Left: Installation of the undulator for the XAIRA beamline. Right: Exterior view of the experimental hutch of the XAIRA beamline.
Cerdanyola del Vallès, 26 January 2021. XAIRA is one of the beamlines under construction in ALBA. This new microfocus beamline is dedicated to challenging Macromolecular Crystallography (MX) experiments and novel techniques. The beamline is designed to support microcrystallography experiments on micron-sized crystals, needles and plates, as well as native phasing and fixed-target serial crystallography experiments. XAIRA’s mission is to provide a reliable yet state-of-the-art beamline to Spanish and worldwide structural biologists.
During the winter shutdown, combined efforts of different ALBA teams from the Accelerators, Engineering and Computing divisions, coordinated by Jordi Marcos, carried out the placing and conditioning of the XAIRA source. This is the longest undulator ever installed at ALBA, with a magnetic length of 2.3 metres and housing 115 magnetic periods. Longer undulators present higher associated magnetic forces, which difficult the mechanical design of the support structure and the gap movement system.
As Jordi Marcos details, “The main difficulty of the installation has been the short period of time we had to do it. Luckily, the detailed planning of tasks together with the great implication of the involved teams has allowed us to complete the operation successfully”.
“This is a great milestone in the construction process of XAIRA. It clearly depicts the current status of the beamline, since we are no longer designing on paper but starting to install devices indeed”, says Damià Garriga, XAIRA beamline scientist.
Undulators consist of periodic structures of dipole magnets creating a static magnetic field that alternates along the length of the undulator. Electrons traversing the structure are forced to undergo oscillations and thus to radiate energy. They enable producing synchrotron light at energy levels, or with very specific characteristics (circular polarization, small divergence, high intensity, etc.).
This undulator has been designed by Josep Campany following the requirements defined by Judith Juanhuix, the beamline responsible; to fulfill the requirements of the XAIRA beamline scientific case: provide a stable, high-flux micron-sized beam (1 µm x 1 µm) at 1 Å wavelength, but also tunable to reach down to ~4 keV while maintaining a good performance.
Remarkably, magnetic measurements to validate the undulator performance were carried out with a patented test bench designed and developed at ALBA. The bench was upgraded with a longer new C-shape piece that holds and keeps taut the carbon fiber that lodges the Hall Effect probe that allows determining the magnetic field inside the undulator.
Following the installation of XAIRA Front End and IVU (in-vacuum undulator), the next milestone is bringing first light at the Optical Hutch, a goal that is expected for 2021.
This project is co-funded by the European Regional Development Fund (ERDF) within the Spanish Pluri-Regional Operative Programme (former Smart Growth Operative Programme) 2014-2020.
