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 moduli 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) has built 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 similar goals to the ILL WASP, we propose to design an inexpensive compact WASP device (I-WASP), based on high-temperature superconducting technology, which we developed for prior DOE Phase I and II STTR projects. Our high-temperature superconducting Wollaston prisms were used to build successful devices for Spin Echo Modulated Small Angle Scattering (SEMSANS), Larmor diffraction and phonon focusing all of which use Larmor labelling in the same way as NSE. We tested these devices at a pulsed spallation source (ISIS in the U.K.), and installed them on a triple axis spectrometer at HFIR at ORNL. Based on our Phase I work, we now propose the construction of a prototype I-WASP module in Phase II suitable for a polarized-neutron beam line at a pulsed neutron source. Commercial Applications and Other Benefits: Installed at one of the U.S. national neutron scattering centers, the proposed instrument will provide U.S. researchers with data, currently available to European scientists. The new I-WASP tool will allow detailed studies of structural fluctuations in a range of materials of direct relevance to important technologies, such as communication, energy storage and medicine. Data obtained with the new I-WASP tool will provide researchers with a better understanding of material properties. This gained understanding would assist or enable development of new technologies. We expect that the new instrument will be installed at neutron scattering centers in the U.S. and could also be sold to laboratories in other countries.