Abstract In this paper, we present an analytic approach to evaluate Legendre moments of hydrogen neutron elastic scattering differential cross section, with and without free-gas thermal treatment. The results for the zero-th ( P 0 ) and first ( P 1 ) moments are given and compared against a 138-group cross sections produced by NJOY. An MCNP thin-wire test was employed as an independent verification for our analytic model for the free-gas zero-th moment. Excellent agreement was observed between the analytic result and MCNP prediction. They both suggest that an increased thermal cut-off in NJOY THERMR module is advisable for higher accuracy. Discrepancy was also found between the analytic model and NJOY multi-group cross section for the first order Legendre moments of the differential cross section, which might indicate a numerical anomaly in NJOY.

中文翻译：

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与 NJOY 相比，游离气体热处理氢中子弹性散射矩的分析评估

摘要 在本文中，我们提出了一种分析方法来评估氢中子弹性散射微分截面的勒让德矩，有和没有游离气体热处理。给出了第零 (P 0 ) 和第一 ( P 1 ) 力矩的结果，并与 NJOY 生产的 138 组横截面进行了比较。MCNP 细线测试被用作我们的游离气体零阶矩分析模型的独立验证。在分析结果和 MCNP 预测之间观察到极好的一致性。他们都建议在 NJOY THERMR 模块中增加热切断对于更高的精度是可取的。对于微分截面的一阶勒让德矩，解析模型与 NJOY 多组截面之间也存在差异，这可能表明 NJOY 中存在数值异常。