应用于白光中子束线的低气压纯氦气正比计数器

Low-Pressure Pure-Helium Proportional Counter Appliedto Back-n White Neutron Source

通过蒙特卡罗模拟和实验测试,研究了不同工作气压下纯^(3)He气体正比计数器的基本性能,包括幅度响应和时间响应;开展了低气压纯^(3)He气体正比计数器α信号的探测实验。实验结果表明,当正比计数器内部^(3)He气压为0.25~1 atm(1 atm=1.013×10^(5)Pa)时,该探测器具有良好的正比计数功能,探测器内中子反应计数为数百每秒,满足中国散裂中子源的反角白光中子源(Back-n)开展中子与^(3)He反应截面测量实验的应用需求,可为未来Back-n配置^(3)He相关探测器、开展^(3)He截面的测量工作及进行白光中子的极化实验等提供参考。

Proportional counters based on^(3)He gas are commonly applied to neutron flux measurement due to its high detection efficiency and stable performances.Low-pressure proportional counters with fast response time and low sensitivity are suitable for application in high-flux neutron environments like CSNS Back-n white neutron sources.The total cross section of^(3)He can be measured with time-of-flight method by irradiating the pure^(3)He proportional counter on Back-n neutron beam line.Basic performances of a pure^(3)He proportional counter at different operating pressures are studied with Monte Carlo simulation and experimental test,such as gas gain and signal rise-time.The experimental results show that when the pressure of^(3)He inside the proportional counter is 0.25~1 atm(1 atm=1.013×10^(5) Pa),the detector has a good proportional counting function,and the neutron reaction count inside the detector is hundreds per second.The results confirmed the feasibility of measuring^(3)He cross sections on white neutron source and provide a reference for applying^(3)He detectors to Back-n in the future.