[Sbs_gems] [EXTERNAL] Fluctuations in Hall A Argon concentrations

[Jack Segal]

   Well, it looks like the BGA is affected by the air temperature in the Gas Shed. It has an internal heater
to keep the temperature stable. But, it looks like it got overwhelmed. The temperature dropped below 45 degF.
   I did not do anything special to set this up, just set it on a table. Plenty of room for improvement.

On 11/16/2021 10:32 AM, Jack Segal wrote:
> John,
>    Thanks for looking.
>    I was a bit concerned because I could not see the mass flow controller set and read voltages using the Wave utility through a web browser.
> https://epicsweb.jlab.org/wave/
> When I got in I looked in the Archiver and can see that they have been regular this whole time. So, it is a problem with the BGA or the
> line going to the ADC. The mix has been steady. The read voltages follow the set voltages. So, that part is OK.
>    The PVs of interest for this are:
> 
> Shed_gas_Ch_28   BB GEMs argon Mass Flow Controller set voltage
> 
> Shed_gas_Ch_29   BB GEMs argon Mass Flow Controller read voltage
> 
> Shed_gas_Ch_30   BB GEMs carbon dioxide Mass Flow Controller set voltage
> 
> Shed_gas_Ch_31   BB GEMs carbon dioxide Mass Flow Controller read voltage
> 
> Shed_gas_Ch_34   BB GEMs Binary Gas Analyzer - % Argon
> 
> 
>    The PVs for the ADC in the Gas Shed can be found here:
> https://hallaweb.jlab.org/tech/Detectors/public_html/hall_a/controls/gas_shed/gs1313.htm
> If it asks you to login it is your CUE.
> 
> 
> On 11/16/2021 10:11 AM, John Boyd wrote:
>> Jack,
>>
>> from the strip charts for the GEM gas monitoring setup in Hall A it shows that the concentration of Argon has been spiking/fluctuating since about 16:30 yesterday. Please see the attached image of the strip charts. You can see that it will periodically 
>> spike from the normal value of about 7.9 to about 8.6.
>>
>> THis has been looked into by some of the GEM team (Zeke, Thir, Anu, and myself) and the assumption is that it may just be a readout issue. But, we aren't sure how to verify this or to proceed. Could you please advise on this?
>>
>> Thank you,
>>
>> John
> 

-- 
John(Jack) Segal
Halls A and C Spectrometer Support Manager
Thomas Jefferson National Accelerator Facility
12000 Jefferson Avenue
Suite 12
Newport News, VA 23606-4486
Phone: (757) 269-7242
Cell: (757) 320-9977