[Sbs_gems] [EXTERNAL] Re: GEM HV scan with new resistors

[Liyanage, Nilanga K (nl8n)]

Hi Holly,

With this change we have increased the voltage across GEM-3 by 10% compared to before.

So the voltage across GEM-3 now with 3653  V is like running with something over  4000 V before, which is really, really high.

Given this I would suggest that we only go up to 3653 in the initial scan. Then check the efficiency curve. If we have reached the plateau, then stop there. If not, we should carefully do the next  point at 3697 V, and as soon as we have the data back down.

We should not go above that

Best

Nilanga
________________________________
From: Sbs_gems <sbs_gems-bounces at jlab.org> on behalf of Holly Szumila-Vance <hszumila at jlab.org>
Sent: Friday, November 19, 2021 4:09 PM
To: sbs_gems at jlab.org <sbs_gems at jlab.org>
Subject: [Sbs_gems] GEM HV scan with new resistors


Hi Kondo, Nilanga, all,



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.



The HV scan we completed previously consisted of running:

3385 (3800 equiv)

3430 (3850 equiv)

3475 (3900 equiv)

3519 (3950 equiv)

3564 (4000 equiv)

3608 (4050 equiv)

3653 (4100 equiv)

3697 (4150 equiv)

3720 (4175 equiv)



Can we reduce some of these points? Should we stay below 3653V or some other limit? These values correspond to the divider before modification.



Thanks,

Holly


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.jlab.org/pipermail/sbs_gems/attachments/20211119/a68d54fc/attachment-0001.html>