Low-spin structure of85Se and theβnbranching of85As

Fission fragments from neutron-induced fission of ${}^{235}$U produced at the high-flux reactor of the Institut Laue-Langevin, Grenoble, were separated with the Lohengrin separator to provide a beam of neutron-rich ${}^{85}$As nuclei. The ${\beta }^{-}$ decay of ${}^{85}$As to ${}^{85}$Se was studied using $\gamma$-$\gamma$ and $\beta$-$\gamma$ coincidence techniques. ${}^{85}$Se was also studied using the prompt-$\gamma$ coincidence data from spontaneous fission of ${}^{248}$Cm and ${}^{252}$Cf measured with the Eurogam2 and Gammasphere Ge arrays, respectively. The combination of $\beta$ decay and prompt-$\gamma$ data enabled the determination of spins and parities of low-energy excited states in ${}^{85}$Se. There are new arguments supporting the $5/2^{-}$ assignment for the ground state of ${}^{85}$As.