Fast Neutron Inelastic Scattering Cross Sections of ²³⁸U for States Between 680 and 1530 keV

Neutron inelastic scattering cross sections for ²³⁸U levels between 680- and 1530-keV excitation energy have been measured in the incident neutron energy range from 0.9 to 2.2 MeV. The (n, n′) time-of-flight (TOF) technique was used to obtain direct differential inelastic cross sections. Neutrons were generated using the ⁷Li(p, n)⁷Be reaction. Experimental parameters were optimized to achieve an energy resolution of <15 keV. Level cross sections were deduced from the measured 125-deg differential scattering cross sections. The validity of this procedure was confirmed by measuring the angular distributions for nine levels at E_n = 1.5 and 2.0 MeV. Background due to fission induced by fast neutrons was subtracted. The TOF spectra were unfolded using the method of the response function. The data were corrected for multiple scattering and neutron attenuation in disk scatterer geometry using an analytic method. Theoretical calculations of the cross sections were carried out using reaction models appropriate to the description of compound nucleus and direct interaction processes. The data are compared to (n, n ′γ) results and the ENDF/B-V evaluation.