Synchrotron light sources are key instruments of modern science, providing unique opportunities for groundbreaking studies in diverse scientific disciplines and driving innovation in numerous scientific and technological fields. Fourth-generation light sources provide unprecedented capabilities in imaging, spectroscopy and diffraction techniques. Ultimate brightness is the key to advancing to a smaller scale, faster response, and higher data measurement and processing rate. The brightness is primarily determined by the electron beam emittance and energy spread at operational intensity. A common feature of fourth-generation synchrotrons is the short length of the electron bunches combined with a very small transverse beam size. Consequently, the high particle density leads to strong collective effects that significantly increase the emittance and limit the achievable brightness at operational beam intensity. In this article, we summarize our studies of the emittance and brightness scaled with the beam energy and intensity, taking into account the effects of intrabeam scattering, beam-impedance interaction and bunch lengthening provided by higher-harmonic RF systems to identify optimal combinations of machine and beam parameters.

Contamination from nearby bending magnet radiation hinders precise and accurate determination of the true beam center of undulator radiation. To solve this problem, a semi-nondestructive method was developed to visualize the detailed profile of a synchrotron radiation beam by using a thin diamond film as a scatterer. As the beam passed through the diamond film, scattered X-rays were imaged using a pinhole camera and measured with a two-dimensional silicon drift detector (SDD) scan. With this configuration, the beam center was accurately determined by visualizing the radiation pattern distribution for each energy level of a pink X-ray beam within an aperture size of 1.5 mm × 1.5 mm, shaped by a front-end slit (FES) positioned upstream of the monochromator. Additionally, by scanning the FES in two dimensions with a reduced aperture of 0.4 mm × 0.4 mm, energy-resolved images were successfully obtained using the SDD at a fixed position. These images revealed the profile of undulator radiation over a broad area (with an aperture extending up to 4 mm) in a pre-slit positioned upstream of the FES, demonstrating good alignment with SPECTRA calculations. This method effectively eliminates contamination from nearby bending magnet radiation, a significant issue in previous approaches, enabling a direct and highly accurate determination of the true beam center.

The European Photon and Neutron campus in Grenoble is a unique site, encompassing the European Synchrotron Radiation Facility Extremely Brilliant Source, the Institut Laue-Langevin, the European Molecular Biology Laboratory and the Institut de Biologie Structurale. Here, we present an overview of the structural biology beamlines, instruments and support facilities available on the EPN campus. These include advanced macromolecular crystallography using neutrons or X-rays, small-angle X-ray or neutron scattering, cryogenic electron microscopy, and spectroscopy. These highly complementary experimental approaches support cutting-edge research for integrated structural biology in our large user community. This article emphasizes our significant contributions to the field, outlines current advancements made and provides insights into our future prospects, offering readers a comprehensive understanding of the EPN campus's role in advancing integrated structural biology research.

While the importance of a systematic overview of scientific data and demands toward data integration are increasing, data capitalization and confidentiality are also emerging competitively. X-ray absorption spectroscopy has a strong tradition of data sharing, as cross-referencing data enhances the detailed understanding of the obtained spectra. While physically integrating databases in various formats is impractical, a system has been successfully developed that allows cross-searching among Japanese, USA and European databases in cyberspace. This achievement is made possible through the realization of `vocabulary unification' and `knowledge unification' on a global scale, implemented in publicly accessible endpoints. This paper provides a summary of the concepts of terminology, ontology and semantics for X-ray spectroscopy behind this system, and presents a pilot case study along with future directions for data integration in synchrotron radiation science.

Circular particle accelerators require precise beam orbit correction to maintain the beam's trajectory close to the ideal `golden orbit', which is centered within all magnetic elements of the ring, except for slight deviations due to installed experiments. Traditionally, this correction is achieved using methodologies based on the response matrix (RM). The RM elements remain constant when the accelerator's lattice includes solely linear elements or when a linear approximation is valid for small perturbations, allowing for the calculation of corrector strengths to steer the beam. However, most circular accelerators contain nonlinear magnets, leading to variations in RM elements when the beam experiences large perturbations, rendering traditional methods less effective and necessitating multiple iterations for convergence. To address these challenges, a machine learning (ML)-based approach is explored for beam orbit correction. This approach, applied to synchrotron SLS 2.0 under construction at the Paul Scherrer Institut, is evaluated against and in combination with the standard RM-based method under various conditions. A possible limitation of ML for this application is the potential change in the dimensionality of the ML model after optimization, which could affect performance. A solution to this issue is proposed, improving the robustness and appeal of the ML-based method for efficient beam orbit steering.

