Fourth-generation Synchrotron Research Articles

Welding of Silicon to Invar for Application in Synchrotron Light Instrumentation

The Double Crystal Monochromator (DCM) will be developed at the Brazilian Synchrotron Light Laboratory (LNLS) to select the desired X-Ray wavelength of Sirius, the new Brazilian fourth generation synchrotron. Components of this optical instrumentation can be obtained through welding processes, such as brazing, soldering, and diffusion bonding. The use of vacuum welding technique ensures union of silicon with FeNi alloy, Invar36 (64Fe-36Ni) from Grupo Metal and Invar39 (61Fe-39Fe) from Scientific Alloys. Union of these materials was performed with filler alloys from Nihon Superior, such as ALCONANO (nanosilver paste), SnSb (95Sn-5Sb), Sn100C (Sn-0.7Cu-0.05Ni-0.01Ge), and Sn100CV (Sn-5Bi-0.8Cu-0.05Ni). Following welding tests, microstructural and metallographic analysis of the interface region between the materials involved are performed to investigate the junction among silicon, filler alloy, and base metal. Microstructural characterization carried out by a QUANTA SEM (Scanning Electron Microscope) with EDS (Energy Dispersive Spectroscopy) technique to identify the composition, distribution, and morphology of the phases. Based on these analyses, the best parameters were Invar39/Sn100CV/Si samples using base materials coated with different depositions: one gold and the other copper. In the mechanical test, the specimen with copper film presented higher shear strength.

Using sound pulses to solve the crystal-harvesting bottleneck.

Crystal harvesting has proven to be difficult to automate and remains the rate-limiting step for many structure-determination and high-throughput screening projects. This has resulted in crystals being prepared more rapidly than they can be harvested for X-ray data collection. Fourth-generation synchrotrons will support extraordinarily rapid rates of data acquisition, putting further pressure on the crystal-harvesting bottleneck. Here, a simple solution is reported in which crystals can be acoustically harvested from slightly modified MiTeGen In Situ-1 crystallization plates. This technique uses an acoustic pulse to eject each crystal out of its crystallization well, through a short air column and onto a micro-mesh (improving on previous work, which required separately grown crystals to be transferred before harvesting). Crystals can be individually harvested or can be serially combined with a chemical library such as a fragment library.

FlexED8: the first member of a fast and flexible sample-changer family for macromolecular crystallography.

Automated sample changers are now standard equipment for modern macromolecular crystallography synchrotron beamlines. Nevertheless, most are only compatible with a single type of sample holder and puck. Recent work aimed at reducing sample-handling efforts and crystal-alignment times at beamlines has resulted in a new generation of compact and precise sample holders for cryocrystallography: miniSPINE and NewPin [see the companion paper by Papp et al. (2017, Acta Cryst., D73, 829-840)]. With full data collection now possible within seconds at most advanced beamlines, and future fourth-generation synchrotron sources promising to extract data in a few tens of milliseconds, the time taken to mount and centre a sample is rate-limiting. In this context, a versatile and fast sample changer, FlexED8, has been developed that is compatible with the highly successful SPINE sample holder and with the miniSPINE and NewPin sample holders. Based on a six-axis industrial robot, FlexED8 is equipped with a tool changer and includes a novel open sample-storage dewar with a built-in ice-filtering system. With seven versatile puck slots, it can hold up to 112 SPINE sample holders in uni-pucks, or 252 miniSPINE or NewPin sample holders, with 36 samples per puck. Additionally, a double gripper, compatible with the SPINE sample holders and uni-pucks, allows a reduction in the sample-exchange time from 40 s, the typical time with a standard single gripper, to less than 5 s. Computer vision-based sample-transfer monitoring, sophisticated error handling and automatic error-recovery procedures ensure high reliability. The FlexED8 sample changer has been successfully tested under real conditions on a beamline.

Laser technology in Poland: 2013–2016

This paper presents the state of art of laser technologies in Poland. A list of primary laser technology development centers is included. The involvement of Polish scientists in the development of lasers and fourth generation synchrotron light sources as well as their applications is discussed. The development of laser applications in medical therapy and diagnostics, material micro- and macro-processing as well as environmental monitoring and protection, safety, and security is presented.

