(Keep in mind, for the most part, we didn't know what we were doing, or what we were accomplishing, or what, if anything we accomplished, and the details are somewhat sketchy after 30+ years,but it was neat nonetheless)
Back in high school (~1985 or so), a friend of mine, Paul, and I were doing some mild reading about radioactivity at the local library. Somehow, we got it in our heads we could build a particle accelerator.
We "borrowed" a geiger counter from the high school for the weekend, picked up a spool of telephone wire, a chunk of 1 inch PVC pipe, and built up an oscillator from a HAM book we got from the library. I don't remember what frequency range or power output, or even if we built it right at all. In addition, we needed a source of radioactivity. Back then, you could get your hands on fire detectors with americium in them. Don't know if that's the case these days.
We wound all of the wire as tight as we could get it around the PVC pipe, hooked up the coil of wire to the oscillator, put the americium 'pellets' at one end, and the geiger counter at the other end.
With the oscillator off, the geiger count would click once in awhile, seems I remember maybe once every few seconds or so.
When we fired up the oscillator and ran it thru it's tuning, there was a few spots in the tuning where the geiger counter would start counting markedly faster than when the oscillator was off or not tuned correctly.
Like I said, don't know what we accomplished, if anything at all...but it was neat.
And no, we didn't stand in front of the business end of the tube or walk around with the americium in our pockets for days on end. I think we used a pair of winter gloves to handle the stuff, but that was about it. Not sure how much we could've possibly been hurt by the thing. Should try to build another one up and see what happens.