One million scans later: the evolution of the I16 material and magnetism beamline at Diamond Light Source.

Here, we review the capabilities of beamline I16 at Diamond Light Source after nearly 20 years of operation and continuous development. I16 is an X-ray scattering beamline operating in the 2.46-16 keV energy range with energy scans with a resolution of 1 meV. The beamline is equipped with a six-circle kappa diffractometer, offering flexible experimental geometries and support for a variety of ancillary equipment. Available equipment includes cryostats and cryofurnaces that span temperatures from 4.2 K to 700 K, which can be combined with applied electric fields, permanent magnets up to 1 T, and uniaxial strain cells. A range of detectors is mounted on the diffractometer arm, including a photon-counting area detector and an avalanche photodiode, both compatible with crystal analyzers for polarization analysis. Diamond single-crystal phase retarders provide full control of the incident X-ray polarization. These capabilities establish I16 as a state-of-the-art instrument for resonant and non-resonant X-ray scattering, multi Bragg coherent diffraction imaging, and grazing-incidence small- and wide-angle X-ray scattering. Together, they allow for studies of complex electronic, magnetic and structural phenomena in single crystals and thin films. We also outline the software infrastructure supporting experiment planning, data acquisition and rapid on-the-fly data analysis, and discuss ongoing developments and the anticipated benefits of the upgrade to a fourth-generation source.