The measurement of atomic momentum distributions can provide detailed microscopic information on the single particle density matrix. The quantum liquids, helium three and helium four, provide an interesting and technically easy system in which to study the momentum distribution. They are an extreme example of liquids where both quantum zero point motion and quantum statistics dominate the behavior. The bulk liquids have been extensively studied theoretically. Calculations have also been made for the mixed Boson-Fermion system of helium three-helium four. Recently, the properties of liquid helium three and helium four in confined geometries have received considerable attention. The restricted geometries extend the liquid phase well into the region where the bulk solid is stable. Surface solid layers play an important role, especially in helium three where a ferromagnet transition has been observed in the surface solid layer. Professor Sokol proposes to use high energy inelastic neutron scattering to study the properties of the momentum distribution in liquid helium four, helium three, helium three- helium four mixtures, and in restricted geometries. Measurements of the width of the momentum distribution will be used to study the local environment of the particles as a function of temperature and pressure. For restricted geometries the momentum distribution can be used to extract information on the molecules bound to the surface as well. Work will be carried out using existing spectrometers at Argonne National Laboratory and Rutherford Appleton Laboratory, in the United Kingdom, as well as a newly constructed dedicated spectrometer at Argonne.

Agency
National Science Foundation (NSF)
Institute
Division of Materials Research (DMR)
Application #
8704288
Program Officer
E. Diane Ruffner
Project Start
Project End
Budget Start
1987-06-01
Budget End
1988-07-31
Support Year
Fiscal Year
1987
Total Cost
$41,500
Indirect Cost
Name
Harvard University
Department
Type
DUNS #
City
Cambridge
State
MA
Country
United States
Zip Code
02138