The neutron spectrum resulting from the interaction of protons with the materials in the cyclotron must be characterized to predict the effects of neutron activation on the various cyclotron component materials. Neutron spectrum measurements were carried out using a single moderator neutron spectrometer (SCNS) with an Au activation foil detector to analyze proton-induced effects on a natural titanium target in a self-shielding 11 MeV cyclotron. During the experiment, a disk-shaped Ti-nat target, 5 mm in diameter and 1 mm thick, was irradiated with proton beam at a current of 15 μA for 5 min. The neutron spectrometer, located inside the self-shielding, was then used to measure the 198Au activity of each Au foil employing an HPGe detector of gamma spectrometer. The neutron spectrum was determined using UMG software based on the 198Au activity values measured from each foil and the calculated response values for each foil detector. The obtained neutron spectrum showed a maximum energy of 8.5 MeV and a peak fast neutron energy of 2.5 MeV, with a total flux of (5.72 ± 0.40) × 105 n/cm2·s, consisting of 75% fast neutrons, 20% epithermal neutrons, and 5% thermal neutrons. The results of measuring the neutron spectrum using SCNS–Au are quite accurate because they only have a 10% difference compared to the simulation results using PHITS software.

中文翻译：

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使用被动单慢化剂中子谱仪表征 11 MeV 回旋加速器中 Ti-nat 靶上的质子诱导中子谱


必须表征质子与回旋加速器中材料相互作用产生的中子谱，以预测中子活化对各种回旋加速器组件材料的影响。使用带有 Au 活化箔检测器的单慢化中子谱仪 （SCNS） 进行中子谱测量，以分析质子诱导对自屏蔽 11 MeV 回旋加速器中天然钛靶的影响。在实验过程中，用质子束以 15 μA 的电流照射直径为 5 mm、厚度为 1 mm 的圆盘状 Ti-nat 靶材 5 min。然后，使用位于自屏蔽内部的中子谱仪，使用伽马能谱仪的 HPGe 探测器测量每个金箔的 198Au 活度。使用 UMG 软件根据从每个箔片测得的 198Au 活度值和每个箔检测器的计算响应值确定中子谱。获得的中子谱显示最大能量为 8.5 MeV，峰值快中子能量为 2.5 MeV，总通量为 （5.72 ± 0.40） × 105 n/cm2·s，由 75% 的快中子、20% 的浅成热液中子和 5% 的热中子组成。使用 SCNS-Au 测量中子谱的结果非常准确，因为与使用 PHITS 软件的仿真结果相比，它们只有 10% 的差异。