ThALES—three axis low energy spectroscopy at the Institut Laue–Langevin

Abstract

Building on the strength of the present cold neutron three-axis spectrometer IN14, but using state-of-the-art neutron optics, we conceived the next generation three-axis instrument for low energy spectroscopy (ThALES) at the Institut Laue–Langevin (ILL). The main aims of the new instrument are: (i) to increase the overall data collection rate by rebuilding the neutron optics of the primary spectrometer achieving a higher incident neutron flux as well as by multiplexing the analyser–detector system, (ii) to provide an efficient and easy-to-use polarized neutron option, (iii) to extend the incident neutron range towards higher energies bridging the gap with thermal instruments, and (iv) to be able to use high-field magnets—such as the currently available 15 T cryomagnet—under all possible experimental conditions, i.e. in a wider range of incident energies. The expected increase in count rate by at least one order of magnitude allows for new experiments such as high pressure experiments on small sample sizes or investigations of magnetic excitations in thin films. Polarized inelastic neutron measurements should equal count rates of the present IN14 in unpolarized mode. The implementation of various optical elements enhances the flexibility of the instrument and allows trading momentum resolution for high neutron intensity.