Finding a Neutrino Detector in the Deep Ocean: Acoustic Positioning for P-ONE

Synopsis

Neutrinos are tiny, nearly massless particles that interact so weakly with matter that trillions pass through our bodies every second without leaving a trace. Some of the highest-energy neutrinos are produced in extreme environments such as exploding stars, active galaxies, and regions surrounding black holes. Unlike charged cosmic rays, neutrinos travel in straight lines, and unlike light, they can escape from dense regions that would otherwise be hidden from view. This makes them valuable cosmic messengers, but also exceptionally difficult to detect. The Pacific Ocean Neutrino Experiment (P-ONE) aims to transform a cubic kilometre of deep ocean off Vancouver Island into a telescope capable of detecting these elusive particles. Its location in the Northeast Pacific will provide a complementary view of the sky to existing neutrino telescopes and help identify the sources of the universe’s most energetic particles.

Building a telescope in the deep ocean introduces an unusual challenge: its light sensors hang along flexible, kilometre-long cables that move with ocean currents. To determine where a neutrino came from, researchers must know where each sensor was located when the event occurred. My research is developing a framework that converts the measured travel times of underwater sound signals into a three-dimensional map of the detector as it moves, while also estimating how certain we are of each reconstructed position. Early laboratory and ocean tests have highlighted the importance of accounting for background noise, signal calibration, and uncertainty in the locations of the acoustic transmitters themselves. In this talk, I will introduce neutrino astronomy and P-ONE, describe the challenge of constructing a moving telescope on the seafloor, and show how my work is helping provide the detector geometry needed to trace detected neutrinos back toward their possible cosmic origins.