Asymmetric Band-flipping for Time-of-flight Neutron Data

Abstract

Abstract Charge-flipping with powder diffraction data is known to produce a result more reliably with high resolution data, i.e. visible reflections at small d-spacings. Such data is readily accessible with the neutron time-of-flight technique but the assumption that negative scattering density is non-physical is no longer valid where elements with negative scattering lengths are present. The concept of band-flipping was introduced in the literature where a negative threshold is used in addition to a positive threshold during the flipping. However it was not tested with experimental data at the time. Band-flipping has been implemented in TOPAS (Coelho, 2015) together with the band-modification of low-density elimination and tested with experimental powder and Laue single crystal neutron data.