Doorway States and Background Cross Sections inSi29(γ,n)

A study of the reaction ${}_{}{}^{29}{}_{}{}^{}\mathrm{Si}(\gamma ,n)$ near threshold suggests that a doorway state with $J^{\pi }={\frac{3}{2}}^{-}$ common to the channels ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}+n$ and ${}_{}{}^{29}{}_{}{}^{}\mathrm{Si}+\gamma$ lies near 750 keV. We observe experimentally Lane's prediction of a significant nonresonant background cross section associated with strong partial-width correlations.