Recent upgrades to ANSTO's thermal neutron spectrometer, TAIPAN

Full text: TAIPAN is the thermal neutron spectrometer located at the reactor face of Australia's OPAL reactor (ANSTO). TAIPAN hosts two interchangeable secondary instruments; the triple-axis spectrometer (TAS) and the Beryllium-filter spectrometer - which is a high-throughput, low-energy, band-pass filter spectrometer. The TAS option has been operating in the user program since 2010 whilst the Be-filter is a newer addition, which began operating in 2015. TAIPAN is renowned for its versatility and high neutron flux which has allowed the TAS to successfully measure a broad range of samples including single crystals, powders, thin films, and co-aligned multi-crystal arrays. While the TAS option is used mostly to study structural and magnetic excitations in materials, the Be-filter spectrometer is used to measure vibrational density of states from mainly powder samples. TAIPAN has recently undergone some significant upgrades to improve the accessible momentum and energy range of both the TAS and the Be-filter spectrometers. Four key features have been modified to improve performance: a new sapphire filter translation stage mechanism has been installed to allow epithermal neutrons to pass to the monochromators; a new Cu-200 double-focussing monochromator has been installed to allow monochromatic scattering of neutrons up to 160 meV; a new tertiary shutter and snout have been designed to improve the signal to noise ratio and reduced background outside the instrument enclosure; and finally the accessible momentum transfer has been increased by re-designing the enclosure and expanding the available instrument range of motion. (author)