Eta of U²³³ from 1 to 800 ev

Eta of U²³³ has been measured in the energy range from 1 to 800 ev by counting fast fission neutrons in ZnS-loaded plastic scintillators; incident neutron energies were measured in a time-of-flight system with a betatron as pulsed source. The data are normalized at one electron volt to data reported at Geneva by the MTR group; the latter results were normalized to an absolute thermal value. Corrections have been made for multiple scattering by a rigorous single velocity analysis and by a Monte Carlo calculation which also accounts for energy degradations.