Gamma-rays from neutron capture in and between resonances

Experiments on neutron capture γ-ray emission in and between resonances, and the extent of their conformity to, or departure from, purely statistical assumptions are examined. Resonance capture with subsequent radiative transitions to discrete final states can be a powerful tool in nuclear spectroscopy, with the non-specific character of the (n,γ) reaction leading to populating states of differing nuclear structure. Capture between resonances, however, is expected to be influenced by direct components. Capture γ-ray spectra obtained in the off-resonance region can be fitted with interfering resonance and background amplitude terms, and the direct component extracted. Near neutron strength function peaks, especially near the 3s and 3p maxima, width correlations are clearly seen in resonance and resonance averaged spectra. Valence transitions are shown to be inadequate to describe these correlations. (Auth.)