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Abstract: This paper describes fabrication methods used to demonstrate the advantages of nested or Montel optics for micro/nanofocusing of synchrotron X-ray beams. A standard Kirkpatrick-Baez (KB) mirror system uses two separated elliptical mirrors at glancing angles to the X-ray beam and sequentially arranged at 90° to each other to focus X-rays successively in the vertical and horizontal directions. A nested KB mirror system has the two mirrors positioned perpendicular and side-by-side to each other. Compared to a standard KB mirror system, Montel optics can focus a larger divergence and the mirrors can have a shorter focal length. As a result, nested mirrors can be fabricated with improved demagnification factor and ultimately smaller focal spot, than with a standard KB arrangement. The nested system is also more compact with an increased working distance, and is more stable, with reduced complexity of mirror stages. However, although Montel optics is commercially available for laboratory X-ray sources, due to technical difficulties they have not been used to microfocus synchrotron radiation X-rays, where ultra-precise mirror surfaces are essential. The main challenge in adapting nested optics for synchrotron microfocusing is to fabricate mirrors with a precise elliptical surface profile at the very edge where the two mirrors meet and where X-rays scatter. For example, in our application to achieve a sub-micron focus with high efficiency, a surface figure root-mean-square (rms) error on the order of 1nm is required in the useable area along the X-ray footprint with a ∼0.1mm-diameter cross section. In this paper we describe promising ways to fabricate precise nested KB mirrors using our profile coating technique and inexpensive flat Si substrates. [Copyright &y& Elsevier]

Abstract: Timely development of materials for the demanding fusion energy environment requires a broad range of advanced scientific tools, including advanced structural characterization methods. The current state-of-the-art and emerging capabilities in electron microscopy, atom probe tomography, neutron scattering and X-ray scattering are reviewed with respect to potential applications in fusion materials research and development. Recent dramatic advances in capabilities in all four of these characterization tools are transforming the spatial precision and quantitative information that can be extracted during structural characterization. Examples include spectroscopic identification of single atoms in bulk materials, three-dimensional mapping of millimeter-scale volumes of materials with nanometer resolution, and high-resolution in situ measurements of internal stress and strain during mechanical testing. [Copyright &y& Elsevier]

Abstract: We have developed software to accelerate the analysis of the diffuse scattering data and to recover the short-range-order (SRO) and other parameters. The software is applied to data collected from a Cu50Au50 single crystal. [Copyright &y& Elsevier]

Abstract: The nature of residual damage from atomic displacement cascades in iron has been investigated by diffuse X-ray scattering. A single crystal iron sample was irradiated at ∼60°C in the High Flux Isotope Reactor at the Oak Ridge National Laboratory to a fluence of 1×1023 n/m2 (E >0.1MeV), or ∼0.01 dpa. Diffuse X-ray scattering measurements were carried out at the Advanced Photon Source at the Argonne National Laboratory on three specimens: unirradiated, as-irradiated, and irradiated and annealed for one hour at 450°C (IA). The specimens were cooled to ∼40K to minimize thermal diffuse scattering. Subsequent measurements of the specimen lattice parameter were completed at ORNL. The diffuse scattering in the as-irradiated specimen was dominated by interstitial defect clusters exhibiting a tetragonal distortion consistent with a 〈100〉 type defect. Substantial recovery of this defect component was observed following the anneal at 450°C. A lattice parameter increase was observed following irradiation, which is also consistent with a substantial population of interstitial type defects. A net lattice parameter decrease was observed in the IA specimen, indicating loss of the interstitial defects with a residual population of vacancy-type defects. [Copyright &y& Elsevier]