Flat-cone diffractometer utilizing a linear position-sensitive detector

The recent development of linear position-sensitive detectors for neutrons and X-rays leads to the possibility of large improvements in the efficiency of data collection in single-crystal diffractometers. In order to take advantage of the properties of a linear position-sensitive detector it is desirable to use a diffraction geometry which causes the diffracted beams from many different reflecting planes to lie in a common plane. A design for a diffractometer utilizing the flat-cone geometry is described, and the relevant mathematical formulas are summarized. An instrument using this design has been constructed as a modification to an existing four-circle diffractometer and is now operating. Practical details of its construction, of the collection and handling of data, and of data rates are discussed.