β-γandβ-delayed neutron-γdecay of neutron-rich copper isotopes

The$\ensuremath{\beta}$-decay properties of neutron-rich Cu isotopes produced in proton-induced fission of ${}^{238}$U were studied at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The data were collected using high-resolution online mass separation, reacceleration, and digital $\ensuremath{\beta}\text{\ensuremath{-}}\ensuremath{\gamma}$ spectroscopy methods. An improved decay scheme of $N=49$ ${}^{78}$Cu and the first observation of $N=50$ ${}^{79}$Cu $\ensuremath{\beta}$-delayed neutron decay followed by a gamma transition are reported. Spin and parity (5${}^{\ensuremath{-}}$) are deduced for ${}^{78gs}$Cu. The $\ensuremath{\beta}$-delayed neutron branching ratios (${P}_{\ensuremath{\beta}n}$) for the ${}^{77}$Cu and ${}^{79}$Cu precursors are analyzed with the help of nuclear structure models.