[Sbs_gems] [EXTERNAL] Re: [New Logentry] Goodnight Gas Shed

[Sean Jeffas]

Hi Xinzhan,

This function does work but this is how it works: The GEM HV is triggered
to turn off *only *at the moment that the gas mixture alarm goes off. If
the GEM HV is then turned back on, but the gas is still alarming then the
HV will stay on. This is how Steve implemented it and I assume it is
complicated to force the HV off constantly if the mixture alarm is on. We
can ask Steve about this if everyone agrees that this needs to be done.

In this particular case the GEMs had been turned off for Moller
measurements. Then 30 minutes later the GEM gas mixture went bad, but it
was not noticed since the alarm handler was red for every detector. It then
stayed this way all day because everything was off and work was being done
in the hall. Do overall this is a bad coincidence because this would have
been easily caught if we were taking beam data, but it came up almost
immediately after we stopped that.

Best,
Sean

On Mon, Feb 27, 2023 at 10:18 PM Xinzhan Bai via Sbs_gems <sbs_gems at jlab.org>
wrote:

> Hi Zeke,
>
> I think we have implemented a function: when the gas ratio is off, HV will
> be turned off automatically. Did this function work, or is it useful?
> Thanks.
>
> Best,
>
> Xinzhan
>
> On Mon, Feb 27, 2023 at 9:55 PM ewertz--- via Sbs_gems <sbs_gems at jlab.org>
> wrote:
>
>> Goodnight Gas Shed <https://logbooks.jlab.org/entry/4140465>
>>
>>    - Edit
>>    <https://logbooks.jlab.org/entry/4140465/edit?destination=email/send>
>>    - Delete
>>    <https://logbooks.jlab.org/entry/4140465/delete?destination=email/send>
>>
>> Lognumber 4140465 <https://logbooks.jlab.org/entry/4140465>. Submitted
>> by ewertz <https://logbooks.jlab.org/user/ewertz> on Mon, 02/27/2023 -
>> 21:52
>> <https://logbooks.jlab.org/entries?start_date=1677549146&end_date=1677556346&book=HALOG>.
>>
>> Logbooks: HALOG <https://logbooks.jlab.org/book/halog>
>> Entry Makers: ewertz
>>
>> So around 23:00 yesterday there was an alarm for the BBGEM gas shed mix
>> ratio. Somehow it got silenced and the GEMs filled up with only CO2. This
>> is not great because there is no ionizer. But is ok from a safety
>> standpoint cause CO2 is a quencher. So HV was not harmed. Holly and I
>> realized this right before we were taking optics data. Figured out that
>> somehow the system got bamboozled because there were 2 full cylinders of
>> Argon on the line. But 1 cylinder was not opened so the system just stopped
>> accepting Argon. Pretty weird behavior. Now we have opened up the Argon ad
>> purged the line to get it back to the proper mix ratio. See
>> https://logbooks.jlab.org/entry/4140460 for picture of plot of gas ratio
>> over time as proof.
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