Speaker
Description
The BL06-XAIRA beamline is the microfocus macromolecular crystallography (MX) instrument at the ALBA synchrotron, that just accomplished its first year of User Operation.
XAIRA currently delivers a highly stable, intense X-ray beam of 4 × 3 $µm^2$ (FWHM at 1 Å wavelength) in the energy range of 4.0 to 14 keV, specifically tailored for demanding structural biology projects. This high-flux beam is paired with a state-of-the-art Dectris Eiger2 XE 9M photon-counting detector capable of acquiring data at frame rates up to 1 kHz. This configuration enables rapid data collection and supports time-resolved serial synchrotron crystallography (SSX) experiments within the millisecond regime.
Another differential trait of XAIRA is its specialized end-station chamber, in which the entire experimental setup —including the sample environment, detector, and cryostream— is enclosed within a controlled helium atmosphere. Operating in helium prevents flux attenuation at low energies, improves the signal-to-noise ratio of diffraction images at all photon energies, and mitigates the vibrations induced by the cryogenic stream blowing the crystal. Preliminary results with lysozyme show that, in a “worst case scenario” of a big crystal (100 µm per side), photon energy of 12,661 keV and short (76mm) sample-detector distance, at 1 Å resolution the signal-to-noise ratio increases by a factor of 3 and the resolution improves by ~0.1 Å. The chamber encasing the end stationgrants full compatibility with standard MX sample formats and conventional operation in air, while the associated circuit allows for full recovery of helium.
Since welcoming its first official users in July 2025 and its transition into full operation, XAIRA has demonstrated its value for challenging structural biology projects. Here we present case examples of successful results, describe how the beamline can be used to obtain the best data set for different types of challenging samples, and how the automated data processing software is used to provide immediate feedback and guide the data collection decision-making.
We will also discuss the future unique experiments enabled by the routine and automated operation of XAIRA in helium, and present the foreseen upgrades to be implemented in the upcoming ALBA-II Beamlines Upgrade Plan, which will improve both the beamline optics system and the End Station capabilities.