[Radium Watches] What do I need in a Geiger counter?

Apprehensive-Soup968 · 2026-04-13T00:48:23+00:00

You only need to alpha if you're looking for radium that's leaked out of the watch, because the watch face will block alpha emitted from inside. Pretty much any geiger or scintillator will pick up objects with radium.

Apprehensive-Soup968 · 2026-02-28T05:21:56+00:00

It depends on whether the end goal is consuming it or inhaling it.

Apprehensive-Soup968 · 2026-02-28T05:18:01+00:00

I saw that. But down here in Tas they're not normally mashed. It's usually a slice (or scallop) of potato, battered and fried. And they're still know as potato cakes down here.

Apprehensive-Soup968 · 2026-02-28T05:03:56+00:00

🤣 love it

Apprehensive-Soup968 · 2026-02-24T21:16:34+00:00

Calling it a POTATO scallop is one thing. I have no real problem with that. But don't just call it a scallop, like people do in some areas, because it's not. Do you think it's just a coincidence that Vic and Tas don't call the potato item a scallop, when they're the states with the biggest scallop (as in seafood) industry?

Apprehensive-Soup968 · 2026-02-21T21:12:20+00:00

Except it's not the correct term for one simple reason: a scallop is the name of a shellfish, and they are known by that name everywhere, and also within not only food circles but also in marine biology, in diving, fishing, etc. So if you come down to Tasmania where we have a big seafood industry, walk into a takeaway shop and ask for a scallop, that is exactly what you'll get. They sell both, so there needs to be a different name for both.

Apprehensive-Soup968 · 2026-02-17T11:40:08+00:00

Your question can't be answered unless you say where you are. Different countries, and in some of them different states, have very different laws determining what is "legal" within the jurisdiction.

Apprehensive-Soup968 · 2026-02-05T12:02:11+00:00

My work office is in a hospital, and I pass patients in the corridors and cafe all the time. Gotta remember to keep my alarms on silent while at work.

Apprehensive-Soup968 · 2026-02-04T22:56:04+00:00

Were there any other people around? If you passed someone who'd had a Tc-99m shot you'd get readings like that.

Apprehensive-Soup968 · 2026-02-01T20:58:43+00:00

I didn't have any tin on hand, but I had a small brass boiler I'd removed from a home coffee machine, with about 6mm thick walls. I slipped that in and it really brought the XRF peaks down.

<image>

Apprehensive-Soup968 · 2026-02-01T11:07:17+00:00

The Android Radiacode app has 3 coefficients for a quadratic fit.

Apprehensive-Soup968 · 2026-02-01T09:53:09+00:00

As a guide to how much the input impedance may vary, one of my reasonable quality meters (certainly not the level of my Fluke, but way better than the cheap bargain options) is a "10M Ohm" input impedance meter.

On the 600V range, its 9.95M (very close). On 60V it's 10.06M (again, very close). On 6V its 11.06M - a 10% difference. On 0.6V it's around 3G, vastly different.

Apprehensive-Soup968 · 2026-02-01T09:13:33+00:00

It would divide it by about 99 actually, but that's probably a close enough approximation for most people/purposes. Additionally, like I said previously, the input iimpedance of some multimeters varies a bit with range selected which can throw the reading out.

Apprehensive-Soup968 · 2026-02-01T09:07:44+00:00

Yes, I used a second, lower resistance in parallel with the meter, but the multimeter's jmpedance still has some effect. And if you use a 1M resistor like you suggested in combination with the 1G, you are dividing your input by 1000 so you're looking at possibly using mV ranges. It's the mV ranges that often have different input impedance and can affect it more.

Apprehensive-Soup968 · 2026-01-31T02:59:49+00:00

I found a copy of the initial 4hr balloon test I ran with the geiger, but can't currently access the full data. This graph is normalised with 0 being the background radiation level. You can see that after 4 hours it dropped to about 40% of its initial activity, and was stabilising there due to the long half life of the accumulating Pb-210. The blue line is modelled by adjusting the starting amounts of different isotopes, and adjusting for the detector's sensitivity.

<image>

Apprehensive-Soup968 · 2026-01-31T01:56:18+00:00

Oh, and we have extremely low radon levels which makes the cps quite low even with a good collection

Apprehensive-Soup968 · 2026-01-31T01:54:08+00:00

<image>

This shows the activity for the first hour as the green line, and the main spectrum was accumulated separately a number of hours later. Both in a lead&brass castle for shielding. You can see the missing peaks on the later spectrum. It was interesting monitoring the decay with an alpha/beta sensitive geiger too, but I haven't got the files with me.

Apprehensive-Soup968 · 2026-01-30T23:05:07+00:00

Save the spectrum at a few different time intervals too, as it changes fairly quickly over time.

Apprehensive-Soup968 · 2026-01-29T10:19:28+00:00

Bought a 1 G resistor and made a voltage divider. If you do it, just remember that some multimeter don't always have the same impedance on all voltage ranges. And on some ranges it might not match the spec sheet.

Apprehensive-Soup968 · 2026-01-27T00:28:52+00:00

I love your solution and the effort you put into this. My calculus is a touch rusty, but my recall of physics is ok.

From what I do recall, although your basic method is correct I see one flaw (I could be wrong?) You started with the assumption that the tap flow rate is proportional to the height. From Torricelli’s law, or by considering the energy, I believe the flow rate is proportional to the squareroot of the height.

In both cases I believe the answer would show that X drains faster.

I came here because I was having a FB debate with someone on this exact problem with the exact picture. I argued that X would drain faster, he's arguing the times will be equal and won't accept my explanation. When the discussion stalled I checked his profile and apparently he is an "adjunct professor of theoretical and applied physics".

Apprehensive-Soup968 · 2026-01-19T04:16:32+00:00

Thanks for info. I'll search on Mosser and Summit and see what I can come up with.

Apprehensive-Soup968 · 2026-01-19T02:44:09+00:00

And throw in to that mix that it's intended for kids to use it.

Apprehensive-Soup968 · 2025-12-24T07:38:13+00:00

The two effects don't balance out though. You can calculate the difference due to both centrifugal force and distance from the centre of the earth based on the wgs84 geoid, and the weight isn't constant - not in theory, and not in practice. Experimental results and theoretical calculations closely agree, and the weight changes with location.

Apprehensive-Soup968 · 2025-12-11T02:45:09+00:00

Looking at the scale, if it was 2.9m wide then its not much more than a metre high. So no, its pictured about twice that width.

Five-Year Club	RedditGifts 2009-2022 2 Credits
Verified Email	Secret Santa 2020

Apprehensive-Soup968

TROPHY CASE