Quartz Tuning Fork: Thermometer, Pressure- and Viscometer for Helium Liquids

TL;DR

This paper investigates quartz tuning fork oscillators as sensitive thermometers, pressure sensors, and viscometers for helium liquids, analyzing their performance and response in normal and superfluid helium at very low temperatures.

Contribution

It provides a detailed analysis of quartz tuning forks' performance as sensors in helium liquids, including their quality factors and hydrodynamic response at millikelvin temperatures.

Findings

Q factors range from 10^5 to 10^6 in vacuum below 1.5 K

Sensor variability is large, requiring preselection for low-temperature use

Hydrodynamic response matches theoretical models in helium liquids

Abstract

Commercial quartz oscillators of the tuning-fork type with a resonant frequency of ~32 kHz have been investigated in helium liquids. The oscillators are found to have at best Q values in the range 10^5-10^6, when measured in vacuum below 1.5 K. However, the variability is large and for very low temperature operation the sensor has to be preselected. We explore their properties in the regime of linear viscous hydrodynamic response in normal and superfluid 3He and 4He, by comparing measurements to the hydrodynamic model of the sensor.