PNSensor (Germany)

Structure determination is a key application of XFELs and 4th generation synchrotron sources, particularly using the coherent and pulsed X-ray radiation from X-ray free-electron lasers (XFEL). Scientific interest focuses on understanding the physical, biological, and chemical properties of samples at the nanometer scale. The X-rays from XFELs enable Coherent X-ray Diffraction Imaging (CXDI), where coherent X-rays irradiate a sample, and a far-field diffraction pattern is captured by an imaging detector. By the nature of the underlying physics, the resolution, at which the sample can be probed with the CXDI technique, is limited by the wavelength of the X-ray radiation and the exposure time if a detector can record the diffraction pattern to very large scattering angles. The resolution that can be achieved under real experimental conditions, depends strongly on additional parameters. The Shannon pixel size, linked to the detector resolution, the coherent dose that can be deposited in the sample without changing its structure, the image contrast, and the signal-to-noise ratio of the detected scattered radiation at high $q$, i.e. at high scattering angles $2\Theta$, have a strong influence on the resolution. The signal-to-noise ratio at high $q$ defines the "effective" maximum solid angle in a specific experiment setup up to which a detector can efficiently detect a signal and in consequence determines the achievable resolution. The image contrast defines how well bright image features can be distinguished from dark ones. We present the preliminary results of our study on the influence of the PSF on SNR, image contrast, position resolution, and achievable sample resolution for different pixel sizes.

We showcase the application of a 2-dimensional detector for observing energy and momentum-correlated x-ray pairs. This detector introduces novel possibilities for applications in quantum x-ray optics.

Journal Article Combine 4D STEM and EELS Using a Fast Pixelated Direct Detector with Center Hole Get access M Huth, M Huth PNDetector GmbH, München, Germany Corresponding author: bjoern.eckert@pndetector.de Search for other works by this author on: Oxford Academic Google Scholar B Eckert, B Eckert PNDetector GmbH, München, GermanyUniversity of Siegen, Department of Physics, Siegen, Germany Corresponding author: bjoern.eckert@pndetector.de Search for other works by this author on: Oxford Academic Google Scholar S Aschauer, S Aschauer PNDetector GmbH, München, Germany Search for other works by this author on: Oxford Academic Google Scholar E Hedley, E Hedley University of Oxford, Department of Materials, Oxford, United Kingdom Search for other works by this author on: Oxford Academic Google Scholar P Nellist, P Nellist University of Oxford, Department of Materials, Oxford, United Kingdom Search for other works by this author on: Oxford Academic Google Scholar P Majewski, P Majewski PNDetector GmbH, München, Germany Search for other works by this author on: Oxford Academic Google Scholar L Strüder, L Strüder University of Siegen, Department of Physics, Siegen, GermanyPNSensor GmbH, München, Germany Search for other works by this author on: Oxford Academic Google Scholar H Soltau H Soltau PNDetector GmbH, München, Germany Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 29, Issue Supplement_1, 1 August 2023, Pages 401–402, https://doi.org/10.1093/micmic/ozad067.188 Published: 22 July 2023

The 100 m long X-ray test facility (100XF for clarity) in Institute of High Energy Physics of CAS has been playing an increasingly important role in the X-ray astronomy field in China. 100XF has been contributing to the missions under development, such as the Einstein Probe mission. The facility has also been providing support to R&D of focusing X-ray optics in China that will enable future X-ray telescopes to be realized, such as the enhanced X-ray Timing and Polarization (eXTP) mission. A pnCCD-based camera has been employed at 100XF to rapidly measure the performance of the X-ray optics. In this work, we study the performance of the camera and its spectral and imaging applications at 100XF. The camera system can provide a high frame readout rate, with a low readout noise <3 e−. It is sensitive to X-ray photons in the 3–10 keV energy band with a high quantum efficiency exceeding 90%. Actually, the low threshold of detection energy range can reach down to 0.2 keV. The energy resolution can reach 145.2 eV for single events and 154.8 eV for all valid events (including single events and split events) at 6.4 keV. The camera also exhibits excellent imaging capability in both the full frame mode and the windowing mode, with a readout rate of up to 1000 Hz. Finally, a prototype of a focusing X-ray mirror shell of eXTP was smoothly measured with this camera. The obtained on-axis point-spread function and half-power diameter are consistent with expectations. It is proven that the camera can improve the capability of 100XF in characterizing the X-ray optics. This camera will be very useful for performing on-ground calibrations for future X-ray telescope missions.

This article reports on energy-dispersive micro Laue (µLaue) diffraction of an individual gold nanowire that was mechanically deformed in three-point bending geometry using an atomic force microscope. The nanowire deformation was investigated by scanning the focused polychromatic X-ray beam along the nanowire and recording µLaue diffraction patterns using an energy-sensitive pnCCD detector that permits measurement of the angular positions of the Laue spots and the energies of the diffracted X-rays simultaneously. The plastic deformation of the nanowire was shown by a bending of up to 3.0 ± 0.1°, a torsion of up to 0.3 ± 0.1° and a maximum deformation depth of 80 ± 5 nm close to the position where the mechanical load was applied. In addition, extended Laue spots in the vicinity of one of the clamping points indicated the storage of geometrically necessary dislocations with a density of 7.5 × 1013 m-2. While µLaue diffraction with a non-energy-sensitive detector only gives access to the deviatoric strain, the energy sensitivity of the employed pnCCD offers absolute strain measurements with a resolution of 1%. Here, the residual strain after complete unloading of the nanowire amounted to maximum tensile and compressive strains of the order of +1.2 and -3%, which is comparable to the actual resolution limit. The combination of white-beam µLaue diffraction using an energy-sensitive pixel detector with nano-mechanical testing opens up new possibilities for the study of mechanical behavior at the nanoscale.

The Mercury Imaging X-ray Spectrometer is a highly novel instrument that is designed to map Mercury’s elemental composition from orbit at two angular resolutions. By observing the fluorescence X-rays generated when solar-coronal X-rays and charged particles interact with the surface regolith, MIXS will be able to measure the atomic composition of the upper ∼10-20 μm of Mercury’s surface on the day-side. Through precipitating particles on the night-side, MIXS will also determine the dynamic interaction of the planet’s surface with the surrounding space environment.MIXS is composed of two complementary elements: MIXS-C is a collimated instrument which will achieve global coverage at a similar spatial resolution to that achieved (in the northern hemisphere only – i.e. ∼ 50 – 100 km) by MESSENGER; MIXS-T is the first ever X-ray telescope to be sent to another planet and will, during periods of high solar activity (or intense precipitation of charged particles), reveal the X-ray flux from Mercury at better than 10 km resolution. The design, performance, scientific goals and operations plans of the instrument are discussed, including the initial results from commissioning in space.