Neutron capture cross section measurement of Np-237 below 10 keV by linac time-of-flight method

The neutron capture cross section of 237Np has been measured in the energy region from 0.01 eV to 10 keV by using the neutron time-of-flight (TOF) method with a 46 MeV electron linear accelerator (linac) at the Research Reactor Institute, Kyoto University (KURRI). A pair of C6D6 scintillation detectors, which was placed at a distance of 12.0 ± 0.02 m from the pulsed neutron source, was employed for the prompt capture gamma-ray measurement from the 237Np sample. The measured result has been normalized to the reference value of the 237Np(n,γ)238Np reaction in ENDF/B-VI at 0.0253 eV. The existing experimental and the evaluated capture cross sections in ENDF/B-VI and JENDL-3.2 have been compared with the present measurement. For the neutron capture cross section of 237Np, the data by Weston et al. and the evaluated data are in good agreement with the present measurement. However, the data by Hoffman et al. are obviously lower in the relevant energy region. The data, which were measured before using a lead slowing-down spectrometer at KURRI, have been in good agreement with the data obtained by energy-broadening the present TOF measurement. (author)