Synchrotron Radiation Beamline Research Articles

A distributed data processing scheme based on Hadoop for synchrotron radiation experiments.

With the development of synchrotron radiation sources and high-frame-rate detectors, the amount of experimental data collected at synchrotron radiation beamlines has increased exponentially. As a result, data processing for synchrotron radiation experiments has entered the era of big data. It is becoming increasingly important for beamlines to have the capability to process large-scale data in parallel to keep up with the rapid growth of data. Currently, there is no set of data processing solutions based on the big data technology framework for beamlines. Apache Hadoop is a widely used distributed system architecture for solving the problem of massive data storage and computation. This paper presents a set of distributed data processing schemes for beamlines with experimental data using Hadoop. The Hadoop Distributed File System is utilized as the distributed file storage system, and Hadoop YARN serves as the resource scheduler for the distributed computing cluster. A distributed data processing pipeline that can carry out massively parallel computation is designed and developed using Hadoop Spark. The entire data processing platform adopts a distributed microservice architecture, which makes the system easy to expand, reduces module coupling and improves reliability.

Development of a microwave chemical cell coupled with post-wall waveguide for in situ/operando soft x-ray absorbance spectroscopy under microwave irradiation

In this study, we developed a microwave chemical cell for total electron yield soft x-ray absorption spectroscopy (XAS) using synchrotron radiation under microwave irradiation. In addition, in situ XAS measurements of ammonia borane were performed using the device developed. The device comprises a post-wall waveguide housing a sample holder formed within it. Electrons emitted from the sample during soft x-ray irradiation pass through the metal plates of the waveguide and are measured using a picoammeter. Integration of the microwave irradiation structure into a synchrotron radiation beamline, which is a challenge in soft x-ray analysis requiring measurements in a high-vacuum atmosphere, was achieved by miniaturizing the device using 24.125 GHz ISM band microwaves, instead of the typical 2.45 GHz microwaves. Performance of the device was thoroughly assessed through temperature distribution simulation, temperature measurement of water, and evaluation of frequency characteristics. When the sample holder was filled with water and irradiated with 3 W microwaves, the temperature increased to 97 °C, which is close to the boiling point. The in situ XAS measurements performed using this device with ammonia borane/graphite (2:1) powder at the B-K edge during microwave irradiation showed that peaks associated with hydrogen desorption intensified with prolonged microwave exposure. This result indicates that microwave heating in a vacuum and soft x-ray analysis during microwave heating were achieved. The developed microwave chemical cell emerges as a powerful tool, facilitating advancements in our understanding of elementary chemical processes and elucidating microwave-specific effects such as local heating during microwave irradiation.

Characterization in the extreme ultraviolet (XUV) domain of microchannel plate based device using synchrotron radiation

Innovative, low-loss, and compact optical systems are essential to meet the experimental requirements of emerging novel radiation sources. The microchannel plate (MCP), a metamaterial-based optical device, shows promising potential for shaping, condensing, and focusing soft x-ray radiation at synchrotron radiation (SR) facilities. This study highlights the impact of MCP optical devices on SR beam condensing capability and their sensitivity to the degree of coherence by investigating the profile of transmitted beams through single and double MCP optical devices. Transmitted diffraction patterns of soft x-ray SR radiation change with energy and radiation modes. At 92 eV, the double MCP-based device affects the beam divergence and degree of coherence more than the single MCP. Moreover, the double MCP device shows potential as a condensing optics at shorter wavelengths, i.e., 480 eV. Experiments were performed at the available end-station of the Circular Polarization beamline at the Elettra synchrotron facility in Trieste, using a high-vacuum chamber with a hexapod system, providing the precise movement necessary to align these diffractive optics. The findings contribute to the development of innovative optical systems for SR and free-electron laser beamlines, paving the way for advanced experiments in spectroscopy, microscopy, and imaging in a wide energy range.

