High-energy Synchrotron Radiation Research Articles

X-ray science using the ESRF—extremely brilliant source

The Extremely Brilliant Source (EBS), the first high-energy 4th-generation synchrotron radiation source, constructed at the ESRF and based upon the novel concept of a Hybrid Multi-Bend Achromat (HMBA), has started user operation on August 25th, 2020. We report here on selected recent scientific results exploiting the greatly improved performances of this novel X-ray source.

Enhanced particle acceleration in a pulsar wind interacting with a companion

Context. Pulsar winds have been shown to be preferred sites of particle acceleration and high-energy radiation. Numerous studies have been conducted to better characterize the general structure of such relativistic plasmas in isolated systems. However, many pulsars are found in binary systems and there are currently no ab initio models available that would include both the pulsar magnetosphere and the wind of the pulsar in interaction with a spherical companion. Aims. We investigate the interaction between a pulsar wind and a companion to probe the rearrangement of the pulsar wind, assess whether it leads to an enhancement of particle acceleration, and predict the high-energy radiative signature that stems from this interaction. We consider the regime where the companion is small enough to hold between two successive stripes of the wind. Methods. We performed two-dimensional (2D) equatorial particle-in-cell simulations of an inclined pulsar surrounded by a spherical, unmagnetized, perfectly conducting companion settled in its wind. Different runs correspond to different distances and sizes of the companion. Results. We find that the presence of the companion significantly alters the structure of the wind. When the companion lies beyond the fast magnetosonic point, a shock is established and the perturbations are advected in a cone behind the companion. We observe an enhancement of particle acceleration due to forced reconnection as the current sheet reaches the companion surface. Hence, high-energy synchrotron radiation is also amplified. The orbital light curves display two broad peaks reaching up to 14 times the high-energy pulsed flux emitted by an isolated pulsar magnetosphere. These effects increase with the growth of the companion size and with the decrease of the pulsar-companion separation. Conclusions. The present study suggests that a pulsar wind interacting with a companion induces a significant enhancement of high-energy radiation that takes the form of an orbital-modulated hollow cone of emission, which should be detectable by galactic-plane surveys, possibly with long-period radio transient counterparts.

Scattered high-energy synchrotron radiation at theKARA visible-light diagnostic beamline.

To characterize an electron beam, visible synchrotron light is often used and dedicated beamlines at synchrotron sources are becoming a more common feature as instruments and methods for the diagnostics are, along with the accelerators, further developed. At KARA (Karlsruhe Research Accelerator), such a beamline exists and is based on a typical infrared/visible-light configuration. From experience at such beamlines no significant radiation was expected (dose rates larger than 0.5 µSv h-1). This was found not to be the case and a higher dose was measured which fortunately could be shielded to an acceptable level with 0.3 mm of aluminium foil or 2.0 mm of Pyrex glass. The presence of this radiation led to further investigation by both experiment and calculation. A custom setup using a silicon drift detector for energy-dispersive spectroscopy (Ketek GmbH) and attenuation experiments showed the radiation to be predominantly copper K-shell fluorescence and is confirmed by calculation. The measurement of secondary radiation from scattering of synchrotron and other radiation, and its calculation, is important for radiation protection, and, although a lot of experience exists and methods for radiation protection are well established, changes in machine, beamlines and experiments mean a constant appraisal is needed.

Multi-scale investigation of microstructure and texture evolution during equal channel angular pressing of silver

A multi-scale investigation was carried out on pure silver subjected to equal channel angular pressing up to 3 passes. Microstructure and texture were examined using scanning and transmission electron microscopy as well as diffraction of neutron and high-energy synchrotron radiation. The evolution of the deformation substructure in the material is in accordance with its low stacking fault energy followed by restoration mechanisms leading to overall microstructural refinement. The restoration mechanism sets in as early as after 3 passes. Twinning involved in the deformation process supports grain refinement through mechanisms of dynamic recrystallization involving strain-induced boundary migration contributing to a steady-state grain size. The global texture, as measured by neutron diffraction, forms through a twin-assisted deformation mechanism. The texture is found heterogeneous through thickness.Graphical abstract

Influence of Manganese Content on Martensitic Transformation of Cu-Al-Mn-Ag Alloy.

