Variable-period undulators as synchrotron radiation sources

Undulators with the capability to change the length of the magnetic period can deliver radiation with unique properties. A concept for such a variable-period undulator has been described and its applicability to storage-ring, ERL and FEL sources is discussed.

Counting statistics of X-ray detectors at high counting rates

A model of the overlap of electronic pulses in the counting chain of X-ray detectors is developed. The model is used to derive the counting losses and the statistical accuracy of measurements made with pulse-counting detectors.

Comparison of intravenous coronary angiography using synchrotron radiation with selective coronary angiography

Intravenous coronary angiography is the most advanced medical application of synchrotron radiation. The results of a large study of 230 patients at HASYLAB demonstrate the feasibility and safety of the method.

Lattice parameters and structural phase transition of lanthanum titanate perovskite, La_0.68(Ti_0.95,Al_0.05)O₃

High-resolution synchrotron radiation powder diffraction experiments indicate that the reversible orthorhombic–tetragonal phase transition in La_0.68(Ti_0.95,Al_0.05)O₃ occurs continuously and reversibly at 622.3 ± 0.2 K.

Diffractive refractive optics: the possibility of sagittal focusing in Laue-case diffraction

The sagittal focusing of a Laue-diffracted X-ray beam may be achieved if a parabolic profile is machined into the exit and/or entrance surface of the crystal. To obtain a sufficiently large focusing effect, the Laue crystal must be cut asymmetrically.

An X-ray diffractometer for accurate structural invariant phase determination

A simple X-ray diffractometer for exploitation of the linear polarization of synchrotron radiation in three-beam diffraction experiments is described. Examples of data-collection procedures for extracting triplet-phase values with good accuracy are given.

Development of light-modulated XAFS spectroscopy

The light-modulated XAFS method was developed for the study of photoexcited states. It is found to be applicable to systems with an excited-state ratio of less than a few percent.

Diffraction of short X-ray pulses in the general asymmetric Laue case – an analytic treatment

The intensity distribution behind an asymmetric Laue crystal of a δ-like incident X-ray pulse is explicitly given, adopting the results from dynamic theory.

A focusing crystal analyser for the rejection of inelastic X-ray scattering

This paper describes the design and use of a focusing crystal analyser in diffuse X-ray scattering experiments. This geometry allows a major increase in efficiency for accurate structure-factor measurements.

The ReflEXAFS station at the GILDA beamline (BM08) of ESRF

The ReflEXAFS facility active at the GILDA CRG beamline at the European Synchrotron Radiation Facility is described. Examples of studies feasible on this experimental apparatus are given.

Integrating near-edge X-ray absorption fine structure (NEXAFS) microscopy and crystallography: the effects of molecular order

The orientations of the carbonyl and the phenyl groups within submicrometre bis-urea crystals were determined using scanning transmission X-ray microscopy (STXM). The STXM data were confirmed using the single-crystal X-ray structure obtained from a larger crystal.

Magnetic counterforce for insertion devices

This paper contains a description of a technique for nulling the mechanical forces in insertion devices by means of magnetic counterforce. Calculations are presented for pure permanent-magnet and hybrid-magnet structures, and a prototype pure permanent-magnet device is described.

Swelling behaviour of poly(methylmeth­acrylate) thick resist layers in deep X-ray lithography

The causes and consequences of gas formation during X-ray irradiation of poly(methylmethacrylate) thick resist layers under various conditions are discussed. Remedies for minimizing swelling are explored.

Soft X-ray radiation-damage studies in PMMA using a cryo-STXM

The effectiveness of cryogenic specimen conditions for reducing soft X-ray radiation damage is explored. Cryo-conditions protect against mass loss, but less so against the loss of chemical bonds as measured using oxygen X-ray absorption near-edge structure or XANES on poly(methylmethacrylate) (PMMA).

High-energy diffuse scattering on the 1-ID beamline at the Advanced Photon Source

Experiments in which high-energy (65.35 keV) X-rays were used to record the detailed diffuse diffraction patterns of a number of ceramic materials are reported

Beamstop with integrated X-ray sensor

A versatile X-ray beamstop with integrated sensor is described. The beamstop has an overall diameter of 1.5 mm and an active area of approximately 100 µm in diameter.

Imaging of selenium in plants using tapered metal monocapillary optics

Novel tapered metal capillary optics that produce X-ray beams of 5–10 µm diameter have been used to generate chemically specific images of selenium in Astragalus bisulcatus, a hyperaccumulating plant.

Praveen Chaudhari takes the helm at Brookhaven National Laboratory

Diamond construction commences

Funding for first phase of 4GLS announced

USA prepare a 20-year roadmap for basic energy sciences facilities