Abstract The n-p scattering angular distribution was measured with 14.9 MeV incident neutrons produced at the neutron facility of Ohio University. The traditional time-of-flight technique with neutron-gamma discrimination was applied for the measurement of the number and energy of scattered neutrons. The scattering angle varied from 20 to 65 deg (laboratory system) in 5 deg incremental steps corresponding to an ejectile energy range from 13.16 to 2.66 MeV. The efficiency of the neutron detectors was measured in the energy range 2 to 9 MeV relative to the 252Cf standard and was calculated using Monte Carlo methods in the 2 to 14 MeV energy range. Two methods of analysis were applied for experimental and simulated data: a traditional approach with a fixed threshold ~0.1MeVee and a dynamic threshold approach. The efficiencies determined by both methods are in excellent agreement for simulated and experimental results within the energy interval 2 to 9 MeV. The experimental (<9 MeV) and calculated efficiencies (>9 MeV) were applied for evaluation of the n-p scattering experimental result. The corrections for neutron attenuation in the “scatter-detector” were calculated with analytical formulas and by the Monte Carlo method. Additional minor corrections for edge effect, C(n,n’)3α background and dead time were also included. The present data agree with recent evaluations for the n-p angular distribution within about 1.6%. The current state-of-the-art of experimental uncertainties that can be realized for a neutron counting experiment were reached in this investigation. An additional correlation analysis allows us to conclude that the standard deviation connected with existing correlations may be the main component of the total uncertainty.

中文翻译：

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14.9 MeV 的高精度标记中子 np 散射测量

摘要 np 散射角分布是用俄亥俄大学中子设施产生的 14.9 MeV 入射中子测量的。传统的具有中子-伽马辨别力的飞行时间技术被用于测量散射中子的数量和能量。散射角从 20 到 65 度（实验室系统）以 5 度增量步长变化，对应于 13.16 到 2.66 MeV 的喷射能量范围。中子探测器的效率在相对于 252Cf 标准的 2 至 9 MeV 能量范围内测量，并在 2 至 14 MeV 能量范围内使用蒙特卡罗方法计算。对实验和模拟数据应用了两种分析方法：具有固定阈值 ~0.1MeVee 的传统方法和动态阈值方法。两种方法确定的效率在 2 到 9 MeV 能量区间内的模拟和实验结果非常吻合。实验 (<9 MeV) 和计算效率 (>9 MeV) 用于评估 np 散射实验结果。“散射检测器”中的中子衰减校正是用解析公式和蒙特卡罗方法计算的。还包括对边缘效应、C(n,n')3α 背景和死区时间的额外小修正。目前的数据与最近对 np 角分布的评估一致，误差在 1.6% 以内。在这项调查中达到了中子计数实验可以实现的当前最先进的实验不确定性。