[Sbs_gems] [EXTERNAL] UV GEM HV Settings

[Gnanvo, Kondo (kg6cq)]

Sean, all
There is no reason to change from previous setting. Like Nilanga said, we should stick to the setting we had before.

The new chamber need HV scan to know the optimal value (don’t assume that it is the same exactly than the other UV layers). You can start with 3653 and see what you get or do a HV scan. But keep I mind that we need to be careful regarding increasing the HV before we really understand all the consequences in modifying HV divider.
If there is no clear reason, to go higher I would be very conservative. That is my default mode

Best regards
Kondo

From: Sbs_gems <sbs_gems-bounces at jlab.org> On Behalf Of Holly Szumila-Vance
Sent: Thursday, November 18, 2021 3:45 PM
To: Andrew Puckett <puckett at jlab.org>; Liyanage, Nilanga K (nl8n) <nl8n at virginia.edu>; Jeffas, Sean (sj9ry) <sj9ry at virginia.edu>; sbs_gems at jlab.org
Subject: Re: [Sbs_gems] [EXTERNAL] UV GEM HV Settings

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

From: Sbs_gems <sbs_gems-bounces at jlab.org<mailto:sbs_gems-bounces at jlab.org>> on behalf of Andrew Puckett <puckett at jlab.org<mailto:puckett at jlab.org>>
Date: Thursday, November 18, 2021 at 3:43 PM
To: "Liyanage, Nilanga K (nl8n)" <nl8n at virginia.edu<mailto:nl8n at virginia.edu>>, "Jeffas, Sean (sj9ry)" <sj9ry at virginia.edu<mailto:sj9ry at virginia.edu>>, "sbs_gems at jlab.org<mailto:sbs_gems at jlab.org>" <sbs_gems at jlab.org<mailto: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<mailto:sbs_gems-bounces at jlab.org>> on behalf of Liyanage, Nilanga K (nl8n) <nl8n at virginia.edu<mailto:nl8n at virginia.edu>>
Date: Thursday, November 18, 2021 at 3:30 PM
To: Jeffas, Sean (sj9ry) <sj9ry at virginia.edu<mailto:sj9ry at virginia.edu>>, sbs_gems at jlab.org<mailto:sbs_gems at jlab.org> <sbs_gems at jlab.org<mailto: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<mailto:sbs_gems-bounces at jlab.org>> on behalf of Sean Jeffas <sj9ry at virginia.edu<mailto:sj9ry at virginia.edu>>
Sent: Thursday, November 18, 2021 3:22 PM
To: sbs_gems at jlab.org<mailto:sbs_gems at jlab.org> <sbs_gems at jlab.org<mailto: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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