[Sbs_gems] [EXTERNAL] BB GEM Efficiency Results

[Liyanage, Nilanga K (nl8n)]

Hi Sean

Thank you for completing this analysis quickly; the results look very nice.

I have a couple of questions:


  1.  Looks like there is a mismatch between your tables and plot. For example, according to the table, for M5 at 3650 V, the efficiency is 78%, but according to the plot it is 84%
  2.  I would argue that looking at your data, for M5 and M6 the suggested voltage of 3650 V is too low. I would suggest at least 3700 V for these two modules.

Best

Nilanga
________________________________
From: Sbs_gems <sbs_gems-bounces at jlab.org> on behalf of Sean Jeffas <sj9ry at virginia.edu>
Sent: Friday, October 14, 2022 11:46 AM
To: Sbs_gems at jlab.org <sbs_gems at jlab.org>
Subject: [Sbs_gems] [EXTERNAL] BB GEM Efficiency Results

Hello All,

We have completed the BB HV efficiency scans. See full results here, https://logbooks.jlab.org/entry/4055432. As listed our HV settings will be:

UV Layer 0 - 3650 V
UV Layer 1 - 3600 V
UV Layer 2 - 3600 V
UV Layer 3 - 3600 V
XY Mod 4 - 3600 V
XY Mod 5 - 3650 V
XY Mod 6 - 3650 V
XY Mod 7 - 3600 V

These numbers have been chosen as the beginning of the efficiency plateau. They all produce above 86% efficiency Please feel free to respond if you look at the graphs and think they should be different. Generally we are comfortable with all the GEMs operating up to 3650 V, so we can reasonably increase some of them.

Efficiency plateaued a bit earlier than I expected. For example UV layer 2 was used in GMn and we found it was 84% efficient at 3600 V, meanwhile for this run we found it is 92% efficient at the same voltage. I wonder if the new CM calculations are causing this improvement. Regardless we will run like this for now, and increase the voltage if there are any issues when we start taking production data.

Best,
Sean


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