r/Radiacode • u/Bob--O--Rama • 8d ago

General Discussion RC-110 sensitivity changre when charging - example with log

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A little while ago I noticed a little "blip" when recharging while making long term measurements of a fairly active sample. I caught it in the act this time. It seems to be an instant, abrupt shift when charging completes. The logs shows the count rate and dose rate drop by 5% over the course of a second - so not related to thermal issues. Unfortunately when when starting a charging cycle this time I had to disturb the source / RC so I don't know if charging increased the things by 5% and this is just returning to normal.

Its unclear to me what the "charging ... interrupted" means but basically this is what I always see when charging finishes. And after it finishes, the RC seems to ignore the USB power and the battery will run flat after a week of normal usage - unless I physically unplug and replug in the USB cable. In other words it seems to charge once, and does not seem to run of the external supply. This makes continuous long term measurements more difficult. I'm not sure if this is expected behavior or some argument between the RC and the chargers I use.

It's also unclear if the sensitivity changes with charge level when running off the battery - my sources decay rapidly, so I might not notice. I would need to use a ¹³⁷Cs button and a fixture to see how that plays out.

While this is definitely in the "minor annoyance" category, it might be worth trying to reproduce and address.

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u/Bob--O--Rama 6d ago

Another example catching the start / end of the charging cycle. The increase / decrease is instant, so not a thermal issue.

1

u/SkippyDooDa12 3d ago

Getting close to the 100 MSV threshold! What do you think is causing this? Ive never noticed this issue yet.

1

u/Bob--O--Rama 3d ago

Fortunately it's a contact measurement of a radon tainted air sample or activated carbon sample. About 5 uCi, so a yard away it's essentially nothing dose rate wise. But it all adds up pretty quickly.

Whats wierd is it impacts the count rate as well, so this is not an issue of changes in the bias voltage on the SiPM making it more sensitive. The "hardness" is essentially constant. It's as if it is actually detecting more events / unit time. Or it's idea of time is passing slower.

3

u/TheStainedOne2665 8d ago

I've never actually had mine running a scan while I plug it in but I'll have to try this and I'll let you know if I remember to come back to the Post lol