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Abstracts
P2.31
Investigation of electric response in standing wave of first and second
sound
Tymofiy Chagovets
Institute of Physics of the Czech Academy of Sciences
We report an experimental investigation of the electric response of superfluid
helium that arises in an acoustic resonator in the presence of a first sound
standing wave. Previous experiments showed a strong correlation between the
resonance frequency of the electric response and the frequency of the second sound
resonance. In recent experiments we observed the appearance of an potential
difference on electrostatic probe whose resonance frequency is corresponded to the
frequency of the first sound resonance in the experimental range of temperature
(1.75 - 2.15K). It was found that the amplitude of the electric potential, ∆U, in
resonance is proportional to the amplitude of the pressure oscillations in the first
sound wave. Possible reasons of the electric response onset induced by first and
sound will be discussed.
P2.32
Solid helium study using elasticity-sensitive torsional oscillator under
DC rotation
Tsuiki tomoya(1,4), Takahashi daisuke(2,4), Murakawa satoshi(3,4), Kono
kimitoshi(4), Shirahama keiya(1,4)
1) Keio University, Department of Physics, Yokohama 223-8522
2) Ashikaga Institute of Technology, Department of General Education, Ashikaga
326-8558
3) University of Tokyo, Cryogenic Research Center, Bunkyo-ku 113-0032
4) RIKEN, Low Temperature Phys. Lab., Wako-shi 351-0198
Recent elastic measurement of solid
4
He under DC rotation shows the
insensitiveness of its elasticity to DC angular velocity, while the same rotation
condition makes the characteristic period change in solid-packed torsional
oscillator (TO) experiments. This contradiction must be due to the difference of
the AC velocity; TO method is done within 10-100 times larger AC velocity than
the elasticity measurements. To study the solid property under DC rotation in
large AC velocity, we employ a “floating core” TO (Reppy, JLTP2012) that is
sensitive to the elasticity of solid. This should reveal whether the “fast” elastic
response affects to the change in period of TO under rotation or not.
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