Third minima in actinides - do they exist?

TL;DR

This paper investigates the existence of third hyperdeformed minima in actinide nuclei using a Woods-Saxon model, finding that previously reported deep minima are likely spurious and that shallow third wells may exist in specific thorium isotopes.

Contribution

The study clarifies the existence of third minima in actinides, resolving discrepancies between different theoretical models and suggesting shallow minima in certain thorium isotopes.

Findings

Deep minima previously reported are spurious when general shapes are included.

Shallow third wells may exist in $^{230,232}$Th with barriers ≤ 200 and 330 keV.

The discrepancy between microscopic-macroscopic and self-consistent predictions is resolved.

Abstract

We study the existence of third, hyperdeformed minima in a number of even-even Th, U and Pu nuclei using the Woods-Saxon microscopic-macroscopic model that very well reproduces first and second minima and fission barriers in actinides. Deep ($3 \div 4$ MeV) minima found previously by \'Cwiok et al. are found spurious after sufficiently general shapes are included. Shallow third wells may exist in $^{230,232}$Th, with IIIrd barriers $\le$ 200 and 330 keV (respectively). Thus, a problem of qualitative discrepancy between microscopic-macroscopic and selfconsistent predictions is resolved. Now, an understanding of experimental results on the apparent third minima in uranium becomes an issue.