New possibilities with inelastic fixed window scans and linear motor Doppler drives on high resolution neutron backscattering spectrometers

We report on the realisation of a new type of inelastic fixed window scans (IFWS) in neutron backscattering spectroscopy using the flexibility of linear motor Doppler drives to choose the velocity profile. We discuss more generally the information content obtained from such scans and point out how scans at a few different energy offsets can lead to a large improvement in statistics compared to full quasielastic spectroscopy. We discuss both the technical and statistical aspects and illustrate the method assuming a simple model for the scattering law and show some first experimental results.