Estimation of Absorbed Dose due to Gas Bremsstrahlung Based on Residual Gas in Electron Storage Rings

Gas bremsstrahlung, generated by the interaction between stored electrons and residual gas in electron storage rings, is an important radiation source for the shielding of synchrotron radiation (SR) facilities. In recent SR facilities, hydrogen was found dominant in the residual gas of the vacuum chambers of the electron storage rings, although air has been conventionally assumed as the bremsstrahlung target for the shielding designs of SR beamlines extended from the electron storage ring. To study the effect of residual gas composition on the dose rate outside shields, we calculated the intensity of gas bremsstrahlung based on the gas composition for both the air and the residual gas expected in the recent electron storage rings using an analytical formula and general-purpose Monte Carlo codes for particle transport calculations. The analytical shielding calculation with a realistic gas composition was found to well reproduce the energy spectra of gas bremsstrahlung simulated by the Monte Carlo codes. The correction factors between the air and the realistic gas compositions are applied to the conventional analytical formulas for dose estimation of secondary radiations generated by the interaction between the bremsstrahlung from air and beamline components.

Synchrotron radiation stability with meV-level energy resolution: in situ characterization.

One of the most critical parameters in synchrotron radiation (SR) experiments is the stability of the photon energy, which is primarily affected by the stability of the light source and the optical elements in the beamline. Due to the characteristics of SR and the use of dispersive elements such as monochromators in the beamline, the change of the beam position is usually accompanied by the change of energy and flux, while most traditional beam monitoring methods are based on the direct or indirect measurement of total flux, and are therefore sensitive to the beam position only, having no energy resolution. In this paper, an in situ monitoring system has been designed to measure the short-term (jitter) and long-term (drift) characteristics of the energy variation in the SR beamline. The system consists of a double-crystal monochromator, an orthogonal analysis crystal, and an X-ray imaging detector, which could decouple the angle and energy spread of the photon beam based on the dispersion effect in Bragg diffraction. The time response and the energy resolution of the system could reach millisecond and millielectron volt level, respectively.

Real-time machine-learning-driven control system of a deformable mirror for achieving aberration-free X-ray wavefronts.

A neural-network machine learning model is developed to control a bimorph adaptive mirror to achieve and preserve aberration-free coherent X-ray wavefronts at synchrotron radiation and free electron laser beamlines. The controller is trained on a mirror actuator response directly measured at a beamline with a real-time single-shot wavefront sensor, which uses a coded mask and wavelet-transform analysis. The system has been successfully tested on a bimorph deformable mirror at the 28-ID IDEA beamline of the Advanced Photon Source at Argonne National Laboratory. It achieved a response time of a few seconds and maintained desired wavefront shapes (e.g., a spherical wavefront) with sub-wavelength accuracy at 20 keV of X-ray energy. This result is significantly better than what can be obtained using a linear model of the mirror's response. The developed system has not been tailored to a specific mirror and can be applied, in principle, to different kinds of bending mechanisms and actuators.

An electron–ion coincidence spectrometer for commissioning of a synchrotron radiation beamline: Absolute photon intensity and content of higher harmonic radiation

We describe the commissioning of a new electron-ion coincidence spectrometer used to diagnose the photon beam from a plane grating monochromator beamline at the ASTRID2 synchrotron radiation facility. The spectrometer allows determination of the absolute photon intensity by calibration to the photoabsorption cross sections of known gases, such as the rare gases Ar, Kr, and Xe presented here. The spectrometer operates at very low pressure (∼10-8-10-9 mbar) and-due to the coincidence electron-ion detection scheme-the detector efficiencies can be determined routinely; hence, the spectrometer can be recalibrated swiftly. By variation of a single potential of the spectrometer, the content of higher order radiation in the monochromatized synchrotron radiation can be analyzed. The layout and operation of the synchrotron radiation beamline at ASTRID2 and its additional photon diagnostic units are additionally described.

Integrated optical design method for the synchrotron radiation beamlines

In this paper, a new beamline optical system design method is reported in which the calculation of synchrotron radiation source flux distribution, monochromator spectral resolving power, mirror reflectance and grating diffraction efficiency are integrated together in one program to evaluate the whole beamline optical system performance. We demonstrate the advantage of this method by applying it to the Surface Physics beamline at Hefei Light Source to find out better optical system parameters. By using this method, a higher photon flux with the same spectral resolving power than the original design is achieved. The integrated optical system design method provides a great promising application in the beamline optical design and optimization in the future.

A versatile biaxial stretching device for in situ synchrotron radiation small- and wide-angle x-ray scattering measurements of polymer films.

