Doorway states and background cross sections in 29Si(γ,n)

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