[Sbs_gems] [EXTERNAL] UV GEM HV Settings

[Holly Szumila-Vance]

3653 for layers 0,2 and new 3. The back tracker has had no changes.

From: Sbs_gems <sbs_gems-bounces at jlab.org> on behalf of Andrew Puckett <puckett at jlab.org>
Date: Thursday, November 18, 2021 at 3:43 PM
To: "Liyanage, Nilanga K (nl8n)" <nl8n at virginia.edu>, "Jeffas, Sean (sj9ry)" <sj9ry at virginia.edu>, "sbs_gems at jlab.org" <sbs_gems at jlab.org>
Subject: Re: [Sbs_gems] [EXTERNAL] UV GEM HV Settings

Okay, so then what are the recommended settings for ALL UVA layers/modules? I’m confused. Because we have been running with a mix of 3653 and 3697

Andrew

From: Sbs_gems <sbs_gems-bounces at jlab.org> on behalf of Liyanage, Nilanga K (nl8n) <nl8n at virginia.edu>
Date: Thursday, November 18, 2021 at 3:30 PM
To: Jeffas, Sean (sj9ry) <sj9ry at virginia.edu>, sbs_gems at jlab.org <sbs_gems at jlab.org>
Subject: Re: [Sbs_gems] [EXTERNAL] UV GEM HV Settings
HI Sean,

No, I think it would be best to run at 3653 V  with this modified divider for right now.

We are going to study the modified divider with the  x_ray source here over the new couple of weeks. Once we know more, we can consider going higher if needed

Best

Nilanga
________________________________
From: Sbs_gems <sbs_gems-bounces at jlab.org> on behalf of Sean Jeffas <sj9ry at virginia.edu>
Sent: Thursday, November 18, 2021 3:22 PM
To: sbs_gems at jlab.org <sbs_gems at jlab.org>
Subject: [Sbs_gems] [EXTERNAL] UV GEM HV Settings

Hi Kondo and Nilanga,

After we changed the resistor on UV GEM layer 0 back in October Kondo recommended to lower the HV a bit to monitor the GEM HV. Here is the logbook reference https://logbooks.jlab.org/entry/3930480. However we discovered this week that the voltage has never been returned to 3697 V since then, and we ran all this week at 3653 V. From Kondo's log it is my impression that he meant to only set it to 3653 V for a few hours. Is it ok to change to 3697 V at this point? Also with the two other UV GEMs in BB we also have these new dividers. Then ran all night at 3653 V with cosmics with no issues. Can we set those to 3697 V as well?

Best,
Sean
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