Notes This project involves the handling of radioactive material. Replicate at your own risk. The method to generate true quantum random numbers in this project is to measure the time interval between alpha decay events which is a quantum phenomenon. Consecutive time intervals are then compared and if the latter is longer than the former a '1' is generated or else a '0' is generated, this is of course arbitrarily chosen and can be reversed. This is then repeated indefinitely and should in theory generate a normal distributed sequence of true random bits. The time intervals between detection events are not normal distributed but poisson distributed, however by comparing two poisson distributed events the result becomes normal distributed according to the central limit theorem. To detect the alpha particles a sensitive PIN-photodiode and MOSFET-transimpedance amplifier is used. These two components are then completeley isolated from the outside world in a faraday cage together with the radiation source. The source for the alpha particle radiation is 0.9 microcurie (which equates to 37000 decays per second) of Americium-241 (the decay product when Plutonium-241 emits a beta particle) which emits alpha particles with an average energy of about 5.5 MeV. The Americium-241 is also a source for gamma radiation but only at an average energy of 60 keV. (The PIN-photodiode is also sensitive to infrared, visible and ultraviolet wavelengths so the faraday cage must be completeley closed and not let visible light in)

Downloads The schematic and PCB layout  Scale 1:1 pdf document of the PCB The Bill of Materials pdf version The Bill of Materials xml version Pictures and videos

References & Links NIST Random Number Test Suite The inspiration for this project, Sean Boyce presentation at DEFCON 17 Sean Boyce presentation video Interesting document about photodiode amplifiers