XVIII. The decay of potassium 40

Abstract

Abstract The decay of 40K has been reinvestigated and values of the branching ratio, defined as the ratio of gamma or electron capture to beta transitions, have been determined by two methods, giving the values 0·124±0·002 and 0·121±0·004 respectively. The absolute beta and gamma decay rates and the half-life have been measured, the value of the latter being 1·28±0±02 × 109 years. A fresh determination of the gamma energy is described, and evidence as to the mode of decay is discussed. Finally, the results are given of experiments on the reflection of electrons by solid source supports.