ABSTRACT

Neutron capture cross-section measurements for ${ }^{237}$Np have been conducted with the Accurate Neutron Nucleus Reaction Measurement Instrument (ANNRI) at the Materials and Life Science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC) using neutrons with energy ranging from thermal energy to 1 MeV. A time-of-flight (TOF) method using a NaI(Tl) detector was employed and the data were analyzed based on the pulse-height weighting technique in order to derive the neutron capture cross-section. The absolute capture cross-section was determined using the first resonance from JENDL-4.0 together with the total neutron flux derived from a ${ }^{197}$Au sample measurement in which the first resonance was completely saturated. Both normalization techniques present agreement within 1$\mathrm{\%}$. The present results are also compared evaluated data libraries. There is a discrepancy of 10–25$\mathrm{\%}$ discrepancy from 0.5 to 20 keV with JENDL-4.0. Nonetheless, above this energy JENDL-4.0 seems to reproduce the present data better as the results agree within uncertainties up to 500 keV. The cross-section results contain uncertainties below 4$\mathrm{\%}$ from 0.5 to 30 keV. However, the total uncertainty increases to over 8$\mathrm{\%}$ above 30 keV. Along with the cross-section measurement, theoretical calculations with the CCONE code were performed to reproduce the present results.

摘要

中子捕获截面测量 ${ }^{237}$日本质子加速器研究中心 (J-PARC) 的材料和生命科学设施 (MLF) 使用精确中子核反应测量仪 (ANNRI) 进行 Np，使用能量范围从热能到 1 MeV 的中子。采用了使用 NaI(Tl) 检测器的飞行时间 (TOF) 方法，并基于脉冲高度加权技术分析数据，以推导出中子捕获截面。绝对俘获截面是使用来自 JENDL-4.0 的第一次共振以及来自${ }^{197}$Au 样品测量，其中第一次共振完全饱和。两种标准化技术都在 1$\mathrm{\%}$. 目前的结果也比较评估数据库。有 10-25 的差异$\mathrm{\%}$与 JENDL-4.0 的差异从 0.5 到 20 keV。尽管如此，在这个能量之上 JENDL-4.0 似乎可以更好地再现当前数据，因为结果在高达 500 keV 的不确定性内一致。横截面结果包含低于 4 的不确定性$\mathrm{\%}$从 0.5 到 30 keV。然而，总的不确定性增加到超过 8$\mathrm{\%}$高于 30 keV。除了横截面测量外，还使用 ​​CCONE 代码进行了理论计算以重现当前结果。