A measurement of the U233, U235, Pu239 total cross sections. As well as the fission cross section of U235 for resonance neutrons

The measurement of the interaction cross sections between resonance neutrons and fissionable isotopes are of definite importance both for reactor calculations and for the construction of various nuclear models. In this work we present the results of measurements of the U²³³, U²³⁵, and Pu²³⁹ total cross sections, as well as the fission cross section of U²³⁵. The measurements were performed on a mechanical neutron spectrometer (neutron chopper) with a resolution of 0.1–0.2 sec/m in the neutron energy region from 3–5 to about 500 ev. The resonance parameters are calculated to energies of about 30–50 ev, for which the levels may still be considered resolved. For these resonances the neutron widths g_n are determined; the total widths are determined for sufficiently excited levels when the uncertainty in this determination is no greater than about 50%. For U²³⁵ resonance in the energy region from 2.5 to 20 ev, in addition to the above parameters, the ratio of the fission width _f to the total width is found.