Realizing an Analyzer Instrument for Medium-energy Sub-meV IXS

For the past few years, silicon (800) asymmetric back-diffraction at 9.13 keV has been investigated for use in inelastic x-ray scattering (IXS) analyzer with < 1 meV resolution and > 100 μrad acceptance. While the basic principles have been described and proven, attractive results have become consistently achievable only recently, with particular attention paid to key execution details, including crystal quality (substrate purity, orientation, surface flatness and strain), positioning (resolution, repeatability, and stability of critical axes), thermal environment stability and control, and x-ray diagnostics. While methods for positioning, diagnostics, and thermal stabilization have been refined in our work, crystal quality remains a critical limitation of ultimate performance. An overview of the implementation details is provided in the context of prototype x-ray beam test results collected in preparation for final design of the analyzer instrument to be incorporated into the IXS beamline of NSLS-II.