Calibration study for a 'fission electron-collection' neutron detector

The “fission electron-collection” neutron detector (FECND) is a fission-based neutron detector with flat and fast responses, and is a promising choice for the diagnostics of fusion neutron flux and spectrum. Due to its low sensitivity, the detector output is weak and is disturbed easily in calibration experiments. The backgrounds in the calibration primarily come from scattered neutrons and the γ rays induced by neutron inelastic scattering. A symmetrical structure of FECND was proposed to suppress the output of γ rays, and its effectiveness was validated by Monte Carlo simulations. A method was presented to eliminate the impact of scattered neutrons by utilizing the solid angle effect and the energy difference between source neutrons and scattered neutrons. Through calibration experiments and analyses, a D-T sensitivity of (8.6 ± 0.2)×10−20 C·cm2 was obtained for the FECND.