ANGLE-DISPERSIVE TIME-OF-FLIGHT DIFFRACTION USING THE ISIS SPALLATION SOURCE. G. Will, W. Schafer, E. Jansen, H. Tietze-Jaentsch, W. Kockelmann, Mineralogical Institute, University Bonn, Bonn, Germany

Using the Position Sensitive Scintilation Detektor JULIOS at the Spallation Source ISIS it is possible to measure diffraction diagrams as a function of scattering angle 21[[theta]] and energy. Simultanously the experiments are installed at the ROTAX/DIF time-of-flight diffractometer at ISIS. At a typical diffraction angle of 90deg. (center of the detector) we can cover d- values from 0.668 to 2.707 Å, corresponding to 2 [[theta]] = 72,1deg. to 107,0deg. and [[lambda]]=1.074 Å to 3.223 Å (corresponding to 3 msec to 9 msec). Two detectors are installed at present. The pulse frequency of ISIS is 20 msec, the resolution of the detector JULIOS is 5 msec (theoretical). Due to practical reasons, (because of the pulse frequency), we operate normally with the JULIOS resolution of 18 msec, corresponding to 0.0054 Å.

Numerous diffraction diagrams have been collected in the last 6 months, including diagrams for magnetic structure analysis at low temperature. A good diffraction diagram con be collected within 1 to 2 hours. Refinement of the structures is done by the Rietveld crystal and the two-step POWLS method. Examples will be given.