Beta decay of 71,73Co; probing single particle states approaching doubly magic 78Ni

Low-energy excited states in Ni-71,Ni-73 populated via the eta decay of Co-71,Co-73 were investigated in an experiment performed at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU). Detailed analysis led to the construction of level schemes of Ni-71,Ni-73, which are interpreted using systematics and analyzed using shell-model calculations. The 5/2(-) states attributed to the the f(5/2) orbital and positive-parity 5/2(+) and 7/2(+) states from the g(9/2) orbital have been identified in both Ni-71,Ni-73. In Ni-71 the location of a 1/2(-) beta-decaying isomer is proposed, and limits are suggested as to the location of the isomer in Ni-73. The location of positive-parity cluster states are also identified in Ni-71,Ni-73. Beta-delayed neutron branching ratios obtained from this data are given for both Co-71,Co-73.