Absence of Angular Correlation between β- and γ-Rays in Allowed β-Transitions

Abstract

IF a nucleus is formed by an allowed β-transition in an excited state and emits thereafter γ-radiation, there should be no correlation between the direction of emission of β- and γ-rays^1,2. An experimental confirmation of this absence of correlation is of interest for both theoretical and practical reasons. On one hand, indication of the fact that a β-transition is of the allowed type (Δj = 0, ± 1; ΔL = 0) has so far only been obtained by a careful examination of the low-energy part of the Fermi plot, which is experimentally very difficult. The direct evidence that no change of orbital momentum is associated with such a β-transition is therefore desirable.