This three-year award supports U.S.-U.K. cooperative research in condensed matter physics between Paul A. Sokol of Pennsylvania State University and William G. Stirling of the University of Keele in Staffordshire, United Kingdom. The investigators propose to conduct a series of neutron scattering investigations of quantum liquids. The collaboration will take advantage of unique neutron scattering instrumentation at ISIS (Rutherford Appleton Laboratory) and the IPNS pulsed neutron sources (Argonne National Laboratory). They will study systems where quantum effects dominate the microscopic properties, as well as the final state effects in liquid helium, the properties of liquid helium mixtures and the effects of restricted geometries on the momentum distribution of liquid helium. Both the U.S. and British investigators bring to this collaboration their experimental expertise and will jointly conduct with their students the measurements and the data analysis. The British instrument has the capabilities for measuring momentum distributions in quantum liquids. This will be complemented by temperature, pressure and concentration measurements on the Argonne spectrometer. Liquid helium is an important element in superconductivity. Quantum effects dominate the behavior in helium's condensed phases and are responsible for its unique properties such as superfluidity. Through studies of momentum distribution, the investigators will gain a unique view and significant insight into the microscopic dynamics of these systems. The proposed joint studies represent detailed investigations of momentum distribution in liquids and will add substantially to our knowledge.
