The Hoyle Family: The Search for Alpha-Condensate States in Light Nuclei

Abstract

AbstractOur present understanding of the structure of the Hoyle state in $$^{12}$$12C and other near-threshold states in $$\alpha $$α-conjugate nuclei is reviewed in the framework of the $$\alpha $$α-condensate model. The $$^{12}$$12C Hoyle state, in particular, is a candidate for $$\alpha $$α-condensation, due to its large radius and $$\alpha $$α-cluster structure. The predicted features of nuclear $$\alpha $$α-particle condensates are reviewed along with a discussion of their experimental indicators, with a focus on precision break-up measurements. Two experiments are discussed in detail, firstly concerning the break-up of $$^{12}$$12C and then the decays of heavier nuclei. With more theoretical input, and increasingly complex detector setups, precision break-up measurements can, in principle, provide insight into the structures of states in $$\alpha $$α-conjugate nuclei. However, the commonly-held belief that the decay of a condensate state will result in N$$\alpha $$α-particles is challenged. We further conclude that unambiguously characterising excited states built on $$\alpha $$α-condensates is difficult, despite improvements in detector technology.