Precise normalization of ToF yield measurements of neutron induced fission in fissile targets is challenging, but the appropriate normalization is also of critical importance for nuclear energy and criticality safety, among other applications. A typical normalization relies on the Thermal Neutron Constants (TNC) recommended at the thermal point (fission and capture thermal cross sections) by the Neutron Standards. However, many ToF experiments do not collect data down to the thermal energy and use normalization cross-section integrals defined at different arbitrary energy intervals. Normalization fission cross-section integrals are recommended in between-valleys energy regions 8.1–14.7 eV, 7.8–11 eV, 9–20 eV, and 11.7–19.5 eV for fissile targets U, U, Pu, and Pu with values equal to 689.0(10.8), 245.7(4.1), 1059(6), and 1378(33) , respectively. The U normalization integral derived in this work of 245.7(4.1) is in good agreement within quoted uncertainties with the Neutron Standards value of 247.5(3.0) .

中文翻译：

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裂变目标中 ToF (n,f) 测量的归一化：微观横截面积分

裂变目标中中子诱发裂变的 ToF 产额测量的精确归一化具有挑战性，但适当的归一化对于核能和临界安全等应用也至关重要。典型的归一化依赖于中子标准在热点（裂变和俘获热截面）推荐的热中子常数（TNC）。然而，许多 ToF 实验并不收集热能数据，而是使用在不同任意能量区间定义的归一化截面积分。对于值等于 689.0 的裂变目标 U、U、Pu 和 Pu，建议在谷间能量区域 8.1–14.7 eV、7.8–11 eV、9–20 eV 和 11.7–19.5 eV 中使用归一化裂变截面积分分别为 (10.8)、245.7(4.1)、1059(6) 和 1378(33)。在 245.7(4.1) 的这项工作中导出的 U 归一化积分在引用的不确定性范围内与中子标准值 247.5(3.0) 非常一致。