散裂中子源高气压二维位置灵敏3He探测器的实验研究

为满足中国散裂中子源多功能反射谱仪中子探测器的基本物理要求:有效面积达到200 mm×200 mm、探测效率大于50%（2Å）、位置分辨好于2 mm等，中国科学院高能物理研究所研制了3He高气压二维多丝正比室位置灵敏中子探测器。该探测器采用二维多丝室结构，腔体内充3He/C₃H₈（6 atm/2.5 atm）的组合气体。本文首先利用Am/Be中子源完成对探测器全面积均匀性测试，均匀性指标达到了95.1%；探测器在中国散裂中子源的20号束流线站安装后，对其进行了在束测量，通过飞行时间选取波长2.8Å的慢中子，测量了探测器二维位置分辨和二维成像性能。在X方向（垂直于阳极丝的方向）的位置分辨为0.99 mm，Y方向（平行于阳极丝的方向）的位置分辨为1.36 mm，探测器具有很好的二维位置分辨和二维成像能力。测量结果表明探测器满足反射谱仪的研制要求。

Experimental Study on Two-dimensional Position Sensitive Detector Filled with Helium-3 for the China Spallation Neutron Source

Aimed to the Multipurpose Reflectance spectrometer device(MR) physics requirements, which is that the active area with 200 mm×200 mm, the detection efficiency with more than 50% and the position resolution with better than 2 mm, for China Spallation Neutron Source (CSNS) in Dongguang, China. A 3He two-dimensional multi-wire proportional chamber position sensitive neutron detector has been developed by the Institute of High Energy Physics of the Chinese Academy of Sciences (IHEP, CAS). The high-pressure two-dimensional multiwire proportional chamber neutron detector filled with 3He/C₃H₈(6 atm/2.5 atm) mixture gases and the multiwire technology. Firstly, the detection uniformity was tested using the Am/Be neutron source in IHEP and the uniformity could reach to 95.1%. After assembled at #20 beam station in CSNS, the performance of the detector were studied under the neutron beam. Under the selection neutron beam with 2.8Å by the time of flight (TOF), the two-dimensional position resolution and two-dimensional imaging of the detector were measured. The position resolution is 0.99 mm in the X direction (perpendicular to the direction of the anode wire), 1.36 mm in the Y direction (parallel to the direction of the anode wire) and the two-dimensional imaging is clear to identity. The results show that the detector has a good resolution and two-dimensional imaging capability, and it could meet the physics requirements of Multipurpose Reflectance spectrometer device in CSNS.