Remember that Giger Counter* I made a while ago? Well, I wanted to take it to Dragon*Con to use as a prop for a panel I was on. But I really wanted a radioactive source to demonstrate how it works. I’d ordered a cesium 137 check source from United Nuclear well in advance (I thought) but it didn’t show up in time for my trip to Atlanta.
As a backup, I bought a bunch of potassium salt, which I was assured was radioactive enough to tick over a Geiger counter. When it didn’t have any effect (at least that I could tell), I began to wonder if maybe the Geiger counter unit I’d put inside the Giger Counter was defective. While at Dragon*Con, I asked around to see if anyone had any radioactive materials. I didn’t get any but I did get a lot of funny looks. Can’t imagine why.
When I got home, sure enough, there was a package waiting on my front porch, where it had been sitting in the rain all weekend. I’m sure that’s perfectly safe and nothing at all to be worried about. I’ll probably keep an eye out for mutant raccoons anyway, though.
But at least now I know the Geiger counter unit definitely works. Here’s a video of it being tested against the 5uCi Cs137 check source (radioactive), and a plate of potassium salt (totally not).
*still not a typo
Update: I was able to get a reading off the potassium salt but only by taking the Geiger counter unit out and pressing it into the pile. Probably not the most practical means of determining if a substance is radioactive.