A biaxial stretching device is designed and developed for the real-time structural measurements of polymer films. This device adopts a vertical layout to perform real-time x-ray scattering measurements. It has a maximum stretching ratio of 8 × 8 in two perpendicular directions. Its maximum experimental temperature and stretching rate are 250 °C and 100 mm/s, respectively. The control accuracies of the experimental temperature and stretching rate are ±1 °C and 0.01mm, respectively. All the parameters related to film biaxial processing, such as stretching speed, stretching ratio, and temperature, can be independently set. The device feasibility is demonstrated via a real-time experiment in a synchrotron radiation beamline. Wide-angle x-ray diffraction, small-angle x-ray scattering, and stress-strain data can be simultaneously obtained during various stretching modes. The proposed device fills the gap between the synchrotron radiation x-ray scattering technique and the biaxial stretching processing of polymer films. This device will play an important role in improving the understanding of the physics behind biaxial polymer processing.

Early Microjet Experimentation with Liquid Water in Vacuum.

ConspectusIn this brief look at the history of liquid microjets, I recollect some personal reminiscences on initial challenges for introduction of this method, as well as unexpected problems and exemplary results using this new tool for liquid evaporation and photoelectron spectroscopy studies.Many efficient and direct, atomic level diagnostic instruments in use at solid state surfaces and in gas-phase atom or cluster studies require high vacuum. They have therefore not been applied to investigations of aqueous solutions because liquid water both strongly evaporates and rapidly freezes in vacuum. Only fairly recently, over the past three decades, have liquid microjets been considered as practicable targets for research on liquid-water interfaces in vacuum. The working principle is analogous to the functioning of a free molecular beam source, where molecules enter through a small aperture into a vacuum without being disturbed by subsequent collisions in their original Maxwellian velocity distribution. Similarly, above a microjet surface in vacuum, water vapor molecules do not interact with each other, or with different probe particles, as long as the liquid jet diameter is small in relation to the mean free path of the liquids' vapor at equilibrium conditions. For pure liquid water, this constraint is Djet < λvap < 10 μm for 6.1 mbar vapor pressure at the triple point of water. A high streaming velocity of the liquid jet, >50 m/s, delays freezing and exposes a steadily renewed fresh vacuum surface for experiments.For experimental verification of the microjet free surface concept, H2O vapor velocities were measured in a molecular beam time-of-flight experiment. These studies showed Maxwellian velocity distributions with the expected local water-jet temperatures for 5 and 10 μm jets, whereas larger liquid jet diameters of 50 μm exhibit narrowed vapor velocity profiles. This narrowing is the known signature of incipient, collision dominated, supersonic hydrodynamic expansions in nozzle beam sources. As a completely unexpected new result in evaporation studies of carboxylic acid solutions, freely evaporating acetic acid dimers showed apparent non-equilibrium liquid surface source temperatures several hundred kelvin above the simultaneously measured monomer temperatures, a phenomenon shown to be correlated with surface tension.Continuing with improvements, the vacuum water microjets were implemented inside a photoelectron spectroscopy apparatus that was modified for handling large amounts of water vapor. After initial complications with liquid jet charging phenomena, the first partial liquid-water photoelectron spectra were recorded using 21 eV photons from a He I discharge lamp. In the next step, the equipment was taken to a synchrotron radiation beamline at BESSY II, resulting in substantial improvements of signal intensity and in photon tunability for narrow band monochromatic soft X-rays up to 1 keV. Two early examples of these continuing experiments are considered, briefly, for aqueous alkali halide salt solutions and for the pH-value dependent protonation of an NH2/NH3+ group in an amino acid directly in a photoelectron spectrum of a solution.In conclusion, liquid microjets have opened up a completely new approach to studies of arbitrary liquids with chemical and biological relevance.