Planar PMMA X-ray compound refractive lenses with cascaded parabolic microstructures

X-ray compound refractive lenses (CRLs) have been successfully integrated into third- and fourth-generation synchrotron radiation sources. We have developed a new planar CRL architecture using cascaded parabolic microstructures constructed with polymethylmethacrylate. Two sets of CRL elements with different parabolic profile parameter values, radius of curvature R, and geometric aperture R0 were integrated. One half of the set had a large geometric aperture (R1=100μm and R01=141μm), while the other half of the set had a small radius of curvature (R2=50μm and R02=70μm). The cascaded parabolic CRLs (CP-CRLs) were tested for hard X-ray microfocusing in the BL15U1 beamline at the Shanghai Synchrotron Radiation Facility. Experimental results showed that the developed CP-CRLs achieved two-dimensional focusing of the incident X-ray beams. The measured focal length was 0.341 m, and the transmission was 10.12%. The measured horizontal and vertical full width half maxima of the focused X-ray spot were 9.78μm and 9.70μm, respectively. Thus, the experimental results obtained in this work confirmed the theoretical calculations of CP-CRL microfocusing performance.

China’s new light sources prove it’s serious about funding science

Government investment in basic scientific research leads to new products and stronger economic growth. Although this argument doesn’t work as well as it used to for scientists seeking public funding in Western countries and Japan, it still does wonders in China. There, funding for basic research is growing, largely on Beijing’s buy-in that it will be good for the economy. In Dalian, Chinese scientists unveiled earlier this month a new type of free-electron laser that generates extremely bright, short-wavelength light called vacuum ultraviolet. And in Beijing’s Huairou District, China is spending about $750 million on a state-of-the-art synchrotron that will help raise the country’s scientific capabilities and develop new products, Chinese scientists have told their government. Scheduled to start operating in 2023, the Huairou synchrotron will be a so-called fourth-generation low-emittance synchrotron with the ability to concentrate X-rays into the 10 nm range. The world’s first fourth-generation synchrotron started operating

Non-dipole effects in the angular distributions of photoelectrons on sodium-like ions

Photoionization processes widely exist in the astrophysical plasma and the high temperature laboratory plasma. Compared with the traditional photoelectron energy spectrum, the photoelectron angular distribution is not only related to the amplitude of the photoionization channels, but also sensitive to the phases of these channels. So the photoelectron angular distribution contains much more quantum information about the photoionization processes and is used to provide stringent tests of our understanding of basic physical processes underlying gas- and condensed-phase interaction with radiation, as well as a tool to probe physical and chemical structure in solids and surfaces. For a long time, the dipole approximation has been the basis in the study of the photoelectron angular distribution, but with the progress of light source, such as the fourth generation synchrotron facilities, more and more attention is paid to the non-dipole effect of the photoelectron angular distribution. In thispresent work, the photoionization processes of sodium-like ions (20Z92) are studied for the different incident photon energies based on the multiconfiguration Dirac-Fock method and the density matrix theory. The influences of the non-dipole terms on the photoelectron angular distributions, which arise from the multipole expansion of the electron-photon interaction, are discussed in detail. The relationship between the dipole and non-dipole parameters of the photoelectron angular distribution along with the atomic number is given. It is found that the influence of non-dipole terms on the photoelectron angular distribution is related to the incident photon energy and the atomic number of the target ion and the subshell of the ionized electron. In general, the influences of the non-dipole terms on the photoelectron angular distribution of p subshell are larger than those of the s subshell. In the electric dipole approximation, the s subshell photoelectron angular distribution is nearly independent of the photon energy and nuclear charge number, but this situation is not for the p subshell. With the increase of photon energy, an abnormal angular distribution is found for the p subshell photoelectron. However, if the non-dipole effects are included, the abnormal photoelectron angular distribution of p subshell disappears and the photoelectron distribution has maximum values respectively near 45o and 135o with respect to the polarization vector of incident light, that is, the photoelectron distribution has an obvious forward scattering characteristic.

Radiation Damage in Macromolecular Crystallography.

Radiation damage inflicted on macromolecular crystals during X-ray diffraction experiments remains a limiting factor for structure solution, even when samples are cooled to cryotemperatures (~100 K). Efforts to establish mitigation strategies are ongoing and various approaches, summarized below, have been investigated over the last 15 years, resulting in a deeper understanding of the physical and chemical factors affecting damage rates. The recent advent of X-ray free electron lasers permits "diffraction-before-destruction" by providing highly brilliant and short (a few tens of fs) X-ray pulses. New fourth generation synchrotron sources now coming on line with higher X-ray flux densities than those available from third generation synchrotrons will bring the issue of radiation damage once more to the fore for structural biologists.

