Francis Halzen wins 2026 Nobel Prize in Physics for IceCube neutrino research

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

Halzen, 82, is a professor at the University of Wisconsin–Madison and principal investigator of IceCube, an observatory embedded deep in Antarctic ice. The detector uses thousands of light sensors spread through a cubic kilometre of ice to record rare flashes produced when neutrinos collide with atomic nuclei.

Neutrinos are electrically neutral particles with very little mass that usually pass through matter without leaving a trace. Those arriving from distant, high-energy events can carry information about the environments that produced them. IceCube made the first detection of high-energy extraterrestrial neutrinos in 2013, opening another way to study the universe alongside electromagnetic radiation and gravitational waves.

Halzen first proposed using South Pole ice as a neutrino detector in the 1980s. The academy said his vision and scientific leadership were fundamental to the observatory.

“It was a great surprise, and I obviously didn’t expect it,” Halzen said by telephone after the announcement. He added that he hoped the award would reflect on the people who joined the project in its early years.

The prize includes 12 million Swedish kronor, about $1.2 million, as well as a medal and diploma.