Speaker
Description
We have been systematically studying shape coexistence and shape evolution in neutron-rich nuclei. These are one of the important subjects to understand appearance of variety of nuclear structure as increase of neutron and proton numbers. We have studied change of nuclear structure by the $\beta$ decay in wide isospin region such as neutron-rich Mg and Al isotopes close to ‘Island of Inversion (IoI)’ and neutron-rich $A$ ~ 140 nuclei, which are located in the northeast region of the doubly-magic nucleus on the nuclear chart.
In the former case, experiments have been performed by using spin-polarized beam at TRIUMF with effectiveness to unambiguously assign the spins and parities of the states in daughter nucleus by measuring the $\beta$-decay spatial asymmetry of the spin-polarized isotope. We have been systematically studying shape coexistence and shell evolution of neutron-rich nuclei in and around the $N$ = 20 IoI.
In the latter case, the experiment was performed as one in EURICA campaign at BigRIPS in RIKEN. Nuclear structure gradually changes from spherical (single-particle like) shape in nuclei close to the doubly-magic 132Sn to deformed (collective like) shape for nuclei located in transitional region with increasing neutron and proton number. Additionally, octupole correlation can be observed in nuclei around 144Ba (Z=56 and N=88). Namely, we a variety of structure, such as prolate deformation and vibrational states (octupole band, beta band, and gamma band) can be observed in low-lying states.
In this workshop, I will talk mainly results of EURICA experiment about nuclear structure of $^{141-144}$Xe nuclei by the beta decay of $^{141-144}$I as well as results of TRIUMF experiments.
