The study of so-called 'deformed' atomic nuclei with a non-spherical charge distribution is essential for testing nuclear interactions and structure models. Almost all nuclei have an intrinsic prolate (elongated) shape and very few are oblate (flattened). A very small number of nuclei exhibit coexistence of shapes (e.g. prolate-oblate), a phenomenon allowed by the quantum nature of the atomic nucleus. One of the research themes of the nucleus structure group of the DPhN (Departement de Physique Nucléaire) is to search for these nuclei within the Segrè map in order to study them and characterise their shape.

Experiments will be performed with the European germanium detector array AGATA. The unprecedented efficiency and resolution of this new detector will permit spectroscopic studies further away from the valley of stability than previously possible. The Nuclear Structure Group is strongly involved in the exploitation of AGATA with a particular focus on the study of shape coexistence.