Momentum density of hcp and liquid helium-4 by inelastic neutron scattering

Thesis/Dissertation · Sat Jan 01 04:00:00 EST 1983

DOI:https://doi.org/10.2172/5643034· OSTI ID:5643034

Hilleke, Russell Otto ^[1]

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1. Univ. of Illinois, Urbana-Champaign, IL (United States)

A measurement of the momentum density in hcp and liquid ⁴He by inelastic neutron scattering is reported. Using the Low Resolution Medium Energy Chopper Spectrometer at the Intense Pulsed Neutron Source at Argonne National Laboratory, momentum transfers in the range 12 to 22.5 A^-1 were attained. At these momentum transfers, the momentum density of the sample is related to the dynamic structure factor by the impulse approximation. The measured momentum distribution is Gaussian and the kinetic energy is larger than proposed by existing theories. Data were taken on two solid samples, the first was a 19.45 cm³mole hcp solid, the second was 18.20 cm³ mole; both solid samples were maintained at 1.70 K during data collection. Data were also taken on a liquid sample with a molar volume of 18.20 cm³mole at 4.00 K. At 1.70 K the two solid samples are essentially in their ground states so that the measurement is of the ground state momentum density. The liquid sample was included to see if the difference between the liquid and solid momentum density at the same molar volume was observable.

• Research Organization: Univ. of Illinois, Urbana-Champaign, IL (United States)
• Sponsoring Organization: USDOE Office of Energy Research (ER)
• DOE Contract Number: AC02-76ER01198
• OSTI ID: 5643034
• Report Number(s): DOE/ER/01198--1403; ON: DE84000468
• Country of Publication: United States
• Language: English

Related Subjects

640450 -- Fluid Physics-- Superfluidity
654003* -- Radiation & Shielding Physics-- Neutron Interactions with Matter
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DATA
DIFFRACTION
ELEMENTS
ENERGY TRANSFER
EXPERIMENTAL DATA
FLUIDS
GASES
HCP LATTICES
HELIUM
HEXAGONAL LATTICES
IMPULSE APPROXIMATION
INELASTIC SCATTERING
INFORMATION
LIQUIDS
MEASURING INSTRUMENTS
MOMENTUM TRANSFER
NEUTRON DIFFRACTION
NEUTRON SPECTROMETERS
NONMETALS
NUMERICAL DATA
RARE GASES
SCATTERING
SOLIDS
SPECTROMETERS
STRUCTURE FACTORS
TIME-OF-FLIGHT SPECTROMETERS
ULTRALOW TEMPERATURE