Measurement of Fission Cross Section of Neptunium-237 in Resonance Region with Electron Linac—Driven Lead Spectrometer

Abstract Making use of a lead neutron slowing-down spectrometer combined with an electron linear accelerator and back-to-back type double fission chambers, we measured the fission cross section of 237Np relative to that of 235U from about 1 eV to about 5 keV with energy resolution (δE/E) of about 40%. The experimentally obtained result has been compared with two newly evaluated data files, JENDL-3 and ENDF/B-VI, and with previously measured values by Plattard et al. and by Hoffman et al. Although the shape of the present energy dependent cross section agrees with that of ENDF/B-VI, that of JENDL-3 below 120 eV and that of Plattard et al., the absolute values of above three are from 3 to 4 times smaller than those of the present data. However the Hoffman et al.'s data are rather closer to the present data.