Proton Shell Evolution below ^{132}Sn: First Measurement of Low-Lying β-Emitting Isomers in ^{123,125}Ag

Cross-Shell Excitation in F and Ne Isotopes around N = 20

Within the framework of the configuration–interaction shell model, the present work applies three effective interactions to investigate the effects of the cross-shell excitation on F and Ne isotopes around N = 20, which are significantly proton–neutron asymmetric, and have different properties compared with the proton–neutron symmetric nuclei. It is shown that cross-shell excitation is necessary in order to reproduce separation energies, neutron drip lines, and low-energy levels of these isotopes. Furthermore, the cross-shell excitation of (0–5)ħω is suggested to be important in the description of 29F and 30Ne. However, the three interactions are insufficient in describing the bound structure of 29,31Ne, and provide inconsistent shell structures and evolutions in the target nuclei. Their cross-shell interactions are suggested to be improved.

Shell evolution and isomers below 132Sn: Spectroscopy of neutron-rich 46Pd and 47Ag isotopes

Neutron-rich isotopes of Pd (Z = 46) and Ag (Z = 47) have attracted considerable interest in terms of the evolution of the N = 82 shell closure and its influence on the r-process nucleosynthesis. Such previously unreachable exotic nuclides have become accessible by means of in-flight fission of a high-intensity 238U beam available at a new-generation radioactive isotope (RI) beam facility, the RI Beam Factory (RIBF) in RIKEN Nishina Center. In this report, recent spectroscopic results of Pd and Ag isotopes obtained as part of the EURICA (EUROBALL-RIKEN Cluster Array) project at RIBF are presented.

Recent shell-model investigation and its possible role in nuclear structure data study

Up to now, the nuclear shell model is rarely used in the nuclear data study because of several reasons. First, medium and heavy mass nuclei far from the shell-model cores, normally doubly magic nuclei, require a huge amount of calculation resource even in a limited shell-model space. Second, large deformation is difficult to be described in the limited model space, which is based on spherical symmetry. Third, high precision evaluation of nuclear structure data challenges the ability of the shell model. Even so, it is worth starting preliminary nuclear data investigations based on the shell model. With the present computational ability, it is possible to investigate 1000 or more nuclei in the framework of the shell model, which should be helpful for nuclear data study. In the present work, some recent shell-model investigations are briefly introduced. Based on these works, a simple nuclear force is suggested to be used in the systematic nuclear structure data study. The south-west region of 132Sn is taken as an example to show the ability of such a simple nuclear force.