Lifetimes of Fast R+ Rotons due to Scattering by Thermal Phonons in Superfluid 4He
| ISSN: |
1573-7357
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| Source: |
Springer Online Journal Archives 1860-2000
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| Topics: |
Physics
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| Notes: |
Abstract We have injected R + rotons into superfluid 4 He at low temperatures (0.05K〈T〈0.25K), and measured the attenuation of roton → atom quantum evaporation signals with increasing liquid temperature. The most important cause of this attenuation is the interaction of the rotons with thermal phonons via the R + p → R′ + p′ process. As the liquid temperature is increased, we find that the fastest rotons are attenuated more than the slower rotons. This corresponds to a scattering rate which increases with roton velocity due to the increasing density of final states. We have modelled the attenuation using Landau and Khalatnikov's expression for the interaction between rotons and phonons. This yields the observed behaviour of the roton mean free path as a function of velocity. The mean free paths and lifetimes of the fastest rotons are ≍ two orders of magnitude shorter than those of the slowest rotons observed.
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| Type of Medium: |
Electronic Resource
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| URL: |