Exploring towards the nuclear limit: neutron drip line and beyond

How many neutrons can be added to a bound nucleus before it becomes unbound? The location of the neutron drip line, the bound limit in the neutron-rich side in the nuclear chart, is indeed one of the fundamental unsolved questions in nuclear physics, as this is established experimentally only up to Z=8. The other question we address here is how atomic nuclei behave near the drip line and beyond. With these questions in mind, I present and discuss the recent experimental studies on exotic neutron-rich nuclei using RIBF (RI-Beam Factory) at RIKEN, which may be the most advanced rare-isotope beam facility in the world [1]. Neutron-rich nuclei, in particular near and beyond the neutron-drip line, show characteristic structure due to the weakly-binding (or unbinding), and large difference between neutron and proton Fermi energies. Key aspects are the nuclear shell evolution, deformation, continuum effects, neutron halo, and the strong two neutron correlations called dineutrons, which are discussed. Here, I will focus on the results on nuclei near/beyond the neutron drip line, using SAMURAI facility at RIBF. Finally, I will provide perspectives on experimental studies using the new-generation RI-beam facilities along the neutron drip line.

[1] T.Nakamura, H. Sakurai, H. Watanabe, Prog. Part. Nucl. Phys. 97, 53 (2017).