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Benedikt Günther

Publications and source records attributed to Benedikt Günther.

2 recordsLinked to original sources

Characterizing an inverse Compton X-ray source and determining its electron beam parameters using a genetic algorithm

Inverse Compton X-ray sources are laboratory-scale devices providing quasi-monochromatic synchrotron radiation which is generated by laser photons Compton-scattering off highly relativistic electrons. Since the shape and width of the X-ray spectrum are determined by the properties of the colliding beams, these must be carefully optimised. However, device compactness limits the space for diagnostics, rendering a complete characterisation challenging, especially if an electron storage ring is combined with a laser enhancement cavity. Here, a framework for laser, electron and X-ray beam parameter determination is proposed to address this issue. First, methods for determining the laser- and X-ray parameters are presented. Knowing these, electron beam parameters are retrieved from the shape of the X-ray spectrum. To this end, an analytical physical model enabling a rapid calculation of inverse Compton scattering spectra is developed and combined with a genetic algorithm. This strategy's effectiveness is demonstrated by applying the concept at the Munich Compact Light Source, a storage ring-based inverse Compton X-ray source facility. Since the analytical model is computationally very inexpensive, the proposed framework could enable real-time monitoring of inverse Compton X-ray sources or be used as a non-invasive diagnostic based on a single spectrum for the electron beam emittance of storage rings or accelerators.

physics.acc-ph↗

Super-Resolution Structured-Illumination X-Ray Microscopy based on Fourier Decomposition

X-ray microscopy has become an important tool for non-destructive testing, e.g., in battery research. However, imaging a cm-scale battery cell at the desired (sub-)micrometer resolution has been challenging. State-of-the-art X-ray microscopy techniques with a suited field-of-view provide (sub-) $10\,μm$ resolution, typically limited by the detector point-spread function and the (effective) detector pixel size. This work presents a super-resolution X-ray microscopy approach overcoming both limitations. It requires a structured X-ray illumination to encode high-frequency sample information that is natively unresolved within the resolved region of support. A mathematical framework is developed that decodes this information and generates a super-resolved image from multiple acquisitions with different phase shifts of the structured X-ray illumination. The presence of this encoded high-frequency information is first experimentally demonstrated, followed by quantification and validation using a resolution test chart. A resolution improvement by a factor of 2.2 is shown. Finally, we extend the proposed super-resolution technique to X-ray microtomography. Since the image acquisition scheme is inherently multimodal, phase-contrast and dark-field X-ray images can be computed additionally. These results showcase the direct impact of the proposed technique across both non-destructive testing and biomedical imaging, alleviating pixel-size limitations in detectors and sample-size restrictions.

physics.optics↗