A study on the neutron sensitivity of a composite neutron detector based on 4He gas scintillator
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摘要: 研制了能用于脉冲混合辐射场的基于4He气闪烁体的组合式中子探测器,其具有中子能量响应平坦、中子/伽马分辨较高等优点。采用蒙特卡罗方法模拟计算了不同能量中子和聚乙烯靶、4He原子核作用产生的反冲质子、反冲氦核在4He气中的能量沉积,以及探测器的中子灵敏度,计算结果表明,1~15 MeV中子在4He气中的能量沉积曲线十分平坦,探测器对1~15 MeV中子的灵敏度约为4.0×10−15 C·cm2。在原子能科学研究院K600高压倍加器上对探测器的中子灵敏度进行了实验标定,实验结果与理论计算结果相差约8.9%。Abstract:
Background A radiation field with a significant mixture of neutrons and gamma rays exhibits the following characteristics: wide range of neutron energy, serious mixing of neutron and gamma ray, etc. Therefore, to measure the total neutron emission from such a source with relatively high precision, the detector must possess high neutron sensitivity, a flat energy response, and a strong n/γ discrimination capability.Purpose To this end, a neutron detector based on combined 4He gas scintillator is proposed, which has the advantages of flat neutron energy response and high n/γ resolution, and the neutron sensitivity of the detector is studied in this paper.Methods Using the Monte Carlo method, simulations were conducted to calculate the energy deposition of recoil protons and recoil helium nuclei generated by interactions of neutrons with polyethylene targets and 4He nuclei in the gas, as well as the neutron sensitivity of the detector.Results The computational results indicate that the energy deposition curve for 1–15 MeV neutrons in the 4He gas is remarkably flat, with the detector’s neutron sensitivity to 1–15 MeV neutrons reaching approximately 4.0×10−15 C·cm2. Experimental calibration of the detector’s neutron sensitivity was performed on the K600 high-voltage multiplier at the China Institute of Atomic Energy.Conclusions The theoretical results of neutron sensitivity are in good agreement with the experimental results. The theoretical calculation model of the detector proposed in this paper correctly calculates the neutron sensitivity, and the detector's performance conforms to the expected targets.-
Key words:
- helium gas scintillator /
- recoil proton /
- neutron detector /
- neutron sensitivity /
- flat energy response
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表 1 实验结果
Table 1. Experimental results
measurement type I/nA φn/(cm−2·s−1) S/(C·cm2) Sn /(C·cm2) signal measurement 1.84 1.16×105 1.58×10−14 3.47×10−15 background measurement 1.46 1.18×105 1.24×10−14 -
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