The concept of nuclear cluster forbiddenness

TL;DR

This paper refines the concept of nuclear cluster forbiddenness, providing a simple, extendable method for its determination, with applications to light clusters and nuclear decay channels.

Contribution

It offers a more accurate and straightforward way to determine nuclear cluster forbiddenness, correcting previous errors and applicable to multiple cluster systems.

Findings

A simple rule for minimizing forbiddenness based on SU(3) irreps.

Application of the method to light cluster systems and decay channels of uranium isotopes.

Correction of previous misconceptions in the concept of forbiddenness.

Abstract

In nuclear cluster systems, a rigorous structural forbiddenness of virtual nuclear division into unexcited fragments is obtained. We re-analyze the concept of forbiddenness, introduced in Ref. 1 for the understanding of structural effects in nuclear cluster physics. We show that the concept is more involved than the one presented previously, where some errors were committed. Due to its importance, it is reanalyzed here. In the present contribution a simple way for the determination of forbiddenness is given, which may easily be extended to any number of clusters, though in this contribution we discuss only two-cluster systems, for illustrative reasons. A simple rule is obtained for the minimization of the forbiddenness, namely to start from a cluster system with a large SU(3) irrep (lambda,mu), but minimizing (lambda-mu), i.e. the system has to be oblate. The rule can be easily implemented in structural studies, done up to now with an oversimplified definition of forbiddenness. The new method is applied to various systems of light clusters and to some decay channels of 236U and 252Cf.