βdecay of neutron-rich118Agand120Agisotopes

Abstract

$\ensuremath{\beta}$ decays of on-line mass-separated neutron-rich ${}^{118}\mathrm{Ag}$ and ${}^{120}\mathrm{Ag}$ isotopes have been studied by using $\ensuremath{\beta}\ensuremath{-}\ensuremath{\gamma}$ and $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidence spectroscopy. Extended decay schemes to the ${}^{118,120}\mathrm{Cd}$ daughter nuclei have been constructed. The three-phonon quintuplet in ${}^{118}\mathrm{Cd}$ is completed by including a new level at 2023.0 keV, which is tentatively assigned the spin and parity of ${2}_{4}^{+}.$ The intruder band in ${}^{118}\mathrm{Cd}$ is proposed up to the ${4}^{+}$ level at 2322.4 keV. The measured $\ensuremath{\beta}$-decay half-life for the high-spin isomer of ${}^{120}\mathrm{Ag}$ is $0.40\ifmmode\pm\else\textpm\fi{}0.03\mathrm{s}.$ Candidates for the three-phonon states, as well as the lowest members of the intruder band in ${}^{120}\mathrm{Cd},$ are also presented. These data support the coexistence of quadrupole anharmonic vibration and proton particle-hole intruder excitations in ${}^{118,120}\mathrm{Cd}.$