The influence of manganese content on the formation of martensite structure and the final properties of a quaternary Cu-Al-Mn-Ag shape memory alloy (SMA) was investigated. Two alloys with designed compositions, Cu- 9%wt. Al- 16%wt. Mn- 2%wt. Ag and Cu- 9%wt. Al- 7%wt. Mn- 2%wt. Ag, were prepared in an electric arc furnace by melting of high-purity metals. As-cast and quenched microstructures were determined by optical microscopy and scanning electron microscopy equipped with EDS. Phases were confirmed by high-energy synchrotron radiation and electron backscatter diffractions. Austenite and martensite transformations were followed by differential scanning calorimetry and hardness was determined using the Vickers hardness test. It was found that the addition of silver contributes to the formation of the martensite structure in the Cu-Al-Mn-SMA. In the alloy with 7%wt. of manganese, stable martensite is formed even in the as-cast state without additional heat treatment, while the alloy with 16%wt. of manganese martensite transforms only after thermal stabilization and quenching. Two types of martensite, β1' and γ1', are confirmed in the Cu-9Al-7Mn-2Ag specimen. The as-cast SMA with 7%wt. Mn showed significantly lower martensite transformation temperatures, Ms and Mf, in relation to the quenched alloy. With increasing manganese content, the Ms and Mf temperatures are shifted to higher values and the microhardness is lower.

High-energy synchrotron flares powered by strongly radiative relativistic magnetic reconnection: 2D and 3D PIC simulations

ABSTRACT The time evolution of high-energy synchrotron radiation generated in a relativistic pair plasma energized by reconnection of strong magnetic fields is investigated with 2D and 3D particle-in-cell (PIC) simulations. The simulations in this 2D/3D comparison study are conducted with the radiative PIC code OSIRIS, which self-consistently accounts for the synchrotron radiation reaction on the emitting particles, and enables us to explore the effects of synchrotron cooling. Magnetic reconnection causes compression of the plasma and magnetic field deep inside magnetic islands (plasmoids), leading to an enhancement of the flaring emission, which may help explain some astrophysical gamma-ray flare observations. Although radiative cooling weakens the emission from plasmoid cores, it facilitates additional compression there, further amplifying the magnetic field B and plasma density n, and thus partially mitigating this effect. Novel simulation diagnostics utilizing 2D histograms in the n-B space are developed and used to visualize and quantify the effects of compression. The n-B histograms are observed to be bounded by relatively sharp power-law boundaries marking clear limits on compression. Theoretical explanations for some of these compression limits are developed, rooted in radiative resistivity or 3D kinking instabilities. Systematic parameter-space studies with respect to guide magnetic field, system size, and upstream magnetization are conducted and suggest that stronger compression, brighter high-energy radiation, and perhaps significant quantum electrodynamic effects such as pair production, may occur in environments with larger reconnection-region sizes and higher magnetization, particularly when magnetic field strengths approach the critical (Schwinger) field, as found in magnetar magnetospheres.

A reactor for time-resolved X-ray studies of nucleation and growth during solvothermal synthesis.

Understanding the nucleation and growth mechanisms of nanocrystals under hydro- and solvothermal conditions is key to tailoring functional nanomaterials. High-energy and high-flux synchrotron radiation is ideal for characterization by powder X-ray diffraction and X-ray total scattering in real time. Different versions of batch-type cell reactors have been employed in this work, exploiting the robustness of polyimide-coated fused quartz tubes with an inner diameter of 0.7 mm, as they can withstand pressures up to 250 bar and temperatures up to 723 K for several hours. Reported here are recent developments of the in situ setups available for general users on the P21.1 beamline at PETRA III and the DanMAX beamline at MAX IV to study nucleation and growth phenomena in solvothermal synthesis. It is shown that data suitable for both reciprocal-space Rietveld refinement and direct-space pair distribution function refinement can be obtained on a timescale of 4 ms.

Piezoelectric Actuation Mechanism Involving Extrinsic Nanodomain Dynamics in Lead-Free Piezoelectrics.

