Alpha clustering in nuclei: Another form of shape coexistence?

Abstract

Shape coexistence, where different deformed minima compete within a small range of excitation energy, appears to be ubiquitous across the chart of nuclides. In many light alpha-conjugate nuclei, experimental data points to the coexistence of highly deformed nuclear configurations. It has long been suggested, with strong theoretical justification, that these deformed states are attributable to nuclear clustering based on building blocks of alpha particles. This short review will consider how well alpha clustering fits within the shape coexistence canon and point to future opportunities for experiments that can place the topic on a firmer footing.