Nuclear systematics of the heavy elements—II Lifetimes for alpha, beta and spontaneous fission decay

Abstract

The experimental half-lives for alpha, beta and spontaneous fission decay are analysed for the heavy elements ( A ≥ 140). From the systematic behaviour of these data, semi-empirical relationships are derived for use in the prediction of lifetimes for undiscovered nuclides. α-decay predictions are based on a square well nuclear model; β-decay is approximately treated in terms of average log ( tft) values, and spontaneous fission is considered from the point of view of the liquid drop model. Particular emphasis is given to nucleosynthesis problems involving the trans-ferium nuclei. On the basis of this study, it is estimated that there exist a number of relatively stable nuclei with mass number A∼270 to 290. For nuclei having 184 neutrons, or slightly less, special stability is expected because of the closed neutron shell at N = 184. Nuclei with N > 184 should have extremely short alpha and spontaneous fission decay lifetimes. The implications of these predictions for various problems relating to chemistry and cosmology are also briefly discussed.