Prompt and delayed γ spectroscopy of neutron-rich ⁹⁴Kr and observation of a new isomer

Prompt and delayed γ-ray spectroscopy of the neutron-rich ⁹⁴ Kr was performed, as part of the fission campaign at the ALTO facility of the IPN Orsay, using the fast-neutron-induced fission reaction ²³⁸ U(n,f) in combination with the ν-Ball array, a novel hybrid γ spectrometer for energy and lifetime measurements. Several new yrast and nonyrast transitions were observed for the first time, extending the previously known level scheme. Additionally, we report on the observation of a new short-lived isomer at 3444 keV with a half-life of 32(3) ns. The analysis of the Nilsson orbitals obtained from Gogny cranked Hartree-Fock-Bogoliubov calculations suggests a (9^-) spin and an oblate deformation for this isomer corresponding to a two-quasineutron state, indicating an isomeric structure very similar to that of the neighboring isotones ⁹⁶ Sr and ⁹² Se.