Angular Resolution of Parallel Foils on a Synchrotron Powder Diffractometer

In an attempt to improve the resolution in flat-plate diffraction geometry, a new set of parallel foils, 100 µm spacing, 365 mm long with an aperture of 20 × 20 mm², has been commissioned. The study was carried out using the two-circle diffractometer of station 2.3 at the SRS. In order to properly quantify the improvements, a detailed and comparative study of the instrumental resolution using the new and existing foils, of 200 µm spacing, is reported. A number of cubic materials, BaF₂, Si and CeO₂, that are known to show well defined Bragg peaks over the full 2θ angular range available, were investigated.