用于GPPD谱仪的大面积闪烁体中子探测器性能测试

中国散裂中子源（Chinese Spallation Neutron Source，CSNS）的建成为中子散射技术的发展和应用奠定了基础。通用粉末衍射谱仪（general purpose powder diffractometer，GPPD）是CSNS一期建设的三条谱仪之一。研制了用于GPPD的大面积闪烁体探测器阵列，在CSNS的BL20中子束线上开展了探测器关键性能参数的实验测试。测试结果显示，对波长为1.4 Å和2.8 Å的中子，其探测效率分别为（38.5±1.7）%和（56.1±1.1）%，模拟与实验相结合，给出对2 Å的中子，其探测效率约为（46.1±2.0）%，有效面积内的探测效率不均匀度约为19.6%，经优化后可以降低到14.9%；探测器位置分辨可以达到4.0 mm×4.0 mm，最高计数率约79 kHz。探测器单元的整体性能指标能满足GPPD的物理需求。

Performance Test of the Array Scintillator Detector with a Large Area for GPPD

The construction of Chinese Spallation Neutron Source (CSNS) laid the foundation for the development and application of neutron scattering technology General Purpose Powder Diffractometer (GPPD), which is one of the three spectrometers of CSNS in the first phase. The large area scintillator detector array for GPPD was developed and the key performance parameters of the detector has been tested on the BL20 of CSNS. The test results showed that the detection efficiency for 1.4 Å and 2.8 Å neutrons is (38.5±1.7)% and (56.1±1.1)% respectively. In accordance with simulation results, the detection efficiency is about (46.1±2.0)% for 2.0 Å neutrons. The position resolution of the detector is 4.0 mm×4.0 mm, the maximun counting rate is about 79 kHz and the count nonuniformity is about 19.6% and reduced to 14.9% after optimization. The performance of the detector unit can fulfill the physical requirements of GPPD.