Aberration-free short focal length x-ray lenses

We treat the problem of defining the ideal x-ray refractive lens design for point focusing of low emittance x-ray beams at third- and fourth-generation synchrotron sources. The task is accomplished by using Fermat's principle to define a lens shape that is completely free from geometrical aberrations. Current microfabrication resolution limits are identified, and a design that tolerates the inherent fabrication imperfections is proposed. The refractive lens design delivers nanometer-sized focused x-ray beams and is compatible with current microfabrication techniques.

Approaches to automated protein crystal harvesting.

The harvesting of protein crystals is almost always a necessary step in the determination of a protein structure using X-ray crystallographic techniques. However, protein crystals are usually fragile and susceptible to damage during the harvesting process. For this reason, protein crystal harvesting is the single step that remains entirely dependent on skilled human intervention. Automation has been implemented in the majority of other stages of the structure-determination pipeline, including cloning, expression, purification, crystallization and data collection. The gap in automation between crystallization and data collection results in a bottleneck in throughput and presents unfortunate opportunities for crystal damage. Several automated protein crystal harvesting systems have been developed, including systems utilizing microcapillaries, microtools, microgrippers, acoustic droplet ejection and optical traps. However, these systems have yet to be commonly deployed in the majority of crystallography laboratories owing to a variety of technical and cost-related issues. Automation of protein crystal harvesting remains essential for harnessing the full benefits of fourth-generation synchrotrons, free-electron lasers and microfocus beamlines. Furthermore, automation of protein crystal harvesting offers several benefits when compared with traditional manual approaches, including the ability to harvest microcrystals, improved flash-cooling procedures and increased throughput.

Ultrafast AMO physics at the LCLS x-ray FEL

The Linac Coherent Light Source at the SLAC National Accelerator Laboratory, Stanford University, began operation in 2009 as the world's first hard x-ray free electron laser. Early experiments have concentrated on atomic physics, and have demonstrated several key features of the ultrafast high field x-ray-atom interaction. This paper reviews some of these early results. 1. INTRODUCTION: WORLD'S BRIGHTEST ULTRAFAST X-RAY SOURCE, LCLS The new class of so-called fourth generation synchrotron light sources are a revolutionary departure from storage ring-based electron synchrotrons. They are true x-ray lasers, which use relativistic electrons as a gain medium. The Linac Coherent Light Source (LCLS) at the SLAC National Accelerator Laboratory in Menlo Park California is the world's first hard x-ray free electron laser (XFEL) (1). It produces coherent x-ray fields that exceed the brightness of any previous source (measured in energy per unit time per unit solid angle per unit frequency interval) by a factor of one billion or more. The increase of peak brightness is due to a combination of increased pulses energy and decreased pulse duration. These novel lasers allow us to observe the fastest timescales in atoms and molecules, which are due to the interactions among electrons. The timescales involved can be characterized by electronic energy separations, which can be many electron volts. Any ultrafast laser source is limited to pulse durations no shorter than a single cycle of the electromagnetic field. For the conventional Ti : Sapphire laser ( = 800nm), this is about 2fs. But for x-rays, the pulse duration can be much shorter. Simulations show that the LCLS is capable of sub-femtosecond pulses, which could capture electronic coherences in molecules. X-rays can reveal multielectron processes inside atoms and molecules. Furthermore, these sources have not yet reached their intrinsic limits in pulse duration, where sub-femtosecond pulses are possible (2). Accelerator and x-ray laser scientists and engineers at SLAC have also begun to explore techniques that will one day provide routine operation with pulses whose time-bandwidth product is near the Fourier transform limit (3). Such control over x-ray fields could be exploited just as in the field of quantum optics with visible and ultraviolet laser pulses. This short review will highlight some of the first results, and the opportunities for further work in strong-field x-ray physics of atoms and molecules. The work described here was all done at the LCLS x-ray free electron laser by the Stanford PULSE Institute AMO group in collaboration with other AMO research groups around the world (4-9). Some of the experiments described form the thesis research of two Stanford students, Mike Glownia and James Cryan (10, 11).

Fast acquisition of extensive X-ray diffraction patterns of a gas–liquid interface in grazing-incidence geometry

The development of third-generation synchrotron sources has inspired qualitative and quantitative breakthroughs in structural studies of monomolecular organic layers. To study such systems formed at the gas–liquid interface, grazing-incidence diffraction (GID) has proved to be the most powerful technique. Until quite recently, in most cases, GID was performedviaa scanning approach with use of a collimating system in front of the detector to eliminate the effect of parallax and to achieve the required angular resolution. Owing to the long counting time required, this kind of measurement often introduces significant radiation damage to a sample and considerably restricts time-resolved studies, preventing the pursuit of emerging scientific areas such as the investigation of fast kinetic structural changes in two-dimensional systems. This problem can apparently become a real obstacle for the application of the scanning GID technique at fourth-generation synchrotron sources because of the extremely high X-ray fluxes involved. This article discusses the possibility of significantly reducing the measuring time and avoiding the beam parallax problem by using a high-brilliance submillimetre beam and a large-area two-dimensional detector (e.g.PILATUS) in a single-shot GID measurement on large-area sample surfaces. Both theoretical considerations of the problem and experimental GID results from monomolecular layers of behenic acid at the gas–water interface are presented, with a detailed description of the experimental conditions. The possibility of a diffraction imaging study of the texture of Langmuir monomolecular layers is demonstrated.