Multi-objective genetic algorithm for synchrotron radiation beamline optimization

In beamline design, there are many floating parameters that need to be tuned; manual optimization is time-consuming and laborious work, and it is also difficult to obtain well optimized results. Moreover, there are always several objectives that need to be considered and optimized at the same time, making the problem more complicated. For example, asking for both the flux and energy to be as large as possible is a usual requirement, but the changing trends of these two variables are often contradictory. In this study, a novel optimization method based on a multi-objective genetic algorithm is introduced, the first attempt to optimize a beamline with multiple objectives. In order to verify this method, beamline ID17 of the European Synchrotron Radiation Facility (ESRF) is taken as an example for simulation, with energy and dose rate as objectives. The result shows that this method can be effective for beamline optimization, and an optimal solution set can be obtained within 30 generations. For the solutions whose objectives are both improved compared with those of ESRF beamline ID17, the maximums of energy and dose rate increase by around 7% and 20%, respectively.

Enhanced-spatial-resolution optical surface profiler based on focusing deflectometry.

Deflectometric slope profiler is an essential technique for accessing the surface metrology of mirrors used in synchrotron radiation beamlines. To increase the upper spatial frequency bandwidth limits of deflectometric slope profiler, reducing the beam spot size on the mirrors is necessary. In this paper, we introduce a profiler system: the focusing long trace profiler (FLTP). It contains a newly developed optical head capable of raising upper spatial frequency bandwidth limits by using a focused beam instead of a collimated beam to scan the sample. This feature has been proven in a numerical simulation experiment, where a spatial resolution of up to around 0.05 mm was reached when the sample is set at focus plane. The system is implemented and characterized in several experiments; calibration of the focusing optical head shows that it can achieve a high angular accuracy of sub-50 nrad root-mean-square (rms) and defocusing of sample under test (SUT) has no effect on the measurement results; the measurement tests also demonstrate the system's advantage in highly curved mirror profile metrology.

Design of nano-spintronics beamline at 3-GeV next-generation synchrotron radiation facility, NanoTerasu

A synchrotron radiation beamline in the soft- and tender-X ray energy range of 180-3000 eV with versatile polarization control has been designed for NanoTerasu, the 3-GeV next-generation synchrotron radiation facility at Tohoku, Japan. A series of four APPLE-II type undulators is adopted as a photon source to realize the required beam properties with high-speed polarization switching. The beamline optics is designed for a highly efficient and precise use of x-ray magnetic circular/linear dichroism (XMCD/XMLD) technique balancing high photon flux and energy resolution. The simulated performance of the segmented undulator together with the monochromator optics achieved the sufficiently high flux and energy resolution (E/ΔE) in whole target energy range. Two endstations with the different re-focus optics, one for marginal spot size with high flux and the other for ultimate focus down to ∼10 nm are also designed. The simulated performance of the beamline encourages the future researches of high-throughput and nm-focused spintronic measurements.

Advanced optical simulation tools in the OASYS suite and their applications to the design of last generation synchrotron radiation beamlines

Since 2013, OASYS (OrAnge SYnchrotron Suite) has been developed as a versatile, user-friendly and open-source graphical environment for modeling X-ray sources, optical systems, and experiments. Its concept stems from the need for modern software tools to satisfy the demand for performing more complex analyses and designing optical systems for 4th generation synchrotron radiation and FEL facilities. The ultimate purpose of OASYS is to integrate in a synergetic way the most powerful calculation engines available to perform virtual experiments in a synchrotron beamline. For X-ray Optics, OASYS integrates different simulation strategies by implementing adequate simulation tools, which communicate by sending and receiving encapsulated data. The OASYS suite has been extensively used in the optical design process for the upgrade projects of several synchrotron radiation facilities worldwide. Several new tools have been created to perform advanced calculations needed for the design of the beamlines and provide accurate specifications for the procurement of the optics.

Automatic transmission optimization of the plane-grating monochromator using collimated light

It is essential to perform plane-grating monochromator transmission optimization for synchrotron radiation beamlines. Usually, The optimization is time-consuming. In this contribution, an automatic transmission optimization method for the plane-grating monochromator using collimated light based on the Differential Evolution (DE) algorithm is introduced. This method can quickly find the optimal solution. To test this method, a program developed using C++ is verified by optimizing the efficiency of a plane-grating monochromator with a 2000 lines/mm lamellar grating at soft X-ray region. Furthermore, the transmission optimizations of most of the PGM using lamellar gratings in soft x-ray region are performed.

