The Andreev reflection of rotons at the free surface of liquid {sup 4}He

Journal Article · Thu Apr 01 04:00:00 EST 1993 · Bulletin of the American Physical Society

OSTI ID:243890

Baddar, H; Pettersen, M S; Edwards, D O ^[1]

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1. and others

A.F. Andreev first noted, in 1964, that quasiparticles reflected from a boundary in a superconductor could have all three velocity components change sign. Later, I. lguchi, G. Ihas, and others have calculated a similar effect for excitations in superfluid {sup 4}He. The authors have observed the Andreev reflection of rotons with positive group velocity (R{sup +}) to rotons with negative group velocity (R{sup {minus}}). Assuming conservation of energy and transverse momentum, rotons from point source (a heater) which are Andreev reflected at the free surface are focussed on to a line perpendicular to the surface and passing through the heater. A bolometer moving parallel to the surface, across the focussing line, detects a peak in the signal intensity. Both bolometer and heater (which can be used interchangeably) were made of graphite strips on which fibrous polyaniline was grown. The polyaniline was intended to increase the roton creation and detection efficiencies. The authors have not yet observed the reverse process, the reflection of R{sup {minus}} to R{sup +}.

• OSTI ID: 243890
• Report Number(s): CONF-9304297--; CNN: Grant DMR 8905385
• Journal Information: Bulletin of the American Physical Society, Journal Name: Bulletin of the American Physical Society Journal Issue: 2 Vol. 38; ISSN BAPSA6; ISSN 0003-0503
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
HELIUM 4
REFLECTION
ROTONS
SURFACES