Development of a superconducting RF flipper

A recent report by the Basic Energy Sciences Advisory Committee entitled “Challenges at the Frontiers of Matter and Energy” pointed to the need to better understand hierarchical and heterogeneous materials, often at the mesoscopic scale. Such structures can be studied by x-ray and neutron scattering techniques, but they do not generally yield narrow signals in momentum or energy space. The natural way to probe the structure and dynamics of such systems is in terms of the space and time dependence of density correlations within the material. While this need is partially met by Neutron Spin Echo (NSE), and by Spin Echo Small Angle Neutron Scattering (SESANS), no technique is currently able to simultaneously probe both the space and time dependence of the density-density correlation function of materials, over a wide range of length and time scales. General statement of how this problem is being addressed. We have recently developed and built a compact apparatus, which allows static spatial correlation to be measured over length scales, ranging between a few nanometers and several microns. Scattering samples can be placed in any environment, including high magnetic fields, allowing a wide range of materials and thermodynamic parameters to be studied. In its present form, the apparatus, called the double Wollaston prism, is not able to measure the time dependence of density fluctuations. A relatively simple modification to the device, which combines one or two, high-temperature-superconducting (HiTc), radio-frequency (RF) flippers and the HiTc Wollaston prisms, will allow this goal to be met. We propose to design and build a superconducting HiTc, high-frequency, resonant RF flipper for neutrons, which exceeds the currently available RF flipper technology, and would allow us to address scientific questions at the forefront of modern material science. Commercial Applications and Other Benefits By combining the ability to probe both the spatial and time dependence of density fluctuations simultaneously, within a wide range of hierarchical and disordered meso-scale materials, the proposed instrument will open new fields of material science studies. Possibilities include visualizing precipitate coarsening in metal alloys, cavity growth in fatigued metals and ceramics, as well as many aggregation and self-assembly phenomena. Applications are in petrochemicals (colloidal and aggregate dynamics), biotechnology and medicine (membranes, macromolecules), and industry (metallurgy, ceramics, polymers, electrolytes in fuel cells, magnetic sensors and memory). The device we build will exceed the capabilities of existing RF flippers and may be used to replace them on a range of existing neutron instrumentation around the world.