High spin states in 57Co

High spin states of 57Co have been studied via prompt γ-ray spectroscopy in the reactions 48Ti(12C, p2n) and 54Fe(α, p) at 26-48 MeV and 12-24 MeV, respectively. The energies and decay modes of these levels were determined from the analysis of γ-ray singles and γ-γ coincidence spectra, excitation functions, angular distributions and correlations. The relevant lifetimes were measured by the Doppler-shift attenuation method. The new levels established in this work are at 4037, 4814 and 5918 keV with the most probable Jsup(π) assignment of 15/2-, 17/2- and 19/2-, respectively. The previously known level at 2524 keV was assigned to have Jsup(π) = 13/2-. These together with the known 9/2-(1224 keV) and 11/2-(1690 keV) levels constitute the yrast states of 57Co. The lifetimes of the above six levels are also measured. (Auth.)