До природи вузької ротонної лінії поглинання в спектрі дискового НВЧ резонатора

We calculate the probability of the creation of a circular phonon (c-phonon) in He II by a c-photon of the resonator. It is shown that this probability has sharp maxima at frequencies, where the effective group velocity of the c-phonon is equal to zero; the density of states of c-phonons strongly gr...

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Bibliographic Details
Date:2022
Main Authors: Loktev, V.M., Tomchenko, M.D.
Format: Article
Language:English
Published: Publishing house "Academperiodika" 2022
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Online Access:https://ujp.bitp.kiev.ua/index.php/ujp/article/view/2022154
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Journal Title:Ukrainian Journal of Physics

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Ukrainian Journal of Physics
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Summary:We calculate the probability of the creation of a circular phonon (c-phonon) in He II by a c-photon of the resonator. It is shown that this probability has sharp maxima at frequencies, where the effective group velocity of the c-phonon is equal to zero; the density of states of c-phonons strongly grows at such frequencies. For He II, these frequencies correspond to a roton and a maxon. From theprobability of the c-roton creation, we calculate the roton line width which is found to approximately agree with the experimental one. We conclude that the roton line observed in the super-high-frequency (SHF) absorption spectrum of helium is related to the creation of c-rotons. A possible interpretation of the Stark effect observed for the roton line is also proposed.