Resonance Analysis of the U233 Fission Cross Section

The neutron-induced fission and capture cross sections of $^{233}\mathrm{U}$ were measured by time of flight with a nuclear detonation as the neutron source. Cross-section data are presented from 20 to ${10}^{6}$ eV for fission and from 30 to 63 eV for the capture-to-fission ratio $\ensuremath{\alpha}$. Data in the resonance region (20 to 63 eV) were fitted both by a single-level function consisting of a sum of Breit-Wigner levels and by the Reich-Moore multilevel function based on $R$-matrix theory. The resulting resonance parameters are listed and discussed. A study of cross sections derived from two and three hypothetical resonances under various conditions of interference is presented to determine the validity of the resonance parameters derived from the multilevel fit.