Neutron studies of liquid and solid helium
The progress made during 5/1/86--4/31/87 under contract No. F902- 34ER45082 is reported. The validity of the Impulse Approximation (IA) to the dynamic form factor, S(Q,{omega}), has been investigated using realistic models of solid helium. The calculations suggest that the IA can be used to obtain the momentum distribution, n(p), within 1% at Q {approx} 30 {Angstrom}{sup {minus}1}, if S(Q,{omega}) is first symmetrized about the recoil frequency, {omega}{sub R}. For solid helium under pressure (e.g. 5 kbar) a Q {approx gt} 50 {Angstrom} {sup {minus}1} is required. The S(Q,{omega}) in liquid {sup 3}He and {sup 4}He in the wave vector transfer range 3 {le} Q {le} 10 {Angstrom}{sup {minus}1} has been evaluated, beginning from the pair potential. The general shape and width of S(Q,{omega}) obtained agrees well with existing experiment. The width of S(Q,{omega}) is found to oscillate as a function of Q in {sup 4}He but not in {sup 3}He. The dynamics of atoms adsorbed in solid layers on surfaces has been studied using self-consistent methods.
- Research Organization:
- Delaware Univ., Newark, DE (USA). Dept. of Physics
- Sponsoring Organization:
- DOE/ER
- DOE Contract Number:
- FG02-84ER45082
- OSTI ID:
- 6211287
- Report Number(s):
- DOE/ER/45082-T3; ON: DE91006311; TRN: 91-002020
- Country of Publication:
- United States
- Language:
- English
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Neutron studies of liquid and solid helium: Progress report, May 1, 1987-April 30, 1988
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