Compton scattering in the ALS booster

Robin, D.; Kim, C.; Sessler, Andrew M.

doi:10.1109/pac.1995.504611

Cited by 1 publication

(1 citation statement)

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“…However, local demands chiefly from the protein crystallography community required the development of hard x-ray sources at the facility. As a result, three 6 Tesla superconducting bending magnets replaced three 1.2 Tesla regular bending magnets 1,2 . This resulted in a shift in the critical energy for these three sources from 3 keV to 12 keV allowing for the development of various hard x-ray programs.…”

Section: Introductionmentioning

confidence: 99%

A dedicated superbend x-ray microdiffraction beamline for materials, geo-, and environmental sciences at the advanced light source

Kunz

Tamura

Chen

et al. 2009

Review of Scientific Instruments

168

115

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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.

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Section: Introductionmentioning

confidence: 99%