H. Grimm, R. Schätzler and T. Starc

The backscattering spectrometer BSS at the research reactor FRJ2 allows for neutron scattering experiments in the range of GHz. Its performance has been strongly improved by the equipment with new analyzer plates -a step which is based on the availability of large silicon wafers. Thereby a much steeper resolution function is achieved. It is shown that this improvement is essential for the discernibility of small inelastic signals close to the usually dominant elastic line. In addition, the width of this 1ine could be narrowed by 12% without loss of intensity. This improvement is based on the separate recording of the positive and negative acceleration periods of the doppler drive by means of a suitable gate.