The Scintillation Counter as a Low Resolution Gamma-Ray Spectrometer

Abstract

A scintillation gamma-ray spectrometer has been developed, which is of particular use for the study of isotopes of low specific activity and in which the energies of the gamma-rays are identified from the pulse height distributions of the recoil electrons produced in an activated NaI crystal. The Compton distributions are easily recognized, and a study of the gamma-radiation of Co60 and I131 shows a proportionality to exist between the total light output per scintillation and the energy of the corresponding secondary beta-ray particle. The noise level of the RCA 5819 photo-multiplier, as used in this test, corresponded to an energy on the pulse height scale of less than 20 kev. A brief description is given of a new type of differential pulse height analyzer which has been developed for work of this type.