An experimental view on shape coexistence in nuclei

Abstract

Nuclear shape coexistence is the phenomenon in which distinct shapes occur within the same nucleus and at a similar energy. In this work, we provide an overview of the experimental investigations of shape coexistence, focusing on those regions of the nuclear chart that have been the most actively investigated within the past decade. In particular, we focus on coexistence phenomena at low angular momentum and on the new experimental information, placed within the context of previous results. We first give a summary of the experimental signatures that can be used for assessing shape coexistence, and then discuss the evidence for shape coexistence from experimental results, with particular attention paid to regions where its presence has been suggested along isotopic or isotonic chains, and in regions where “islands” of such structures have been proposed. We conclude with an overview, with an emphasis on the emerging regions where indications for multiple shape coexistence exist.