A planar refractive x-ray lens made of nanocrystalline diamond

Diamond has unique properties which make it the ideal material for use in synchrotron instrumentation. X-ray optics made of diamond are almost transparent, they possess strength, and are subject to very low thermal expansion; therefore they will be able to withstand the powerful beams generated by fourth-generation light sources without compromising brilliance. For this reason, several groups are attempting fabrication of refractive lenses and zone plates made of diamond. Lithography and, in general, microfabrication technology, are the ultimate tools for the innovation of synchrotron focusing optics. We propose to combine modern silicon microtechnology with advanced deposition methods to fabricate nanocrystalline-diamond lenses for third- and fourth-generation synchrotron sources. The fabrication method is described here and microfocusing synchrotron tests are illustrated.

Solving X-ray protein structures without a crystal: using X-ray Free Electron Laser, the fourth generation synchrotron light sources

A synchrotron light source is a source of electromagnetic radiation artificially produced by specialized electron accelerators. Compared to the commonly used in-house X-ray sources, it is wavelength adjustable, much stronger and more focused. In the last two decades, synchrotron usage has become the mainstream for X-ray protein structure determination. Taking the advantage of micro-focus light beams of the third generation synchrotron, the size of a usable protein crystal for data collection decreases to micron level, which increases the rate of macromolecular structure determination to about 10 new protein data bank entries per day. The fourth generation synchrotron light sources not only inherit the above advantages of traditional synchrotron but also develop them to a higher level: you do not even need a protein crystal for atomic resolution X-ray structure determination by using the nano-focus beam line at the fourth generation synchrotron! This is obviously exciting news for those structural biologists working on membrane proteins and large macromolecular complexes which are notorious for crystallization. X-ray Free Electron Laser (XFEL), provided by the fourth generation synchrotron light sources, has femtosecond pulse length and both peak and average brightness largely exceeding the beam of 3rd generation sources. XFEL is a laser that shares the same optical properties as conventional lasers such as emitting a beam consisting of coherent electromagnetic radiation which can reach high power, but it uses a relativistic electron beam as the lasing medium, which moves freely through a magnetic structure. In other words, it is coherent in phase and has very high brightness. The world's first XFEL, called Linac Coherent Light Source (LCLS), was completed at Stanford's Linear Accelerator Center in 2009 (Hand, 2009). Theoretically, a beam emitted by this machine will have “a brightness that is 10 billion times greater than that of any existing X-ray source on earth,” reported by the press office at the Argonne National Laboratory. At an XFEL, a nano-focus beam line is available. Together with the incredible intensity, a crystal with 1 μm might be large enough to yield the necessary scattering data. Of course the radiation damage will cause serious problems here. So people need to change their strategy for collecting a complete data set from rotating one crystal during exposure while collecting and merging the images from maybe hundreds of different crystals. It is unlikely that a nano-crystal could survive from one shot of XFEL. The very short pulse of XFEL also provides a way out of the damage problem. Compared to the picosecond pulse of a conventional synchrotron, XFEL could provide femtosecond pulse length. A computer simulation showed that one can rapidly image a sample with such a short pulse before the atoms in the molecule may be destroyed (Neutze et al., 2004). The most revolutionary impact of an XFEL on structural biology is the collection of X-ray scattering data without crystals. The basic idea of processing X-ray scattering data of single molecule is developed from electron microscopy (EM) studies (Huldt et al., 2003). In EM research, the images are sorted and averaged by the cross correlation between them. Then the mutual orientation of the averaged images can be determined based upon the idea that any two projections through a three-dimensional object have at least one same line. It is very similar in X-ray studies that any two scattering images share at least one curve in common where the Ewald spheres intersect in reciprocal space. By sorting and averaging the X-ray scattering images collected from

A stitching figure profiler of large X-ray mirrors using RADSI for subaperture data acquisition

In the third- and coming fourth-generation synchrotron radiation facilities, X-rays having both high brightness and high coherency can be utilized. Such X-rays require high accuracy in the reflective optics. In this study, we developed an ultra-precise measurement instrumentation for tangentially long X-ray mirrors using a Fizeau interferometer. In the system, the mirror figure is measured by stitching the subaperture profiles measured by the relative-angle determinable stitching interferometry, which we developed previously. High measurement accuracy of approximately 2 nm (peak to valley) was achieved in the measurement of a 400 mm-long aspherical surface.

