A2 Beamline

A versatile undulator beamline for high-resolution diffraction

A2 Beamline Specifications
Monochromator: Diamond <111> Bragg DCM
Insertion Device: 1.5 m CHESS Compact Undulator
Energy Range: 5 – 70 keV
Energy Resolution: E / ΔE ~ 10-4
Techniques: Resonant and non-resonant diffraction, single crystals, powders, high energy diffraction, PDF, diffuse scattering, magnetic scattering, custom sample environments
Special Equipment: PiXirad and Pilatus photon counting detectors, GE and Dexela flat panel detectors, 4-circle diffractometer, low temperatures, applied mechanical loads, Cyberstar scintillation detector
Alternate Configurations: White beam / pink beam / blue beam
Alternate Techniques: Transmission Laue diffraction, rapidly evolving mechanical systems

The A2 beamline receives x-rays produced by electrons passing through one of two 1.5 m CHESS Compact Undulators newly installed in the west flare of CESR. The undulator harmonics are coupled to those generated for the G2/G3 endstations by the counter-rotating positron beam. A2 offers users maximum flexibility in the use of this undulator beam, delivering photons over an unusually wide range of incident energies. A2 can access K-edges of ~ 52 different elements (L edges of ~ 40 different elements) for resonant scattering and absorption measurements, spanning the scientifically and technologically important transition metals, lanthanides, and actinides. Additionally, it is possible to pass high-flux white and pink beams into the hutch, for specialized time-resolved experiments and transmission Laue diffraction. Commensurate with this versatility, the A2 user base has long been eclectic and multidisciplinary, with ongoing academic research programs in chemistry, physics, materials science, and engineering, as well as industrial research. A central goal in upgrading A2 to undulator beams was to preserve and expand this versatility. Typical beamline configuration will now use a focusing 0.8 m white-beam mirror and diamond monochromator for incident energies between 5-30 keV, with the mirror removed for work between 30-70 keV and the monochromator removed for white beam measurements. Inside the hutch, A2 specializes in accommodating custom sample environments, with measurements performed at low and high temperature, under pressure or mechanical load, inside electrochemical cells, or under applied thermal gradients.