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

[Tyler Lemon]

Hello,

I wasn’t able to complete all work in the hall before a meeting at 11 so I will return after lunch.

Right now, the two S1 airflows have been changed over to the new readout device and are all good.

Air pressure and n2 flow are changed over but need some debugging, hence the very high, incorrect values for them.

-Tyler

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From: Tyler Lemon <tlemon at jlab.org>
Sent: Tuesday, February 17, 2026 9:28:54 AM
To: Valery Kubarovsky <vpk at jlab.org>; 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 Valery,

I'm going to start working on the RICH S1 hardware interlocks soon.

My plan is:
1. Make software updates remotely from the EEL
2. Go down to hall and swap out hardware
3. Verify system is working after changes
4. Check humidity sensors

Between steps 1 and 2, there will be some time where all gas system readout for S1 will be lost since the software updates re-map ADC channels (the same thing would happen if the order of steps 1 and 2 were swapped).

During this time, the nitrogen flow to S1 can be inferred from the S4 nitrogen purge flow and the nitrogen gas panel pressures at the bottom of the RICH Sector 4 Nitrogen Volume Interlocks EPICS screen. Since  the nitrogen purge flow is for both detector is provided by the same panel, if those Sector 4 values are normal, there is high confidence that Sector 1's nitrogen flow is okay.

I will make a log book entries when everything is done.

-Tyler


________________________________
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 4:27 PM
To: Valery Kubarovsky <vpk at jlab.org>; tlemon--- via dsg-hallb_rich <dsg-hallb_rich at jlab.org>
Subject: Re: [dsg-hallb_rich] Update/modify RICH S1 hardware interlock system on Feb. 17 to improve reliability?

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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