A New Powder Diffractometer for Synchrotron Radiation with a Multiple‐Detector System

A new powder diffractometer for synchrotron radiation with six detector arms has been constructed. Five detector arms are attached radially at intervals of 25° to the 2 θ axis and form a multiple‐detector system. Five scintillation counters coupled with flat Ge(111) crystal analyzers on the respective arms can simultaneously record the whole powder pattern divided into five segments, each with an equal 2 θ span. The optics design is based on flat‐specimen reflection geometry using a parallel beam. The intensity data are collected using a 2 θ step‐scan technique in asymmetric diffraction at a fixed incident angle. A sixth multi‐purpose detector arm can be used in the conventional single‐arm scan mode. It can be equipped with various kinds of analyzers such as long horizontal parallel slits, a fiat or channel‐cut crystal analyzer, a receiving slit and a solid‐state detector. Test operations of the multiple‐detector system, conducted at the Photon Factory in Tsukuba, recorded a full width at half maximum of 0.022° and a peak maximum intensity of more than 40000 counts s −1 for the (111) reflection from Si powder. The whole powder pattern of Mg 2 SiO 4 over a 2 θ range of 130° could be step‐scanned at a step interval of 0.004° (2 θ ) in just 4 h. Results of whole‐powder‐pattern decomposition and Rietveld refinement of the Mg 2 SiO 4 pattern are given.