Piezoelectric materials play a key role in applications, while there are physically open questions. The physical origin of piezoelectricity is understood as the sum of contributions from intrinsic effects on lattice dynamics and those from extrinsic effects on ferroic-domain dynamics, but there is an incomplete understanding that all but intrinsic effects are classified as extrinsic effects. Therefore, the accurate classification of extrinsic effects is important for understandingthe physical origin of piezoelectricity. In this work, high-energy synchrotron radiation X-ray diffraction is utilized to measure the response of BiFeO3 -BaTiO3 piezoelectrics and the intrinsic/extrinsic contribution to electric fields. It is found from crystal structure and intrinsic/extrinsic contribution, using the analysis involving structure refinement with various structural model and micromechanics-based calculations, that Bi3+ -ion disordering is important for realization of piezoelectricity and nanodomains. Here, an extrinsic effect on the rearrangement of nanodomains is suggested. The nanodomains, which are formed by the locally distorted structure around the A-site by Bi-ion disordering, can significantly deform the material in the BiFeO3 -BaTiO3 system, which contributes to the piezoelectric actuation mechanism apart from the extrinsic effect on ferroic-domain dynamics. Bi-ion disordering plays an important role in realizing piezoelectricity and nanodomains and can provide essential material design clues to develop next-generation Bi-based lead-free piezoelectric ceramics.

XIDER: a novel X-ray detector for the next generation of high-energy synchrotron radiation sources

Next-generation sources of synchrotron radiation pose significant challenges for 2D pixelated X-ray detectors, such as at the ESRF Extremely Brilliant Source (EBS), the first fourth-generation high-energy synchrotron facility. In particular, scattering and diffraction experiments require fast detectors with a high dynamic range, from single photon sensitivity to pile-up conditions under very high photon fluxes. Furthermore, in the case of high-energy applications, the high-Z sensor materials needed for efficient photon detection introduce other difficulties. Leakage current, bias- and flux-induced polarisation, and afterglow all must be carefully managed for the detector system to reach the required specifications. The XIDER project aims to fulfil the needs of the above-mentioned applications by implementing a novel incremental digital integration readout scheme. XIDER detectors seek to operate efficiently under the high-flux EBS beam of up to 100 keV photons, with a time resolution that can cope with near-continuous and pulsed beams. Simultaneously, non-constant leakage current contributions can be removed for noise-free single photon detection, resulting in a very high dynamic range. This contribution presents the recent developments of the XIDER project, including the first characterisation measurements with cadmium telluride sensors.

Phase Transformation Induced by High Pressure Torsion in the High-Entropy Alloy CrMnFeCoNi.

The forward and reverse phase transformation from face-centered cubic (fcc) to hexagonal close-packed (hcp) in the equiatomic high-entropy alloy (HEA) CrMnFeCoNi has been investigated with diffraction of high-energy synchrotron radiation. The forward transformation has been induced by high pressure torsion at room and liquid nitrogen temperature by applying different hydrostatic pressures and large shear strains. The volume fraction of hcp phase has been determined by Rietveld analysis after pressure release and heating-up to room temperature as a function of hydrostatic pressure. It increases with pressure and decreasing temperature. Depending on temperature, a certain pressure is necessary to induce the phase transformation. In addition, the onset pressure depends on hydrostaticity; it is lowered by shear stresses. The reverse transformation evolves over a long period of time at ambient conditions due to the destabilization of the hcp phase. The effect of the phase transformation on the microstructure and texture development and corresponding microhardness of the HEA at room temperature is demonstrated. The phase transformation leads to an inhomogeneous microstructure, weakening of the shear texture, and a surprising hardness anomaly. Reasons for the hardness anomaly are discussed in detail.

In-situ study of tensile deformation behaviour of medium Mn TWIP/TRIP steel using synchrotron radiation

This investigation proposes a pathway for generating optimum microstructure for a medium Mn containing twinning-induced plasticity/transformation-induced plasticity (TWIP/TRIP) steels. The steel contains a two-phase microstructure consisting of austenite and ferrite phase arranged in a lamellar fashion. The microstructure was developed following a specially designed thermo-mechanical processing schedule that involved quenching and partitioning. The feedback for the design of thermo-mechanical processing was obtained by carrying out in-situ deformation in high energy synchrotron radiation under tensile loading. Diffraction patterns were analysed for estimating the retained austenite phase fraction and other aspects of microstructural evolution. X-ray line profile analysis was performed to determine crystallite size, dislocation density, and twin density at individual stages of deformation. In the early stages, deformation occurs by dislocation slip in both phases, while in the later stages, deformation in the austenite phase occurs via twinning and martensitic transformation, and in the ferrite phase by dislocation slip. Strain hardening behaviour has been analysed and correlated with microstructural parameters.

