γ-ray Spectroscopy of ⁸⁵Se Produced in ²³²Th Fission

Excited states in the neutron-rich ⁸⁵Se nucleus have been studied using for the first time a fast neutron-induced fission of ²³²Th. The experiment was performed at the ALTO facility of the IPN Orsay. Coupling of the LICORNE directional neutron source with the v-ball high-resolution γ-ray spectrometer provided unique access to high-spin states in neutron-rich fission fragments from the ²³²Th(n,f) reaction. A preliminary level scheme of 85Se was established by the analysis of prompt γ– γ– γ coincidences. Identification of the all known yrast states in ⁸⁵Se is the first step towards studies of more neutron-rich Se isotopes.