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We present a 3D reciprocal‐space mapping (RSM) method using a pink self‐amplified spontaneous emission (SASE) X‐ray free‐electron laser beam. The energy of each specific pulse in a SASE beam can be determined using the diffraction pattern of a specimen excited by pumping itself as a spectroscopic reference. A thin slab of RSM, whose thickness corresponds to the energy bandwidth of the pink beam, is successfully reconstructed using the proposed method. By rocking a sample in a few steps, we obtained a 3D RSM covering both the diffuse scattering and the Bragg rod in NiO thin films during a pump–probe X‐ray diffraction measurement. Pump–probe 3D X‐ray reciprocal‐space mapping (RSM) is devised using energy‐resolved pulses in self‐amplified spontaneous emission X‐ray free‐electron laser beams. Extended 3D RSMs covering both the diffuse scattering and the Bragg rod in an NiO thin film were obtained.

We report on recent developments that enable megahertz hard X-ray phase contrast imaging (MHz XPCI) experiments at the Single Particles, Clusters, and Biomolecules and Serial Femtosecond Crystallography (SPB/SFX) instrument of the European XFEL facility (EuXFEL). We describe the technical implementation of the key components, including an MHz fast camera and a modular indirect X-ray microscope system based on fast scintillators coupled through a high-resolution optical microscope, which enable full-field X-ray microscopy with phase contrast of fast and irreversible phenomena. The image quality for MHz XPCI data showed significant improvement compared with a pilot demonstration of the technique using parallel beam illumination, which also allows access to up to 24 keV photon energies at the SPB/SFX instrument of the EuXFEL. With these developments, MHz XPCI was implemented as a new method offered for a broad user community (academic and industrial) and is accessible via standard user proposals. Furthermore, intra-train pulse diagnostics with a high few-micrometre spatial resolution and recording up to 128 images of consecutive pulses in a train at up to 1.1 MHz repetition rate is available upstream of the instrument. Together with the diagnostic camera upstream of the instrument and the MHz XPCI setup at the SPB/SFX instrument, simultaneous two-plane measurements for future beam studies and feedback for machine parameter tuning are now possible.

The diagnostics of X‐ray beam properties has a critical importance at the European X‐ray Free‐Electron Laser facility. Besides existing diagnostic components, utilization of a diamond sensor was proposed to achieve radiation‐hard, non‐invasive beam position and pulse energy measurements for hard X‐rays. In particular, with very hard X‐rays, diamond‐based sensors become a useful complement to gas‐based devices which lose sensitivity due to significantly reduced gas cross‐sections. The measurements presented in this work were performed with diamond sensors consisting of an electronic‐grade single‐crystal chemical‐vapor‐deposition diamond with position‐sensitive resistive electrodes in a duo‐lateral configuration. The results show that the diamond sensor delivers pulse‐resolved X‐ray beam position data at 2.25 MHz with an uncertainty of less than 1% of the beam size. To our knowledge this is the first demonstration of pulse‐resolved position measurements at the MHz rate using a transmissive diamond sensor at a free‐electron laser facility. It can therefore be a valuable tool for X‐ray free‐electron lasers, especially for high‐repetition‐rate machines, enabling applications such as beam‐based alignment and intra‐pulse‐train position feedback. Diamond sensors have been developed and tested for operation with high‐energy X‐ray beams at the European XFEL.

Partial discharge (PD) is an important phenomenon that reflects the insulation condition of electrical equipment. In order to protect the safety of power grids, it is of significance to diagnose the type of insulation defects inside the equipment accurately and early through PD pattern recognition. In this article, phase resolved pulse sequence (PRPS) graphs in 3D were constructed by the PD pulse data of the gas-insulated switchgear (GIS) acquired, then the histogram of oriented gradient (HOG) features were extracted directly from the 3D PRPS graphs, and finally the attribute selective Naïve Bayes classifier was used to recognize the discharge pattern. In addition, this method was compared with two traditional methods, i.e., the statistical method and the grayscale gradient co-occurrence matrix method, from three aspects. The result shows that 3D PRPS graphs have different morphology characteristics in vision under different defects, and the similarity among different voltages applied is higher than among different defects, so it is reasonable to use them as the basis for PD pattern recognition. The contrast indicates that the HOG method not only has the highest accuracy with the least requirement for pretreatment and training, but it also has robustness when the voltage applied changes. Consequently, this method has the universality for PD pattern recognition that is based on 3D PRPS graphs.

