Speaker
Description
Heavy and superheavy nuclei show, besides a wide variation of spontaneous fission half-lives, a consistent fission hindrance of 3-5 orders of magnitude for odd-A species (no systematics exists for odd-odd species). There is also some evidence pointing to a similar hindrance in decays from high-K isomers.
In contrast to chemistry, a description of collective tunneling in nuclei lacks a firm definition of the mass parameter. A widely used adiabatic approximation that has some rationale for even-even nuclei (due to a paired character of the wave function) breaks down for both odd-A and high-K configurations as the evolution of singly-occupied orbitals becomes undetermined. An assumption of a fixed configuration for the unpaired orbital is unrealistic and leads to a pointwise diverging mass parameter.
Some understanding of fission rates from odd-A and high-K states would be desirable in view of their occurence in superheavy nuclei. We discuss possible ways of a more consistent, instanton-inspired approach that might account for the observed hindrance and illustrate them with some examples.