Abstract:

This dissertation describes experiments with superfluid 4 He diaphragm-aperture oscillators that have been configured to act as sensitive detectors of rotation. The goal of this thesis was to increase the rotational sensitivity of the newly developed superfluid 4 He phase slip gyroscope in an effort to understand the intrinsic mechanisms that might ultimately limit the sensitivity of this class of device. Four separate devices were built and tested using two different methods of analysis. Two of these experimental cells demonstrated a sensitivity to rotation, culminating with a large area multi-turn device with a sensing loop area that is 2 orders of magnitude larger than our original proof-of-principle prototype. The sensitivity of this device exceeds any other superfluid 4 He gyroscope by a factor of ~25. In addition, this rotation sensor has excellent long term stability and we have found no fundamental mechanisms that will prevent even further improvements. On the other hand, the two devices that failed as gyroscopes provided useful insight into the characteristics that make certain apertures better suited than others for these phase slip experiments. Detailed numerical simulations were used to interpret and analyze our data within the framework of the thermal nucleation theory for the creation of vortices. The formulism developed here also provides a methodology for characterizing the sensitivity of future devices operating in a noisy rotational environment.