Physical Random Numbers Generated by Radioactivity

We have developed a physical random number generator in which radioactivity, i.e., one of the most random phenomena, is used. The long-lived radioactive nuclide 241Am and a clock pulse generator are used for generating random pulses and regular pulses, respectively. A 1024 channel scaler counts clock pulses between two consecutive random pulses. This procedure is repeated and the counts are stored in a computer. The last digit of a count at the scaler gives a digit of uniform physical random number. We have tested our random numbers for randomness and uniformity, and stored 600 million random digits on each compact disc for users.