ABSTRACT It is important to perform neutron transport simulations with accurate nuclear data in the neutronics design of a fusion reactor. However, absolute values of large-angle scattering cross sections vary among nuclear data libraries even for well-examined nuclide of iron. Benchmark experiments focusing on large-angle scattering cross sections were thus performed to confirm the correctness of nuclear data libraries. The series benchmark experiments were performed at a DT neutron source facility, OKTAVIAN of Osaka University, Japan, by the unique experimental system established by the authors’ group, which can extract only the contribution of large-angle scattering reactions. This system consists of two shadow bars, target plate (iron), and neutron detector (niobium). Two types of shadow bars were used and four irradiations were conducted for one experiment, so that contribution of room-return neutrons was effectively removed and only large-angle scattering neutrons were extracted from the measured four Nb reaction rates. The obtained experimental results were compared with calculations for five nuclear data libraries including JENDL-4.0, JEFF.-3.3, FENDL-3.1, ENDF/B- VII, and recently released ENDF/B-VIII. It was found from the comparison that ENDF/B-VIII showed the best result, though ENDF/B-VII showed overestimation and others are in large underestimation at 14 MeV.

中文翻译：

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使用两个阴影条对 14 MeV 铁的大角度散射反应截面进行基准实验 – 与 ENDF/B-VIII 的实验结果比较 –

摘要 在聚变反应堆的中子学设计中，使用准确的核数据进行中子输运模拟非常重要。然而，即使对于经过充分检查的铁核素，大角度散射截面的绝对值在核数据库中也会有所不同。因此进行了专注于大角度散射截面的基准实验，以确认核数据库的正确性。系列基准实验是在日本大阪大学的 DT 中子源设施 OKTAVIAN 上通过作者团队建立的独特实验系统进行的，该系统只能提取大角度散射反应的贡献。该系统由两个阴影条、靶板（铁）和中子探测器（铌）组成。使用两种类型的阴影条，对一个实验进行了四次辐照，从而有效地去除了房间返回中子的贡献，并且从测得的四个 Nb 反应速率中仅提取了大角度散射中子。将获得的实验结果与包括 JENDL-4.0、JEFF.-3.3、FENDL-3.1、ENDF/B-VII 和最近发布的 ENDF/B-VIII 在内的五个核数据库的计算进行比较。从比较中发现ENDF/B-VIII表现出最好的结果，虽然ENDF/B-VII表现出高估，而其他人在14 MeV时被大大低估了。将获得的实验结果与包括 JENDL-4.0、JEFF.-3.3、FENDL-3.1、ENDF/B-VII 和最近发布的 ENDF/B-VIII 在内的五个核数据库的计算进行比较。从比较中发现ENDF/B-VIII表现出最好的结果，虽然ENDF/B-VII表现出高估，而其他人在14 MeV时被大大低估了。将获得的实验结果与包括 JENDL-4.0、JEFF.-3.3、FENDL-3.1、ENDF/B-VII 和最近发布的 ENDF/B-VIII 在内的五个核数据库的计算进行比较。从比较中发现ENDF/B-VIII表现出最好的结果，虽然ENDF/B-VII表现出高估，而其他人在14 MeV时被大大低估了。