GeoSoilEnviroCARS, The University of Chicago The University of Kentucky, College of Agriculture Environmental Sciences Department, Brookhaven National Laboratory

Welcome to X26A
Information For Users

Beamline Information
Contact Information
Configuration Info
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Software Manual
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Beamtime Schedules
APS Sector 13

X26A Science
Science Highlights
Required Acknowledgement

External Links
NSLS WebSite
BNL WebSite
BNL Visitor's Guide

  Beamline Description


  • Research Program: Development and application of analytical techniques (e.g. microprobe, microspectroscopy, microdiffraction, fluorescence
    microtomography) in geochemistry, environmental science, chemistry,
    biology, and other fields.

  • Ring: X-Ray

  • Status: Operational

  • Time Dedicated to General User Program: 25%

PRT Institutions

  • University of Chicago, Consortium for Advanced Radiation Sources

  • University of Kentucky, Dept. of Plants and Soil Sciences

  • BNL, Environmental Science Dept.

Research Types
  • Environmental Science, Geology, Biology, Chemistry
  Beamline Staff
  • Spokesperson: Steve Sutton (U. Chicago)
  • Scheduling and Scientific Oversight: Tony Lanzirotti (U. Chicago)
  • Local Contact: Sue Wirick (U. Chicago)
  • Safety Coordinator: Sue Wirick
  • Training Coordinator: Sue Wirick
  • Beamline Staff: William Rao (U. Kentucky)
  Optical Configuration
Energy Range (keV) Beamline Configuration Spot Size Total Horizontal Angular Acceptance (mrad)
3-40 Unfocused White 10 m2 - 25mm H x 2mm V 3.0
4-18 Focused White 150m H x 350m V 0.5
4-28 Unfocused Monochromatic 10 m2 - 25mm H x 2mm V 3.0
4-28 Focused Monochromatic 5m V x 9m H 0.5
  Experimental Apparatus
Radiation hutch, Canberra 9-element HPGe Array, Radiant Vortex-EX silicon drift, and Canberra Si(Li) x-ray detectors, using cPCI based XIA XMap digital multi channel analyzer system. Ion chamber and PIN diode detectors, wavelength dispersive spectrometer (deltaE/E ~ 10-3), xyztheta sample position stage, remote optical microscope with Mitutoyo infinity-corrected long working distance objectives, microdiffraction capabilities using Rayonix SX-165 CCD detector and MAR 345 Image Plate.
  Computer System - Hardware and Software
Six PC workstations operating Windows XP Pro and Linux OS systems. EPICS Control System using an MEDM front-end. VME and soft IOC system monitors, Ethernet data access and acquisition, Interactive Data Language (IDL) software, optical and digital image capture and processing system with hardcopy. Rayonix SX-165 CCD and MAR 345 Image Plate area detectors.
       The x-ray microprobe at beamline X26A is primarily operated in focused, monochromatic mode utilizing microfocusing optics consisting of two, 100 mm long, dynamically bent silicon mirrors arranged in a Kirkpatrick-Baez (KB) geometry (designed and built by P. Eng, CARS-University of Chicago). The KB mirrors (40:1, 9 meters from the source) focus a 400 x 400 m beam down to about 5-10 m (FWHM) resulting in a gain in flux/m2 of about 1500 over a pinhole. Photon Flux at 18 keV is roughly 1x109 photons/sec in focused monochromatic mode. The focusing mirrors are Rh coated and reside inside a He enclosure. The incoming white beam is collimated using a water-cooled, copper 'ladder and slit' assembly. Typically this beam is collimated to 400 m in the vertical to reduce effects of thermal heating on the monochromator. A second set of tantalum, motor-driven 4-jaws are then used to collimated the beam entering the hutch (either monochromatic or white).

       Two channel-cut, silicon crystal monochromators are available to monochromatize the x-ray beam for XAFS applications, one with a (111) lattice cut and the other with a (311) lattice cut located 6 meters from source. Both crystals are cut to a 7 mm gap and are rotated using a Huber 410 one-circle goniometer (40:1 gear reducer). Crystals are cooled to 9C using a Neslab chiller. The crystals can be translated into position using a motorized translator. To minimize backgrounds from Compton scattering, the X-ray detectors reside in the storage ring plane and at 90 to the incident beam. Currently the detectors we have available include a Canberra 9-element HPGe Array detector, Canberra SL30165 Si(Li) detector (rarely used), two Radiant Vortex-EX Silicon Drift Diode (SDD) detectors, and a Microspec Wavelength Dispersive Spectrometer (requires prior notification for use). The HPGe and SDD solid state detectors are the default systems in daily use and utilize the XMap series of compact PCI based digital spectrometers produced by XIA. Custom made mini ion chambers and PIN diode detectors are also available for transmission analysis. The sample stage sits at 45 to the incident beam, allowing an optical microscope with a gigabit ethernet CCD attachment to be mounted horizontally to view the sample surface in normal incidence.

       The entire microprobe apparatus, including final beam collimator, sample stage, optical microscope and X-ray detector, rests on a 107 x 107 cm breadboard, which in turn sits on a motor-driven lift table. The lift table allows the entire instrument to be positioned vertically and horizontally to intercept the most intense and most highly polarized portion of the synchrotron radiation profile and also pivot about an arbitrary fixed point in space. The X26A x-ray microprobe is currently capable of trace element analyses with ~ 1 ppm sensitivity and X-ray absorption near edge spectroscopy (XANES) analyses with 10-100 ppm sensitivity. Microdiffraction analysis is also available utilizing Bragg techniques, instrumentation includes Rayonix SX-165 and MAR 345 array systems. Both systems offer large input active area and highest available spatial resolution, optimized for collection of data out to higher 2 theta angles, and on very weakly diffracting samples. Since X26A is optimized for spatially collimated microbeams, we have been able to obtain high-resolution microdiffraction data on very small (5 m) crystals. A fluorescence microtomography setup is also available, but arrangements must be made in advance.

  Beamline Safety Documents
X26A Safety Checklist
X26A Hazardous Equipment List
Beamline X26A receives support the following organizations:

Basic Energy Sciences Geosciences Research Program NSF Division of Earth Sciences

NASA Space Sciences