Isomerism in the "south-east" of ${}^{132}$Sn and a predicted neutron-decaying isomer in ${}^{129}$Pd

Abstract

Excited states in neutron-rich nuclei located south-east of ${}^{132}$Sn are investigated by shell-model calculations. A new shell-model Hamiltonian is constructed for the present study. The proton-proton and neutron-neutron interactions of the Hamiltonian are obtained through the existing CD-Bonn $G$ matrix results, while the proton-neutron interaction across two major shells is derived from the monopole based universal interaction plus the M3Y spin-orbit force. The present Hamiltonian can reproduce well the experimental data available in this region, including one-neutron separation energies, level energies and the experimental $B(E2)$ values of isomers in ${}^{134,136,138}$Sn, ${}^{130}$Cd, and ${}^{128}$Pd. New isomers are predicted in this region, $e.g.$ in ${}^{135}$Sn, ${}^{131}$Cd, ${}^{129}$Pd, ${}^{132,134}$In and ${}^{130}$Ag, in which almost no excited states are known experimentally yet. In the odd-odd ${}^{132,134}$In and ${}^{130}$Ag, the predicted very long $E2$ life-times of the low-lying $5^{-}$ states are discussed, demanding more information on the related proton-neutron interaction. The low-lying states of ${}^{132}$In are discussed in connection with the recently observed $\gamma$ rays. The predicted $19/2^{-}$ isomer in ${}^{129}$Pd could decay by both electromagnetic transitions and neutron emission with comparable partial life-times, making it a good candidate for neutron radioactivity, a decay mode which is yet to be discovered.

Accepted for publication in Physics Letters B

References in corpus (4)

• Shell-model study of boron, carbon, nitrogen and oxygen isotopes based on monopole-based-universal interaction
• Nature of isomerism in exotic sulfur isotopes
• Large-scale shell-model calculations for unnatural-parity high-spin states in neutron-rich Cr and Fe isotopes
• 6${}^{+}$ isomers in neutron-rich Sn-isotopes beyond N$=82$ and effective interaction

Cited by in corpus (8)

• Neutronic Analysis on Potential Accident Tolerant Fuel-Cladding Combination U${}_3$Si${}_2$-FeCrAl
• An {\it ab-initio} Gamow shell model approach with a core
• Recent progress in configuration-interaction shell model
• First $\beta$-decay spectroscopy of ${}^{135}$In and new $\beta$-decay branches of ${}^{134}$In
• High-precision measurements of low-lying isomeric states in ${}^{120-124}$In with JYFLTRAP double Penning trap
• Partial conservation of seniority in semi-magic nuclei
• Level structure of light neutron-rich La isotopes beyond the N=82 shell closure
• Reduction in nuclear size and quadrupole deformation of high-spin isomers of 127,129In