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<p class="MsoNormal"><span style="font-size:11.0pt">Hi everyone, <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">I think Holly meant to say 14% efficiency, not occupancy. But that number was from before I figured out the alignment. The real number is that the efficiency is high (at least 80-90%). I don’t have a firm
number yet because I am still replaying the cosmic data after the first iteration of alignment and the statistics of good cosmic ray tracks are relatively low. But the “14%” number is artificial and stems from the fact that I was badly off (about 4 cm) in
my initial guess for the Z position of the new layer. The X and Y position guesses were pretty close to the mark. Due to the steep angles of the cosmic ray tracks, the tracking residuals are quite sensitive to the Z position of the layer. We will be ready
for the HV scan when it comes.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Cheers,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Andrew<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><b><span style="color:black">From:
</span></b><span style="color:black">Sbs_gems <sbs_gems-bounces@jlab.org> on behalf of Gnanvo, Kondo (kg6cq) <kg6cq@virginia.edu><br>
<b>Date: </b>Friday, November 19, 2021 at 5:28 PM<br>
<b>To: </b>Holly Szumila-Vance <hszumila@jlab.org>, sbs_gems@jlab.org <sbs_gems@jlab.org><br>
<b>Subject: </b>[Sbs_gems] [EXTERNAL] RE: GEM HV scan with new resistors<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt">Hi Holly, <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Sorry but I am missing something,
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">What does the 14% occupancy means and how does that compare with the other layers? Why is 14% occupancy an issue for you. I am just not up to date with the details I want to understand
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">My point about the scan not needed alignment is that it is a relative measurement, everything kept equal when doing the HV scan at some point whatever you define by efficiency no longer depends on HV and that
all that matter. But you are right that if there are other concerns related to the alignment, it needs to be looked at.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">I seem to remember that when I tested this layer back at UVa, it was operating at lower gain (for same HV setting) compared to the first two that were initially in BB, that is why I am asking for HV scan,
I believe that to keep everything equal the nominal voltage for this layer will have to be higher than the other 2 U-V layers but only the HV scan will tell.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">You can skip half of the data point. Whether to stay below 3653 in my view depends on what you are seeing with the HV scan. I don’t think there are magic numbers like that. Each module has its optimal setting.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Best regards <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Kondo<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt">From:</span></b><span style="font-size:11.0pt"> Sbs_gems <sbs_gems-bounces@jlab.org>
<b>On Behalf Of </b>Holly Szumila-Vance<br>
<b>Sent:</b> Friday, November 19, 2021 4:09 PM<br>
<b>To:</b> sbs_gems@jlab.org<br>
<b>Subject:</b> [Sbs_gems] GEM HV scan with new resistors<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Hi Kondo, Nilanga, all, <o:p>
</o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">I realize the voltage scan doesn’t need good alignment, but right now the alignment was showing the new HV layer with about 14% occupancy, which is why I brought up the point about making sure alignment will
be somewhat ready. Andrew says it will be, so we should be able to see in real time if we are getting plateaus.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">The HV scan we completed previously consisted of running:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">3385 (3800 equiv)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">3430 (3850 equiv)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">3475 (3900 equiv)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">3519 (3950 equiv)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">3564 (4000 equiv)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">3608 (4050 equiv)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">3653 (4100 equiv)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">3697 (4150 equiv)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">3720 (4175 equiv)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Can we reduce some of these points? Should we stay below 3653V or some other limit? These values correspond to the divider before modification.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Holly<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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