Platypus: a time-of-flight neutron reflectometer at Australia’s new research reactor

A time-of-flight neutron reflectometer is to be built at the new 20 MW research reactor (OPAL) in Sydney. The instrument will be positioned at the end of a curved supermirror neutron guide that will provide optimal transmission of cold neutrons (2–20 Å) while removing fast neutrons and high-energy γ-rays. The reflectometer will utilise a white neutron beam that will be pulsed using a series of boron coated disc choppers. Typically three angle settings will be required to collect a complete reflectivity profile (from Q_z = 0.005–0.5 Å⁻¹). The new instrument will operate with a vertical scattering plane, making it suitable for both solid and “free-liquid” surfaces. The instrument will also be capable of producing a spin-polarized neutron beam making provision for polarized neutron reflectometry studies. Detection of the reflected neutrons will take place using a 2-dimensional ³He delay-line detector with high-speed data acquisition electronics.