Study of micro-channel geometries for internally cooled Si monochromators

Rocking curves of micro-channel (MC) water-cooled monochromators are broadened by stresses introduced during fabrication and under X-ray thermal load. This is a problem which will be even more serious with the rise of the fourth-generation synchrotron sources, i.e. the free-electron lasers. The X-ray optics group at the Institute of Physics at the ASCR v.v.i. in Prague is designing, testing and, with company Polovodice a.s., fabricating novel internally water-cooled Si monochromators. Here three new micro-channel geometries are introduced which reduce rocking-curve enlargement owing to the fabrication to less than 2.5 microrad ( approximately 0.5 arcsec). All three MC designs show less rocking-curve enlargement and smoother topographic images. The designs also show better cooling efficiencies than the classical MC design in finite-element analysis calculations.

Time-dependent FEL wavefront propagation calculations: Fourier optics approach

Numerical examples of time-dependent FEL wavefront propagation calculation and coherence analysis are presented. The calculations are performed using the Synchrotron Radiation Workshop (SRW)—wave-optics computer code optimized for synchrotron radiation, and the 3D FEL simulation code GENESIS 1.3. In the examples described, the electric field obtained at the exit of an FEL undulator after running GENESIS in time-dependent mode is transformed from time to frequency domain, and then propagated, using Fourier-optics methods implemented in SRW, through interferometer-type optical schemes. Time-averaged intensity patterns, obtained in image planes of the interferometers as a result of these simulations, allow for straightforward coherence characterization by visibility of interference fringes. The presented examples show that Fourier optics-based wavefront propagation method, as implemented in the SRW, can be effectively used for detailed analysis of characteristics of FEL radiation in time and in frequency domains. Besides, due to its high accuracy and CPU-efficiency, this method is very well suited for optimization of optical beamlines for fourth generation synchrotron radiation sources, for which accurate treatment of wave-optical phenomena, aimed to preserve radiation coherence and time structure, is of paramount importance.

Advances in germanium detector technology

This paper summarizes some of the recent advances in high-purity germanium (HPGe) detector technologies and their applications. These important advances were driven by the necessity to support the recent increase in applications, uses and requirements for germanium detectors. Performances of single and multi-element closely packed HPGe detector arrays are discussed for various applications. Some of the developmental work to further improve the packing density of both large and small germanium detectors by using monolithic segmentation technology is presented along with the results. Monolithically segmented large germanium detectors are described which have high efficiency and high-energy resolution. Such detectors supply both interaction position and energy information of incident high-energy photons thereby providing powerful tools for gamma-ray tracking, polarimetry studies, low-energy filtration, and low-energy background rejection, etc. Monolithically segmented small germanium detectors provide improved solid angle ratio in X-ray detection systems without sacrificing energy resolution or throughput. Advancements in this detector technology are required for the fourth-generation Synchrotron Light Sources that are at the planning stage. This paper also reports on a revolutionary monolithic structure that is believed to be the first ever fabricated on large HPGe crystal.

Interaction of atomic systems with X-ray free-electron lasers.

The planned construction of an X-ray free-electron laser (XFEL) will provide new opportunities for research in various areas of physics, chemistry and biology. The proposed design of the XFELs at DESY (Deutsches Elektronen-Synchrotron) and SLAC (Stanford Linear Accelerator Center) is built on the concept of a fourth-generation synchrotron source and will provide an intense pulse (I(0) approximately 10(16) W cm(-2), tau(gamma) approximately 100 fs) for photon wavelengths down to 1 A. Some guidelines for applications of these sources pertaining to atomic physics are presented here. Issues such as the onset of strong photon-field effects, multiple ionization and hollow-atom formation are analyzed. Attention is especially given to studying the interaction with rare-gas atoms, for which some numerical estimates are provided.

Measurement of x-ray pulse widths by intensity interferometry.

The pulse width of hard undulator radiation (32 ps width, energy 14 keV) was determined by intensity interferometry. The method, in combination with various x-ray monochromators, enables measurements to be taken over a wide range of time frames, from ns to fs. The applicable target includes measurements of ultrafast x-ray pulse widths from fourth generation synchrotron light sources.