Nobel Prize in Physics awarded to Francis Halzen for IceCube neutrino discovery

Belgian-born physicist Francis Halzen has won the 2026 Nobel Prize in Physics for his decisive contributions to the IceCube Neutrino Observatory and the discovery of high-energy neutrinos of astrophysical origin, the Royal Swedish Academy of Sciences announced on Tuesday.

Halzen, a professor at the University of Wisconsin-Madison, was recognised for his scientific vision and leadership in developing IceCube, a giant neutrino detector embedded in about a cubic kilometre of Antarctic ice at the South Pole.

Neutrinos are extremely elusive particles that can pass through the Earth and human bodies largely undetected. Because they carry no electric charge, they are not deflected by magnetic fields and can travel across the universe without changing direction or losing energy.

This makes high-energy neutrinos valuable to astronomers trying to understand some of the universe's most violent environments.

Halzen first presented his vision of detecting neutrinos at the South Pole in 1988. When a neutrino interacts with an atomic nucleus in the ice, it can produce a flash of light that is recorded by IceCube's sensors.

The Antarctic ice offered several advantages for such an observatory, including its clarity, geological stability and relatively low levels of interference.

Preliminary tests of sensors in the ice began a few years after Halzen proposed the idea. IceCube was completed in 2011 and covers about one cubic kilometre of ice.

Researchers subsequently detected high-energy neutrinos and were able to establish that some originated far beyond the solar system, opening a new avenue for studying the universe.

“Francis Halzen has led an international team of researchers and engineers who have provided us with a fantastic instrument. His tenacity and scientific vision has paved the way for a new kind of astronomy,” Mark Pearce, Chair of the Nobel Committee for Physics, said.

The observations could help scientists understand the extreme environments where high-energy neutrinos are produced and potentially reveal previously unknown cosmic phenomena, the academy said.

Halzen, born in 1944 in Tienen, Belgium, received his PhD from KU Leuven in 1969 and is a professor at the University of Wisconsin-Madison.

The Nobel Prize carries an award of 12 million Swedish kronor.