Effects of micro-alloying with lead for battery grid material

Pb-alloys are used as grid material for lead-acid batteries and have been implemented for years, and studying these Pb-alloys is critical to understanding the effects minor alloying additions on material characteristics. The current objective of this research is to evaluate the effects of minor alloying additions of Sb, As, Ca, Sn, Al, In, and Bi in Pb-alloy grid material during thermal cycling. In this study, Pb-grid material alloyed with a combination of elements mentioned above are examined using high-energy Synchrotron radiation X-ray diffraction measurements during in situ thermal cycling from RT to 75 °C to analyze grain inhibition and potential phase evolution. In addition, sulfation studies are performed in a solution of approximately 0.5 M H2SO4 and the Pb-alloys are added to an electrochemical cell to undergo cyclic voltammetry. Results show In mitigates grain growth, and, during electrochemical testing, increases passivation of Pb-alloys. Bi causes increased grain growth during thermal cycling and promotes sulfate formation. Ca refines and stabilizes grains during thermal cycling and increases corrosion resistance during cyclic voltammetry testing. Sn and Al attribute to texturing in the material and increase corrosion rates.

Operando reaction cell for high energy surface sensitive x-ray diffraction and reflectometry.

A proof of concept is shown for the design of a high pressure heterogeneous catalysis reaction cell suitable for surface sensitive x-ray diffraction and x-ray reflectometry over planar samples using high energy synchrotron radiation in combination with mass spectrometry. This design enables measurements in a pressure range from several tens to hundreds of bars for surface investigations under realistic industrial conditions in heterogeneous catalysis or gaseous corrosion studies.

The effect of Ni or Co additions on the structure of Zr60Cu30Al10 bulk metallic glass revealed by high-energy synchrotron radiation

The effect of substituting Cu by elemental additions of Ni or Co on the atomic structure of the Zr60Cu30Al10 ternary bulk metallic glass (BMG) is studied using high-energy synchrotron radiation X-ray diffraction. Analyses of the structural features in reciprocal and real space using the structure factors S(Q) and pair-distribution functions (PDF) point to an increase in the structural disorder for the Ni- or Co-bearing quaternary alloys. This is consistent with the “confusion principle” since upon alloying the initially nearly identical atomic sizes of Cu, Ni and Co diversify due to local electronic interactions. In real space, the disordering is manifested by a reduced deviation from the average particle density visible in the nearest-neighbour (NN) atomic shell structure over the complete short- and medium-range order region. Despite their similar atomic size, enthalpies of mixing with the main alloy elements and apparent disordering of the structure, the additions of Ni or Co have different effects on thermal stability of the ternary “mother” alloy.

In-situ investigation of strain relaxation in an Al/Si–MMC using high energy synchrotron radiation

AbstractThermal and mechanical loading induce phase specific strains/stresses in MMCs. At elevated temperature part of the phase-specific strains/stresses relax. The relaxation of the phase-specific strains/stresses is determined by in-situ experiments using white high-energy synchrotron radiation. The experiments reveal that such time-resolved strain measurements are possible and that short-time phenomena can be accessed using white high-energy synchrotron radiation. The elastic strain relaxation behavior is similar for all lattice planes accessed. The influence of the temperature on the characteristic relaxation time is determined. The characteristic relaxation time appears to be independent of the amount of plastic deformation the sample suffers before strain/stress relaxation.

Temperature dependence of lattice mismatch and γ′ volume fraction of a fourth-generation monocrystalline nickel-based superalloy

AbstractThe strain distribution in a new generation nickel-based single crystal superalloy has been determined in the temperature range 293 K– 1598 K. Measurements have been performed using diffraction of high energy synchrotron radiation (150 keV,λ= 0.008 nm) to determine the variations with temperature of the γ/γ′ lattice mismatch and of the γ′ volume fraction. The chemical segregation at the dendrite scale and the internal stress induce a large range of values for the lattice mismatch. The measurements of the γ′ volume fraction determined by X-ray diffraction are in agreement with those obtained by atom probe tomography, image analysis or computation.

