[Sbs_gems] [EXTERNAL] Re: [New Logentry] BB GEM Ar/CO2 ratio keeps going up along with the flow rates - GEM HV Must Stay OFF until it is understood what is going on.

[Liyanage, Nilanga K (nl8n)]

That sounds OK,
If there is N2 still in the chamber after one hour the gain would be low, but it would get better as the chambers get purged more
________________________________
From: Wertz, Ezekiel <ewertz at wm.edu>
Sent: Tuesday, January 31, 2023 11:22 PM
To: Liyanage, Nilanga K (nl8n) <nl8n at virginia.edu>; Liyanage, Nilanga K (nl8n) via Sbs_gems <sbs_gems at jlab.org>; jboyd at jlab.org <jboyd at jlab.org>; Jack Segal <segal at jlab.org>; adr at jlab.org <adr at jlab.org>
Subject: Re: [Sbs_gems] [EXTERNAL] Re: [New Logentry] BB GEM Ar/CO2 ratio keeps going up along with the flow rates - GEM HV Must Stay OFF until it is understood what is going on.

Hi Nilanga;

We have had the flow off to the GEMs for about an hour to trouble shoot this problem. I was planning to flush the GEMs for at least an hour at the correct mix ratio before considering anything with HV. Does this sound reasonable? Should we wait longer?

Zeke

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From: Liyanage, Nilanga K (nl8n) <nl8n at virginia.edu>
Sent: Tuesday, January 31, 2023 11:21 PM
To: Wertz, Ezekiel <ewertz at wm.edu>; Liyanage, Nilanga K (nl8n) via Sbs_gems <sbs_gems at jlab.org>; jboyd at jlab.org <jboyd at jlab.org>; Jack Segal <segal at jlab.org>; adr at jlab.org <adr at jlab.org>
Subject: Re: [Sbs_gems] [EXTERNAL] Re: [New Logentry] BB GEM Ar/CO2 ratio keeps going up along with the flow rates - GEM HV Must Stay OFF until it is understood what is going on.


Sounds good Zeke, and thanks for taking care of this.

Please make sure the mix and the flow rate OK before turning HV back on
________________________________
From: Wertz, Ezekiel <ewertz at wm.edu>
Sent: Tuesday, January 31, 2023 11:19 PM
To: Liyanage, Nilanga K (nl8n) via Sbs_gems <sbs_gems at jlab.org>; jboyd at jlab.org <jboyd at jlab.org>; Jack Segal <segal at jlab.org>; adr at jlab.org <adr at jlab.org>; Liyanage, Nilanga K (nl8n) <nl8n at virginia.edu>
Subject: Re: [Sbs_gems] [EXTERNAL] Re: [New Logentry] BB GEM Ar/CO2 ratio keeps going up along with the flow rates - GEM HV Must Stay OFF until it is understood what is going on.

Hi GEM Folks,

Jack is out of town this week and is not able to troubleshoot. I was called in to look at the problem. Long story short there was a gas bottle that was labeled Argon but is actually Nitrogen. The bottle has 2 labels. This explains the rise in mix ratio and pressure to the detectors.

Hooked up an Argon bottle and purging the line to bring ratio back down. More details to come I future log entry.

Zeke

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From: Sbs_gems <sbs_gems-bounces at jlab.org> on behalf of Liyanage, Nilanga K (nl8n) via Sbs_gems <sbs_gems at jlab.org>
Sent: Tuesday, January 31, 2023 9:59 PM
To: jboyd at jlab.org <jboyd at jlab.org>; sbs_gems at jlab.org <sbs_gems at jlab.org>; Jack Segal <segal at jlab.org>; adr at jlab.org <adr at jlab.org>
Subject: [Sbs_gems] [EXTERNAL] Re: [New Logentry] BB GEM Ar/CO2 ratio keeps going up along with the flow rates - GEM HV Must Stay OFF until it is understood what is going on.

Hi Anuruddha

If the flow rate is going up, I think we should turn gas off the GEMs until Jack checks out the system and decides it is under control.

Turning of HV was the right thing

Best

Nilanga
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Sent: Tuesday, January 31, 2023 9:55 PM
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Subject: [Sbs_gems] [New Logentry] BB GEM Ar/CO2 ratio keeps going up along with the flow rates - GEM HV Must Stay OFF until it is understood what is going on.

BB GEM Ar/CO2 ratio keeps going up along with the flow rates - GEM HV Must Stay OFF until it is understood what is going on.<https://logbooks.jlab.org/entry/4121342>

  *   Edit<https://logbooks.jlab.org/entry/4121342/edit?destination=email/send>
  *   Delete<https://logbooks.jlab.org/entry/4121342/delete?destination=email/send>

Lognumber 4121342<https://logbooks.jlab.org/entry/4121342>. Submitted by adr<https://logbooks.jlab.org/user/adr> on Tue, 01/31/2023 - 21:53<https://logbooks.jlab.org/entries?start_date=1675216423&end_date=1675223623&book=HALOG&book=SUPERBIGBITE>.

Logbooks:       HALOG<https://logbooks.jlab.org/book/halog> SUPERBIGBITE<https://logbooks.jlab.org/book/superbigbite>
Tags:   GEM<https://logbooks.jlab.org/tag/gem>
Entry Makers:   adr
References:     4121329 - BB UVa GEM gas alarm<https://logbooks.jlab.org/entry/4121329>

Received a call from the CH about the BBGEM gas ratio being off. They tried to call GEM on call but ended up calling me as he wasn't reachable at the moment.

I looked at the strip charts and seems like the ratio started going up after the bottle Ar bottle changeover happened around 20:51 hrs. Currently the ratio is at 9.09 which is quite high and GEM HV MUST stay OFF or it could be lethal for the GEMs. The gas flow rates going into the GEMs also seem to be increasing.
Not sure whether this is because something is wrong with the new bottle that it switched over or something going wrong with the gas mixing system / binary gas analyzer. Asked Bhasitha who is on shift to put a new Ar bottle in and forced to draw from that.
I am copying John (on-call) and Jack so that they can follow up with this.

[https://logbooks.jlab.org/files/styles/plentybig/public/2023/01/4121342/bb_ar_co2-ratio_off.png]
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