Fission Cross - Section Measurements of the Odd - Odd Isotopes 232 Pa , 238 Np , and 236 Np

Transmutation of actinide waste into fission products could be enhanced by using resonance fISsion of odd-odd target materials; those of interest are mpa, 238Np, and u2Am. Fission cross-section . measurements of two of these short-lived materials were performed at Los Alamos National Laboratory. Samples were produced by the (d,2n) reaction in the Los Alamos Ion Beam Facility followed by fast radiochemistry to separate the odd-odd target of interest. The fission cross section of the nanogram samples was measured in a high intensity pulsed neutron beam produced by 800-MeV proton spallation. Using this procedure, the fission cross sections of the 1.3-day mPa and 2.1-day 238Np were successfully measured in the energy range from 0.01 eV to 50 keV. The fission cross section of the relatively long-life isotope 236Np was also measured in the same system while the short half-life isotopes were being prepared. The results and resonance analysis are presented.