Transmission through aluminum of beta particles emitted by infinitely-thick sources

Abstract

The problem of determining the energy of beta-particles emitted from sources containing low concentrations of radioactive substances is examined. Transmission curves of beta particles emitted by “infinitely-thick” disc-shaped sources were obtained with two different detectors and compared to the curves similarly obtained for beta-particles coming from very thin “weightless” deposits on similar solid disc. Different matrix materials and beta-particle energies were used. The curves were studied for shape, secondary radiations and half-thickness. A series of curves were also obtained from four different potassium-salt thick sources, in order to investigate possible influences from variations of effective atomic number. No substantial difference was found between the curves corresponding to the three types of sources, in connection with half-thickness-maximum-energy relationship. Guiding rules are proposed for the determination of maximum beta-ray energies by means of absorption studies and half-thickness determination.