Position-sensitive thermal neutron detector with 6 Li-foil converter coupled to wire chambers

Abstract

A two-dimensional position-sensitive thermal neutron detector is presented which is based on a thin foil acting as a neutron converter. In a metallic 6Li foil 135 μm thick, neutrons interact with 6Li and produce tritons and α-particles. Escaping charged particles are detected on both sides of the foil by gas-filled multistep avalanche chambers. The presently existing detector has a detection area of 300 cm2, a parallax-free spatial resolution of 0.7 mm (fwhm), a time resolution of 100 ns (fwhm), is capable of achieving counting rates of >1 MHz and promises low γ-sensitivity. The detection efficiency e was measured in the wavelength region 0.05 nm<λ<0.7 nm (e=25% at λ=0.18 nm) and was found to be in good agreement with calculations.