[dsg-hallb_rich] Update/modify RICH S1 hardware interlock system on Feb. 17 to improve reliability?

[Tyler Lemon]

Valery,

My answer regarding the Sector 1 humidity sensors is the same as it always is.

The humidity in the detector is so low that the sensors cannot read that low and are returning zero percent relative humidity. It has been like that for the lifetime of the detector.

Additionally, if the sensors were truly broken, every single temperature readout for the Sector 1 nitrogen volume sensors would be -45 (it’s lowest possible value).
The same sensor measures temperature and humidity, so if one read out is broken, both will be broken.
This can be seen with T3 and T29.
The other 46 sensors are responding as normal and have valid temperatures and valid humidity values and therefore are working.


But, regardless of all that, I will still check the nitrogen volume sensors after the other work on Tuesday.
I will also send the procedure for how I checked the sensors so you can replicate the test  yourself if there is still doubt.

-Tyler

________________________________
From: Valery Kubarovsky <vpk at jlab.org>
Sent: Friday, February 13, 2026 3:52:28 PM
To: tlemon--- via dsg-hallb_rich <dsg-hallb_rich at jlab.org>; Tyler Lemon <tlemon at jlab.org>
Subject: Re: Update/modify RICH S1 hardware interlock system on Feb. 17 to improve reliability?

Hello Tyler,
Please go ahead and implement your proposed changes to the RICH1 interlock. Tuesday, February 17 works well for me.
I still have a question regarding the humidity measurement in the nitrogen volume of the RICH1 detector. All channels are indicating 0.00%. In my view, this suggests that something may not be functioning correctly in the measurement system.
Best regards,
Valery



________________________________
From: dsg-hallb_rich <dsg-hallb_rich-bounces at jlab.org> on behalf of Tyler Lemon via dsg-hallb_rich <dsg-hallb_rich at jlab.org>
Sent: Friday, February 13, 2026 13:55
To: tlemon--- via dsg-hallb_rich <dsg-hallb_rich at jlab.org>
Subject: [dsg-hallb_rich] Update/modify RICH S1 hardware interlock system on Feb. 17 to improve reliability?

Hello Valery,

In 2025, there were four times where the expansion chassis responsible for measuring RICH Sector 1's two cooling air flows, cooling buffer tank pressure, and nitrogen purge flow failed.
On all four occasions, the system could not be recovered remotely and I had to go down to the hall to resolve the problem.

This clearly indicates that the expansion chassis is a weak point in the interlock system.
DSG has therefore determined alternate measurement methods for these four parameters, allowing us to remove the expansion chassis and improve system reliability.

In brief, the changes involve:
- moving the two cooling air flows to two spare ADC channels on the system's main controller
- moving the cooling buffer tank pressure and nitrogen purge flow to a two-channel, I2C ADC board

A DSG Note posted on our group webpage<https://www.jlab.org/sites/default/files/dsg/notes/2026-02.pdf> has more details on the changes.


Would next Tuesday, February 17, 2026 be a good day to make these changes?

The work would involve updating the hardware interlock software and minor rewiring inside a de-energized interlock chassis (all work covered by existing EPASes).


Also, feel free to reply with any questions you may have.

-Tyler
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