No abstract

For many scientific questions gaining three-dimensional insight into a specimen can provide valuable information. We here present an instrument called "tOMography Nano crYo (OMNY)," dedicated to high resolution 3D scanning x-ray microscopy at cryogenic conditions via hard X-ray ptychography. Ptychography is a lens-less imaging method requiring accurate sample positioning. In OMNY, this in achieved via dedicated laser interferometry and closed-loop position control reaching sub-10 nm positioning accuracy. Cryogenic sample conditions are maintained via conductive cooling. 90 K can be reached when using liquid nitrogen as coolant, and 10 K is possible with liquid helium. A cryogenic sample-change mechanism permits measurements of cryogenically fixed specimens. We compare images obtained with OMNY with older measurements performed using a nitrogen gas cryo-jet of stained, epoxy-embedded retina tissue and of frozen-hydrated Chlamydomonas cells.

X-ray crystallography at third-generation synchrotron sources permits tremendous insight into the three-dimensional structure of macromolecules. Additional information is, however, often required to aid the transition from structure to function. In situ spectroscopic methods such as UV-Vis absorption and (resonance) Raman can provide this, and can also provide a means of detecting X-ray-induced changes. Here, preliminary results are introduced from an onaxis UV-Vis absorption and Raman multimode spectrometer currently being integrated into the beamline environment at X10SA of the Swiss Light Source. The continuing development of the spectrometer is also outlined.

A transverse profile imager for ultrabright electron beams is presented, which overcomes resolution issues in present designs by observing the Scheimpflug imaging condition as well as the Snell-Descartes law of refraction in the scintillating crystal. Coherent optical transition radiation emitted by highly compressed electron bunches on the surface of the crystal is directed away from the camera, allowing to use the monitor for profile measurements of electron bunches suitable for X-ray free electron lasers. The optical design has been verified by ray tracing simulations, and the angular dependency of the resolution has been verified experimentally. An instrument according to the presented design principles has been used in the SwissFEL Injector Test Facility, and different scintillator materials have been tested. Measurements in conjunction with a transverse deflecting radiofrequency structure and an array of quadrupole magnets demonstrate a normalized slice emittance of 25 nm in the core of a 30 fC electron beam at a pulse length of 10 ps and a particle energy of 230 MeV.

The photon diagnostics available at the SwissFEL Aramis beamline are described. The working principles of various devices, their function and their expected or measured performance are discussed.