Abstract Templates of uncertainties expected in specific measurement types were recently developed. One aim of these templates is to help evaluators in identifying (1) missing or suspiciously low uncertainties and (2) missing correlations between uncertainties of the same and different experiments, when estimating covariances for experimental data employed in their evaluations. These templates also provide realistic estimates of standard deviations and correlations for a particular uncertainty source and measurement type that can be used by evaluators in situations where they are not supplied by the experimenters. This information allows for a more comprehensive uncertainty analysis across all measurements considered in an evaluation and, thus, more realistic evaluated covariances. Here, we extend a template that is applicable to uncertainties expected in neutron-induced fission, (n,f), cross-section measurements. It is applied to improving covariances of 239Pu(n,f) cross-section measurements in the database underlying the Neutron Data Standards evaluations. This particular example was chosen since this evaluation is primarily based on experimental information. Also, some uncertainties of individual 239Pu(n,f) cross-section experiments in this database were suspected to be underestimated. The evaluated uncertainties obtained after updating the covariances in the database by means of the template indeed do increase compared to their original values. Even more importantly, the evaluated mean values change noticeably. These modified cross sections impact application calculations significantly, as is demonstrated by employing them in simulations of the effective neutron multiplication factor for a few selected critical assemblies. However, this updated evaluated 239Pu(n,f) cross section should not be interpreted as the final one that should replace values of the current Neutron Data Standards project. Evaluations for the Neutron Data Standards of the 239Pu(n,f) cross section must be linked to many other observables included in the associated database, most notably to cross sections for 235U(n,f), but also to those for 10B(n,α), 6Li(n,t), 238U(n,f), and 238U(n,γ), because of included measurements of the 239Pu(n,f) cross section that appear as ratios to these reactions. Some of these other reactions are correlated to further observables in the database. Hence, updating uncertainties of data sets of any of these observables can potentially impact the 239Pu(n,f) cross section. Uncertainties for all measurements of these linked physical observables have to be updated before a comprehensive evaluation of the 239Pu(n,f) cross section and its corresponding uncertainties can be provided.

中文翻译：

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应用预期不确定性模板更新中子数据标准数据库中的 239Pu(n,f) 截面协方差

摘要 最近开发了特定测量类型中预期的不确定性模板。这些模板的一个目的是帮助评估者在估计评估中使用的实验数据的协方差时识别 (1) 缺失或可疑的低不确定性和 (2) 相同和不同实验的不确定性之间缺失的相关性。这些模板还提供了对特定不确定性来源和测量类型的标准偏差和相关性的实际估计，评估人员可以在实验人员未提供的情况下使用这些模板。此信息允许对评估中考虑的所有测量进行更全面的不确定性分析，从而更现实地评估协方差。这里，我们扩展了一个模板，该模板适用于中子诱发裂变 (n,f) 截面测量中预期的不确定性。它用于改进中子数据标准评估基础数据库中 239Pu(n,f) 截面测量的协方差。选择此特定示例是因为此评估主要基于实验信息。此外，怀疑该数据库中个别 239Pu(n,f) 横截面实验的一些不确定性被低估了。通过模板更新数据库中的协方差后获得的评估不确定性与它们的原始值相比确实增加了。更重要的是，评估的平均值会发生显着变化。这些修改后的横截面会显着影响应用程序计算，正如在几个选定的关键组件的有效中子倍增因子的模拟中使用它们所证明的那样。然而，这个更新的评估 239Pu(n,f) 横截面不应被解释为应该取代当前中子数据标准项目值的最后一个。对 239Pu(n,f) 截面的中子数据标准的评估必须与包含在相关数据库中的许多其他观测值相关联，最显着的是与 235U(n,f) 的截面以及 10B(n ,α)、6Li(n,t)、238U(n,f) 和 238U(n,γ)，因为包含的 239Pu(n,f) 横截面测量值显示为与这些反应的比率。这些其他反应中的一些与数据库中的进一步观察相关。因此，更新任何这些可观测值的数据集的不确定性可能会影响 239Pu(n,f) 横截面。在对 239Pu(n,f) 横截面及其相应的不确定性进行综合评估之前，必须更新这些相关物理观测值的所有测量的不确定性。