A hybrid pixel detector with 4D information for dynamic synchrotron radiation applications

TETPIX is a hybrid pixel detector designed for dynamic synchrotron radiation applications. It is based on hit-driven readout scheme. 4D information of every incoming photon, including 2D position, timing, and energy, can be detected at the same time. The chip consists of a 64 × 32 pixel array with a pixel size of 150 μm × 150 μm. A module system is designed with a sensitive area of 2 cm × 2 cm, and tested at synchrotron radiation beamlines. The results show an energy resolution better than 16% over a range of 10–15 keV, and a capability of fine timing structure detection.

Beamline simulations using monochromators with high d-spacing crystals.

Monochromators for synchrotron radiation beamlines typically use perfect crystals for the hard X-ray regime and gratings for soft X-rays. There is an intermediate range, typically 1-3 keV (tender X-rays), which common perfect crystals have difficulties covering and gratings have low efficiency, although some less common crystals with high d-spacing could be suitable. To evaluate the suitability of these crystals for a particular beamline, it is useful to evaluate the crystals' performance using tools such as ray-tracing. However, simulations for double-crystal monochromators are only available for the most used crystals such as Si, Ge or diamond. Here, an upgrade of the SHADOW ray-tracing code and complementary tools in the OASYS suite are presented to simulate high d-spacing crystals with arbitrary, and sometimes complex, structures such as beryl, YB66, muscovite, etc. Isotropic and anisotropic temperature factors are also considered. The YB66 crystal with 1936 atomic sites in the unit cell is simulated, and its applicability for tender X-ray monochromators is discussed in the context of new low-emittance storage rings.

In situ study of the preoxidation of polyacrylonitrile fibers

In the production of polyacrylonitrile-based carbon fibers (PAN-CFs), preoxidation is a key step to improving the thermal stability of the fibers and forming their structural prototype. However, structural evaluation of PAN fibers during preoxidation remains ambiguous, partly due to a lack of in situ studies. This contribution reports an in situ study of the preoxidation of PAN fibers using wide-angle X-ray scattering and small-angle X-ray scattering techniques on a synchrotron radiation beamline. The structural changes of the skeleton and pores in the fibers are revealed and correspond to five kinds of diffraction spots (peaks) and two kinds of scattering streaks, respectively. The preoxidation shows obvious stages, and the corresponding possible mechanism is analyzed.

Fast automated energy changes at synchrotron radiation beamlines equipped with transfocator or focusing mirrors.

Algorithms and procedures to fully automate retuning of synchrotron radiation beamlines over wide energy ranges are discussed. The discussion is based on the implementation at the National Institute of General Medical Sciences and the National Cancer Institute Structural Biology Facility at the Advanced Photon Source. When a user selects a new beamline energy, software synchronously controls the beamline monochromator and undulator to maintain the X-ray beam flux after the monochromator, preserves beam attenuation by determining a new set of attenuator foils, changes, as needed, mirror reflecting stripes and the undulator harmonic, preserves beam focal distance of compound refractive lens focusing by changing the In/Out combination of lenses in the transfocator, and, finally, restores beam position at the sample by on-the-fly scanning of either the Kirkpatrick-Baez mirror angles or the transfocator up/down and inboard/outboard positions. The sample is protected from radiation damage by automatically moving it out of the beam during the energy change and optimization.

A double crystal von Hamos spectrometer for traceable x-ray emission spectroscopy.

A novel double full-cylinder crystal x-ray spectrometer for x-ray emission spectroscopy (XES) has been realized based on a modified von Hamos geometry. The spectrometer is characterized by its compact dimensions, its versatility with respect to the number of crystals used in series in the detection path, and the option to perform calibrated XES measurements. The full-cylinder crystals used are based on highly annealed pyrolytic graphite with a thickness of 40μm, which was bent to a radius of curvature of 50mm. The flexible designof the spectrometer allows for an easy change-within the same setup-between measurements with one crystal for maximized efficiency or two crystals for increased spectral resolving power. The spectrometer realized can be used at different end-stations of synchrotron radiation beamlines or can be laboratory-based. The main application focus of the spectrometer is the determination of x-ray fundamental atomic parameters in the photon energy range from 2.4 to 18keV. The evaluation of chemical speciation is also an area of application, as demonstrated in the example of battery electrodes using resonant inelastic x-ray scattering.