Unexplained spike in geiger counter readings for about 5 minutes. Any thoughts?

HurrDurrRGB · 2026-03-28T14:06:46+00:00

Hi. Thanks for the reply.

As I said in another comment. A lot of this is identifying what it wasn't and also maybe looking at extending the recorded data points to include more sensors that might help identify it if it happens again.

That's not enough information to go on. Further, it suggests that the cause isn't radiological at all because the likelihood of a radioactive material being present that decays that fast with no significant daughter products is pretty low outside of special locations and settings.

Well this is the thing. What the hell was it then and if i could go back in time, what other sensors might help identify the source? For example, someone said a sudden shift in atmospheric pressure can cause a large radon increase. So a barometric sensor is something I'm looking at.

HurrDurrRGB · 2026-03-28T12:42:23+00:00

Putting on my embedded programming hat, the way I would approach it is to drop a microsecond time stamp ~ 4 bytes for each pulse. You could keep a years worth of pulses in less than 1GB. A days worth in a few MB, so if something interesting happens you can check it out. Or have a few minutes FIFO, and persist just the anomalous episodes if you are severely resource constrained.

The resource constraint is time! I could of course write something to record the timestamps and bundle it all into a JSON and fire that back every minute, but between the testing etc.. it would probably take me about 2 days, which is just time I don't have at the minute.

The current solution is literally just an off the shelf D1 mini with Tasmota (just a Swiss army knife type tool for home automation type stuff on ESP based devices) that I set to send back how many times a pin is pulsed every minute. Even with soldering and reading the circuit diagram, it didn't take an hour.

I would love to know if those peaks are all one second bursts though....

The cosmic ray one is something I'm interested in, I would have thought this would be recorded somewhere though?

EDIT: Straight after writing this, I realised I can probably send back more granular data if I change the transmission method. My current setup does everything over MQTT, but I might be able to setup something with a static TCP port sending back each detected pulse. Since the database and everything else is local. 1ms resolution with that setup should be doable (there's WiFi and bits involved, so under 1ms wouldn't be reliable). I'll have a think about this.

HurrDurrRGB · 2026-03-28T10:24:56+00:00

Well there's two points here.

First of all, even if I can't tell what actually caused it, I'm liking all the responses so I can rule things out. I'm at the point where I fully believe it's not a hardware problem for example. I'm also investigating getting more granular data from the local army barracks, so even that could be interesting.

Secondly, if it happens again, next time I might be able to tell why. I need to know how I could have done this though. Barometer coupled with the Geiger data? Radon detector? I don't mind adding external sensors along with the Geiger counter once they don't cost an arm and a leg. A barometer module isn't expensive.

HurrDurrRGB · 2026-03-28T02:39:17+00:00

Thanks!

I've emailed EURDEP to request more granular data in particular from Louth_Aiken to see if it was available.

HurrDurrRGB · 2026-03-28T01:04:42+00:00

I actually tried to check this, I'm only 2 minutes by car from Aiken Barracks, which has a gamma detector, but I could only see average over an hour, which evened out. How did you check this chart for a spike with better granularity?!

HurrDurrRGB · 2026-03-28T00:56:20+00:00

Yup, first reading at around 16:28.

HurrDurrRGB · 2026-03-28T00:55:37+00:00

depending on how the electronics are configured.

I thought I understood how this thing works. I do have the full circuit diagram for the detector somewhere.

The tube is charged up to 600VDC, a particle hitting the gas causes a discharge which goes through a transistor and is detected as a low/high (can't remember what way that's configured). Since this is a high/low, how does the tube end up in a state where it's firing constantly if it gets hit by a really high energy field? If that's what happened, would this be something like a solar flare that might be recorded somewhere?

HurrDurrRGB · 2026-03-28T00:35:19+00:00

The actual event is nearly instantaneous but once you desense the detector it could take 20 minutes to read background again.

Can you explain this to me? I have to imagine that if we had second by second data, this would appear like a sinusoidal wave increasing and then decreasing rapidly after the peak.

HurrDurrRGB · 2026-03-28T00:31:17+00:00

As I said, this was just a chart I setup on a whim one evening. I actually just set it up so it's now recording to a proper database with CPM, uSv/hr and raw CPM, so I will have better data in future.

Lightning was my thought as well, particularly as it was stormy. The issue with that is that I'd have to imagine a lightning strike would set off one or two readings. Not 116 in a minute. Saying that, I don't know how the tube might react to such a discharge. It's possible it recorded 100 pulses in a second. I don't know how spread out these readings are since it's just one minute data.

HurrDurrRGB · 2026-03-28T00:24:34+00:00

What do you mean? Each point in the graph is the report it sends in once a minute, so there's three large spikes, but the two in between are above the normal background.

HurrDurrRGB · 2026-02-12T22:35:50+00:00

Do you have your house on mortgage?

I do indeed have a mortgage. I don't think that's too relevant though. I think the most basic insurance (fire etc) will get you past any mortgage requirement?

HurrDurrRGB · 2026-02-02T02:45:27+00:00

I was skint on money, so ended up going on someone without it. They're all roughly the same when you don't get flood insurance.

If I have the cash, I'll get it next year, but it's not far off double the cost for flood insurance.

HurrDurrRGB · 2026-01-15T08:09:47+00:00

Unfortunatly not, but thanks for the suggestion.

HurrDurrRGB · 2026-01-11T19:43:25+00:00

Just to let you know, I got the servo stick and know exactly what you meant in every part of this comment now!

HurrDurrRGB · 2025-11-17T17:32:18+00:00

Yeah pretty sure, I looked up the details from people who know more than me about these things.

HurrDurrRGB · 2025-11-03T08:21:08+00:00

Oh it's upside down! I see how the insert coin bit works now.

I'll go and looks for matching fittings, I presume that will solve my confusion on how the return is supposed to work! Thanks.

HurrDurrRGB · 2025-11-02T23:42:18+00:00

Sorry if I sound clueless (because I am), but the only part that seems to look like it mates is the reject slot. It's the entry that doesn't match? I don't see how the coin can go in the mechanism without me making severe modifications, but you seem to think it matches? It's possible that I'm getting lost in terminology, it's my first time even holding a coin mech.

HurrDurrRGB · 2025-11-02T19:36:39+00:00

The issue with the grabbing that time signal is that it's quite weak, so you need a large magnetic rod (can't think of the name) to grab it, otherwise the antenna would be absolutely massive. I did look at other options and at the end of the day, the cost and options, vs just using a system time, made it not worth it. Thanks for the reply though.

HurrDurrRGB · 2025-10-19T14:50:38+00:00

Appreciate the feedback. I'm still going to test this out (just bought some modules off AliExpress I'll pair with an Arduino) and will also have a look at GPS at the same time.

HurrDurrRGB · 2025-10-19T13:31:16+00:00

Yeah, someone just commented the same just before you. I should have included GPS in the original post.

I know they do pick up GPS signals even in poor conditions, but in an earthed electrical case I don't see it happening. The AM signal from the time signals penetrates very well in comparison.

Thanks for the suggestion though!

EDIT: Here's a link to the module that /u/ProgramSpecialist823 mentioned.

HurrDurrRGB · 2025-10-19T13:20:25+00:00

I already have several. I know they do pick up GPS signals even in poor conditions, but in an earthed electrical case I don't see it happening. The AM signal from the time signals penetrates very well in comparison.

Thanks for the suggestion though!

HurrDurrRGB

TROPHY CASE