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Optical enhancement cavities enabling laser pulses to be coherently stacked in free space are used in several applications to enhance accessible optical power. In this study, we develop an optical cavity that accumulates harmonically mode-locked laser pulses with a self-resonating mechanism for X-ray sources based on laser-Compton scattering. In particular, a Fabry-Perot cavity composed of 99% reflectance mirrors maintained the optical resonance in a feedback-free fashion for more than half an hour and automatically resumed the accumulation even if the laser oscillation was suspended. In contrast to conventional optical enhancement cavity systems with a dedicated feedback controller, this characteristic is highly beneficial in practical applications, such as for laser-Compton scattering X-ray sources. Lastly, upscaling and adoption of the proposed system might improve the operability and equipment use of laser Compton-scattering X-ray sources.
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http://dx.doi.org/10.1364/OE.472917 | DOI Listing |
Phys Rev Lett
August 2025
Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
We have observed the signatures of valence electron rearrangement in photoexcited ammonia using ultrafast hard x-ray scattering. Time-resolved x-ray scattering is a powerful tool for imaging structural dynamics in molecules because of the strong scattering from the core electrons localized near each nucleus. Such core-electron contributions generally dominate the differential scattering signal, masking any signatures of rearrangement in the chemically important valence electrons.
View Article and Find Full Text PDFPhys Rev Lett
August 2025
Durham University, Department of Physics, South Road, Durham DH1 3LE, United Kingdom.
The unabating discovery of nanoskyrmions in centrosymmetric magnets challenges the conventional Dzyaloshinskii-Moriya (DM) skyrmion stabilization mechanism. We investigate Gd_{2}PdSi_{3} using polarized resonant x-ray scattering and find that the low-field incommensurate modulations are elliptical helices, evolving into spin-density waves at higher fields. Quasi-2D magnetism arises via local DM interactions generated by inversion symmetry breaking around Gd-Gd bonds, which we characterize using atomistic simulations.
View Article and Find Full Text PDFCereb Cortex
August 2025
Section on Functional Imaging Methods & Functional MRI Core Facility, National Institute of Mental Health, 10 Center Drive, Rm 1D80, Bethesda, MD 20892, United States.
Statistical Parametric Mapping (SPM) has been profoundly influential to neuroimaging as it has fostered rigorous, statistically grounded structure for model-based inferences that have led to mechanistic insights about the human brain over the past 30 years. The statistical constructs shared with the world through SPM have been instrumental for deriving meaning from neuroimaging data; however, they require simplifying assumptions which can provide results that, while statistically sound, may not accurately reflect the mechanisms of brain function. A platform that fosters the exploration of the rich and varying neuronal and physiologic underpinnings of the measured signals and their associations to behavior and physiologic measures needs a different set of tools.
View Article and Find Full Text PDFJ Synchrotron Radiat
November 2025
Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China.
Synchrotron light sources are powerful platforms for cutting-edge, multidisciplinary research, with dozens currently in operation, construction or commissioning worldwide. It is widely recognized that different research areas have specific demands for source capabilities. For the majority of synchrotron facilities, delivering high-brightness, high-flux synchrotron radiation stably through high-current electron beams is the primary mode of operation.
View Article and Find Full Text PDFJ Synchrotron Radiat
November 2025
Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439, USA.
Nano-laminography combines the penetrating power of hard X-rays with a tilted rotational geometry to deliver high-resolution, three-dimensional images of laterally extended, flat specimens that are otherwise incompatible with, or difficult to image using, conventional nano-tomography. In this work, we demonstrate a full-field, X-ray nano-laminography system implemented with the transmission X-ray microscope at beamline 32-ID of the upgraded Advanced Photon Source at Argonne National Laboratory, USA. By rotating the sample around an axis inclined by 20° to the incident beam, the technique minimizes the long optical path lengths that would otherwise generate excessive artifacts when planar samples are imaged edge-on.
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