Low-cost radon detector

This patent describes a detector for alpha particles produced by radioactive decay in a test medium. It comprises: a solid state diode having a depletion layer disposed close enough to the test medium that alpha particles emitted in the test medium deposit energy in the depletion layer; a first amplifier connected to amplify a signal produced by the diode. The first amplifier being operable to produce an output pulse upon energy being deposited in the depletion layer; a second amplifier having at least one connection in common with the first amplifier. The second amplifier having inputs connected other than to the signal produced by the diode. Both the first and second amplifiers produce output pulses due to transients and only the first amplifier produces output pulses due to alpha particles; and means to sense output pulses occurring on the first amplifier only, and to ignore output pulses occurring on both the first and second amplifiers