‘Quokka’—the small-angle neutron scattering instrument at OPAL

A small-angle neutron scattering instrument (Quokka) is being built as part of the initial instrument suite for the 20 MW Australian Research Reactor, OPAL. The 40m long instrument will be located at the end of a curved supermirror neutron guide and will receive neutrons from a large liquid-D 2 cold source. The instrument will have incident beam polarisation and focusing optics using MgF 2 lenses and gravity-correcting prisms in the collimation system. The secondary flight path includes a 1 m 2 area detector with high-speed data acquisition electronics with provision for the inclusion of polarisation analysis at a later date.