Neutron Scattering Studies of Quantum Systems

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9624762 Sokol Neutron scattering studies of quantum systems will be carried out in this research project. The behavior of the condensed phases of quantum liquids and solids, such as helium and hydrogen, are dominated by quantum and statistical effects which are responsible for many unique properties such as superfluidity. More recently, confinement of these systems in restricted geometries has shown that the properties can be substantially different from the bulk. Elastic and inelastic neutron scattering will be used to probe the microscopic structure and dynamics of these phases. This work will focus on the helium isotopes (3He and 4He), isotopic mixtures (3He-4He), and hydrogen (H2) where the properties of the condensed phase are dominated by quantum effects. Elastic and total neutron scattering measurements will provide information on the spatial correlation's. Inelastic neutron scattering measurements will be used to study diffusive motion, collective excitations, and the one-body density matrix. (momentum distribution). Measurements will be carried out in both bulk systems and for liquids and solids in confined geometries such as porous Vycor glass, aerogels and solgels, and zeolites. %%% Neutron scattering studies of quantum systems will be carried out in this research project. Quantum solids and liquids, such as helium and hydrogen to be studied, provide a useful model system for studying many of the quantum effects that are found in metals, superconductors, and magnetic materials. However, they do not suffer the same materials preparation problems so that the central physical principles are more easily extracted. Elastic and inelastic neutron scattering will be used to probe the microscopic structure and dynamics of these solid and liquid phases. These measurements will provide information on the static and dy namic interaction of helium atoms and hydrogen molecules in the condensed phases. This work will focus on the helium isotopes (3He and 4He), isotopic mixtures (3He- 4He), and hydrogen (H2) in both the bulk phases and in confined geometries. ***