[Sbs_gems] [EXTERNAL] Upper limits in terms of beam current for the GEM study planned for tomorrow

[Gnanvo, Kondo (kg6cq)]

Hi Holly,
I  think there are two distinct studies here.

  *   To your question on current limit, the limit on the power supply is 1 mA. There is no limit on the maximum GEM current other than limit that we would impose ourselves, so at this point, any limit we set is arbitrary when we increase the beam current to study the chambers.
  *   This leads to what I was proposing when we had the discussion with Nilanga. If we want to push the beam current as high as we are talking about, then we might as well study the impact on one layer (instead of 5) and determine how confident we are operating the GEMs at these high beam currents. Then we can set limit based on that
  *   I believe Nilanga’s plan is to study the gain drop / tracking efficiency as a function of higher beam current and in that case, the limit is not on the GEM current but on how far any meaningful tracking can be performed (i.e. it is Andrew’s call), but here again I am afraid that the negative signal issues (specially its impact on common mode correction)  will completely corrupt any results / interpretation of results
Best regards
Kondo

From: Sbs_gems <sbs_gems-bounces at jlab.org> On Behalf Of Holly Szumila-Vance
Sent: Sunday, February 6, 2022 10:45 AM
To: Rathnayake, Anuruddha (adr4zs) <adr4zs at virginia.edu>
Cc: Sbs_gems at jlab.org; Arun Tadepalli <arunts at jlab.org>
Subject: Re: [Sbs_gems] [EXTERNAL] Upper limits in terms of beam current for the GEM study planned for tomorrow

To be clear, the question is what current limits are we willing to test up to for the gem test tomorrow on swing- probably a question for Nilanga and/or Kondo. I think this is for coordination with MCC purposes.


On Feb 6, 2022, at 9:52 AM, Anuruddha Rathnayake <adr4zs at virginia.edu<mailto:adr4zs at virginia.edu>> wrote:

Dear All,

There is a discussion going on between our current RC (Arun) and some of us here in Jlab about what would be the beam current limits that we should adhere to, if it is possible to come into such a limit looking at the observations we have made so far.

I'm attaching the GEM linearity studies we have done so far, if that helps to make a decision. https://logbooks.jlab.org/entry/3932489

I believe if you use linearity studies done at SBS-11, that would be the best as our current spectrometer angles at SBS-9 are similar to what we had at SBS-9 (Please correct me if I am wrong, I know this more of as a word of mouth rather than referring to any official documentation).

Best,
Anu
_______________________________________________
Sbs_gems mailing list
Sbs_gems at jlab.org<mailto:Sbs_gems at jlab.org>
https://mailman.jlab.org/mailman/listinfo/sbs_gems
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.jlab.org/pipermail/sbs_gems/attachments/20220206/d1024075/attachment-0001.html>