The Development and Application of a Beta-Gamma-Gamma Multidimensional Spectrometer

A beta-gamma-gamma multidimensional spec trometer has been developed which employs two 12-inch diameter by 8-inch thick NaI(Tl) crystals with associated 4-inch thick NaI light pipes and two 5-inch diameter by 1/2-inch thick gas proportional counters as principal detectors and which utilizes two 40-inch diameter by 24-inch thick plastic phosphors as anticoincidence shields. The detector system is coupled to two 4096 word computer memories which record gamma-ray events in coincidence with either beta detector. The gamma-ray energies identify the radionuclide while the beta detectors can identify the relative position of the radioactivity in the specimen being analyzed. The background and efficiency of the system and its application to the identification of radionuclides in environmental, biological, and extraterrestrial materials are discussed.