[Sbs_gems] [EXTERNAL] RE: [New Logentry] Follow-up Re: Question UVA UV GEM

[Gnanvo, Kondo (kg6cq)]

Hi Andrew,
Thanks for the clarification. From the HALLOG post I was under the impression that it was unusually high but if that is the way it is everywhere I agree then
Best regards
Kondo

From: Andrew Puckett <puckett at jlab.org>
Sent: Sunday, December 5, 2021 11:49 AM
To: Gnanvo, Kondo (kg6cq) <kg6cq at virginia.edu>; Kondo Gnanvo <kagnanvo at jlab.org>
Cc: Sbs_gems at jlab.org
Subject: Re: [Sbs_gems] [New Logentry] Follow-up Re: Question UVA UV GEM

We see saturation  in some fraction of events in basically all modules. This one is not an outlier compared to other modules. If memory serves, from the HV/efficiency scan data the only module that has any significant headroom to lower the HV and stay in the plateau is the third U/V layer.

Andrew

From: Gnanvo, Kondo (kg6cq) <kg6cq at virginia.edu<mailto:kg6cq at virginia.edu>>
Date: Sunday, December 5, 2021 at 11:21 AM
To: Andrew Puckett <puckett at jlab.org<mailto:puckett at jlab.org>>, Kondo Gnanvo <kagnanvo at jlab.org<mailto:kagnanvo at jlab.org>>
Cc: Sbs_gems at jlab.org<mailto:Sbs_gems at jlab.org> <Sbs_gems at jlab.org<mailto:Sbs_gems at jlab.org>>
Subject: [EXTERNAL] RE: [Sbs_gems] [New Logentry] Follow-up Re: Question UVA UV GEM
Hi Andrew,
I think this depends on how this ADC distribution compare with the other layers. If it is not a outlier, then I agree with you. But if it is larger than the other chambers, it will be safer to lower the HV a little bit (not too much) we can quickly see if it affects efficiency (which I would doubt).
It always safer to operate at the lowest HV that do not affect the performances considering that this is the first layer with the most exposure to high rate

Thanks
Kondo

From: Sbs_gems <sbs_gems-bounces at jlab.org<mailto:sbs_gems-bounces at jlab.org>> On Behalf Of Andrew Puckett
Sent: Sunday, December 5, 2021 11:07 AM
To: Kondo Gnanvo <kagnanvo at jlab.org<mailto:kagnanvo at jlab.org>>
Cc: Sbs_gems at jlab.org<mailto:Sbs_gems at jlab.org>
Subject: Re: [Sbs_gems] [New Logentry] Follow-up Re: Question UVA UV GEM

I would not recommend changing the HV based on this plot alone without more care analysis. We inevitably see saturation in some small fraction of events. I don’t think it is anything to worry about.
puckett.physics.uconn.edu

On Dec 5, 2021, at 10:55 AM, kagnanvo at jlab.org<mailto:kagnanvo at jlab.org> wrote:

Follow-up Re: Question UVA UV GEM<https://logbooks.jlab.org/entry/3956838>

  *   Edit<https://logbooks.jlab.org/entry/3956838/edit?destination=email/send>
  *   Delete<https://logbooks.jlab.org/entry/3956838/delete?destination=email/send>

Lognumber 3956838<https://logbooks.jlab.org/entry/3956838>. Submitted by kagnanvo<https://logbooks.jlab.org/user/kagnanvo> on Sun, 12/05/2021 - 10:50<https://logbooks.jlab.org/entries?start_date=1638715842&end_date=1638723042&book=BIGBITE&book=HALOG&book=SUPERBIGBITE>.
Logbooks:
BIGBITE<https://logbooks.jlab.org/book/bigbite> HALOG<https://logbooks.jlab.org/book/halog> SUPERBIGBITE<https://logbooks.jlab.org/book/superbigbite>
References:
3956665 - Question UVA UV GEM<https://logbooks.jlab.org/entry/3956665>

It looks like APV25 saturation which might indicate that the gain is a bit too high.
GEM expert on call might want to consider lowering HV a little bit (~25 V). Should be safer and not affect efficiency.
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