March 2020 saw the start of commissioning of the Structure of Materials group s beamlines with the new Extremely Brilliant Source (EBS). Despite the shortened commissioning time due to the COVID-19 pandemic, most of our beamlines were able to start operation in User Service Mode (USM) in August, as planned. Since then, our beamlines and users have been carrying out experiments by remote access.

Commercial mail-in experiments at our beamlines beamlines were among the first following the restart. More than 40 industrial imaging and topography experiments have been carried out, mainly at instrumentation facility BM05, but also at ID19 and ID06 (page 166). At BM05, acquisition times are reduced by a factor of two, throughput is increased with better automation and equipment upgrades, and the phase contrast at this bending magnet beamline, now housing a two-pole wiggler source, is further enhanced by a 25%-smaller horizontal source size compared to an insertion device source. BM05 has thus become a cornerstone of COVID-19 research at the ESRF, allowing the imaging of entire organs from victims of the disease and revealing damage caused to human lungs in unprecedented detail.

In September 2020, the hard X-ray microscope allocated the first user experiment from the spring 2020 proposal round, inaugurating the public user programme on ID06-HXM. The beamline staff, in remote contact with users, successfully carried out these first experiments. The workshop for hard X-ray microscopy, originally planned for April 2020, will be rescheduled as soon as conditions permit. Meanwhile, a virtual workshop will be organised in the first half of 2021 to inform potential users of the microscope s capabilities and to highlight results already obtained. The hard X-ray microscope was selected as an EBS upgrade beamline (EBSL2) and, in 2023, will become a fully dedicated beamline on ID03, doubling the capacity for user experiments.

At the materials science beamline ID11, a new Eiger2 4M CdTe diffraction detector has been installed on the nanofocus end-station, and a new imaging detector on the 3D-XRD end- station. Together with the large increase in X-ray flux from EBS, this opens up new opportunities to study smaller samples with higher resolution in both real and reciprocal space. The use of high-energy X-rays to measure very small distortions in crystallographic structures is an active research area. Magnetite has a complex

low-temperature structure and E. Pachoud et al. (page 130) show that there are site-selective doping effects of the ordered charge states in non-stoichiometric samples. In-situ grain imaging experiments can show the evolution of microstructures, and J. Zhang et al. (page 144) used the DCT method to track a statistical ensemble of grains. The results could be used to extract mobilities for a vast number of different types of grain boundaries, which gives a unique dataset for modelling and understanding microstructures.

The main areas of activity at ID15A are battery science, catalysis, and the study of glasses and other disordered systems. ID15A offers a wide range of integrated sample environments for in- situ/operando experiments including furnaces, cryostats, a potentiostat and a high-pressure gas-feed system, and ancillary equipment including an IR spectrometer and a mass spectrometer. A cryogenically cooled undulator (CPMU18), optimised for the production of very- high-energy X-rays, was installed in spring 2020. The combination of the CPMU18 and EBS increased the photon flux on the sample by almost two orders of magnitude, offering users the ability to perform multidimensional studies of working systems under operando conditions with unprecedented time resolution. The control system upgrade from SPEC to BLISS has been key in developing new experimental methods such as multi-resolution XRD-CT.

The EBS upgrade beamline BM18 for high- throughput and large-field phase-contrast tomography is progressing well, with infrastructure works nearly finished and radiation tests of the lead hutches taking place soon. The first tomography tests are planned in January 2022 and the first user experiments for March 2022. This beamline will also accommodate an innovative project for imaging the human body, in collaboration with UCL and partially funded by the Chan Zuckerberg Initiative as part of a global initiative to advance deep-tissue imaging. The exceptional beam characteristics of BM18 and its initial design for hierarchical imaging make it possible to image the complete human body with 25-µm resolution and localised scans down to the submicron level. This most precise anatomical data will make it possible to relate the general anatomy in any organ to the cellular structures and functions through 3D virtual histology.

Microtomography beamline ID19 successfully restarted the user programme remotely: a sample robot, initially installed for high-throughput

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STRUCTURE OF MATERIALS