713 67698715 67698703 67698713 67698715 67698703 67698713 67698715;}
@list l2:level1
{mso-level-text:%1-;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l2:level2
{mso-level-number-format:alpha-lower;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l2:level3
{mso-level-number-format:roman-lower;
mso-level-tab-stop:none;
mso-level-number-position:right;
text-indent:-9.0pt;}
@list l2:level4
{mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l2:level5
{mso-level-number-format:alpha-lower;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l2:level6
{mso-level-number-format:roman-lower;
mso-level-tab-stop:none;
mso-level-number-position:right;
text-indent:-9.0pt;}
@list l2:level7
{mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l2:level8
{mso-level-number-format:alpha-lower;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l2:level9
{mso-level-number-format:roman-lower;
mso-level-tab-stop:none;
mso-level-number-position:right;
text-indent:-9.0pt;}
@list l3
{mso-list-id:814418036;
mso-list-template-ids:-473660740;}
@list l3:level1
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:.5in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l3:level2
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:1.0in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l3:level3
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:1.5in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l3:level4
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:2.0in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l3:level5
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:2.5in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l3:level6
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:3.0in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l3:level7
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:3.5in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l3:level8
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:4.0in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
@list l3:level9
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:4.5in;
mso-level-number-position:left;
text-indent:-.25in;
mso-ansi-font-size:10.0pt;
font-family:Symbol;}
ol
{margin-bottom:0in;}
ul
{margin-bottom:0in;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="EN-US" link="blue" vlink="purple">
<div class="WordSection1">
<p class="MsoNormal">Dear all, <o:p></o:p></p>
<p class="MsoNormal">Following a quick phone conversation with Xinzhan, I produce a table with possible sources of sparks with GEM in the experiment (based on my understanding of how these detector operate).
<o:p></o:p></p>
<p class="MsoNormal">I listed the most likely sources, where it affects the most in the chamber, and what we can do about them.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">To summarize, with the BB GEMs been operational for more than 2 months now, only the spark caused by large ionization and the one caused by defects on the GEM foils are in my view the one we should expect during the runs.
<o:p></o:p></p>
<ol style="margin-top:0in" start="1" type="1">
<li class="MsoListParagraph" style="margin-left:0in;mso-list:l2 level1 lfo4">The first one with large ionization is likely to cause no damage as long as it is not happening on a week spot of a GEM foil. It also likely going to happen on the third GEM foil where
the concentration of charge around the holes is huge. The probability of this to happens increase with beam current and with HV on the GEMs. I am pretty sure this is what we are seeing right now. Setting an HV trip will do nothing other than forcing us to
ramp up very frequently the GEMs (should be avoided)<o:p></o:p></li></ol>
<p class="MsoListParagraph"><o:p> </o:p></p>
<ol style="margin-top:0in" start="2" type="1">
<li class="MsoListParagraph" style="margin-left:0in;mso-list:l2 level1 lfo4">The second is if there is a local defect on the GEM foils. This defects comes with the fabrication of the GEM foil and are normally cured during the assembly process. But there is
no certainty that all the defect can be eliminated. So an avalanche around this area will trigger the spark (even with low ionization event and low beam current) and the spark have a high probability to short the sector. There is nothing we can do about this
one if I happens. A current trip limit in operational condition will not do us any favor. If the spark happens, it will do the damage it want to do, whether you shot the HV down or not. I believe this is what happens with INFN GEM as well as UV layer 0 HV
sector.<o:p></o:p></li></ol>
<p class="MsoListParagraph"><o:p> </o:p></p>
<p class="MsoNormal">The other causes are the one in our hands i.e avoid humidity in the chamber, operating with clean gas mixture, and knowing the HV divider etc … Considering the chambers has been running for quite sometime now, I would not worry too much
about these causes. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">In any cases, we can reduce the spark rate probability by lowering the HV on the GEMs and / or the beam current. So there is a compromise between safety and long term stability and the performance in term of high rate capability and efficiency
and I think this is a discussion we need to have within the GEM experts of the collaboration.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hope that helps <o:p></o:p></p>
<p class="MsoNormal">Kondo<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><b>From:</b> Sean Jeffas <sj9ry@virginia.edu> <br>
<b>Sent:</b> Monday, December 6, 2021 4:06 PM<br>
<b>To:</b> Gnanvo, Kondo (kg6cq) <kg6cq@virginia.edu><br>
<b>Cc:</b> David Flay <flay@jlab.org>; Liyanage, Nilanga K (nl8n) <nl8n@virginia.edu>; sbs_gems@jlab.org<br>
<b>Subject:</b> Re: [Sbs_gems] [EXTERNAL] RE: [New Logentry] Brief Voltage Spike on uva_xygem_2<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal">Hi All,<o:p></o:p></p>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">I scrolled through the logbook and found we had sparks causing > 20 uA jumps three times total in the past week of running. Therefore it seems like a rare spark to me, and should not cause any issues, and does not need any action. We chose
our current operating voltages at the very beginning of the plateau so I think it would be a significant change to decrease any of them by 50 V.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Best,<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">Sean<o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div>
<p class="MsoNormal">On Mon, Dec 6, 2021 at 3:51 PM Gnanvo, Kondo (kg6cq) <<a href="mailto:kg6cq@virginia.edu">kg6cq@virginia.edu</a>> wrote:<o:p></o:p></p>
</div>
<blockquote style="border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in">
<div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Hi all,
<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I think we should be clear on what we are discussing here!
