<div dir="ltr">Hi All,<div><br></div><div>We have finished analyzing a cosmic test after turning the gas flow down on layers 1 and 3 from 525 cc/min to 375. The data is attached below. For reference:</div><div><br></div><div><div><b>Run 13240: </b>Taken January 11th with all four UV layers and 2 uA on LH2 at the <span class="gmail-il">SBS</span>-14 kinematic. Gas flow at 525 cc/min</div><div><b>Run 12423:</b> Taken January 14th with cosmic data. UV layers 1 and 3 gas flowing at 375 cc/min</div></div><div><br></div><div>These runs are a bit difficult to compare since one is with beam and the other is comsic, but it's all that we have. Overall you can see that the timing distribution is a bit better for layer 1 and 3, but still not great. Also the efficiencies and gains are not significantly reduced by the lower gas flow. So I think we can run with this setting. </div><div><br></div><div>Kondo/Nilanga/Xinzhan: Will this reduced gas flow have a greater effect with the beam on? I suppose we will find out in two hours anyway.</div><div><br></div><div>Also I would be interested in turning up the voltage on layer 1 and module 1 in the XY layer by 25 V. Are there any objections?</div><div><br></div><div>Best,<br>Sean</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Jan 13, 2022 at 3:49 PM Sean Jeffas <<a href="mailto:sj9ry@virginia.edu">sj9ry@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"><div dir="ltr">Hi Andrew,<div><br></div><div>I am not sure if you meant to only reply to only me, but here are the plots you asked for. I actually already had them but decided it was kind of overkill.</div><div><br></div><div>Best,</div><div>Sean</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Jan 13, 2022 at 3:21 PM Andrew Puckett <<a href="mailto:puckett@jlab.org" target="_blank">puckett@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">
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<p class="MsoNormal"><span style="font-size:11pt">Hi Sean, <u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt">Interesting results. Another interesting way to visualize these results would be in terms of the strip mean times, which might (or might not) have somewhat better resolution than the time sample peaking distribution.
I would also be curious to see a couple of alternative ways of visualizing the data. For example:
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<p class="MsoNormal"><span style="font-size:11pt"><u></u> <u></u></span></p>
<ol style="margin-top:0in" start="1" type="1">
<li style="margin-left:0in"><span style="font-size:11pt">A more “binary” approach: 1D and 2D distributions vs. x and/or y for hits peaking in sample 5 and for hits NOT peaking in sample 5<u></u><u></u></span></li><li style="margin-left:0in"><span style="font-size:11pt">Same as 1, but perhaps broken out by hits peaking in samples 1, 2, 3, 4, 5, etc.<u></u><u></u></span></li></ol>
<p class="MsoNormal"><span style="font-size:11pt"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt">Cheers,<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt">Andrew<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt"><u></u> <u></u></span></p>
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<p class="MsoNormal" style="margin-bottom:12pt"><b><span style="font-size:12pt;color:black">From:
</span></b><span style="font-size:12pt;color:black">Sbs_gems <<a href="mailto:sbs_gems-bounces@jlab.org" target="_blank">sbs_gems-bounces@jlab.org</a>> on behalf of Sean Jeffas <<a href="mailto:sj9ry@virginia.edu" target="_blank">sj9ry@virginia.edu</a>><br>
<b>Date: </b>Thursday, January 13, 2022 at 3:03 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] [EXTERNAL] UV Latency Analysis Results<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:11pt">Hi All,<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:11pt"><u></u> <u></u></span></p>
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<p class="MsoNormal"><span style="font-size:11pt">I have finished analyzing the spatial distribution of the peak time samples. I have attached the results below for two runs.<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:11pt"><u></u> <u></u></span></p>
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<p class="MsoNormal"><b><span style="font-size:11pt">Run 13240: </span></b><span style="font-size:11pt">Taken January 11th with all four UV layers and 2 uA on LH2 at the SBS-14 kinematic.<u></u><u></u></span></p>
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<p class="MsoNormal"><b><span style="font-size:11pt">Run 12423:</span></b><span style="font-size:11pt"> Taken December 1st with J0 still in the layer 1 position but the UV layer was in layer 3 position. This was 2 uA on LD2 at SBS-11.<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:11pt"><u></u> <u></u></span></p>
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<p class="MsoNormal"><span style="font-size:11pt">In the recent run (13240) you can clearly see the peak time sample is uniform over the hit map for every layer except for layer 1 and layer 3. Similarly if you look at the December run (12423) the same issue
was present in layer 3, but we never noticed it because we were always the first and last bin out of the analysis. John and I measured the resistors on the GEMs today and did not find a resistance that would suggest that the gas window has collapsed onto the
cathode. Unfortunately the shielding blocks us from seeing the gas window, otherwise it would be very easy to tell. <u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:11pt"><u></u> <u></u></span></p>
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<p class="MsoNormal"><span style="font-size:11pt">Therefore our current conclusion is that since the GEM layers 1 and 3 both have a non uniform gas flow, this is probably causing some bend in the readout board, which causes this issue. To fix this we can
turn down the gas flow rate and see how everything is affected. Since the experiment is down for a few days it would be good to turn it down today and take some cosmic data, if possible.<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:11pt"><u></u> <u></u></span></p>
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<p class="MsoNormal"><span style="font-size:11pt">Best,<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:11pt">Sean<u></u><u></u></span></p>
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