Validation of large-angle scattering data via shadow-bar experiment

Highlights: • An experiment to validate large-angle scattering cross section is conducted. • Pieces of Nb foil are set behind a shadow bar to obtain the ^92mNb production rates. • The results calculated using ENDF/B-VI library data exhibit a 57% overestimation. • The adjustment of cross section in large-angle region makes the C/E close to 1. - Abstract: An experiment emphasizing the influence of large-angle scattering on nuclear data was conducted, in which a Fe shadow bar and a Fe slab target were placed before a deuterium–tritium fusion (DT) neutron source. Two Nb foils were set on both sides of the shadow bar in order to monitor the neutron source intensity and to measure the neutrons scattered from the slab target. The ⁹³Nb(n,2n)^92mNb reaction rate of the foil was measured following the DT neutron irradiation and calculated using the MCNP5 Monte Carlo radiation transportation code. The ^92mNb production rates calculated using data from the JEFF-3.1 and JENDL-4.0 libraries agreed with that measured in the experiment, while the result calculated using data from the ENDF/B-VI library exhibited a 57% overestimation. Because the sensitivity of the ^92mNb production rate to the scattering angular distribution was large in the angular region between scattering direction cosines of −0.9 and −0.4, the scattering angular distribution was adjusted in that region. This adjustment resulted in a calculation-to-experiment ratio close to 1, but had little influence on the existing integral benchmark experiment.