Scanning objects with a tightly focused beam (of photons or electrons for example) can provide high-resolution images. However, rapid deposition of energy into a small area can damage tissues in organic samples or may rearrange the chemical structure or physical properties of inorganic materials. Scanning an object with a broad, or diffuse, beam can deliver an equivalent probe energy but spread it over a much wider footprint. However, typically the imaging resolution is proportional to the probe diameter and a diffuse probe sacrifices resolution. Here we propose a method to achieve `high resolution' imaging (in the sense that resolution is smaller than the probe diameter) using a diffuse probe. We achieve this by encoding a pattern onto the probe and employing a decoding step to recover a tight delta-like impulse response. Huffman sequences, by design, have the optimal delta-like autocorrelation for aperiodic (non-cyclic) convolution and are well conditioned. Here we adapt 1D Huffman sequences to design 2D Huffman-like discrete arrays as diffuse imaging probes that have spatially broad, relatively thin, uniform intensity profiles and have excellent aperiodic autocorrelation metrics. Examples of broad shaped diffuse beams were developed for the case of X-ray imaging. A variety of masks were fabricated by the deposition of finely structured layers of tantalum on a silicon oxide wafer. The layers form a pattern of discrete pixels that modify the shape of an incident uniform beam of low-energy X-rays as it passes through the mask. The intensity profiles of the X-ray beams after transmission through these masks were validated, first by acquiring direct-detector X-ray images of the masks, and second by raster scanning a pinhole over each mask pattern, pixel-by-pixel, collecting `bucket' signals as applied in traditional ghost imaging. The masks were then used to raster scan the shaped X-ray beam over several simple binary and `gray' test objects, again producing bucket signals, from which sharp reconstructed object images were obtained by deconvolving their bucket images.

Avalanche photodiode detectors (APDs) at X-ray synchrotrons are typically limited to recording at most one photon per synchrotron pulse. Digitizing the APD amplifier outputs enables signal processing to accurately measure a mean count rate of at least four photons per pulse based on initial synchrotron measurements. Higher rates are readily achievable. This method allows APDs to be utilized for time-resolved measurements at much higher intensities thanbefore.

We present the development of a portable and compact nanofocusing system utilizing Kirkpatrick-Baez optics for X-ray free-electron lasers (XFELs). The system has a total length of merely 340 mm from the initial elliptical mirror to the focal point. With this setup, we achieve focusing capabilities reaching dimensions as small as 150 nm horizontally and 220 nm vertically, resulting in an intense beam with an intensity of 2.5 × 1019 W cm-2 for a 10 keV XFEL with a pulse energy of 110 µJ. As a demonstration of its applicability in X-ray nonlinear optics, we successfully observed an 8.64 keV Zn Kα laser by irradiating a Zn foil with the focused XFEL beam. The attained photon energy is currently the highest photon energy for amplified spontaneous emission via bound-bound transitions of electrons in the world. We anticipate that this portable and compact nanofocusing system will pave the way for new frontiers in X-ray nonlinear optics and high-energy density science, owing to its adaptability to various experimental conditions.

Camera or lens-based detector calibration is essential for spatial accuracy in applications like dimensional tomography, optical metrology, and computer vision. Many methods and software exist yet there is still a lack of approaches that achieve both high accuracy and robustness while being easy to use and capable of handling a wide range of distortions. Radial lens distortion is common in high-resolution X-ray detector optics used in parallel-beam tomography at synchrotrons. Achieving sub-pixel accuracy requires calibrating with an optical target image. Although methods for characterizing radial distortion are well established, acquired images often also include perspective distortion and optical center offset. Here, we present our approaches to individually characterize and correct both types of distortion using a single calibration image, implemented in the Discorpy software.

The Structural Biology Research Center (SBRC) and the Photon Factory at the High Energy Accelerator Research Organization (KEK) have played a key role in advancing macromolecular crystallography (MX) and have developed advanced experimental systems in the MX field. Key innovations include a long-wavelength MX beamline for native single-wavelength anomalous diffraction phasing (BL-1A), a crystal-shaping machine, an automated crystal-centering system and a fully automated diffraction data-acquisition system. In addition to the beamline technologies, the SBRC has developed a fully automated protein crystallization and monitoring system (PXS/PXS2). The crystallization plate prepared by PXS2 can be mounted directly onto an in situ data-acquisition system at BL-17A. These technologies have transformed experimental workflows, enabling high-throughput structure determination and supporting drug discovery. Furthermore, the SBRC can integrate advanced imaging techniques, including MX, cryogenic electron microscopy (cryo-EM) and small-angle X-ray scattering (SAXS), under one roof. This interdisciplinary approach facilitates hybrid structural analysis by combining techniques such as MX and SAXS or MX and cryo-EM.