Elastic Scattering of Fast Neutrons from U²³⁵

The differential cross section for the elastic scattering of neutrons from U²³⁵ was measured at ∼ 50-keV intervals throughout the incident neutron energy range 0.3 to 1.5 MeV. Pulsed-beam time-of-flight techniques were employed to resolve the elastically scattered neutrons from those inelastically scattered and from the spectrum of fission neutrons. The experimental resolution extended from ∼ 25 to ∼ 65 keV at respective neutron energies of 0.3 and 1.5 MeV. All neutrons incurring an energy loss at the time of scattering, equal to or less than the respective resolution function, were considered “elastically” scattered. The experimental results were expressed in the form where σ(el) is the total elastic cross section, P_i are Legendre polynomials, and W_i are experimentally determined coefficients. The elastic transport cross section was derived from the measurements.