Electromagnetic nuclear moments around neutron magic number 20 and 28

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The purpose of this study is to investigate the structure of far neutron-rich nuclei around neutron magic number N = 20 and 28 through the measurement of electromagnetic nuclear moments. In the nuclear region of N = 20, a ground-state electric quadrupole (Q) moment of 33Al was measured at GANIL, France. The obtained Q shows a large outward discrepancy from a single particle value and shell model calculations within the conventional sd model space, suggesting the erosion of N = 20 shell closure. For the N = 28 region, the Q moment of the isomeric state of 43S at 320 keV was measured at the RIKEN RIBF facility. The data shows that the 43S deformation is modest in spite of the level inversion, suggesting a strong deformation of the ground state and a shape coexistence in the low-lying states. In this study, a noble method to produce spin-aligned RI beams utilizing two-step fragmentation reaction combined with momentum dispersion-matching of the ion optics technique has been developed.