The deuterium-tritium neutron generator is a common neutron source for fast neutron activation analysis. The 14.1 MeV neutrons emitted from a deuterium-tritium neutron generator are difficult to shield due to their strong penetrability and the induced secondary gamma rays in the shield. A rough calculation based on attenuation factors shows that when 14.1 MeV neutrons with a yield of 1 × 10 ns penetrate the designed shielding layers, which consist of a 0.5-m-thick concrete layer and a 0.5-m-thick water layer, the neutron ambient dose equivalent rate is 2.48 μSv h. A geometric model of a neutron shielding room is constructed based on the calculation. Monte Carlo simulations indicate that the highest neutron ambient dose equivalent rate outside the neutron shielding room is 0.73 μSv h, and the neutron ambient dose equivalent rate at the detector position in the shielding room is 2.12 μSv h. The experimental results show that the highest neutron ambient dose equivalent rate outside the neutron shielding room is 1.43 μSv h, and the neutron ambient dose equivalent rate at the detector position inside the shielding corridor is 2.74 μSv h. Comparative investigations show that the experimental results are basically consistent with the results of the Monte Carlo simulations, except for some positions with large proportions of fast neutrons where it is too difficult for the neutron dose equivalent meter to provide reliable values. Moreover, the radiation dose rate outside the designed shielding room is lower than the occupational exposure dose limit, which is in line with the design expectations. Finally, the gamma spectrum at the position of the gamma detectors is measured by a high-purity germanium detector. The analyzed results show that many secondary gamma rays are generated by the interaction of neutrons with the shield materials and detector probe crystals, and some gamma rays are produced from natural background radionuclides such as K, Tl, Bi, Bi, Pb, Pb, and Ac.

中文翻译：

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DT中子发生器中的中子和光子剂量率：MCNP模拟和实验。

氘tri中子发生器是用于快速中子活化分析的常见中子源。从氘-中子发生器发射的14.1 MeV中子由于其强大的渗透性和在屏蔽层中感应出的二次伽马射线而难以屏蔽。基于衰减因子的粗略计算表明，当14.1 MeV中子的产额为1×10 ns时，穿透由0.5 m厚的混凝土层和0.5 m厚的水层组成的设计屏蔽层时，中子环境剂量当量率为2.48μSvh。基于该计算，建立了中子屏蔽室的几何模型。蒙特卡洛模拟表明，在中子屏蔽室外部的最高中子环境剂量当量率为0.73μSvh，屏蔽室中探测器位置的中子环境剂量当量率为2.12μSvh。实验结果表明，在中子屏蔽室外部的最高中子环境剂量当量率为1.43μSvh，在屏蔽走廊内的探测器位置处的中子环境剂量当量率为2.74μSvh。对比研究表明，实验结果与蒙特卡洛模拟的结果基本一致，除了一些快速中子比例较大的位置，中子剂量当量计很难提供可靠的值。此外，设计的屏蔽室外的辐射剂量率低于职业暴露剂量极限，这与设计预期相符。最后，伽马探测器的位置处的伽马光谱是由高纯度锗探测器测量的。分析结果表明，中子与屏蔽材料和探测器探针晶体的相互作用产生了许多次级伽马射线，而天然背景放射性核素如K，Tl，Bi，Bi，Pb，Pb和Pb则产生了一些伽马射线。交流