THERMAL DIFFUSE-SCATTERING IN TIME-OF-FLIGHT NEUTRON DIFFRACTOMETRY

The coherent one-phonon scattering cross section measured in time-of-f light (TOF) neutron diffractometry is derived for any ratio between th e sample-to-detector flight path and the total flight path. For the pa rticular case of scattering by acoustic phonons in monocrystals, the d ifferential cross section is described in terms of the scattering surf ace in four-dimensional space (Q(e,omega)), where HBARQ(e) is the mome ntum transfer for elastic scattering and HBARQ(e) is the energy transf er. This cross section is required in calculating the thermal diffuse scattering (TDS) correction for TOF neutron diffractometry.