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Beamline BW1: 8-Circle Diffractometer
Multi-Purpose 8-Circle Diffractometer
An universal X-ray diffractometer is installed at beamline BW1. This device offers an extraordinary large number of degrees of freedom for sample adjustments and detector movements.
The diffractometer consists of a modified Huber 5020 6-Circle diffractometer and an additional, independent detector arm that supplies a movement of a second detector on a sphere around the sample. The whole diffractometer is mounted on a lift table allowing a vertical adjustment of ± 100 mm (variable sample height from 1580 mm up to 1780 mm above the concrete floor in the experimental hutch). Furthermore, there is a horizontal translation of ± 100 mm perpendicular to the beam. Two big independent goniometers (Huber 480) are based on the translation table. Both are rotating around a vertical axis through the sample position. The lower one moves the outer detector arm whereas the upper one turns the Huber 5020 instrument to change the angle of incidence on the sample surface. Along the horizontal axis of the spectrometer a stable goniometer head is built up by an X-Y-Translation (made by Risø) and two circle segments (Franke, ± 20°) to orientate the sample with respect to the beam.
This setup is compatible with beamlines C and W1 and thus allows convenient interchange of components and sample environments between these experiments. Additionally, a Huber Z-table 5103.1 can be used on top of the goniometer head to move the sample into the center of the rotation of the two circle segments. As alternative an Eulerian cradle can be mounted on the X-Y-translation table yielding the same sample position. It is possible to install relatively heavy sample chambers like an UHV-baby chamber or closed cycle cryostats, which can be balanced by a variable counter weight. Optical benches (X-95 profiles) can be mounted on the base of the spectrometer to e.g. attach monitors for the intensity of the primary beam in a fixed position.
All movements of the diffractometer are done by stepper motors, which are controlled by the beamline µVAX. The type of detector used will depend on the experimental methods employed (available are e.g. a position sensitive detector Braun OED 70M, NaJ-counters, Si(Li)-semiconductor detector and ionisation chambers). Most of the experiment control and data acquisition is done using CAMAC hardware.
Applications
It is possible to carry out investigations e.g. in the field of surface X-ray diffraction in UHV at high and low temperatures, experiments with standing waves, scattering studies of amorphous materials using anomalous dispersion, XAFS, DAFS and grazing-incidence diffraction.
Literature on Instrumentation
R. Treusch: "Charakterisierung und Test einer Synchrotronstrahlungsoptik für DORIS III, Diploma Thesis, Hamburg, Germany 1992 (in German)
R. Frahm, J. Weigelt, G. Meyer and G. Materlik: X-ray undulator beamline BW1 at DORIS III, Rev. Sci. Instruments 66 (1995) 1677
Instrument Specification
Photon beam | |
|---|---|
Source to sample distance |
38 m |
