ABSTRACT

The neutron capture cross section of ²⁴³Am was measured by the time-of-flight method with a pulsed neutron beam from a spallation neutron source of the Japan Proton Accelerator Research Complex. An Fe neutron beam filter was used to make the incident neutron beam quasi-monoenergetic around 23.5 keV. The neutron capture γ-rays were detected with a NaI(Tl) detector. The pulse height weighting technique was employed to derive the neutron capture cross section from the pulse height spectrum. The cross section was determined relative to the capture cross section of ¹⁹⁷Au of JENDL-4.0. The obtained neutron capture cross section of ²⁴³Am was 2.52 ± 0.14 b, determined with a much smaller uncertainty than those of past measurements.

摘要

²⁴³ Am的中子捕获截面是通过飞行时间法测量的，使用来自日本质子加速器研究中心散裂中子源的脉冲中子束。使用 Fe 中子束过滤器使入射中子束在 23.5 keV 左右准单能。用 NaI(Tl) 探测器探测中子俘获γ射线。脉冲高度加权技术被用来从脉冲高度谱中导出中子俘获截面。横截面是相对于JENDL-4.0的¹⁹⁷ Au的捕获横截面确定的。获得的²⁴³ Am 的中子俘获截面为 2.52  ± 0.14 b，以比过去测量值小得多的不确定性确定。