A new ('Super') reflectometer for Supermirror characterisation at the ILL
The team involved in the project and the T3 instrument
T3, the new polarised cold neutron reflectometer developed by the Neutron Optics Service at the ILL, is now fully operational. Dedicated to characterising the neutron supermirrors produced at the ILL, this is the latest instrument to emerge from the H15 neutron guide project. It is also a vital milestone for the development of advanced neutron optics systems at the ILL. Congratulations and a big thank you to everyone involved in making this project a success!
T3 brings a great improvement in performance compared to the previous reflectrometer, in particular thanks to the new graphite monochromator with variable vertical focusing. Combined with the new H15 neutron guide, the neutron flux on the sample has been increased by a factor of around 100. Such a significant increase in flux will improve the quality and accuracy of the analyses carried out on super-mirrors, and thus better understand and optimise the processes involved in their production. In addition, the increased available space and the new, larger, and position-sensitive detector will make it possible to characterise complex optical components as a whole.
T3, the new polarised cold neutron reflectometer developed by the Neutron Optics Service at the ILL. © Laurent Thion - Ecliptique.com
The 'Multilayers' group of the ILL Neutron Optics service next to the T3. © Laurent Thion - Ecliptique.com
Supermirrors
© Laurent Thion - Ecliptique.com
Neutrons totally reflect from material surfaces up to a critical angle that depends both on the neutron wavelenght and on the material Critical angles vary with wavelength and material, with nickel having the highest reflection angle. Supermirrors are multilayer structures designed to reflect neutrons at angles exceeding the critical angle. These devices consist of alternating layers of materials with varying neutron scattering lengths. The performance of these supermirrors depends on layer thickness,composition, and perfection. At ILL, supermirrors are manufactured using magnetron sputtering to deposit materials with precise control of layer thickness on the nanometre scale. Polarising supermirrors use alternating magnetic material layers to preferentially reflect neutrons of one spin state while absorbing or transmitting the other. Substrate choice and geometry also play a crucial role in optimising performance
H15
The new cold (low energy) neutron guide H15 is one of the impressive technical achievements of the Endurance ILL upgrade programme. H15, designed and engineered at the ILL, is the most complex neutron guide system ever realised. With installation finished in February 2024, the guide is now delivering neutrons to instruments D007, D11+, SAM and SHARPER. Simulations of neutron transport and guide optics played a crucial role, revealing routes to optimisation otherwise hidden by complexity.
ILL's 'Neutron technologies' brochure
From the design and optimisation of advanced neutron optics to the development of high-performance detectors and cutting-edge sample environments, ILL teams push technological boundaries to ensure the highest quality neutron beams and experimental setups for scientific users. Major technical developments achieved at the ILL are made available to the wider neutron community. This is highlighted in the newly issued Neutron technologies brochure.