用于n/γ混合场测量的涂硼电离室研制

Development of Boron-lined Ionization Chamber Used in n/γ Mixed Field

摘要: 研制了一种能同时测量混合场中γ和中子注量率的涂硼电离室，并实验测试了其性能。涂硼电离室由两个大小和结构一致的腔室组成：1个仅对γ灵敏，另1个对γ与中子均灵敏。用强度为2.7×10⁷ s^-1的Am-Be源测得电离室的中子灵敏度达9.2×10^-16 A/(cm^-2•s^-1)，在剂量率为5.24 μGy/h的¹³⁷Cs γ场中，电离室的γ灵敏度达7.36×10^-16 A/(MeV•cm^-2•s^-1)。涂硼电离室I-V曲线坪长为600 V，坪斜小于4%/100 V，在工作电压为-400 V时，其γ补偿修正系数<5%，可用于核设施周围的混合场监测。

Abstract: A boron-lined ionization chamber used in n/γ mixed field with better performance was developed. The boron-lined ionization chamber consists of two cavity rooms with the same size: One is for γ, the other is for both γ and neutron. The neutron sensitivity reaches a level of 9.2×10^-16 A/(cm^-2•s^-1) with a calibrated AmBe neutron source with neutron intensity estimated to be 2.7×10⁷s^-1, and the γ sensitivity reaches a level of 7.36×10^-16A/(MeV•cm^-2•s^-1) with a calibrated ¹³⁷Cs source with 5.24 μGy/h dose rate. The plateau length is 600 V and the slope is less than 4%/100 V. An average γ compensation coefficient is less than 5% at work voltage of -400 V, which can be used to monitor the n/γ mixed field around reactors.