<o:p></o:p></p>
<ul type="disc">
<li class="gmail-m-6284437974280400217msolistparagraph" style="mso-list:l3 level1 lfo1">
What I saw on the logbook looks like a spark from me and I don’t really think it is something to worry about. We expect that with GEMs unless there is a specific pattern with that spike and in that case we should take ab look and try to understand. I would
suggest that GEM expert look at the chart and come with a clear conclusion on that
<o:p></o:p></li></ul>
<p class="gmail-m-6284437974280400217msolistparagraph"> <o:p></o:p></p>
<ul type="disc">
<li class="gmail-m-6284437974280400217msolistparagraph" style="mso-list:l0 level1 lfo2">
Reducing HV for 50 V because of APV saturation is a discussion that we had yesterday , so I will not repeat the argument here but let’s try not to mix issues and solution we apply to try to address.
<o:p></o:p></li></ul>
<p class="gmail-m-6284437974280400217msolistparagraph"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Best regards
<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Kondo<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<div>
<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b>From:</b> Sbs_gems <<a href="mailto:sbs_gems-bounces@jlab.org" target="_blank">sbs_gems-bounces@jlab.org</a>>
<b>On Behalf Of </b>David Flay<br>
<b>Sent:</b> Monday, December 6, 2021 3:46 PM<br>
<b>To:</b> Liyanage, Nilanga K (nl8n) <<a href="mailto:nl8n@virginia.edu" target="_blank">nl8n@virginia.edu</a>>;
<a href="mailto:sbs_gems@jlab.org" target="_blank">sbs_gems@jlab.org</a><br>
<b>Subject:</b> Re: [Sbs_gems] [New Logentry] Brief Voltage Spike on uva_xygem_2<o:p></o:p></p>
</div>
</div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;background:white">
<span style="font-size:12.0pt;color:black">Thanks Nilanga,</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;background:white">
<span style="font-size:12.0pt;color:black"> </span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;background:white">
<span style="font-size:12.0pt;color:black">Zeke and I will do that before we start the next run. </span><o:p></o:p></p>
</div>
<div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;color:black"> </span><o:p></o:p></p>
</div>
<div id="gmail-m_-6284437974280400217Signature">
<div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;color:black">Best regards,</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;color:black">David </span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;color:black"> </span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;background:white">
<span style="font-size:12.0pt;color:black">----------------------------------------------------------------</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;color:black">David Flay, Ph. D.</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;color:black">Hall A/C Staff Scientist</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;color:black">Thomas Jefferson National Accelerator Facility</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;color:black">Office: CEBAF Center, C119</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;color:black">----------------------------------------------------------------</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:12.0pt"><span style="font-size:12.0pt;color:black"> </span><o:p></o:p></p>
</div>
</div>
</div>
</div>
<div class="MsoNormal" align="center" style="text-align:center">
<hr size="1" width="98%" align="center">
</div>
<div id="gmail-m_-6284437974280400217divRplyFwdMsg">
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="color:black">From:</span></b><span style="color:black"> Liyanage, Nilanga K (nl8n) <<a href="mailto:nl8n@virginia.edu" target="_blank">nl8n@virginia.edu</a>><br>
<b>Sent:</b> Monday, December 6, 2021 3:37 PM<br>
<b>To:</b> David Flay <<a href="mailto:flay@jlab.org" target="_blank">flay@jlab.org</a>>;
<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> [EXTERNAL] Re: [Sbs_gems] [New Logentry] Brief Voltage Spike on uva_xygem_2</span>
<o:p></o:p></p>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
</div>
</div>
<div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;color:black"> </span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;color:black">Hmmm, that is a bit worrying.</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;color:black"> </span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;color:black">I think, until we understand this a bit more, we should back down the HV on just this one module by 50 V.</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;color:black"> </span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;color:black">I expect the reduction of efficiency to be very small because of this change. So I think we should do this soon.</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;color:black"> </span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;color:black">Best</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;color:black"> </span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;color:black">Nilanga</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;color:black"> </span><o:p></o:p></p>
