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D16

High-resolution diffractometer with variable vertical focusing

High resolution small-q diffractometer

D16 is a highly versatile small-q diffractometer for the study of partially ordered structures with a geometry optimized for diffraction in reflection geometry on multilayer systems, Small- and Wide-Angle Scattering (SANS-WANS) with pinhole geometry, as well as wide-angle diffraction with slit geometry applied to powders, liquids and glasses. Its low Δq/q resolution provided by a Δλ/λ = 0.01 combined to 1D slit collimation or 2D pinhole collimation provides a flexible beam geometry adapted to various sample shapes and sizes and scattering geometries. This flexibility allows for an optimized flux/resolution combination required with respect to the needs of each experiment (sample contrast and concentration, sample size and geometry, resolution, etc.).

The instrument was upgraded recently during the long reactor shutdown in the frame of the Endurance programme. Launched in 2017, the project was completed for the reactor restart in Februry 2023 and commissioned during the first reator cycle. At the core of this upgrade was a new, large, curved 2D MWPC He detector developped at the ILL and delivered at the end of 2022. Major components such as a new granite platform, a new detector table mounted on air-pads and a new flight chamber, were part of the upgrade, all designed to make the best use of the new detector. The upgrade represents a 5-fold gain and a significant improvement of the data quality.

Applications

The strength of the user program lies in a historically strong and stable base in the field of model and biological membranes and the capacity to host in parallel a very diverse community in other scientific fields.

D16 applications range over a very large number of fields: biology (model and biological membrane multilayers), soft condensed matter (colloids, liquid crystals, polymers and surfactants), chemistry and material science (clays, porous materials). Provided that samples can take full advantage of the focusing optics and excellent Δq resolution (e.g. thin films on large flat solid substrates), D16 remains a unique instrument not only with respect to other ILL instruments but also worldwide.

Instrument layout

D16 is a two-circle diffractometer that evolved from the first "biological membrane diffractometers" built in Brookhaven and Harwell in the early seventies. Because of its special characteristics, D16 remains unequalled for the study of a wide range of systems in biology, physics and physical chemistry.