利用金属钆测量热中子通量的实验研究

Experimental research for the measurement of thermal neutron flux with gadolinium

研究了一种测量热中子通量的新方法,利用金属钆与热中子反应产生的次级γ射线来确定热中子通量。使用两个NaI探测器进行符合测量,设计了对伽玛射线和散射中子的良好屏蔽体。经过对本底和钆样品的多次测量,对钆与中子反应产生的伽玛能谱进行了分析,计算出了中子与钆反应产生的计数率(样品净计数率),其最大值达到2.74 Hz,从而证实了这种方法的可行性。

The measurement of thermal neutron flux is an important work in dark matter detection experiment. A new approach, using the prompt gamma rays from the （Gd, nth） reaction to decide the thermal neutron flux, is studied in the work. Two NaI（T1） detectors are used for coincident detection of these prompt gamma rays from （Gd,nth） reaction, and a powerful shield system preventing gamma rays and scattered neutrons from NaI（TI） detectors is designed. After cross - checked measurement of background and neutron events, the spectrum of gamma rays from the reaction of （ Gd, nth ） is obtained and analyzed, the counting rate contributed from this reaction is calculated and its maximum is 2.74 Hz. The feasibility of this approach is confirmed.