Study of theCo59(n,γ)Co60Reaction and the Level Structure ofCo60

Abstract

The level structure of the odd-odd ${}_{}{}^{60}{}_{}{}^{}\mathrm{Co}$ nucleus has been studied using the thermal-neutron capture reaction ${}_{}{}^{59}{}_{}{}^{}\mathrm{Co}(n,\gamma ){}_{}{}^{60}{}_{}{}^{}\mathrm{Co}$. The gamma-ray spectrum from this reaction in the energy intervals 50-1850 keV and 4500-7500 keV has been studied with a Li-drifted Ge spectrometer system. A number of new transitions are reported. The observed levels are compared with those excited by the ${}_{}{}^{59}{}_{}{}^{}\mathrm{Co}\mathrm{}(d,p)\mathrm{}$ reaction. Gamma-gamma coincidence measurements using Ge(Li) and NaI detectors have been made, which provide considerable information about the low—energy-level structure. In these measurements a primary high-energy transition, selected by the Ge(Li) detectors, defines a particular low-lying level. The decay of this level, isolated by the coincidence requirement from extraneous background, is observed with a NaI detector. Spins and parities of the excited states below about 1 MeV are deduced from the observed gamma-ray branches. The low-lying excited states are interpreted in terms of the $\pi {\left(f_{\frac{7}{2}}\right)}^{-1\mathrm{}}\nu {\left(p_{\frac{3}{2}}\right)}^{-1\mathrm{}}$, $\pi {\left(f_{\frac{7}{2}}\right)}^{-1\mathrm{}}\nu {\left(f_{\frac{5}{2}}\right)}^1$, and $\pi {\left(f_{\frac{7}{2}}\right)}^{-1\mathrm{}}\nu {\left(p_{\frac{1}{2}}\right)}^1$ proton-neutron configurations. The spectra of these configurations, calculated using a zero-range central force for the residual interaction, are compared with the observed levels.