Decay of the high-spin isomer in 160Re: Changing single-particle structure beyond the proton drip line

A new high-spin isomeric state (t1/2=2.8±0.1 μs) in 160Re has been identified. This high-spin isomer is unique in that it only decays by γ-decay and not by proton or α-particle emission as is the case in every other proton emitter between Z=64 and 80. Shell model calculations indicate how the convergence of the h9/2 and f7/2 neutron levels in this region could open up a γ-decay path from the high-spin isomer to the low-spin ground state of 160Re, providing a natural explanation for this anomalous absence of charged-particle emission. The consequences of these observations for future searches for proton emission from even more exotic nuclei and in-beam spectroscopic studies are considered.