You can get uranium ore from the four corners area pretty easily (for free) if you know how to spot it, especially around Moab, Utah. You can build a cloud cha

You can get uranium ore from the four corners area pretty easily (for free) if you know how to spot it, especially around Moab, Utah. You can build a cloud chamber with everclear and dry ice easily. If you have enough area (the size of a dinner plate, for example) it's very easy to spot muons at a rate near 1 particle every two seconds. The problem with geiger counters is often the dead time after ionization. If you run at too high of a voltage and/or have too many particles, you risk saturation (which also isn't good for the high voltage power supplies)