</div>
<div class="MsoNormal" align="center" style="text-align:center">
<hr size="1" width="98%" align="center">
</div>
<div id="gmail-m_-6284437974280400217x_divRplyFwdMsg">
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="color:black">From:</span></b><span style="color:black"> 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</span><span style="font-size:9.5pt;font-family:"Trebuchet MS",sans-serif">
</span><o:p></o:p></p>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:8.5pt;font-family:"Trebuchet MS",sans-serif"> </span><o:p></o:p></p>
</div>
</div>
<div id="gmail-m_-6284437974280400217x_x_mimemail-body">
<div id="gmail-m_-6284437974280400217x_x_center">
<div id="gmail-m_-6284437974280400217x_x_main">
<h1><span style="font-size:12.0pt;font-family:"Trebuchet MS",sans-serif"><a href="https://logbooks.jlab.org/entry/3957495" target="_blank"><span style="text-decoration:none">Brief Voltage Spike on uva_xygem_2
</span></a></span><o:p></o:p></h1>
<div>
<ul type="disc">
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l1 level1 lfo3">
<span style="font-size:6.5pt;font-family:"Trebuchet MS",sans-serif"><a href="https://logbooks.jlab.org/entry/3957495/edit?destination=email/send" target="_blank"><span style="text-decoration:none">Edit</span></a></span><o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l1 level1 lfo3">
<span style="font-size:6.5pt;font-family:"Trebuchet MS",sans-serif"><a href="https://logbooks.jlab.org/entry/3957495/delete?destination=email/send" target="_blank"><span style="text-decoration:none">Delete</span></a></span><o:p></o:p></li></ul>
</div>
<div>
<p class="gmail-m-6284437974280400217xxauthor-datetime" style="margin-bottom:1.2pt">
<b><span style="font-size:5.5pt;font-family:"Trebuchet MS",sans-serif">Lognumber <a href="https://logbooks.jlab.org/entry/3957495" target="_blank">
<span style="text-decoration:none">3957495</span></a>. Submitted by <a href="https://logbooks.jlab.org/user/flay" target="_blank">
<span style="text-decoration:none">flay</span></a> on <a href="https://logbooks.jlab.org/entries?start_date=1638818252&end_date=1638825452&book=HALOG" target="_blank">
<span style="text-decoration:none">Mon, 12/06/2021 - 15:17</span></a>. </span></b><o:p></o:p></p>
<table class="MsoNormalTable" border="0" cellspacing="3" cellpadding="0">
<tbody>
<tr>
<td width="15%" style="width:15.0%;padding:1.2pt 1.2pt 1.2pt 1.2pt">
<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:12.0pt"><b><span style="font-size:9.5pt">Logbooks:
</span></b><o:p></o:p></p>
</td>
<td width="0" style="width:.3pt;padding:1.2pt 1.2pt 1.2pt 1.2pt">
<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:12.0pt"><span style="font-size:9.5pt"><a href="https://logbooks.jlab.org/book/halog" target="_blank"><span style="text-decoration:none">HALOG</span></a></span><o:p></o:p></p>
</td>
</tr>
<tr>
<td width="15%" style="width:15.0%;padding:1.2pt 1.2pt 1.2pt 1.2pt">
<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:12.0pt"><b><span style="font-size:9.5pt">Entry Makers:
</span></b><o:p></o:p></p>
</td>
<td width="0" style="width:.3pt;padding:1.2pt 1.2pt 1.2pt 1.2pt">
<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:12.0pt"><span style="font-size:9.5pt">flay</span><o:p></o:p></p>
</td>
</tr>
</tbody>
</table>
</div>
<div>
<p><span style="font-size:6.5pt;font-family:"Trebuchet MS",sans-serif;color:white">Just catching up on this after the DAQ has settled back in and the HCAL HV was power cycled.
</span><o:p></o:p></p>
<p><span style="font-size:6.5pt;font-family:"Trebuchet MS",sans-serif">At around 13:50 we had a HV spike on uva_xygem_2, see attached.</span><o:p></o:p></p>
</div>
<div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:5.5pt;font-family:"Trebuchet MS",sans-serif"><img border="0" width="960" height="316" style="width:10.0in;height:3.2916in" id="gmail-m_-6284437974280400217_x005f_x0000_i1027" src="https://logbooks.jlab.org/files/styles/plentybig/public/2021/12/3957495/uva_xygem_2_spike_12-06-21.png"></span><o:p></o:p></p>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
<p class="MsoNormal">_______________________________________________<br>
Sbs_gems mailing list<br>
<a href="mailto:Sbs_gems@jlab.org" target="_blank">Sbs_gems@jlab.org</a><br>
<a href="https://mailman.jlab.org/mailman/listinfo/sbs_gems" target="_blank">https://mailman.jlab.org/mailman/listinfo/sbs_gems</a><o:p></o:p></p>
</blockquote>
</div>
</div>
</body>
</html>