A four-circle single crystal diffractometer with a rotating anode source

Abstract

An Enraf-Nonius CAD-4 four-circle diffractometer with kappa geometry and an Elliott-GX6 rotating anode generator have been linked to form a single-crystal X-ray data collection system which exploits the high intensity and instrument resolution available from rotating anode sources. A detailed description of this instrument and its construction is given. Experimental results illustrate the potential of the system for the rapid collection of diffraction data of high accuracy and resolution, particularly in the intended application to crystals of proteins, nucleic acids, and other macromolecules. The source can be operated at 3500 watts, and the crystal to source distance is 360 mm implying very narrow peak widths and high instrument resolution. The measurement of symmetry related reflections (Rsym = 2.2% based on intensity) indicates satisfactory overall system reproducibility.