三氟化硼Bonner多球谱仪的中子源能谱测量方法

Measurement of Neutron Source Energy Spectrum Using BF 3 Bonner Multisphere Spectrometer

为解决~3 He气体短缺且价格日益昂贵所造成的中子能谱测量装置灵敏元缺乏问题,研制了一套BF3正比计数管多球谱仪系统。基于蒙特卡罗方法对Bonner多球谱仪系统的细致结构进行建模,模拟计算得到了探测器能量响应灵敏度;在中国原子能科学研究院的高压倍加器上使用2.86MeV与14.84MeV能量的中子对谱仪系统的探测器能量响应灵敏度进行了标定,结合模拟结果确定了谱仪系统在实验条件下的能量响应灵敏度;使用此谱仪系统对241 Am-Be中子源能谱进行了测量,对多球谱仪测量结果使用自编Gravel算法进行逆卷积解谱,解谱所得能谱与^(241)Am-Be中子源标准能谱的对比结果表明,在总体不确定度小于21.46%的范围内二者符合良好,验证了整套多球系统具有较高的可靠性。该三氟化硼多球谱仪系统有望在加速器、反应堆及同位素中子源环境的中子能谱与剂量检测中得到更为广泛的应用。

To solve the problem of lacking sensitive elements in the neutron energy spectrum measuring device caused by the shortage of 3He gas and the increasingly expensive price,a set of BF 3 proportional counter multisphere spectrometer system is developed.Based on the Monte Carlo method,the detailed structure of the multisphere spectrometer system is modeled,and the energy sensitivity of the detector is obtained through simulation calculation.The energy response sensitivity of the spectrometer system is calibrated using 2.86 MeV and 14.84 MeV energy neutrons on the Cockcroft-Walton accelerator in China Institute of Atomic Energy,and the energy response sensitivity of the spectrometer system under experimental conditions is determined with the simulation results.Using this spectrometer system,the energy spectrum of the 241 Am-Be neutron source is measured,and the measurement results are deconvoluted using the self-edited Gravel algorithm.Comparison of the energy spectrum obtained from the unfolding spectrum with the standard energy spectrum of the 241 Am-Be neutron source shows that the two spectra are in good agreement within the overall uncertainty range less than 21.46%,which verifies the high reliability of the multisphere system.This spectrometer system with BF 3 gas as the sensitive element is expected to be widely used in the case where 3He gas is scarce.