QUOKKA, the pinhole small-angle neutron scattering instrument at the OPAL Research Reactor, Australia: design, performance, operation and scientific highlights

QUOKKA is a 40m pinhole small-angle neutron scattering instrument in routine user operation at the OPAL research reactor at the Australian Nuclear Science and Technology Organisation. Operating with a neutron velocity selector enabling variable wavelength, QUOKKA has an adjustable collimation system providing source-sample distances of up to 20m. Following the large-area sample position, a two-dimensional 1m(2) position-sensitive detector measures neutrons scattered from the sample over a secondary flight path of up to 20m. Also offering incident beam polarization and analysis capability as well as lens focusing optics, QUOKKA has been designed as a general purpose SANS instrument to conduct research across a broad range of scientific disciplines, from structural biology to magnetism. As it has recently generated its first 100 publications through serving the needs of the domestic and international user communities, it is timely to detail a description of its as-built design, performance and operation as well as its scientific highlights. Scientific examples presented here reflect the Australian context, as do the industrial applications, many combined with innovative and unique sample environments.