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