Observation of a μs isomer in 134 49In85: Proton-neutron coupling “southeast” of 132 50Sn82

We report on the observation of a microsecond isomeric state in the single-proton-hole, three-neutron-particle nucleus 134In. The nuclei of interest were produced by in-flight fission of a 238U beam at the Radioactive Isotope Beam Factory at RIKEN. The isomer depopulates through a γ ray of energy 56.7(1) keV and with a half-life of T1/2 = 3.5(4) μs. Based on the comparison with shell-model calculations, we interpret the isomer as the Iπ = 5− member of the π0g−1 9/2 ⊗ ν1 f 3 7/2 multiplet, decaying to the Iπ = 7− ground state with a reduced-transition probability of B(E2; 5− → 7−) = 0.53(6) W.u. Observation of this isomer, and lack of evidence in the current work for a Iπ = 5− isomer decay in 132In, provides a benchmark of the proton-neutron interaction in the region of the nuclear chart “southeast” of 132Sn, where experimental information on excited states is sparse