High-energy Synchrotron Radiation Source Research Articles

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.

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.

Thermal decomposition of Yttrium 2-methylbutyrate in argon

The thermal decomposition of yttrium 2-methylbutyrate (Y(C4H9CO2)3) under argon gas flow has been investigated by means of simultaneous thermogravimetry and differential thermal analysis, FTIR-spectroscopy (solid residue and evolved gas analysis), mass spectrometry, hot-stage optical microscopy and X-ray diffraction with a standard laboratory Cu-tube source as well as with a high-energy synchrotron radiation source. At least one structural transition occurs in the solid state between 100 °C and 160 °C. The decomposition of the Y 2-methylbutyrate salt takes place above 400 °C. A first stage results in the formation of Y2O2CO3 between 400 °C and 490 °C. This decomposition step is accompanied by the release of CO2, a symmetrical ketone (3,5-dimethyl-4-heptanone), as well as probably a terminal alkyne, which could not be unambiguously identified. At higher temperature, Y2O2CO3 is slowly converted to Y2O3 with release of CO2, while some carbonaceous residue is eliminated via combustion. The TG trace reaches the final plateau at about 1200 °C.

Design of control algorithm for accelerator magnet power supply with large time constant load

High Energy Photon Source-Test Facility (HEPS-TF) is a pre-research project for the construction of high energy synchrotron radiation source in the 12th five-year plan period. The purpose is to research the key technology and develop the key equipment of high energy synchrotron radiation source. Superconducting 3W1 magnet is the first self-developed superconducting wiggler magnet in China, and it is also one of the key research topics of HEPS. The author has completed a new digital closed-loop control algorithm for the superconducting 3W1 magnet with large load time constant and the nonlinear characteristics of inductance increasing with current, namely three-branch structure algorithm. In the face of the rapid development of high energy accelerator technology, the application of intelligent technology has become an inevitable development trend in the field of accelerator magnet power supply technology. Although the digital control of accelerator magnet power supply has been widely used, it is the first time to apply the new closed-loop control algorithm to realize fast adjustment and precision tracking in accelerator superconducting magnet power supply in China. According to the nonlinear characteristics of inductance and output current of superconducting magnet, a new digital closed-loop control algorithm for the load of superconducting magnet power supply with large time constant is proposed. This algorithm is quite different from the traditional algorithm and can attain the independent tracking and adjustment of the control target. Finally, by testing the ripple, error and stability of superconducting 3W1 magnet power supply, the correctness, practicability and reliability of power supply system as well as the digital control algorithm are verified. The results provide a new idea for the control of accelerator magnet power supply.

Using X-Ray Microtomography for Characterisation of Catalyst Particle Pore Structure

The use of a high-energy synchrotron radiation source has permitted the introduction of high-resolution X-ray microtomography imaging as a method of non-intrusive and non-destructive three-dimensional (3D)visualized characterization of porous media. The use of a combination of X-ray microtomography, along with mercury porosimetry and Low Melting Point Alloy (LMPA) intrusion potentially provides a more complete approach to more accurate catalyst pore structure characterisation and modelling. This combined approach has been applied to the study of an industrial alumina catalysts support. The data collected from the study has been used to develop and generate an improved pore network model basis, in which both heterogeneity and hierarchy are considered in obtaining an improved pore architecture and pore size distribution.

コンプトン散乱を用いた重元素結晶のフェルミ面マッピング

We report on the Fermi surface mapping of heavy element crystals using Compton scattering, which has been possible by the recent advent of intense high energy synchrotron radiation sources. Fermi surface mapping provides us insights for long range distortions or charge density waves in crystals. Two examples are shown : The first one is Fermi surface mapping of the η-Mo4O11 low-dimensional conductor. A clear nesting vector is observed in the Fermi surfaces that have experimentally been obtained. The second example is Fermi surface study of Ba1-xKxBiO3. A clear feature of the Fermi surface nesting is observed across the transition between the distorted (insulating) and non-distorted (metallic) phases.

Observation of Broadband Self-Amplified Spontaneous Coherent Terahertz Synchrotron Radiation in a Storage Ring

Bursts of coherent synchrotron radiation at far-infrared and millimeter wavelengths have been observed at several storage rings. A microbunching instability has been proposed as the source for the bursts. However, the microbunching mechanism has yet to be elucidated. We provide the first evidence that the bursts are due to a microbunching instability driven by the emission of synchrotron radiation in the bunch. Observations made at the Advanced Light Source are consistent with the values predicted by the proposed microbunching model. These results demonstrate a new instability regime for high energy synchrotron radiation sources and could impact the design of future sources.

In situ studies of electrodic materials in Li-ion cells upon cycling performed by very-high-energy x-ray diffraction

A very high-energy synchrotron radiation source (87 keV) was utilized for in situ sampling of the structural changes occurring in the electrodic materials of a Li-ion cell during charge–discharge cycling. The real-time evolution of their crystal lattice was obtained as a function of the degree of Li intercalation. As a result, new information on two electrodic materials, Li–Ti “zero strain” and Li–Ni–Co oxide, both of extreme interest for generation of rechargeable batteries, was gained. The actual change of the Li–Ti oxide lattice parameter upon cycling was observed in greater detail than before, and provided evidence of unexpected behavior in some intervals of the cycle. In the Li–Ni–Co sample, a new phase formed during the early stages of cycling that remained stable in the subsequent cycles was revealed.

In situ surface X-ray diffraction using a new electrochemical cell optimised for third generation synchrotron light sources

Thanks to the new third-generation high energy synchrotron radiation sources it is now possible to study electrochemical interfaces in situ using a cell fulfilling all the electrochemistry requirements. We are presenting here one version of this cell type, especially designed for surface X-ray diffraction. Its geometry allows in and out of plane data collection with the voltammetry fully controlled at any time. Fresh results concerning the gold (1 1 1) surface evolution in diluted H 2SO 4 electrolyte are presented. Finally, the perspectives opened by this in situ studies are discussed.