Theoretical analysis and experimental evaluation of vibration isolation system with broadband characteristic for laser tracker

High-energy synchrotron radiation source, as a large scientific device, is under construction in Beijing, China. This device is one of the fourth-generation synchrotron radiation sources with the highest brightness in the world. It will provide an important support platform for basic science and engineering science. As a kind of high-precision large-scale measurement equipment, laser tracker is used mainly in high-energy particle accelerator equipment installation, precision poses dynamic measurement and antenna feed dynamic motion precision engineering measurement field. At the construction site of high energy synchrotron radiation source, the laser tracker is often used to calibrate and pre-collimate the high energy source magnet equipment and carry on the tunnel measurement . However, the laser tracker is easily affected by the vibration of the surrounding environment, and the adverse vibration seriously affects its measurement accuracy and even causes the equipment to damage. In order to effectively control the influence of environmental vibration and ensure good static bearing capacity, a broadband vibration isolator for laser tracker is proposed. It is installed in the leg position of the triangular bracket of the laser tracker, which ensures the vibration isolation performance and good bearing capacity. For the above system, the equivalent single freedom nonlinear dynamic differential equation is established, and the steady-state response solution of the broadband isolator is obtained by using the complex variable-average method. The numerical finite element method is used to verify the correctness of the theoretical model and corresponding calculation results. On this basis, the stability of a nonlinear system is analyzed by harmonic balance method, and the influence of key designing parameter <i>K</i><sub>3</sub> on vibration isolation performance is considered. Combined with the complexity of the actual working environment of laser tracker, a variety of typical working conditions are set up for test, including long time static pressure test, vertical impact excitation and lateral displacement excitation tests, to evaluate the static stability and vibration control effect of broadband isolator. The experimental results show that the maximum static displacement of the laser tracker is about 2×10<sup>–5</sup> m under static pressure in a long time, and the maximum static load is within the allowable error range. When the occasional impacting is triggered, the installation of broadband isolator can make the combination quickly restore stability in about 2.95 s, exhibiting better vibration isolation performance. Under different dynamic loads, by comparing the acceleration frequency response curves of the laser tracker with and without the isolator, in the frequency band below the fundamental frequency of the laser tracker, the attenuation rate of the combined system can be up to about 97% with and without the vibration isolator. In the frequency band above the fundamental frequency, the attenuation rate of the combined system with and without the vibration isolation system can reach up to about 88%, and the effective vibration isolation frequency band is extended. The broadband vibration isolator meets all technical requirements.

Stress Mapping on Ultrahigh Strength Steel Cut Edges

Cutting operations is one point in the process route from steel plate to finished product that may introduce stress that can be detrimental at later stages of the product’s life. With the realization of high energy X-ray sources, with deep penetration and a small probe, there is the possibility of high resolution mapping of introduced stresses from metal cutting. In this work, article number 2001168, Fredrik Lindberg and co-worker have used high energy synchrotron radiation of beamline P21.2 at PETRA III to map stresses in an ultra-high strength steel material.

Novel characterization of lead-based micro-alloys for battery applications

Although Pb-alloy acid batteries have been incorporated in vehicles for decades, a significant gap exists in the scientific understanding of minor alloying elements in the complex Pb-alloy grid materials. The aim of this research is to close this gap by using modern analytical techniques to examine the effects associated with adding minor alloying elements, less than 100 ppm, in Pb-alloy grid materials during isothermal holds and thermal cycling at relatively high temperatures. In this study, pure Pb, Pb-Bi, and Pb-Ba foils are examined using high-energy synchrotron radiation X-ray diffraction measurements during in situ isothermal holding at 85 °C and thermal cycling from RT to 85°C to analyze the grain inhibition and phase evolution. It is observed that Ba inhibits grain growth while Bi does not, when compared to pure Pb. Furthermore, no obvious phase evolution in any of the three cases is observed. After the synchrotron radiation X-ray diffraction measurements, the three materials are examined ex situ using scanning electron microscopy to verify the results. Additionally, baseline sulfation studies were performed in a solution of approximately 5 M H2SO4 and Pb-Bi and Pb-Ba were added to the electrochemical cell to undergo cyclic voltammetry.

Shape memory effect in metallic glasses

Shape memory effect in metallic glasses