• Creation evidence of the second non-dispersive Zakharenko wave by helium atomic beams in superfluid helium-II at low temperatures

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      https://www.ias.ac.in/article/fulltext/pram/069/04/0617-0629

    • Keywords

       

      Liquid helium-II; low temperatures; bulk elementary excitations; 4He-atomic beams.

    • Abstract

       

      In this work, the experimental results of the creation of the second non-dispersive Zakharenko wave ($C_{ph} = C_{g} \neq 0$) in the negative roton branch (the so-called second sound) of the bulk elementary excitations (BEEs) energy spectra are introduced. Several BEE signals detected by a bolometer situated in the isotopically pure liquid helium-II at low temperatures $\sim 100$ mK are shown, which give evidence of negative roton creation in the liquid by helium atomic beams striking the liquid surface. The negative roton signals were clearly distinguished by the following ways: the negative roton signal created by helium atomic beams appeared earlier than the positive roton signal created by the beams, and presence of both positive and negative roton signals together. It is natural that the negative roton creation by the beams requires the 4He-atom energies $\sim 12$ K, while the positive roton creation by the atomic beams requires energies $\sim 35$ K. Therefore, successive increase in the heater power resulting in an increase in the 4He-atom energies gives solid evidence that the negative rotons are first created in the liquid by the helium atomic beams.

    • Author Affiliations

       

      A A Zakharenko1

      1. International Institute of Zakharenko Waves, 660037, Krasnoyarsk-37, 17701, IIZWs, Krasnoyarsk, Russia
    • Dates

       
  • Pramana – Journal of Physics | News

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