Disappearance of Roton Propagation in Superfluid {sup 4}He at T{sub {lambda}}
- Atomic Energy Chalk Limited, Chalk River Laboratories, Chalk River, Ontario, (Canada) KOJ 1JO
- Netherlands Organization for Scientific Research (NWO), Den Haag (The Netherlands)
- Interuniversitair Reactor Instituut, Delft University of Technology, Mekelweg 15, 2629JB Delft (The Netherlands)
Using neutron scattering, we determine the dynamic structure factor {ital S}({ital q},{nu}) of liquid {sup 4}He for the roton wave number {ital q}=2.0{sup {minus}1} as a function of frequency {nu} at constant density 0.1715 gcm{sup {minus}3} and for ten temperatures in the range 1.08{le}{ital T}{le}2.00 K, primarily near the superfluid transition temperature {ital T}{sub {lambda}}=1.9202 K. The {lambda} transition is marked by a complete softening of the roton mode and a rapid decrease in lifetime. This change is continuous with temperature, and we find no evidence for a new mode appearing as one enters the superfluid phase, as has been proposed on the basis of theoretical considerations. {copyright} {ital 1996 The American Physical Society.}
- OSTI ID:
- 401147
- Journal Information:
- Physical Review Letters, Vol. 77, Issue 21; Other Information: PBD: Nov 1996
- Country of Publication:
- United States
- Language:
- English
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