SAM is up and running

- General news, Scientific news, SAM, France

The first test measurements on the new instrument SAM at the ILL have been performed. SAM is the new small-angle neutron scattering instrument developed by LLB in collaboration with ILL (a so-called collaboration research group instrument, CRG). The first experiments are planned for the second cycle of 2024.


The installation of SAM on the new H15 neutron guide (in the ILL7 guide hall) started in June 2023.  After eight months of intense teamwork involving both the instrument and the technical teams at ILL, the new instrument was ready. ILL’s high-flux reactor cycle number 195 started on 27 February, and SAM received its first neutrons on 4 March. The first tasks were the commissioning with neutrons (“hot commissioning”) of SAM’s position-sensitive neutron detector and the alignment of all neutron-optics elements.

Around mid-March, the qualification of the instrument in terms of radiation protection was completed (with the signature of the DSI, Dossier de Sécurité d’Instrument) and full time operation (7/7, 24/24) could start. Since then, calibration and test measurements with different samples have been performed. The first experiments in the so-called “friendly user” mode are planned for the second cycle of 2024.

SAM is the new small-angle neutron scattering (SANS) instrument developed by LLB - Laboratoire Léon Brillouin in collaboration with ILL –  and thus one of CRG instruments. Its construction was proposed in the framework of ILL’s Endurance, modernisation and upgrade programme, which is now reaching completion. SAM is a highly versatile instrument expanding the capabilities of the SANS technique at ILL. It will also guarantee access to SANS beam time to the French community after the shutdown of CEA’s Orphée reactor in Saclay. As a CRG instrument, the beam time will be evenly split between the ILL user program and the French community.

SANS does not attempt to see atoms but is interested in the organisation of particles in dispersed systems. As scattering elements are large (e.g. grains, bubbles, micelles), diffraction occurs at very small angles. The technique is used to explore the structure of liquids and solids on length scales ranging from 1 nanometre to about a micron. SAM will work with unpolarised or polarised neutrons and will be able to perform high-resolution spectroscopy measurements (measuring the energy transfer between the neutrons and the sample with sub-μeV resolution). Thanks to its position at the end of the fully renovated H15 guide, the incident flux at the sample position will be very similar to that of the world-leading SANS instruments already operating at the ILL.

Have a look at SAM’s very first test of the neutron scattering by a plexyglass sample and very first measurements here: