Third-generation Synchrotron Light Source Research Articles

High-Energy Coherent X-Ray Diffraction Microscopy of Polycrystal Grains: Steps Toward a Multiscale Approach

We present proof-of-concept imaging measurements of a polycrystalline material that integrate the elements of conventional high-energy X-ray diffraction microscopy with coherent diffraction imaging techniques, and that can enable in-situ strain-sensitive imaging of lattice structure in ensembles of deeply embedded crystals over five decades of length scale upon full realization. Such multi-scale imaging capabilities are critical to addressing important questions in a variety of research areas such as materials science and engineering, chemistry, and solid state physics. Towards this eventual goal, the following key aspects are demonstrated: 1) high-energy Bragg coherent diffraction imaging (HE-BCDI) of sub-micron-scale crystallites at 52 keV at current third-generation synchrotron light sources, 2) HE-BCDI performed in conjunction with far-field high-energy diffraction microscopy (ff-HEDM) on the grains of a polycrystalline sample in an smoothly integrated manner, and 3) the orientation information of an ensemble of grains obtained via ff-HEDM used to perform complementary HE-BCDI on multiple Bragg reflections of a single targeted grain. These steps lay the foundation for integration of HE-BCDI, which typically provides a spatial resolution tens of nanometers, into a broad suite of well-established HEDM methods, extending HEDM beyond the few-micrometer resolution bound and into the nanoscale, and positioning the approach to take full advantage of the orders-of-magnitude improvement of X-ray coherence expected at fourth generation light sources presently being built and commissioned worldwide.

An upgraded and integrated large-volume high-pressure facility at the GeoSoilEnviroCARS bending magnet beamline of the Advanced Photon Source

GeoSoilEnviroCARS (GSECARS) is an earth-science-driven X-ray synchrotron facility at the Advanced Photon Source of the Argonne National Laboratory. As a national user facility, we provide users with access to the high-brilliance hard X-rays from this third-generation synchrotron light source. The multi-anvil, large-volume high-pressure facility at the bending magnet beamline (13-BM-D) runs a unique setup permitting an unusually wide range of high-pressure and high-temperature experiments combined with X-rays and other in-situ probing techniques. It has been a great asset for the high-pressure earth science community since its inception in 1997. A series of upgrades and updates occurred in the 2010s. Here we provide a detailed description of the current large-volume press (LVP) setup at 13-BM-D, including hardware, software, and all experimental capabilities. Examples of scientific studies that were performed at GSECARS utilizing the new LVP system are also reported.

Development of an X-ray imaging system to preventscintillator degradation for white synchrotron radiation.

The high flux of the white X-ray beams from third-generation synchrotron light sources can significantly benefit the development of high-speed X-ray imaging, but can also bring technical challenges to existing X-ray imaging systems. One prevalent problem is that the image quality deteriorates because of dust particles accumulating on the scintillator screen during exposure to intense X-ray radiation. Here, this problem has been solved by embedding the scintillator in a flowing inert-gas environment. It is also shown that the detector maintains the quality of the captured images even after days of X-ray exposure. This modification is cost-efficient and easy to implement. Representative examples of applications using the X-ray imaging system are also provided, including fast tomography and multimodal phase-contrast imaging for biomedical and geological samples.

Latest developments at the ALBA magnetic measurements laboratory

ALBA is a third-generation synchrotron light source that has been in operation since 2012 near Barcelona. A magnetic measurements laboratory has been associated with the facility since its very early stages and has been active for the last 20 years. In the first part of this work, the different instruments available at the laboratory are described, and a brief overview of the measurement campaigns carried out during its 20 years of history is presented. In the second part, a more detailed description of the approach to Hall probe measurements adopted at ALBA is offered, with an explanation of the methods and ancillary equipment that have been developed along the years in order to improve the accuracy of the system. In the third part, a new concept of Hall probe bench devoted to the measurement of closed structures is presented. The in-house design and building of a prototype for such a bench is described, together with its mechanical and magnetic characterization. As a conclusion, the first results obtained with this bench are discussed.

Ground motion improvements in SPEAR3**Supported by US Department of Energy (DE-AC02-76SF00515) and the SULI program at SLAC National Laboratory

SPEAR3 is a third-generation synchrotron light source storage ring, about 234 meters in circumference. To meet the beam stability requirement, our goal is to ultimately achieve an orbit variation (relative to the photon beam lines) of less than 10% of the beam size, which is about 1 micron in the vertical plane. Hydrostatic leveling system (HLS) measurements show that the height of the SPEAR3 tunnel floor can vary by tens of microns daily without thermal insulation improvements. We present an analysis of the HLS data that shows that adding thermal insulation to the concrete walls of the storage ring tunnel dramatically decreased diurnal tunnel floor motion.

Control System Design and Implementation of In-Vacuum Undulators for Taiwan Photon Source

An insertion device (ID) is a crucial component in a third-generation synchrotron light source, which produces highly brilliant, forward-directed, and quasi-monochromatic radiation over a broad energy range. The Taiwan Photon Source (TPS) project involves building another synchrotron light source with increased electron energy. In phase I of TPS, seven in-vacuum undulators with magnetic period 22 mm (IU22) were installed; commissioning is in process. The control system for IU22 is based on an EPICS framework. The main control components include motors with encoders for gap adjustment, trimming power supplies for corrector magnets, ion pumps and Bayard-Alpert gauges for vacuum systems, temperature sensors for ID baking, and an interlock system (limit switches, emergency button) for safety. The design and implementation of the IU22 control system are summarized in this report.

VUV and X-ray free-electron lasers: The technology and its scientific promise

Currently available, fully coherent (laser) light sources emit radiation only in a limited range of wavelengths in the infrared, visible and near-ultraviolet range, excluding their use in all the measurements needing tunable photons of energy higher than a few eV. Consequentially, the strong scientific need for tunable, coherent radiation sources from the vacuum ultraviolet (VUV) to the X-ray in the femtosecond and picosecond time domain has spurred international research efforts to develop a new generation of research facilities. Laser-driven light sources that use non-linear processes to create very high harmonics and the interaction between an ultra-short laser pulse and an electron bunch in a storage ring are both able to produce radiation pulses in the femtosecond time domain and in the soft EUV and X-ray region, but with a relatively low useful photon flux on the sample. In contrast Free-Electron Lasers (FELs) can produce light pulses with peak brilliance as much as ten orders of magnitude higher than the pulses generated in present third-generation synchrotron light sources and with photon energies ranging from the VUV to the hard X-rays, i.e. from about 10eV (120nm) to 10keV (0.12nm). This manuscript reviews the scientific fields that can be opened or extended by the new techniques along with the progress of FEL physics and the supporting accelerator physics and technology.

Short X-ray pulses from third-generation light sources

High-brightness X-ray radiation produced by third-generation synchrotron light sources (TGLS) has been used for numerous time-resolved investigations in many different scientific fields. The typical time duration of X-ray pulses delivered by these large-scale machines is about 50-100 ps. A growing number of time-resolved studies would benefit from X-ray pulses with two or three orders of magnitude shorter duration. Here, techniques explored in the past for shorter X-ray pulse emission at TGLS are reviewed and the perspective towards the realisation of picosecond and sub-picosecond X-ray pulses are discussed.

In situsmall-angle X-ray scattering characterization of X-ray-induced local heating

It is shown that small-angle X-ray scattering from binary liquid mixtures close to the critical point of demixing can be used forin situcharacterization of beam-induced heating of liquid samples. For demonstration purposes, the proposed approach is applied on a well studied critical mixture of water and 2,6-lutidine. Given a typical incident X-ray flux at a third-generation synchrotron light source and using a 1.5 mm-diameter glass capillary as sample container, a beam-induced local temperature increase of 0.45 ± 0.10 K is observed.

First multi-bend achromat lattice consideration.

By the beginning of 1990, three third-generation synchrotron light sources had been successfully commissioned in Grenoble, Berkeley and Trieste (ESRF, ALS and ELETTRA). Each of these new machines reached their target specifications without any significant problems. In parallel, already at that time discussions were underway regarding the next generation, the `diffraction-limited light source (DLSR)', which featured sub-nm rad electron beam emittance, photon beam brilliance exceeding 10(22) and the potential to emit coherent radiation. Also, at about that time, a first design for a 3 GeV DLSR was developed, based on a modified multiple-bend achromat (MBA) design leading to a lattice with normalized emittance of ℇx = 0.5 nm rad. The novel feature of the MBA lattice was the use of seven vertically focusing bend magnets with different bending angles throughout the achromat cell to keep the radiation integrals and resulting beam emittance low. The baseline design called for a 400 m ring circumference with 12 straight sections of 6 m length. The dynamic aperture behaviour of the DLSR lattice was estimated to produce > 5 h beam lifetime at 100 mA stored beam current.

