Nuclear disintegration studies with a beta-ray spectrometer

Abstract

Abstract : The use of a beta-ray spectrometer, in the analysis of nuclear decay schemes, makes possible the solution of many of the problems which arise in the course of such analyses. Of particular interest is the application of the instrument to the determination of the energy of beta and gamma-radiation from radioactive isotopes. In addition, it is possible to use the instrument to estimate the relative intensities of the various components of radiation; and to apply the coincidence method, in conjunction with the spectrometer, to the determination of the order in which these components are emitted from the nucleus. The present work was concerned with three particular problems arising in beta-ray spectrometry. A method of improving the intensity-resolution relationship of a thin lens magnetic beta-ray spectrometer, by means of ring focusing, was investigated. The existence of a ring-shaped constriction in the electron beam was demonstrated experimentally by a photographic film method. A theoretical analysis was carried out in an attempt to determine relations from which the relative intensities of beta-rays, gamma-rays and internal conversion electrons might be determined from data obtained with the spectrometer. Simplifying assumptions were made concerning the focusing action of the instrument, and effects due to scattering of electrons in the source of photoelectric radiator were neglected. Formulae were derived from which the observed spectrometer counting rates due to sources of known activity, emitting beta-rays, gamma-rays or internal conversion electrons may be predicted.