Speaker
Dr
Nobuo HINOHARA
(RIKEN Nishina Center)
Description
Microscopic mechanism of breaking the N=20 shell gap and nature of deformation in the `island of inversion' is currently under active discussion both experimentally and theoretically. Significant increase of the E(4)/E(2) ratio and the B(E2;2+->0+) value in magnesium isotopes from 30Mg to 34Mg clearly indicate a rapid growth of quadrupole deformation. Experimental data suggest a kind of quantum phase transition taking place around 32Mg and stimulate a microscopic investigation on large-amplitude collective dynamics unique to this region of nuclear chart.
In this talk, large-amplitude deformation dynamics in low-lying states of neutron-rich Mg isotopes are discussed using the five-dimensional (5D) quadrupole collective Hamiltonian, which is microscopically derived from the constrained HFB plus local QRPA method. Solving the collective Schroedinger equation with use of the pairing-plus-quadrupole Hamiltonian, we evaluate
excitation energies, collective wave functions in the (beta, gamma) deformation plane, E0 and E2 transition properties of excited bands as well as the ground bands in and around the island of inversion. Comparing results of the systematic
microscopic calculation with experimental data, we make a critical analysis of the spherical-prolate shape coexistence/mixing picture. In particular, nature of the low-lying excited 0+ states will be discussed including those in 30Mg and 32Mg recently discovered.
Primary author
Dr
Nobuo HINOHARA
(RIKEN Nishina Center)
Co-authors
Prof.
Kenichi Matsuyanagi
(RIKEN Nishina Center)
Prof.
Kenichi Yoshida
(Niigata University)
Dr
Koichi Sato
(RIKEN Nishina Center)
Prof.
Masayuki Matsuo
(Niigata University)
Prof.
Takashi Nakatsukasa
(RIKEN Nishina Center)
