Stability of heavy and superheavy elements

Abstract

We review several important experimental and theoretical developments that during the past decade have revived interest in the stability properties of the heaviest elements. On the experimental side two accomplishments stand out. One is the extension of the known elements to ₁₀₇Ns, ₁₀₈Hs and ₁₀₉Mt. The other is the collection of an extensive body of data on the transition between asymmetric and symmetric fission in the region close to proton number Z=2*50 and neutron number N=2*82. On the theoretical side it has become dear that some models that appropriately account for the most important nuclear-structure aspects are sufficiently reliable for meaningful applications to new regions of nuclei and to studies of new phenomena. We discuss here in particular the importance of a 'few-parameter approach' and of solving a Schrodinger equation for accurately obtaining microscopic effects. We show how such models now more reliably than earlier describe the stability properties of the heaviest elements when the following important points are treated carefully. In fission studies very precise shape specifications are necessary in the saddle-point region and beyond. Coulomb redistribution effects and higher-multipole effects are important for determining the ground-state masses. We review how consideration of these effects has influenced theoretical work in the last decade and present some current results on alpha -decay, beta -decay and fission properties in the heaviest region.