Neutron elastic and inelastic differential scattering cross-sections by proton recoil spectrum unfolding

A neutron scattering system is described with which elastic and inelastic differential cross-section can be measured over the angular range 20° to 150°. Three NE213 liquid scintillation detectors are used to provide proton recoil spectra due to the scattered neutrons. These spectra are then unfolded to give the energy spectra of the scattered neutrons which can, in turn, give the differential scattering cross-sections. Results for 2.5 MeV neutron scattering by Fe, Sn and Bi are compared with previous cross-section measurements by conventional time-of-flight techniques. The potential usefulness of the proton recoil spectrum unfolding technique for differential cross-section measurement is assessed. Examples of measurements on nuclei with closely spaced excited states are also discussed.