by Prof. Takashi Nakamura
Department of Physics, Tokyo Institute of Technology
How many more neutrons can be added to an atomic nucleus? Indeed, there exists a neutron-rich limit, called "neutron drip line", where any neutrons cannot be added any longer to form
a bound nucleus. For instance, 24O(Z=8,N=16) is the most neutron-rich oxygen isotope,
while that for Z=9 (Florine) is 31F(Z=9,N=22), so both these nuclei are on the neutron drip line. The location of the neutron drip line on the nuclear chart is, however, yet unknown above neon (Z=10) isotopes, and thus this provides challenges for modern nuclear structure theories. We also ask ourselves how atomic nuclei behave near and beyond the neutron drip line.
With these questions in mind, I present recent experimental studies on exotic nuclei
near/beyond the neutron drip line using their reactions at about 200-250 MeV/nucleon
at RIBF(RI-Beam Factory) at RIKEN in Japan, which is currently one of the most advanced rare-isotope facilities in the world. Nuclei near/beyond the neutron drip line show characteristic structures 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 dineutron, which are discussed.
In this seminar, I will present in particular the experimental results on the drip line nuclei
from carbon (Z=6) to oxygen (Z=8) isotopes. The topics I present include reaction cross sections of halo nuclei  as well as the studies of extremely neutron-rich oxygen isotopes beyond the neutron drip line . Finally I will provide perspectives on experimental studies along the neutron drip line and beyond.
 Y. Togano, T.Nakamura et al., Phys. Lett. B761, 412 (2016).
 Y. Kondo, T.Nakamura et al., Phys. Rev. Lett. 116, 102503 (2016).