The high‐resolution powder diffraction beamline at ESRF (ID22), built with a dual‐undulator source on the 6 GeV storage ring, combines a wide continuous range of incident energy (6–80 keV) with high brightness, offering the possibility to carry out high‐flux high‐resolution powder diffraction measurements. In routine operation, a bank of nine scintillation detectors is scanned vertically to measure the diffracted intensity versus 2gθ, each detector being preceded by an Si 111 analyser crystal. Although the current detector system has operated successfully for the past 20 years, recent developments in detector technology could be exploited to improve the overall performance. With this in mind, as a test, a two‐dimensional Pilatus3 X CdTe 300 K‐W pixel detector has been mounted on the arm of the diffractometer, replacing the nine scintillator detectors. At each nominal 2gθ value, a two‐dimensional image is recorded showing nine distinct regions corresponding to the diffraction signals passing via each of the analyser crystals. This arrangement offers new flexibility in terms of data handling and processing, with the possibility to optimize both peak shape and statistics, to remove parasitic effects, and to gain spatial resolution information. Combining the high efficiency of a hybrid photon‐counting area detector with the high angular resolution given by analyser crystals is an effective approach to improving the overall performance of high‐resolution powder diffraction.

Following Phase 2 of the upgrade of the ESRF in which the storage ring was replaced by a new low-emittance ring along with many other facility upgrades, the status of ID22, the high-resolution powder-diffraction beamline, is described. The beamline has an in-vacuum undulator as source providing X-rays in the range 6–75 keV. ID22's principle characteristics include very high angular resolution as a result of the highly collimated and monochromatic beam, coupled with a 13-channel Si 111 multi-analyser stage between the sample and a Dectris Eiger2 X 2M-W CdTe pixel detector. The detector's axial resolution allows recorded 2θ values to be automatically corrected for the effects of axial divergence, resulting in narrower and more-symmetric peaks compared with the previous fixed-axial-slit arrangement. The axial acceptance can also be increased with increasing diffraction angle, thus simultaneously improving the statistical quality of high-angle data. A complementary Perkin Elmer XRD1611 medical-imaging detector is available for faster, lower-resolution data, often used at photon energies of 60–70 keV for pair-distribution function analysis, although this is also possible in high-resolution mode by scanning up to 120° 2θ at 35 keV. There are various sample environments, allowing sample temperatures from 4 K to 1600°C, a capillary cell for non-corrosive gas atmospheres in the range 0–100 bar, and a sample-changing robot that can accommodate 75 capillary samples compatible with the temperature range 80 K to 950°C.

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