X-ray Optics Developments at the APS for the Third Generation of High-Energy Synchrotron Radiation Sources

Third-generation hard-X-ray synchrotron radiation sources simultaneously provide both a need and an opportunity for the development of new short-wavelength optical components. The high power and power densities of the insertion-device-produced X-ray beams have forced researchers to consider what may seem like exotic approaches, such as cryogenically cooled silicon and highly perfect diamond crystals, to mitigate thermal distortions in the first optical components. Once the power has been successfully filtered while maintaining the high beam brilliance, additional specialized optical components can be inserted into the monochromatic beam that take advantage of that brilliance. This paper reviews the performance of such optical components that have been designed, fabricated and tested at the Advanced Photon Source, starting with high-heat-load components and followed by examples of several specialized devices, such as an meV resolution (in-line) monochromator, a high-energy X-ray phase retarder and a phase-zone plate with submicrometer focusing capability.

Treatment of the heat-load—associated contrast in synchrotron radiation topography

We present a model which explains the heat-load-associated contrast in X-ray topographs, which can occur when using third-generation high-energy synchrotron radiation sources. The thermal deformation is treated in terms of an angular distortion σπ, which is a function of the absorbed power and the mechanical, thermal and diffraction properties of the sample. We obtain simple, criteria for the exposure time (and/or filtering of the beam) of a topographic experiment, to remain below an allowed maximum distortionδθ max. Experiments performed using either filters or a stroboscopic shutter confirm the validity of the present criteria.

High energy synchrotron radiation sources

In the world there are now about 43 laboratories in 16 countries engaged in the operation, construction or planning of electron storage rings, from a few hundred MeV to above 10 GeV, as sources of synchrotron radiation for basic and applied research. In this report we describe the new third generation high energy (i.e. hard X-ray) sources. The first of these, the 6 GeV European Synchrotron Radiation Facility (ESRF) in Grenoble, France started operation in mid 1992. The 7 GeV Advanced Photon Source (APS) at Argonne, USA and the 8 GeV Super Photon Ring (SPring-8) in Nishi Harima, Japan are expected to start operation for users around 1996–1998.

Energy-dispersive diffuse X-ray scattering technique. I. Principles

Energy-dispersive diffuse X-ray scattering is a particularly appropriate technique for use with high-energy synchrotron-radiation sources. Its multiplex and geometric advantages are outlined and the comparatively simple principles behind the technique are detailed. The energy-dispersive scan spreads scattering in reciprocal space along radial lines, with equal-energy steps corresponding to equal-scattering-vector steps. In a typical experimental configuration, the resolution function of the apparatus is substantially lozenge shaped in reciprocal space: modest resolution is obtained along radial lines whereas good resolution can be obtained in transverse directions if the limiting geometrical factors are kept narrow. The factors influencing the conversion of the observed scan intensities to absolute units are discussed and methods given of minimizing the difficulties. Paper II of this series will discuss the application of these methods, notably to measurements of silicon.

The APS X-ray undulator photon beam position monitor and tests at CHESS and NSLS

Abstract The advent of third generation synchrotron radiation sources, like the Advanced Photon Source (APS), will provide significant increases in brilliance over existing synchrotron sources. The APS X-ray undulators will increase the brilliance in the 3–40 keV range by several orders of magnitude. Thus, the design of the photon beam position monitor is a challenging engineering task. The beam position monitors must withstand the high thermal load, be able to achieve submicron spatial resolution while maintaining their stability, and be compatible with both undulators and wigglers. A preliminary APS prototype photon beam position monitor consisting of a CVD-diamond-based, tungsten-coated blade was tested on the APS/CHESS undulator at the Cornell High Energy Synchrotron Radiation Source (CHESS) and on the NSLS X-13 undulator beamline. Results from these tests, as well as the design of this prototype APS photon beam position monitor, will be discussed in this paper.

A high energy X-ray scattering beamline for the ESRF

High energy photon or gamma-ray scattering ( E > 100 keV) is a widely recognised technique in condensed matter physics which has specific advantages. For instance, when performing diffraction experiments the low absorption, the small Bragg angles and the small wavelengths substantially reduce or eliminate corrections for absorption, polarisation and extinction, and facilitate sample environment control. A major shortcoming of both elastic and Compton scattering using high energy photons is the relatively weak intensity produced by the nuclear gamma-ray sources which have mainly been used until now. The availability of bright high energy synchrotron radiation sources and the development of adequate X-ray optics will permit a gain of several orders of magnitude in flux and open up new experimental possibilities, for instance high Q scattering and studies of anharmonicities. While designed mainly for diffraction experiments, the instrument recently proposed for the European Synchrotron Radiation Facility in Grenoble also provides the possibility of Compton scattering studies [1].

Performance of the SRS vacuum system

At the Daresbury Laboratory of the Science and Engineering Research Council is the SRS, the world's first dedicated high energy synchrotron radiation source. The SRS has been described elsewhere 1−3 and is essentially a 2 GeV electron storage ring of about 30 m diameter and designed for an ultimate beam current of 1 A. It is over seven years since commissioning of the SRS started, during which time nine out of a possible twelve beam lines have been built and scheduled experiments have been running for over six years. This paper will describe the general performance of the vacuum system and the specific experience gained on the performance of various types of vacuum pumps and gauges.

Status report of the Cornell high energy synchrotron radiation source (CHESS)

Status report of the Cornell high energy synchrotron radiation source (CHESS)