SynopsisA new facility for microdiffraction strain measurements and microfluorescence mapping has been developed at the Advanced Light Source. Details of the mechanics and performance of the beamline and endstation will be given. AbstractA new facility for microdiffraction strain measurements and microfluorescence mapping has been built on beamline 12.3.2 at the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory (LBNL).This beamline benefits from the hard x-radiation generated by a 6 Tesla superconducting bending magnet (superbend). This provides a hard x-ray spectrum from 5 keV to 22 keV and a flux within a 1 µm spot of ~ 5 · 10 9 photons per seconds (0.1% bandwidth at 8 keV). The radiation is relayed from the superbend source to a focus in the experimental hutch by a toroidal mirror. The focus spot is tailored by two pairs of adjustable slits, which serve as secondary source point. Inside the lead hutch, a pair of Kirkpatrick-Baez (KB) mirrors placed in a 2 vacuum tank re-focuses the secondary slit source onto the sample position. A new KB-bending mechanism with active temperature stabilization allows for more reproducible and stable mirror bending and thus mirrorfocusing. Focus spots around 1 µm are routinely achieved and allow a variety of experiments, which have in common the need of spatial resolution. The effective spatial resolution (~0.2 µm) is limited by a convolution of beam size, scan-stage resolution and stage stability. A 4-bounce monochromator consisting of 2 channel-cut Si(111) crystals placed between the secondary source and KB-mirrors allows for easy changes between whitebeam and monochromatic experiments while maintaining a fixed beam position. High resolution stage scans are performed while recording a fluorescence emission signal or an x-ray diffraction signal coming from either a monochromatic or a white focused beam. The former allows for elemental mapping, whereas the latter is used to produce 2-dimensional maps of crystal-phases,-orientation, -texture and -strain/stress. Typically achieved strain resolution is in the order of 5 · 10 -5 strain units. Accurate sample positioning in the x-ray focus spot is achieved with a commercial laser-triangulation unit. A Si-drift detector serves as a high-energy-resolution (~150 eV FWHM) fluorescence detector. Fluorescence scans can be collected in continuous scan mode with up to 300 pixels per second scan-speed. A CCD area detector is utilized as diffraction detector. Diffraction can be performed in reflecting or transmitting geometry. Diffraction data are processed using XMAS, an in-house written software package for Laue and monochromatic microdiffraction analysis.
SynopsisA new high-pressure facility for diffraction and spectroscopy using diamond anvil highpressure cells has been developed at the Advanced Light Source. Details of the mechanics and performance of the beamline and endstation will be given. AbstractA new facility for high-pressure diffraction and spectroscopy using diamond anvil highpressure cells has been built at the Advanced Light Source on Beamline 12.2.2. This beamline benefits from the hard X-radiation generated by a 6 Tesla superconducting bending magnet (superbend). Useful x-ray flux is available between 5 keV and 35 keV. The radiation is transferred from the superbend to the experimental enclosure by the brightness preserving optics of the beamline. These optics are comprised of: a plane parabola collimating mirror (M1), followed by a Kohzu monochromator vessel with a Si(111) crystals (E/∆E ~ 7000) and a W/B 4 C multilayers (E/∆E ~ 100), and then a toroidal focusing mirror (M2) with variable focusing distance. The experimental enclosure contains an automated beam positioning system, a set of slits, ion chambers, the sample positioning goniometry and area detectors (CCD or image-plate detector). Future developments aim at the installation of a second end station dedicated for in situ laser-heating on one hand and a dedicated high-pressure singlecrystal station, applying both monochromatic as well as polychromatic techniques. 2
The next generation of synchrotrons and free electron laser facilities requires x-ray optical systems with extremely high performance, generally of diffraction limited quality. Fabrication and use of such optics requires adequate, highly accurate metrology and dedicated instrumentation. Previously, we suggested ways to improve the performance of the Long Trace Profiler (LTP), a slope measuring instrument widely used to characterize x-ray optics at long spatial wavelengths. The main way is use of a CCD detector and corresponding technique for calibration of photo-response non-uniformity [J. L. Kirschman, et al., Proceedings of SPIE 6704, 67040J (2007)]. The present work focuses on the performance and characteristics of the upgraded LTP-II at the ALS Optical Metrology Laboratory. This includes a review of the overall aspects of the design, control system, the movement and measurement regimes for the stage, and analysis of the performance by a slope measurement of a highly curved super-quality substrate with less than 0.3 microradian (rms) slope variation.
SynopsisThree near identical protein crystallography beamlines with a single 6 Tesla peak field superconducting dipole bend magnet as the source have been built at the 1.9 GeV Advanced Light Source. The design and performance of this new facility is described. AbstractAt the Advanced Light Source (ALS), three protein crystallography (PX) beamlines have been built that use as a source one of the three 6 Tesla single pole superconducting bending magnets (superbends) that were recently installed in the ring. The use of such single pole superconducting bend magnets enables the development of a hard x-ray program on a relatively low energy 1.9 GeV ring without taking up insertion device straight sections. The source is of relatively low power, but due to the small electron beam emittance, it has high brightness. X-ray optics are required to preserve the brightness and to match the illumination requirements for protein crystallography. This was achieved by means of a collimating premirror bent to a plane parabola, a double crystal monochromator followed by a toroidal mirror that focuses in the horizontal direction with a 2:1 demagnification. This optical arrangement partially balances aberrations from the collimating and toroidal mirrors such that a tight focused spot size is achieved. The optical properties of the beamline are an excellent match to those required by the small protein crystals that are typically measured. The design and performance of these new beamlines are described.
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