Neutron Scattering, Momentum Distributions and Final State Effects

1994 ◽  
Vol 376 ◽  
Author(s):  
Henry R. Glyde
Keyword(s):  
Neutron Scattering ◽  
Inelastic Neutron Scattering ◽  
Boltzmann Distribution ◽  
Inelastic Neutron ◽  
Single Atom ◽  
Final State ◽  
Quantum Liquids ◽  
Bose Liquid ◽  
Atomic Momentum ◽  
Sufficient Precision

ABSTRACTInelastic neutron scattering measurements of the atomic momentum distribution, the atomic kinetic energy and other single atom properties in quantum liquids and liquid neon are presented. The data were taken on the MARI instrument at ISIS and analyzed using a new method. The measurements have sufficient precision to show that n(k) in a normal Bose liquid differs significantly and unambiguously from the classical, Maxwell-Boltzmann distribution. The final state broadening function is also extracted from the data and found to be similar in liquid 3He and 4He.

Deep Inelastic Neutron Scattering Studies of Atomic Momentum Distributions in Condensed Argon and Neon

1993 ◽  
Vol 48 (1-2) ◽  
pp. 438-442
Author(s):  
M. A. Fradkin ◽  
S.-X. Zeng ◽  
R. O. Simmons
Keyword(s):  
Neutron Scattering ◽  
Wave Vector ◽  
Inelastic Neutron Scattering ◽  
Dynamic Structure ◽  
Inelastic Neutron ◽  
Longitudinal Momentum ◽  
Final State ◽  
Momentum Distribution Function ◽  
Atomic Momentum ◽  
Liquid Neon

Abstract Using deep inelastic neutron scattering, direct measurements have been made, i) of the dynamic structure factor of a series of condensed argon samples over the temperature range 18 to 85 K, near melting (for wave-vector transfers 12 to 26 Ä -1) and ii) of liquid neon, near 27 K (for wave-vector transfers 10.4 to 27.6 Ä -1). Neutron time-of-flight chopper spectrometers were employed. Single-particle kinetic energies, £ k , can be obtained from the analysis of the Doppler-broadened recoil spectrum of the target particles. For argon the temperature dependence of £ k can be compared to expectations from theory, from thermodynamic data, and from previous neutron scattering measurements on collective vibrational modes. For liquid neon the wave-vector-transfer dependence of J{y), the longitudinal momentum distribution function, is being analyzed for final-state effects.

Deep inelastic neutron scattering from quantum liquids

1987 ◽  
Vol 65 (11) ◽  
pp. 1393-1400 ◽  
Author(s):  
P. E. Sokol
Keyword(s):  
Neutron Scattering ◽  
Liquid Helium ◽  
Inelastic Neutron Scattering ◽  
Zero Point ◽  
Inelastic Neutron ◽  
Quantum Statistics ◽  
Quantum Liquids ◽  
Point Motion ◽  
Large Quantum ◽  
Microscopic Dynamics

Liquid helium has been studied for many years because of its unusual properties. The large quantum zero-point motion and the quantum statistics of the particles have a strong effect on the behavior of the liquid. Deep inelastic neutron scattering provides a unique tool for studying the microscopic dynamics of these systems. The results of recent experiments on both liquid 3He and 4He are discussed.

Single-particle dynamics of the solid heliums from deep inelastic neutron scattering

1987 ◽  
Vol 65 (11) ◽  
pp. 1401-1408 ◽  
Author(s):  
R. O. Simmons
Keyword(s):  
Neutron Scattering ◽  
Single Particle ◽  
Inelastic Neutron Scattering ◽  
Solid Helium ◽  
Dynamic Structure ◽  
Inelastic Neutron ◽  
Hexagonal Close Packed ◽  
Theoretical Predictions ◽  
Atomic Momentum ◽  
Particle Property

Previous neutron-scattering research on solid heliums has been restricted to small momentum transfers, Q, both by large Debye–Waller factors and by scientific interest being restricted to collective modes and their interactions. It has also been limited by insufficient sources of neutron beams of about an electronvolt in energy, which are required to apply the method of deep inelastic scattering to solids. Making use of a spallation neutron source and a suitable chopper spectrometer, one can now collect data in which the dynamic structure factor S(Q,E) directly reflects the atomic-momentum distribution n(p). For 4He, the major determining factor on this single-particle property is the density of the sample, not its microscopic structure. At a strictly constant number density, samples of hexagonal close-packed (hcp), body-centered cubic (bcc), and normal liquid show identical S(Q,E)'s for Q's near 200 nm−1, at current levels of precision. The case of bcc 4He is used to illustrate the method, and the derived kinetic energy is compared with theoretical predictions. The applicability of these results in other areas of solid-helium physics is indicated.

Anomalous vibrational modes in acetanilide as studied by inelastic neutron scattering

1992 ◽  
Vol 2 (10) ◽  
pp. 1929-1939 ◽  
Author(s):  
Mariette Barthes ◽  
Juegen Eckert ◽  
Susanna W. Johnson ◽  
Jacques Moret ◽  
Basil I. Swanson ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Vibrational Modes
Sign in / Sign up

Export Citation Format

Share Document