Partial discharge (PD) is a significant electrical fault in gas-insulated switchgear (GIS), with various types posing different risks to insulation. Accurate identification of PD types is essential for enhancing GIS management and ensuring the reliability of electrical grids. This study proposes a novel approach for PD identification in GIS integrating completed local binary pattern (CLBP) feature extraction, feature engineering, and an optimized support vector machine (SVM). PD faults were simulated in GIS and phase-resolved pulse sequence (PRPS) data for four different forms of PD were gathered. CLBP was used to extract image features, and then the support vector machine recursive feature elimination (SVM-RFE) algorithm was used to evaluate feature importance. Then, linear discriminant analysis (LDA) was used to fuse the selected features and reduce redundancy. The fused features were classified using a bald eagle search algorithm combined with differential evolution (IBES)-optimized SVM, achieving a recognition accuracy of 99.38%. The results indicate that the proposed method effectively distinguishes between different PD PRPS patterns in GIS.

This IUPAC Technical Report describes and compares the currently applied methods for measuring and analyzing time-resolved fluorescence traces using phase-modulation fluorometry as well as pulse fluorometry (direct emission decay measurements, single-photon timing, streak camera measurements, fluorescence upconversion, and optical Kerr gating). The paper starts with a brief description of the basic principles for time and frequency domain fluorescence spectroscopy. The fundamental equations are given, and recommendations for adequate use are emphasized. The up-to-date, commonly employed excitation sources and photodetectors are described in detail. The analysis of time-resolved fluorescence data is discussed. Attention is paid to possible artifacts, and remedies are presented on how to avoid them or to account for them. Finally, fluorescence lifetime standards for the nanosecond and picosecond timescales are collected.

A two-color pump beam (800 and 1200 nm) was introduced into hydrogen for molecular phase modulation, and a probe beam (267 nm) to generate Raman sidebands, by coherent frequency modulation based on four-wave Raman mixing. The phase and temporal profile were evaluated by means of a self-diffraction frequency resolved optical gating (SD FROG) system. The relative phases among the Raman sidebands were controlled by changing the angle of a thin CaF2-plate inserted into the 267-nm beam path, suggesting that a train of 2.6-fs pulses was generated in the deep-ultraviolet region.

This study introduces a compact, portable femtosecond fibre laser system designed for synchronization with SPring‐8 synchrotron X‐ray pulses in a uniform filling mode. Unlike traditional titanium–sapphire mode‐locked lasers, which are fixed installations, our system utilizes fibre laser technology to provide a practical alternative for time‐resolved spectroscopy, striking a balance between usability, portability and cost‐efficiency. Comprehensive evaluations, including pulse characterization, timing jitter and frequency stability tests revealed a centre wavelength of 1600 nm, a pulse energy of 4.5 nJ, a pulse duration of 35 fs with a timing jitter of less than 9 ps, confirming the suitability of the system for time‐resolved spectroscopic studies. This development enhances the feasibility of experiments that combine synchrotron X‐rays and laser pulses, offering significant scientific contributions by enabling more flexible and diverse research applications. This study introduces a compact, portable femtosecond fibre laser system optimized for synchronization with SPring‐8 synchrotron X‐ray pulses in a uniform filling mode, offering a practical and cost‐effective alternative to traditionally, fixed, installed laser systems for time‐resolved spectroscopy combining synchrotron X‐ray pulses and laser pulses.

An algorithm for characterizing attosecond extreme ultraviolet pulses that is not bandwidth-limited, requires no interpolation of the experimental data, and makes no approximations beyond the strong-field approximation is introduced. This approach fully incorporates the dipole transition matrix element into the retrieval process. Unlike attosecond retrieval methods such as phase retrieval by omega oscillation filtering (PROOF), or improved PROOF, it simultaneously retrieves both the attosecond and infrared (IR) pulses, without placing fundamental restrictions on the IR pulse duration, intensity or bandwidth. The new algorithm is validated both numerically and experimentally, and is also found to have practical advantages. These include an increased robustness to noise, and relaxed requirements for the size of the experimental dataset and the intensity of the streaking pulse.