Neutron Inelastic Scattering Cross Sections for States Above 700 keV in ²³²Th

Fast neutron inelastic scattering cross sections for levels between 700- and 1400-keV excitation energy in ²³²Th have been measured using the (n,n′) time-of-flight (TOF) technique. Measurements of 125-deg differential cross sections were made using neutrons with a typical energy spread of 8 to 10 keV, generated by the ⁷Li(p,n)⁷Be reaction. The incident neutron energies covered three regions: (a) 950 to 1550 keV in 50-keV intervals with the TOF spectrometer optimized to detect 200- to 600-keV scattered neutrons, (b) 1200 to 2000 keV in 100-keV intervals with the spectrometer optimized to detect 400- to 800-keV scattered neutrons, and (c) 1700 to 2100 keV in 100-keV steps with the spectrometer optimized for 800- to 1300-keV scattered neutrons. Throughout the experiment, an overall energy resolution of < 15 keV was maintained. Level cross sections were deduced from the 125-deg differential scattering cross sections and are compared with (n,n′λ) measurements and the ENDF/B-V evaluation. Angular distributions for states in the 700- to 900- keV region have been measured at 1.2, 1.5, and 2.0 MeV.