Creation and identification of R sup minus rotons in liquid sup 4 He and an estimate of their probability for quantum evaporation

Journal Article · Mon Jul 16 04:00:00 EDT 1990 · Physical Review Letters; (USA)

DOI:https://doi.org/10.1103/PhysRevLett.65.345· OSTI ID:6707923

Wyborn, G M; Wyatt, A F.G. ^[1]

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1. Department of Physics, University of Exeter, Stocker Road, Exeter EX44QL (United Kingdom)

A beam of {ital R}{sup {minus}} rotons, i.e., rotons which have oppositely directed group velocity and momentum, is reated by condensing an atom beam onto the surface of liquid {sup 4}He. {ital R}{sup {minus}} rotons are identified by quantum evaporation and their time of flight. Measured signal shapes agree well with those modeled. Signal sizes are compared with those from atoms specularly reflected from the He surface, from which it is estimated that the quantum efficiency for the condensation or evaporation process is high and of the order of 0.5 for angles of incidence where mainly rotons are created. {ital R}{sup {minus}} rotons can specularly reflect from a solid-liquid He interface with high probability, if the interface is particularly good.

• OSTI ID: 6707923
• Journal Information: Physical Review Letters; (USA), Journal Name: Physical Review Letters; (USA) Vol. 65:3; ISSN PRLTA; ISSN 0031-9007
• Country of Publication: United States
• Language: English

Related Subjects

640450* -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ATOMIC BEAMS
BEAMS
DATA
DISPERSION RELATIONS
EFFICIENCY
EVAPORATION
EVEN-EVEN NUCLEI
EXPERIMENTAL DATA
HELIUM 4
HELIUM ISOTOPES
INFORMATION
INTERFACES
ISOTOPES
LIGHT NUCLEI
NUCLEI
NUMERICAL DATA
PHASE TRANSFORMATIONS
PHONONS
PROBABILITY
QUANTUM EFFICIENCY
QUASI PARTICLES
ROTONS
STABLE ISOTOPES
VAPOR CONDENSATION