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

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 2.7×10⁷ s^-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.