Neutron Fourier diffractometer FSD for internal stress analysis: first results
At the IBR-2 pulsed reactor in Dubna a new neutron Fourier diffractometer FSD is under construction. FSD continues the development of neutron Fourier diffractometry at long-pulse neutron sources, which was started several years ago with the high-resolution Fourier diffractometer HRFD at the IBR-2. Whereas HRFD is mainly used for precise structural refinement, FSD is optimised for internal stress measurements in bulk materials. The FSD design satisfies the requirements of high luminosity, high resolution, a specific sample environment, a wide range of dhkl, and fixed scattering angles 2θ=±90°. It consists of a mirror neutron guide, a fast Fourier chopper for the neutron-beam intensity modulation, a ±90° MultiCon ZnS(Ag) 6Li-loaded detector system with both geometrical and electronic focusing, a five-axis goniometer ‘Huber’ and loading machines, and VME-based RTOF analysers for data acquisition. Examples of the first experimental results obtained with FSD are presented.