β-decay studies of neutron-rich K isotopes

The beta decay of the neutron-rich nuclei K51-53 has been used to populate bound and unbound states in Ca50-53. Measurements of gamma rays as well as beta-delayed neutrons enabled detailed decay schemes to be established and levels identified in Ca50-53. A delayed one-neutron emission probability P-1n of 63 +/- 8% was determined for the decay of K-51. A total of seven new gamma transitions were observed following the decay of K-51, and 25 neutron branches were found that enrich the level scheme of Ca-51. Delayed neutron emission probabilities of P-1n=74.4 +/- 9.3% and P-2n=2.3 +/- 0.3% were determined for the decay of K-52, and 12 new gamma transitions were observed in Ca-50,Ca-51,Ca-52. Three new gamma transitions were observed in Ca-52,Ca-53 following the beta decay of K-53. New limits on the P-1n and P-2n values were determined for the beta decay of K-53, and a decay scheme was established for Ca-53 for the first time. The data obtained here should help clarify the structure of neutron-rich fp-shell nuclei around the N=32-34 subshell closures.