The new structure powder diffractometer at the FRM-II in Garching

SPODI, the structure powder diffractometer, will be installed on beamline S R 8 at the FRM-II in Garching. The instrument has been designed to achieve an ideal compromise of good resolution up to very high 2 theta (by using a monochromator take-off angle of 155 degrees) and high flux with special emp hasis on 'good' profile shapes and low background. To optimise the paramete rs of the optical components like coatings of neutron guides, monochromator and seller collimators. Monte Carlo simulations were carried out. To check the results of the simulation calculations two different independent progr ams (MCSTAS and RESTRAX) were applied. An option for using a small-angle ne utron scattering (SANS) device will eventually be included to perform Bragg scattering, SANS and diffuse scattering simultaneously on the sample. (C) 2000 Elsevier Science B.V. All rights reserved.