Photon-in/photon-out spectroscopic techniques for materials analysis: some recent developments.

Third-generation synchrotron light source technology has greatly improved the capabilities for materials analysis using tunable X-rays. Two such capabilities developed recently are reported herein - inverse partial fluorescence yield (IPFY) XANES (X-ray absorption near edge structure) and 2D XANES - XEOL (X-ray excited optical luminescence) in both the energy and time domain. These techniques take advantage of recent advances in soft X-ray solid state detector, optical spectrometer with a CCD detector and optical streak camera on a soft X-ray beamline as well as new data acquisition schemes. The studies of LiFePO4 materials for Li ion battery and solid solutions of GaN-ZnO nanostructures for water splitting are used to illustrate these capabilities. The prospects of these and related synchrotron photon-in photon-out techniques are also noted.

Thermal deformation of cryogenically cooled silicon crystals under intense X-ray beams: measurement and finite-element predictions of the surface shape

X-ray crystal monochromators exposed to white-beam X-rays in third-generation synchrotron light sources are subject to thermal deformations that must be minimized using an adequate cooling system. A new approach was used to measure the crystal shape profile and slope of several cryogenically cooled (liquid nitrogen) silicon monochromators as a function of beam power in situ and under heat load. The method utilizes multiple angular scans across the Bragg peak (rocking curve) at various vertical positions of a narrow-gap slit downstream from the monochromator. When increasing the beam power, the surface of the liquid-nitrogen-cooled silicon crystal deforms from a concave shape at low heat load to a convex shape at high heat load, passing through an approximately flat shape at intermediate heat load. Finite-element analysis is used to calculate the crystal thermal deformations. The simulated crystal profiles and slopes are in excellent agreement with experiments. The parameters used in simulations, such as material properties, absorbed power distribution on the crystal and cooling boundary conditions, are described in detail as they are fundamental for obtaining accurate results.

Versatile Modes of Operation to Meet User Needs at SOLEIL

SOLEIL, a 2.75 GeV third-generation synchrotron light source [1], is presently delivering photons to 24 beamlines for users in five different filling patterns with top-up injection. The 430 mA multibunch (with three successive quarters filled; i.e., 312 out of 416 bunches) is complemented with time-resolved (hybrid multibunch, eight bunches and single bunch) and 4-2 ps bunch-length low-alpha modes. Even shorter bunches will be available at the end of 2013 with the forthcoming Femto-slicing project. With the continuous improvements of transverse beam position (200 nm RMS in the vertical plane) and the understanding of collective effects, the beam current and the stability provided to the beamlines have been steadily increased. New exotic modes of operation and upgrades of the optics to reduce the 3.9 nm.rad horizontal emittance are being studied.

Low-α Operation of BESSY II and Future Plans for an Alternating Bunch Length Scheme BESSYVSR

Significant progress has been made in the last few years in short-bunch operation of third-generation synchrotron light sources, achieved by “lowα” optics for storage rings [1–4]. The term α is a machine optics parameter describing the particle orbit length L as a function of the particle momentum p, L = L0(1 + α(p − p0)/p0), with respect to the nominal values indicated by the index “0”. The “zero current” bunch length σ is then proportional to . Included here is the rf-voltage temporal gradient, V′ = dV/dt, which additionally influences the bunch length and will be required further. Thus, lowering α leads to a reduced bunch length all around the ring and radiation of the short bunches is supplied to all beamlines. These short bunches produce short X-ray pulses of equal length suitable for time-resolved measurements. Simultaneously, the short electron pulses emit intense, coherent THz radiation.

Calculation of the pressure in the unit-cell vacuum system of Taiwan Photon Source

Taiwan Photon Source is a third-generation 3-GeV synchrotron light source under construction. The electron storage ring of circumference 518.4 m contains 24 unit cells and 24 long straight sections. Each cell of length about 14 m contains two bending chambers and two short straight chambers. To estimate the pressure distribution in the cell vacuum system, a program combining an iterative method and a Monte-Carlo method was used to calculate the pressure. In the modeling, the rate of thermal outgassing of the chamber surfaces and the yield of photon-stimulated desorption of the absorbers are obtained from the experimental results. To provide the effective pumping speed of various pumps that depends on the gas, the composition of residual gases from photon-stimulated desorption was assumed to be 80% H2 and 20% CO. The pressure calculation for the vacuum cell compares the beam cleaning efficiency during the early commissioning stage when the accumulated beam dose attained 1 A h and 100 A h. The effects of the confined pumping design are evaluated through the modeling to assess whether the commissioning can be accelerated. The result of the pressure calculation obtained with the Monte-Carlo method shows that a mean pressure rise per beam current at 1.9 × 10−10 Pa mA−1 after beam cleaning to a beam dose 100 A h is reasonable and within typical specifications of the synchrotron light source.

