Method and apparatus for measuring radioactive decay

Method and apparatus for counting nuclear scintillations of a specimen containing tritium. A simple system using a single photomultiplier tube and suitable circuitry segregates the pulses which are emitted from a scintillator due on interaction with a nuclear particle from the pulses attributable to random noise. The system is operable with many scintillation materials as long as the characteristic output from the scintillator is long relative to the duration of a random noise pulse. The preferred embodiment of this radiation assay instrument includes a solid scintillator, a photomultiplier tube whose output is split among a two-path circuit containing a first path for providing an integrated pulse signal as input to a pulse height analyzer and a second path which discriminates bases on the number of component pulses in the signal to provide an enable signal to the pulse height analyzer. Also discussed is the response of an apparatus in accordance with the present invention if some relatively high energy isotopes such as carbon-fourteen are tested