Quadrupole collectivity of 28Ne and the boundary of the island of inversion

Abstract

The 0g.s.+→21+ excitation of the neutron-rich nucleus 28Ne has been investigated via heavy-ion inelastic scattering in reversed kinematics. The B(E2;0g.s.+→21+) value was determined to be 132(23)e2fm4, which is smaller than expected from the low excitation energy of the first 21+ state. A comparison with theoretical predictions suggests that the suppressed collectivity in 28Ne is characteristic of nuclei lying on the boundary of the ‘island of inversion’.