A TRIPLE-AXIS BONSE HART CAMERA USED FOR HIGH-RESOLUTION SMALL-ANGLE SCATTERING

A triple-axis diffractometer has been constructed and optimized in our laboratory. It is used on an X-ray point source, using the principle which was pioneered by Bonse and Hart 25 years ago. A triple-reflection channel-cut Ge crystal is used as monochromator and the same as analyser. The width of the direct beam is about FWHM = 17" for Cu K-alpha radiation. Owing to the low background, the stability of the mechanics and the two triple Ge reflections, a signal-to-noise ratio of 10(7) has been achieved between the direct beam and the parasitic scattering without sample. These characteristics allow routine measurement of scattering to be performed for Bragg spacings up to 6000 angstrom for typical colloidal samples in semilinear collimation.