Wide Angle Neutron Spin Echo Device

The Neutron Spin Echo (NSE) method has provided unique information about the dynamics of soft materials, including confirmation of the de Gennes model of polymer reptation, and quantitative measurement of the bending constants of various membranes. In almost all cases these measurements have been made at small neutron scattering angles, where structural correlations with length scales between 10 nm and 100 nm dominate. However, existing NSE instrumentation is not well suited to studies, such as relaxation in spin glasses, solitary magnons in antiferromagnetic chains, the scale dependence of viscosity in ionic liquids, the diffusion of aromatic molecules in graphite, and short-range dynamics in comb- like polymers, where correlations over distances of 0.1 nm to 10 nm are important. To address the limitations of existing NSE instrumentation, the Institut Laue-Langevin (ILL) is building a major new instrument – WASP or Wide-Angle Spin Echo – that will be able to study motions of biological functional groups, diffusive dynamics, dynamics of molecular magnets, and dynamics of molecules confined in one or two dimensions. To achieve the same goals as WASP, we propose to design a compact device, based on high- temperature superconducting technology, which we developed for prior DOE-funded Phase I and II STTR projects. Our high-temperature superconducting Wollaston prisms have been used to build successful devices for Spin Echo Modulated Small Angle Scattering (SEMSANS), Larmor diffraction and phonon focusing.