The IMAT beamline at ISIS is used for non-destructive and in situ imaging across a broad range of areas such as engineering, energy storage, earth sciences, cultural heritage and plant sciences. To expand its capabilities to include diffraction, two new detector banks have been installed. This will enable the collection of both diffraction and imaging data for the sample of interest.
Combining neutron imaging and neutron diffraction offers a more comprehensive material characterisation, which is especially valuable when studying complex engineering components, energy materials and cultural heritage artefacts. For these, both structural integrity and internal crystallography are important to understand how to maximise performance or preservation.
Neutron imaging provides spatially resolved information of internal structures that can reveal features such as cracks and voids, as well as density variations inside a sample. This is useful, for example, for studying the distribution of hydrogen in metals and catalysts, and lithium in batteries. Neutron diffraction, on the other hand, gives crystallographic information including phase composition, residual stress, and texture.
While it's currently possible to do imaging and diffraction on separate beamlines at ISIS, having the ability to do both on a single beamline is valuable when processes are happening within the specimen being studied, such as a battery being charged. Even if this is not the case, being able to keep the sample in one place will reduce the uncertainty caused by dismounting, mounting and realigning the sample.
The two new diffraction detector banks for IMAT each contain seven modules, and inside each one are 512 scintillator sections connected to 1024 wavelength shifting fibres. Everything has been manufactured on site by the ISIS detector team in collaboration with the Technology department. In total, the setup contains 7168 fragile scintillators, and approximately 20 km of wavelength shifting fibres have been bent and routed manually through 57344 holes just 1.2 mm in diameter.
Making the detectors on site is a recent development for ISIS. It has many advantages over outsourcing, including better monitoring and improving communications with less travel. In the past, detector performances could vary due to miscommunication between manufacturers.
Working with the fragile optical fibres and following the procedures developed by the detector development group are skills learnt over time, and it's great for the team that this knowledge gained is now retained. They've found that the best way to learn is to get stuck in and learn on the job – it's a task that requires excellent concentration!
During the last user cycle in June 2025, the detectors were installed by the instrument operations team. They have been tested offline and will be commissioned during the rest of 2025 while the imaging programme on IMAT is being continued. In 2026, the setup will be completed as the large radial collimators and a new motion system for IMAT are installed. This project was partially funded by the Swedish Research Council, initially led by Sten Eriksson and subsequently Maths Karlsson at Chalmers University.
Now the detectors have been developed for IMAT, the team will be learning from this and applying the same production technique to the detectors that will be going into HRPD-X. Although those banks will be 1.5 times bigger, and there will be four of them. Looking further ahead, there will be more instrument upgrades and new instruments that will use this technology.
Further information – some examples of where combined imaging and diffraction will be applied
Additive manufacturing components: Neutron tomography can be used to map porosity and build-defects in 3D-printed metals. Bragg edge imaging can be used to map one strain component across a large part of a sample. The imaging data and strain maps can be used to identify regions of interest for diffraction analysis, to determine the strain tensor linked to build direction.
Battery degradation studies: Imaging reveals lithium distribution (tomography) and structural changes (Bragg edge mapping) in battery electrodes. Diffraction then measures crystallographic states and phase changes in selected regions of interest with much higher structural sensitivity during charge/discharge cycles.
Weld quality in nuclear materials: Imaging detects internal weld flaws or material flow, directing diffraction measurements to measure residual strain in three principal directions and phase distribution in critical points.
Cultural heritage artefacts: Imaging locates corrosion or repair areas in ancient objects or historic metallic artefacts. Diffraction characterises phase composition and manufacturing techniques without opening an object and without taking samples.
