Beneath the waves off Vancouver Island, scientists are planning a vast new observatory to explore the universe from the depths of the Pacific. The project, called the Pacific Ocean Neutrino Experiment (P-ONE), will hunt for high-energy neutrinos, elusive particles that fly through stars, planets, and even our bodies without leaving a trace. The goal is to detect these particles and uncover new insights into the extreme processes that shape the universe. 

Neutrinos are nearly impossible to catch, but when one collides with a water molecule it produces a faint blue glow called Cherenkov radiation. To detect that glow, scientists will deploy vertical strings studded with glass spheres, each holding a light-sensitive photomultiplier tube. Anchored to the seafloor and held upright by buoys, these strings form a towering underwater array. Together they turn a cubic kilometre of seawater into a neutrino detector. 

“These signals allow us to reconstruct where a neutrino came from and how much energy it carried,” says Dr. Nahee Park, Physics, Engineering Physics & Astronomy, and a member of the Queen’s based Arthur B. McDonald Canadian Astroparticle Physics Research Institute (McDonald Institute). “It’s like catching a message straight from the most extreme places in the universe.”
 

From Nobel discovery to ocean depths

The modern hunt for neutrinos traces back to Nobel Prize-winning research at Queen’s, where Dr. Arthur McDonald and the Sudbury Neutrino Observatory proved neutrinos have mass and stream from the sun. That breakthrough inspired the development of inventive ways to detect them. At SNOLAB in Sudbury, scientists built underground detectors shielded from cosmic interference, while international teams created the IceCube Observatory by embedding thousands of sensors in Antarctic ice. Now, with P-ONE, researchers are turning to the depths of the Pacific Ocean to open the next frontier in neutrino discovery.

Catching neutrinos requires scale. Trillions pass through Earth every second, created in vast numbers by cosmic phenomena such as exploding stars and black holes. Because they carry no electric charge and have almost no mass, they almost never interact with matter. That makes them extraordinarily difficult to detect but also powerful messengers. Unlike light or charged particles, neutrinos travel in straight lines without being deflected or absorbed. Tracing them can allow scientists to map the most extreme objects in the universe. 

(Left) The full detector with seven clusters. (Right) A single cluster showing 10 mooring lines anchored to the seafloor (Credit: K. Holzapfel/TUM).

“Water is an ideal medium because it lets the light from Cherenkov radiation travel across the huge distances we need,” says Dr. Ken Clark, Physics, Engineering Physics & Astronomy. “By placing detectors far below the surface, we can reduce background noise and focus on signals from neutrinos themselves.”
 

Collaboration across continents

The McDonald Institute, based at Queen’s University, plays a central role as Canada’s network for astroparticle physics research. It provides engineering expertise, supports students and postdoctoral researchers, and coordinates the Canadian contribution to P-ONE. As part of that work, researchers are testing hundreds of photomultiplier tubes to evaluate their properties and ensure they can accurately record light signals. These sensors are the heart of the detector, and the team will lead the effort to prepare them for deployment.

P-ONE brings together more than 18 institutions from Germany, Poland, the United Kingdom, the United States, with six based in Canada. A key partner is Ocean Networks Canada, a national observatory that operates permanent seafloor infrastructure off the Pacific coast. Its network of undersea cables already supplies power and high-speed data links to instruments on the ocean floor, giving P-ONE the infrastructure it needs to function as a detector.

“It is incredible to be part of a project that connects so many people across countries and disciplines,” says Dr. Clark. “When we work together on something this ambitious, it feels like we are expanding what science can accomplish.”
 

A vision for discovery

In the years ahead, P-ONE could reveal new sources of high-energy neutrinos and reshape our understanding of the universe. The results may deepen what is known about neutrinos and uncover surprises no other observatory has yet seen.

“The dream is to find a source we didn’t know about before,” says Dr. Park. “Even if we simply add new data, it will be a huge contribution to science.”

Learn more about the Pacific Ocean Neutrino Experiment.