Inelastic Neutron Scattering With Fission Neutrons

Abstract

A detailed investigation has been conducted of the usefulness of fission-spectrum neutrons for inelastic neutron scattering studies. A Ge(Li)–NaI(Tl) annular pair spectrometer was employed in conjunction with a versatile in-core irradiation facility to conduct this evaluation. The Doppler broadening and shift which were observed are quantitatively described through the use of a simple model developed for the system. The effectiveness of neutron filters for the reduction of capture reactions which normally produce unwanted background is also discussed. Results indicate that gamma-ray deexcitation, following neutron inelastic scattering, can be readily identified and quantitatively evaluated. During the course of this study resonant neutron capture in the 35 keV resonance of 28Al was observed thus indicating the feasibility of investigation of this type of reaction. Lifetime results for levels in 19F were obtained using a Doppler attenuation method and a possible discrepancy in (dE/dx) values was indicated.