The national bureau of standards 4πβ-γ coincidence-counting and γ-ray intercomparator automatic sample changers

Abstract Instruments of very simple and somewhat novel design will be described. The 4 π β - gg changer holds from 1 to 30 carriers of sources, each of which can be counted for any present number, up to ten, of counting periods. The γ-ray changer accomodates from one to 24 source carriers. In comparing γ-ray source count rates, the detector-to-source distances for individual sources are carefully controlled.