Francis Halzen, Belgian physicist based in U.S., awarded Nobel prize for pioneering work on neutrinos | CBC News

Francis Halzen helped develop the IceCube Neutrino Observatory in Antarctica

Belgian American particle physicist Francis Halzen was announced as the winner of the 2026 Nobel Prize in Physics on Tuesday in Stockholm.

Halzen realized that ice at the South Pole could be used to track ‌neutrinos, sometimes known as "ghost particles" for the way they pass through the Earth and our bodies without a trace, only interacting with matter extremely rarely.

The winners ⁠of the ⁠Nobel ‌physics prize are selected annually by the Royal Swedish Academy of Sciences ⁠and receive a prize totalling 12 million Swedish ‌crowns ($1.7 million Cdn).

The IceCube, which covers an entire cubic kilometre, became operational in 2011 — the culmination of a vision for the South Pole observatory, the academy said, that began in the late 1980s.

Halzen, affiliated for several decades with the University of Wisconsin–Madison in the U.S., told the academy by phone he was "delighted" and "surprised" by the announcement, which came as he was attending a conference in Italy.

Scientists can't glimpse the mysterious ghost particles on their own. Instead, they measure what happens when the tiny particles collide with other bits of matter, producing flashes of light or charged particles.

A view of the IceCube Neutrino Observatory at the South Pole is seen in this undated handout image. (Marc Jacquart/IceCube/NSF/Reuters)

Halzen studied a rare gang of neutrinos that scientists consider messengers from the cosmos, offering clues to how the universe evolved.

An extension, IceCube-Gen2, encompassing eight cubic kilometres of ice, is planned to become operational in 2033 and will be able to detect 10 times as many neutrinos, including much weaker ones.

"The real excitement is that I cannot answer that question yet," he said. "This is just ⁠an introduction to the science, the astronomy is still to come."

The discovery of neutrino oscillations was recognized by the Swedish academy in 2015, with Canadian scientist Dr. Arthur McDonald sharing in the Nobel physics prize that year.