IN8 - Thermal neutron three-axis spectrometer
IN8 is a high-flux three-axis thermal neutron spectrometer designed to measure inelastic neutron scattering on single crystals in a wide energy and momentum transfer range. It is the highest thermal flux spectrometer worldwide with the monochromatic flux at the sample up to 109 neutrons/cm2/s where users can perform demanding experiments not possible anywhere else.
In recent years, the IN8 spectrometer has undergone several major upgrades that have further extended the capabilities of the instrument to the limits achievable with the standard setup. The first part of the upgrade was centred on the replacement of the monochromator assembly, now consisting of four double focusing reflecting crystal faces with enhanced luminosity.
The ensuing upgrade was to replace the entire secondary spectrometer. As the result, the new spectrometer, called Thermes, profits from a compact design and it is well shielded against ambient experimental background. All the incorporated modifications have given the instrument an unprecedented and unique luminosity combined with an improved signal-to-noise level and a remarkable configuration flexibility for a broad range of experimental requirements.
A general view of the instrument
Here IN8 is shown in its advanced configuration (IMPS), a multiplexed spectrometer consisting of a multi-analyser and a position-sensitive detector (PSD). It can also be used in a more classical configuration: mono-analyser and mono-detector. The multiplexed spectrometer allows to measure nine different (Q,ω) points simultaneously by using a multiblade analyser consisting in nine crystal blades of plastically-bent Ge111 together with a two-dimensional PSD consisting in 54 He-filled tubes of 9 mm diameter.
The three-faced monochromator turret of bent perfect Si(111) crystals - IN8 is equiped with a set of double-focusing monochromators mounted on a fully motorised turret. This advanced setup gives IN8 a very high neutron flux at sample position.
Applications
IN8 is optimised for inelastic measurements with an energy transfer in the range from a few meV to about one hundred meV and is used to investigate:
- diverse magnetic excitations and lattice vibrations in single crystals, atomic dynamics in liquids and molecular vibrations in complex polycrystalline solids
- samples of small volume and weak response due to its high incident flux