摘要: 为测量中国锦屏地下实验室（China JinPing underground Laboratory，CJPL）极低通量的中子本底，需要建造大型快中子液体闪烁体探测器。建造探测器需要选用低放射性本底材料，并且化学性质稳定，不与液体闪烁体发生反应而影响液体闪烁体（EJ-335）的性能。为此，建造了小型液闪探测器，在其中分别放入聚四氟乙烯、无氧铜、氟橡胶、全氟醚橡胶这4种材料进行长期浸泡，并分别进行了如下测试：液闪长时间浸泡各种材料前后液闪的吸收光谱测试；用⁶⁰Co γ源检测小型液闪探测器光产额随时间的变化情况；用Am-Be中子源检验探测器在浸泡前后的n-γ甄别性能。最终实验结果表明，聚四氟乙烯和全氟醚这2种材料与液闪有很好的兼容性，可作为大型快中子液闪探测器的容器和密封圈的备选材料。


In order to measure the flux and spectrum of neutron background which is extremely low in China JinPing underground Laboratory (CJPL), liquid scintillator detector with large scale used to detect fast neutron need to be fabricated. Surrounding materials used in detector require the excellent performance, such as low radioactivity as well as stable chemical properties, which do not react with liquid scintillator, so as to avoid affecting the performance of detector. Polytetrafluoroethylene(PTFE), highly purified no-oxygen copper, fluororubber and perfluoroelastomer had been put in a small detector and soaked for a long time. The change of absorption spectrum and light yield along with time as well as the performance of n-γ discrimination after soaked were tested. The results show that PTFE and Perfluoroelastomer are compatible with liquid scintillator, which offers a reference for the selection of material used in container and seal of liquid scintillator detector used to detect fast neutron.