Design and first year-operation results from EMU, the high-resolution backscattering spectrometer at ANSTO
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Date
2017-07-12
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International Conference on Neutron Scattering
Abstract
ANSTO recently commissioned a high-resolution neutron spectrometer, EMU, at its OPAL research reactor. The spectrometer is based on crystal backscattering, implemented through spherical focusing between a Si(111) crystal monochromator and Si(111) analyser arrays, and as first performed on the IN16 spectrometer at ILL. The incident neutron energies are modulated by fast oscillation of the monochromator, yielding a net energy transfer range of ±31 ?eV. The most unique feature of EMU is to maintain its high, 1.2 ?eV energy transfer resolution from 1.95 to 0.1 Å-1momentum transfers. Neutron events are resolved by two 3He LPSD arrays. Data analysis is carried out with the Mantid software package.
Results from the first year of operation are presented to highlight performance. EMU is especially suited to characterizing diffusion processes occurring in macromolecular and functional materials e.g. polymers, proteins, lipid membranes, solid-state conductors, or molecular liquids and crystals. Most scientific user experiments to date were carried out over the accessible
temperature range of 30 mK up to 800 K. Other sample environments such as controlled gas delivery, pressure, electric and magnetic fields, etc. are available or under testing.
EMU presently offers a typical 1000:1 signal-to-noise ratio. Measures aimed at increasing signal-to-noise, as well as energy transfer range, are being considered to further spectrometer performance.
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Keywords
ANSTO, OPAL Reactor, Backscattering, Monochromators, Energy transfer, Diffusion
Citation
de Souza, N. R. (2017). Design and first year-operation results from EMU, the high-resolution backscattering spectrometer at ANSTO. Paper presented at ICNS 2017 (International Conference on Neutron Scattering), Daejeon, South Korea, 9 to 13 July 2017. Retrieved from: http://www.icns2017.org/program.php