Position Reconstruction of Bubble Formation in Liquid Nitrogen using Piezoelectric Sensors

TL;DR

This paper introduces a novel technique using piezoelectric sensors to detect and accurately locate bubble formation in liquid nitrogen, aiding in cryogenic detector diagnostics and heat dissipation monitoring.

Contribution

The study develops a new method employing piezoelectric sensors and TDOA-based algorithms for precise bubble localization in cryogenic liquids, with high accuracy and systematic error analysis.

Findings

Achieved 95.8% convergence rate in bubble position reconstruction.

Reconstructed bubble positions within +/-0.5cm accuracy.

Identified systematic errors near liquid surface boundaries.

Abstract

Cryogenic liquids, particularly liquid xenon and argon, are of interest as detector media for experiments in nuclear and particle physics. Here we present a new detector diagnostic technique using piezoelectric sensors to detect bubbling of the liquid. Bubbling can indicate locations of excess heat dissipation e.g., in immersed electronics. They can also interfere with normal event evolution by scattering of light or by interrupting the drift of ionization charge. In our test apparatus, four sensors are placed in the vacuum space of a double-walled dewar of liquid nitrogen and used to detect and locate a source of bubbling inside the liquid volume. Utilizing the differences in transmitted frequencies through the different media present in the experiment, we find that sound traveling in a direct path from the source to the sensor can be isolated with appropriate filtering. The location of the source is then reconstructed using the time difference of arrivals (TDOA) information. The reconstruction algorithm is shown to have a 95.8% convergence rate and reconstructed positions are self-consistent to an average +/-0.5cm around the mean in x, y, and z. Systematic effects are observed to cause errors in reconstruction when bubbles occur very close to the surfaces of the liquid volume.