Seventeen Years of Backscattering Silicon Spectrometer (BASIS): Unraveling the Dynamics of hard and soft materials

Quasielastic neutron scattering (QENS) is a powerful technique used to probe the dynamics of chemical species in materials over nanosecond–picosecond timescales and atomic to nanometer length scales. The Backscattering Silicon Spectrometer (BASIS), located at the Spallation Neutron Source (SNS) of Oak Ridge National Laboratory (ORNL), is a state-of-the-art, new-generation inverted-geometry neutron spectrometer designed to perform QENS to study single-particle diffusion and reveal the mechanisms underlying dynamic processes. BASIS has been part of the user program since 2008 and has significantly contributed to exploring dynamics in a wide range of materials, including polymers. Because QENS primarily relies on the incoherent scattering cross-section, and hydrogen—a major constituent of most polymers—possesses the highest neutron scattering cross-section, the application of BASIS in studying polymer dynamics will be discussed.