Monolithic active pixel sensors for material science beam lines

The limiting factor to the exploitation of the huge photon flux produced by a third-generation synchrotron light source is very often the detector. Experiments in material science often exploit X-ray diffraction. A fast and efficient detection of diffraction patterns enables dynamic experiments. Monolithic active pixel sensors (MAPS) can be exploited effectively to build fast and efficient detectors for X-ray diffraction. For its material science beam lines Diamond Light Source is developing and evaluating detectors based on commercial MAPS and MAPS developed for scientific applications. The various projects, target performance and some experimental results are reported in this paper.

X-ray Intensity Fluctuation Spectroscopy Using Nanofocused Hard X-rays: Its Application to Study of Relaxor Ferroelectrics

The use of a combination of coherent X-rays from a third-generation synchrotron light source and ultraprecise Kirkpatrick-Baez mirrors enables us to apply nanofocused hard X-rays in solid-state physics. We developed an apparatus for X-ray intensity fluctuation spectroscopy using the nanofocused hard X-rays and applied it to the study of relaxor ferroelectrics. We have successfully detected a large and slow intensity fluctuation of scattered X-rays above cubic-to-tetragonal phase transition temperature with a characteristic time scale on the order of 10 s. We speculated that the intensity fluctuation originates from domain number fluctuation, which is directly related to the dielectric response, particularly the frequency dispersion.

Spatial resolution limits for synchrotron-based spectromicroscopy in the mid- and near-infrared

Spatial resolution tests were performed on beamline 1.4.4 at the Advanced Light Source in Berkeley, CA, USA, a third-generation synchrotron light source. This beamline couples the high-brightness synchrotron source to a Thermo-Electron Continumicrom XL infrared microscope. Two types of resolution tests were performed in both the mid-IR and near-IR. The results are compared with a diffraction-limited spot size theory. At shorter near-IR wavelengths the experimental results begin to deviate from diffraction-limited so a combined diffraction-limit and electron-beam-source-size model is employed. This description shows how the physical electron beam size of the synchrotron source begins to dominate the focused spot size at higher energies. The transition from diffraction-limited to electron-beam-size-limited performance is a function of storage-ring parameters and the optical demagnification within the beamline and microscope optics. The discussion includes how different facilities, beamlines and microscopes will affect the achievable spatial resolution. As synchrotron light sources and other next-generation accelerators such as energy-recovery LINACs and free-electron lasers achieve smaller beam emittances, beta-functions and/or energy spreads, diffraction-limited performance can continue to higher-energy beams, perhaps ultimately into the extreme ultraviolet.

Technical Report: Industrial Use of the SLS-MX Beamlines

The Swiss Light Source, located at the Paul Scherrer Institut, is a third-generation synchrotron light source characterized by its exceptional stability and continuous top-up mode of operation. With a storage ring energy of 2.4 GeV, it provides photon beams of high brightness for research in materials science, biology and chemistry.

A high-resolution angle-resolved photoemission spectrometer combined with laser molecular-beam epitaxy at SPring-8 BL17SU

We have constructed a high-resolution synchrotron-radiation photoemission spectrometer combined with a laser molecular-beam epitaxy (laser MBE) thin film growth system in order to investigate the electronic structure of oxide and nitride thin films. The system was installed at the newly built soft X-ray undulator beamline BL17SU of SPring-8. Total energy resolution of 102 meV was achieved at photon energy of 870 eV. The photoemission apparatus is connected to a laser MBE chamber through a preparation chamber. Single crystal thin-film samples fabricated by laser MBE can be transferred quickly into the photoemission chamber without breaking ultrahigh vacuum. Various new studies are possible using this system and third-generation soft X-ray synchrotron light source, such as direct observation of the bulk electronic band structure of single-crystal films with no cleavable plane, the interface electronic structure of oxide or nitride heterostructures, etc.