Measurement of fast neutron-induced fission cross section ratio of Neptunium-237 relative to Uranium-235 between 6 and 120 keV

To obtain the nuclear data for ²³⁷Np which plays an important role in high burn-up reactors and transmutation systems, we measured neutron-induced fission cross section ratios of ²³⁷Np relative to ²³⁵U between 6 and 120 keV using a pulsed white neutron source produced by the 4.5 MV Dynamitron accelerator of Tohoku University. The fission cross section ratios were measured by two separate runs with the experimental errors of 7% to 25%. The results by two separate runs agreed within the experimental errors. The fission cross section of ²³⁷Np was deduced by averaging two results and by using the fission cross section of U taken from JENDL3.2. The present results agreed with the result of Hoffman et al. and was consistent with the newest experimental result by Yamanaka et al. The present result around 10keV agreed with JENDL3.2, while those near 100 keV were close to ENDF/B-VI.