100 Years of Nuclear Isomers

Heavy nuclei are known to be produced by various nuclear processes such as r-, ν-, νp-, γ- and s-processes in massive stars as well as small-to-intermediate mass stars like AGBs. Several nuclear isomers in heavy nuclei play the critical roles in determining their final abundances. Especially, the first three r-, ν- and νp-processes among them are strongly affected by the ν-nucleus interactions...

The change of the shell structure in atomic nuclei, so-called nuclear shell evolution, occurs due to changes of major configurations through particle-hole excitations inside one nucleus, as well as due to variation of the number of constituent protons or neutrons. We have investigated how the shell evolution affects Gamow-Teller (GT) transitions, which dominate the $\beta$ decay in the...

Self-consistent configuration-constrained Total Routhian Surfaces (TRS) [1,2] have been developed to treat the collective rotations of quasiparticle states built on broken-pair excited configurations. Two types of interaction have been used for the configuration-constrained TRS calculations: the deformed Woods-Saxon potential and the two-body Skyrme force within the Hartree-Fock approximation...

The phenomenon of nuclear shape isomerism, which is an example of extreme shape coexistence in nuclei, arises from the existence of a secondary minimum in the nuclear potential energy surface (PES), at substantial deformation, separated from the primary energy minimum (the ground state) by a high potential energy barrier that hinders the transition between the minima. Shape isomers at spin...

We discuss selected results of a large scale exotic symmetry research project addressing even-even nuclei with Z, N $>$ 10, including exotic and super-heavy nuclei -- calculations performed in multidimensional deformation spaces. In the presentation we focus on realistic nuclear mean-field theory results for two types of nuclear isomers: yrast-trap and K-isomers in axially symmetric nuclei,...

A high rate of producing nuclear isomers is critical for many applications, like nuclear clocks and nuclear γ-ray lasers etc. However, due to small production cross sections and quick decays, as well as limited intensities of driving beams, it is extremely difficult to achieve a high producing rate via traditional accelerators or reactors. Here, we present a pumping of nuclear isomeric states...

Despite being a well-studied nucleus close to stability, the $K$-shell X-ray and Auger fluorescence yield for scandium-44 are not very well defined. However, the low-lying nuclear structure of $^{44}_{21}$Sc and its population in $^{44}$Ti electron capture decay lends itself to extracting these quantities.

The first two excited states in $^{44}$Sc are isomeric and lie at 68 keV and 146 keV...

The nuclear structure of neutron-rich actinide $^{248}$Cf was investigated at the Tokai Tandem Accelerator Laboratory of the Japan Atomic Energy Agency. This isotopes lies two neutrons and two protons below the generally accepted $Z$=100 and $N$=152 deformed shell gaps, but recently the location of these gaps has been heavily debated and $Z$=98 has also been suggested. $^{248}$Cf was produced...

There are two fundamental kinds of excitation modes in the atomic nucleus: collective and single-particle excitations. So far, most of the theoretical effort has focused on the study of the former and the latter has been mostly treated by using the quasiparticle spectrum of neighboring nuclei [1] or the equal-filling approximation [2]. However, these approaches explicitly neglect time-odd...