Observation of Isomeric Decays in the r-Process Waiting-Point Nucleus 130Cd

The gamma decay of excited states in the waiting-point nucleus Cd-130(82) has been observed for the first time. An 8(+) two-quasiparticle isomer has been populated both in the fragmentation of a Xe-136 beam as well as in projectile fission of U-238, making Cd-130 the most neutron-rich N=82 isotone for which information about excited states is available. The results, interpreted using state-of-the-art nuclear shell-model calculations, show no evidence of an N=82 shell quenching at Z=48. They allow us to follow nuclear isomerism throughout a full major neutron shell from Cd-98(50) to Cd-130(82) and reveal, in comparison with Ni-76(48) one major proton shell below, an apparently abnormal scaling of nuclear two-body interactions.