GdI3:Ce闪烁体中子探测性能测试与改进研究

为改善GdI₃:Ce闪烁体在探测中子过程中的γ抑制能力，使用Geant4和XCOM计算了其γ线性吸收系数，并通过模拟计算与实验测量研究了铅屏蔽法抑制γ的有效性。结果表明：GdI₃:Ce闪烁体在探测中子过程中易受低能γ射线的干扰；随着铅层厚度的增加，100 keV~1 MeV的γ射线对中子探测的干扰减小，而3~10 MeV的γ射线的干扰呈先增加后减小的趋势。对²⁵²Cf中子源的实验测试发现，在碘化钆闪烁体外围添加铅层后，中子峰得以显现；随着铅层厚度的增加，中子峰内净计数减小，而净计数与本底计数的比值上升。模拟和实验结果均表明，在使用GdI3:Ce闪烁体探测中子时，应根据中子探测效率和信噪比的优化确定γ屏蔽铅层的厚度。

Testing and Improvement Study on Neutron Detection Performance of GdI3:Ce Scintillator

In order to enhance the gamma rejection capability of the GdI₃:Ce scintillator while improving neutron detection performance, the linear attenuation coefficient of gamma ray was calculated by Geant4 software and XCOM database. Both the simulation and the experimental tests were carried out to study the effectiveness of adding lead shielding layer for gamma rejection. The results indicate that the GdI₃:Ce scintillator is susceptible to the interference of low-energy gamma ray while detecting neutron. With the increase of lead thickness, the interference to neutron detection decreases for gamma ray in the energy range of 100 keV-1 MeV, and tends to increase firstly but decrease thereafter for gamma ray in the energy range of 3-10 MeV. Experimental results on the ²⁵²Cf neutron source show that the neutron peak comes to appear after adding the lead shielding layer. With the increase of lead thickness, the net count in neutron peak decreases but its ratio to the background count keeps increasing. It indicates that the thickness of lead shielding layer should be optimized according to the requirement for the neutron detection efficiency and the signal-to-noise ratio when the GdI₃:Ce scintillator detector is employed.