J. Kurpeta

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.

The level structure of ${}^{114}\mathrm{Ru}$ has been investigated via the $\beta$ decay of very neutron-rich ${}^{114}\mathrm{Tc}$ by means of Penning-trap-assisted $\gamma$ spectroscopy. The deduced $\beta$-decay scheme suggests the existence of two $\beta$-decaying states in ${}^{114}\mathrm{Tc}$ with $I^{\pi }=1^{+}$ and $I⩾$ 4, with half-lives of $t_{1/2}(1^{+})=90(20)$ ms and $t_{1/2}(I⩾4)=100(20)$ ms, respectively. The $Q_{\beta }$ value, which covers a possible mixture of two states, has been determined to be $Q_{\beta }=11\hspace{0.5em}785(12)$ keV. The level energies in ${}^{114}\mathrm{Ru}$ are compared with theory by using a microscopic Bohr Hamiltonian approach with the Sly4 version of the Skyrme interaction.