Spectrum of High-Energy Gamma Rays Following Thermal-Neutron Capture byEr166

Abstract

The thermal-capture $\gamma$-ray spectrum of the ${\mathrm{Er}}^{166}(n, \gamma ){\mathrm{Er}}^{167}$ reaction in a sample enriched in ${\mathrm{Er}}^{166}$(99.97%) has been studied with a Ge(Li) pulse-height spectrometer. Some of the transitions are interpreted as populating states having excitation energies in good agreement with those of known states, and several additional levels with excitation energies less than 2 MeV are tentatively assigned on the basis of the data. The distribution of the radiative strength over final states previously assigned to a specific nuclear motion is compared with that expected for an initial state consisting of an $s$-wave neutron weakly coupled to the deformed target nucleus.