Structure Of The Neutron-Rich Nucleus Mg-30

Structure of the neutron-rich nucleus Mg-30, which is located close to the region of the N = 20 "island of inversion," has been investigated by beta-gamma spectroscopy of spin-polarized Na-30. From the detailed gamma-gamma coincidence relations, nine new states have been established in Mg-30. The spin-polarization of Na-30 enabled firm spin-parity assignments for seven states in Mg-30 by means of the spatial asymmetry of beta-ray counts in coincidence with the Mg-30 gamma rays. Based on the experimental information, it is shown that various characteristic structures coexist in Mg-30: (i) the ground-state vibrational-like band, (ii) the deformed band built on the 0(2)(+) state at 1.788 MeV, (iii) the gamma-vibrational band built on the 2(3)(+) state at 3.543 MeV, and (iv) four states around 5 MeV associated with large beta-transition probabilities: 1(+) and 2(+) states with spherical nature, 1(+) and 2(+) states with collective nature. The experimental results are compared with three theoretical calculations of the CHFB + LQRPA, the AMD + GCM, and the large-scale shell model with the EEdf1 interaction. All these theories reasonably reproduce the three bands.