Unusual features of β transition rates in heavy deformed nuclei

A detailed examination of all the available log ft values for β transitions in heavy (A>228) nuclei reveals a very similar distribution of these values for the allowed and the first-forbidden decays in this region, in sharp contrast with the observed trends over the whole periodic table. Data for over 500 transitions belonging to both the allowed and forbidden categories are presented in the form of histograms. Physical basis for this unusual behavior is sought by examining the interrelationships between the Nilsson model asymptotic quantum numbers of the β connected states. Explicit selection rules specific to this region, in terms of these quantum numbers, are proposed and their applicability is demonstrated by citing illustrative examples from the allowed decays of odd-A actinides