<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<style type="text/css" style="display:none;"> P {margin-top:0;margin-bottom:0;} </style>
</head>
<body dir="ltr">
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Dear All</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Thanks a lot Jack for doing this calibration and check. Thanks Zeke for the summary.</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
I agree that things looks good now, and we seem to be getting the same mix from the mixer as from the pre-mix.</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
The suggested time line is good. I suggest we switch to the mixer gas when flushed enough. Then take cosmics when ready and compare.</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Best</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Nilanga</div>
<div id="appendonsend"></div>
<hr style="display:inline-block;width:98%" tabindex="-1">
<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Sbs_gems <sbs_gems-bounces@jlab.org> on behalf of Ezekiel Wertz <ewertz@email.wm.edu><br>
<b>Sent:</b> Monday, November 8, 2021 12:07 PM<br>
<b>To:</b> sbs_gems@jlab.org <sbs_gems@jlab.org><br>
<b>Cc:</b> Jack Segal <segal@jlab.org><br>
<b>Subject:</b> [Sbs_gems] [EXTERNAL] Mixing System for GEMs</font>
<div> </div>
</div>
<div>
<div dir="ltr">
<div>Hi GEM folks,</div>
<div><br>
</div>
<div>I have attached a plot and will describe a discussion I had with Jack this morning pertaining to the GEM gas mix system. So if you have questions he may be able to address them better. I would like to preface that the mixing system is not connected to
the BigBite GEMs when these tests and manipulations were done. <br>
</div>
<div><br>
</div>
<div>Recently (last couple of days) Jack was able to use the Binary Gas Analyzer, which I think analyzes the gas sample using a molecular technique. Jack would be able to provide a more accurate description of the technique. Whereas, the original mixing system
used a mass slow control based off of a voltage setpoint. What he noticed is that both systems agree pretty well.<br>
</div>
<div><br>
</div>
<div>The plot pretty much summarizes the behavior of the GEM gas system, but I will provide a description as well. The original gas mixing system used for the GEMs was properly calibrated to 75/25 or 74/26 Ar/CO2. We see this early on in the plot (more to the
left). After this Jack then connected premix Ar/CO2 75/25, premix Ar/CO2 80/20, and 100% Argon. What we see is that with the Binary Gas Analyzer the premixed Ar/CO2 75/25 actually displays as closer to 77/23 or 78/22 for Ar/CO2. Then to the right of the plot
we see that Jack has calibrated the mixing system to be fairly identical to the premix gas value. In other words the mixing system is now calibrated to the same concentrations of Ar/CO2 as the premixed gas that the GEM folks are more familiar with.
<br>
</div>
<div><br>
</div>
<div>So the gas system needs to flush for a couple of hours and it has been since about 10am this morning. From last week there is cosmic data using the premix system and GEM efficiencies are available. This afternoon we could switch to the mix system. Let
it flush the now calibrated mixed Ar/CO2 through the BigBite GEMs for at least 10 hours and then some time this week before returning to beam operations we could collect cosmic data and compare it to the efficiencies with the premixed gas.</div>
<div><br>
</div>
<div>If there are any comments or questions please respond to this email.</div>
<div><br>
</div>
<div>Best,</div>
<div>Zeke<br>
</div>
</div>
</div>
</body>
</html>