CHESS East
D1 Station

D1 station receives 4.5 mrad of hard bend radiation from the positron beam of the CESR storage ring. The D1 station has a large shielded white beam cave with a dedicated monochromator enclosure in the upstream end of the cave. Users setup their experiments on the D1 optical table or the D1 optical bench in the downstream half of the hutch.  D1 receives wide-bandwidth monochromatic x-rays.

A variety of multilayers is available for the D-line monochromator.  The usual setup consists of a double bounce set of multilayers with a 25 Å spacing and 1.5% resolution.  A typical measured flux of 10¹² photons/sec/mm²/100mA positron current is achieved at 10 keV with these high band-pass optics.  Further multilayer options are currently in development.

D1 line's mission in recent years has focused on small-angle scattering techniques and on imaging.  For small-angle scattering applications (SAXS), a slit system, sample stage, flightpaths, beamstop, and a CCD detector are mounted on the 3.5 m optical bench inside the hutch.  1000 Å resolution are routinely obtained at 10 keV, which is sufficient for many nanoscience applications (ref).  Using a sample goniometer, samples can be investigated in grazing-incidence scattering geometry (GISAXS), a non-invasive and powerful method to study the internal morphology of block polymer thin films and nanocomposites (ref).

Imaging applications are divided into fluorescence imaging and radiography.  In fluorescence imaging maps of the concentrations of specific chemical elements are obtained, as the sample is scanned through the x-ray beam.  For a spatial resolution of 20 µm or better, x-ray focusing capillaries are used (ref).  In time-resolved radiography experiments, a fast pixel array detector with a resolution of down to 1 µsec has been used to obtain absorption images and tomograms of fuel sprays (ref).  Fuel injectors for more fuel-efficient and cleaner car engines are an ongoing and important R&D project in the auto industry.

For special applications the optical bench and the optical table can be removed from the D1 hutch leaving about 1.5-2 m (width) by 3.5 m (length) by 2 m (height) free space.  If you are interested in this option, please contact the station scientist well in advance, in order to verify that your apparatus will fit.
 

D1 station summary   Source: Hard bend magnet HB5E, positron beam, 4.5 mrad (horizontal) into hutch Source size: FWHM (horizontal) = 1.49 mm, FWHM (vertical) = 1.18 mm Distance to source: 13.3 m to center of hutch Be windows: Total of 0.025 inches of Be into D1 hutch Cave slit sizes: 0 to 50 mm (horizontal), 0 to 5mm (vertical)   Monochromators: Double-bounce upward, offset adjustable (5-15 mm) Multilayers Number of periods Length (mm) Energy range (keV) Band width (%) 25.5 Å  W:C 100 50 6-16 2 30 Å  Mo:B4C 200 100 6-16 2 15 Å  W:B4C* 300 75 7-30 0.5 * on loan from A2 station           Focusing X-ray capillaries Gain Working distance (mm) Cut-off Energy (keV)   8 mrad* 450 55 16   4 mrad* 110 (estimated) 55 24 (estimated)   * in collaboration with Don Bilderback           Detectors Pixel size (m2) Active area size (mm2) Energy resolution   Medoptics CCD * 47.2 x 47.2 48 x 48 -   Gruner 1k CCD *,** 50 x 50 50 x 50 -   Roentec XFlash * - 2 mm dia  about 100 eV   * CHESS detector pool ** on loan from Gruner group           Typical Experiments Energy Range Typical beam size (mm horizontal x mm vertical) SAXS/WAXS 6 - 16 keV 0.5 x 0.5 GISAXS 6 - 12 keV 0.5  x 0.1 Fluorescence Imaging 6 - 30 keV 1 x 1 Fast radiography 6 keV 15 x 3

Last Update: 2006-09-21