Yrast structures in the neutron-rich isotopes Fe59,60 and the role of the g9/2 orbital

The structure of the neutron-rich isotopes Fe59,60 has been studied with the Gammasphere detector array using fusion-evaporation reactions. Level schemes for these nuclei are presented which have been extended to spins of ∼20. Both isotopes exhibit regular, near-yrast γ-decay sequences which are generated by the intrusion of the g9/2 orbital into the fp shell-model space. Lower-spin, natural-parity levels are discussed within the context of shell-model calculations using the GXPF1A interaction in the full fp model space. Experimental features of the high-spin bands are compared with total Routhian surface calculations.