It is known that neutron magic number N=20 disappears in the region of Z=10~12. Study of nuclei in this region, called "island of inversion" is important for understanding the evolution of shell structure in neutron-rich region. Neutron-rich F and Ne isotopes are located at the south boundary of the island of inversion. Due to the difficulty in production of these extremely neutron-rich nuclei, available experimental data are not sufficient.
We performed in-beam gamma-ray spectroscopy of the neutron-rich 29F,
28-30Ne generated by inelastic scattering and single-nucleon removal reactions on a liquid hydrogen target at the RIKEN RI Beam Factory. 29F, 29,30Ne secondary beams were generated by projectile fragmentation of a 48Ca primary beam on a beryllium target at a beam energy of 345 MeV/u. High statistical data was obtained by using MINOS, which consists of 15 cm thick liquid-hydrogen target and recoil-proton tracking detector. Outgoing particles were identified by SAMURAI spectrometer. The de-excitation gamma rays were measured with the NaI(Tl) scintillator array DALI2 arranged to surround the target.
We studied high-lying excited states and gamma-gamma coincidences for decay from the populated nuclei. In case of nucleon-removal reactions of 29,30Ne, partial cross sections have also been investigated. In this presentation, we discuss the nuclear structure of these nuclei based on the experimental results.