Design and performance of the multiwire area X-ray diffractometer at the University of Virginia

A multiwire area diffractometer system for measuring X-ray diffraction intensities has been developed and has been functioning as a Biotechnology Resource since 1984. The system consists of four flat multiwire area detectors and associated electronics, rotating-anode X-ray generator, goniostat, monochromator and crystal cooler. An HP 1000 minicomputer has been used to control the goniostat, to collect the data, and concurrently to process it. This computer is being replaced with a MicroVAX 3600. Computer programs, primarily written in Fortran 77, determine and update the orientation of the crystal, integrate the intensities of the reflections, and continually monitor the quality of the output. A statistical determination of systematic errors using lysozyme crystals showed that data accuracy is limited only by counting statistics for σ/ above about 0.02. A compilation of papers published by users based on data obtained at the facility is presented.