[Sbs_gems] [EXTERNAL] Hall A gas during Holiday

[Gnanvo, Kondo (kg6cq)]

Hi Zeke,
For the UV layers, I really don’t mind reducing the flow rate. I am pretty confident about these chambers. For the X/Y layers, I still have this marginal (probably unwarranted) worry about gas window collapsing possibility.
We have applied a fix that seems to be working extremely well so far, so it might be that I am over worrying about a non-issue but sudden pressure change in the chamber will just be a catalyst for window collapsing.

Again, I don’t want to alarm anyone because I am confident that the fix is working, I just don’t want to have to worry about the potentiality during the Xmas break.

But even if you reduce the flow rate in the chambers and you don’t want to go down too much to preserve the low level of humidity, I think it is quite a waste to flow Ar-CO2 for a full week if we are not taking cosmic data with the chambers.

Best regards
Kondo

From: Sbs_gems <sbs_gems-bounces at jlab.org> On Behalf Of Ezekiel Wertz
Sent: Wednesday, December 15, 2021 5:28 PM
To: Sbs_gems at jlab.org
Cc: Jack Segal <segal at jlab.org>
Subject: [Sbs_gems] [EXTERNAL] Hall A gas during Holiday

Hi GEM folks,

So I was able to talk to Jack today and from that discussion he plans to be in Newport News during the holiday. His current plan for the GEM gas would be to keep it on the mix Ar/CO2, but reduce the flow rate. So that way the Argon and CO2 bottles do not run out as quickly. At the moment I think it would be nontrivial to switch the gas system to only N2 with enough cylinders to last more than a couple of days. I am also not sure we have the N2 cylinders in-hand to make this swap.

For the INFN layer we typically use a standby flow of 100 cc/min per layer. Could Kondo or Nilanga comment on an acceptable reduced flow rate for the standard UV GEMs (production 600 cc/min per layer), the one UV layer with less gas flow (production 520 cc/min per layer), and the UVA XY GEMs (225 cc/min per module)?

I know Kondo had made the comment that he would prefer to not reduce the flow at all for these. But I was curious if it was possible, even if it's only a small quantity?

Once a decision is made about what reduced gas flows we will use. We can then coordinate folks to change the flow meters in the Hall, once it is open before the start of the holiday break. Things already can be remotely monitored so we can have folks do that.

Best,
Zeke
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