Pressure dependent attenuation peaks for quartz tuning forks in superfluid 4He at mK temperatures

27th International Conference on Low Temperature Physics

Tuoriniemi, J.T.^1 ; Manninen, M.S.^1 ; Rysti, J.^1

Low Temperature Laboratory, O.V. Lounasmaa Laboratory, Aalto University, Aalto

FI-00076, Finland^1

关键词: Internal dissipation;    Millikelvin temperatures;    Moving objects;    Pressure-dependent attenuation;    Quartz tuning fork;    Resonance frequencies;    Thermal excitation;    Very low temperatures;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/568/1/012023/pdf
DOI  :  10.1088/1742-6596/568/1/012023

来源: IOP

【 摘 要 】

Pure superfluid4He at very low temperatures is thought to be free of mechanisms producing dissipation for slowly moving objects, and the superfluid merely contributes an effective mass to the motion without any anticipated dependence on temperature below 0.1 K. To our great surprise, we found that the smallest commercially available quartz tuning fork oscillators with tines shorter than 2 mm and resonance frequency 32 kHz experienced attenuation by as much as 100 times more than the internal dissipation of the oscillator at certain values of pressure at millikelvin temperatures in superfluid4He. These features smeared out at temperatures above 20 mK, although practically no thermal excitations in4He are yet present. Another fork somewhat larger showed indication of similar anomalies as well, but at greatly lesser scale.