Doorway Structures in the Radiative Capture of Fast Neutrons

Abstract

A method allowing the inclusion of single particle resonances in the microscopic treatment of the nuclear reaction process is presented. The method based on the K matrix formalism is seen to dampen the scattering wave function in the internal region and to remove all single particle resonances from the continuum. In the application of the method to the quantitative analysis of the ²⁸Si(n,γ) and ³²S(n, γ) reaction both the trend and magnitude of the cross sections are reproduced very satisfactorily. The calculation also predicts the existence of doorway states embedded on the giant dipole and contributing significantly to the cross section. These doorway states are indeed consistent with the existence of rapid fluctuations observed in recent (n, γ_o) and (n, γ₁) measurements.