Nuclear Physics Seminar with Patrick Fasano on Evolution of single-particle structure in neutron-rich beryllium isotopes

The competition between mean-field shell structure and collective motion creates a wide range of phenomena in atomic nuclei. The former describes the appearance of the magic numbers, while the latter leads to the emergence of rotational bands and cluster structure. The neutron-rich isotopes of beryllium exhibit a broad range of behaviors, and thus can serve as a microcosm of nuclear structure. The beryllium isotopes are especially amenable to ab initio techniques which can provide insight into the evolution as neutrons are added to the system. We have performed No-Core Configuration Interaction (NCCI) calculations for 8-14Be, and find that the single-particle properties are consistent with a description in terms of an extremely deformed core around which neutrons move in an deformed mean field. Thus, we see a Nilsson-type picture emerge ab initio, helping to explain the presence of parity inversion in 11Be and the intruder ground state in 12Be.