Abstract: The study of nuclei far from stability is one of the most active and challenging areas of nuclear structure physics. The neutron-proton imbalance in nuclei approaching the dripline(s) affects the detailed impacts of the residual interaction, modifying single-particle energies and potentially leading to altered ground and excited-state properties. In addition, at the very edge of stability, the proximity of the continuum to the bound states may modify wavefunctions further.
I will discuss a range of recent experimental measurements exploring different aspects of the structure in the most neutron-rich isotopes. One of the most exotic neutron-rich nuclei currently accessible to experiment is 40Mg, which lies at the intersection of the nucleon magic number N=28 and the drip line, and is expected to have a large prolate deformation similar to that observed in the neighboring lighter isotopes 32-38Mg. In addition, the occupation of the weakly bound low-l p3/2 state may lead to the appearance of an extended neutron halo. 40Mg offers an exciting possibility and rare opportunity to investigate the coupling of weakly bound valence particles to a deformed core, and the influence of near threshold effects on collective rotational motion. I will discuss the results of an experiment carried out at RIBF to study 40Mg, the unexpected excitation spectrum observed, and possible interpretations for the structure of this key nucleus.