Transition probabilities of intermediate-spin yrast and non-yrast excitations in ${}^{80,82}\mathrm{Se}$ were investigated in a recoil distance Doppler-shift (RDDS) experiment performed at the Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro. The Cologne Plunger device for deep inelastic scattering was used for the RDDS technique and was combined with the AGATA Demonstrator array for the $\gamma$-ray detection and coupled to the PRISMA magnetic spectrometer for an event-by-event particle identification. In ${}^{80}\mathrm{Se}$, the level lifetimes of the yrast ($6_1^{+}$) and ($8_1^{+}$) states and of a non-yrast band feeding the yrast $4_1^{+}$ state are determined. A spin and parity assignment of the head of this sideband is discussed based on the experimental results and supported by large-scale shell-model calculations. In ${}^{82}\mathrm{Se}$, the level lifetimes of the yrast $6_1^{+}$ state and the yrare $4_2^{+}$ state and lifetime limits of the yrast (${10}_1^{+}$) state and of the $5_1^{-}$ state are determined. Although the experimental results contain large uncertainties, they are interpreted with care in terms of large-scale shell-model calculations using the effective interactions JUN45 and jj44b. The excited states' wave functions are investigated and discussed with respect to the role of the neutron $g_{9/2}$ orbital.

• Received 23 January 2018

DOI:https://doi.org/10.1103/PhysRevC.97.044323