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S C I E N T I F I C H I G H L I G H T S

C O M P L E X S Y S T E M S A N D B I O M E D I C A L S C I E N C E S

2021 was another exceptional year for the Complex Systems & Biomedical Sciences group s beamlines, with many experiments performed in remote-access mode due to pandemic-related travel restrictions for our users. On the positive side, the new Extremely Brilliant Source (EBS) performed even better than expected, with exceedingly bright, highly coherent and very stable beams. On the personnel front, several new PhD students joined the group via InnovaXN, a joint ILL/ESRF programme funded by the EU that aims to strengthen links to industry.

The time-resolved SAXS/USAXS/WAXS beamline ID02 performed a large number of user experiments during the year. The refurbishment of the monochromator during the last winter shutdown yielded the expected result, with a coherent flux in excess of 1012 photons/s. A liquid sample delivery system based on a 28-port stream selector was developed, and a new stopped-flow device is available for time-resolved experiments. User operation involving both academic and industrial visitors has been in full swing since summer 2021. The beamline review in autumn was very successful and the panel appreciated the performance of the instrument, especially after the EBS upgrade.

ID09 is the beamline for time-resolved experiments that can be performed to a time resolution of 100 ps. These experiments are carried out by pump-probe with a short laser pulse initiating the sample. The pink beam is now extensively used to boost the intensity in SAXS, WAXS and diffraction experiments. The spectral line shapes from EBS undulators are very sharp, 1.0-2.5%, and freed from the previous low-energy tail. The narrow-band pink beam is particularly important for high-pressure shock experiments where the sample is destroyed. Thanks to EBS, the powder diffraction patterns are well resolved with the raw pink beam, which is essential for structural refinement. Conformational changes in proteins were also studied using wide-angle X-ray scattering with the pink beam. In collaboration with M. Andersson s group at Umeå University, one of the goals is to guide MD simulations of potential protein structures to the experimental scattering curves. Intense X-ray pulses were also used to examine electronic circuit boards in computers, in collaboration with aerospace companies, to check sensitivity to radiation damage from cosmic rays when operated in space. A long- term proposal led by ST Microelectronic is ongoing, and beam time is also sold to industry for this purpose.

Beamline ID10 has two end-stations, ID10-EH1 for studies of soft interfaces and ID10-EH2 for coherent scattering applications. Both stations successfully explored