Belgian-American physicist Francis Halzen has won the 2026 Nobel Prize in Physics for his work on the IceCube Neutrino Observatory.

The Royal Swedish Academy of Sciences cited him "for decisive contributions to the IceCube Neutrino Observatory and the discovery of high-energy neutrinos of astrophysical origin". The announcement was made on October 6.

Halzen, 82, is a professor at the University of Wisconsin-Madison. He first proposed using Antarctic ice to detect neutrinos in 1988. IceCube, a cubic kilometre of ice wired with light sensors at the South Pole, was completed in December 2010.

In 2013, IceCube detected the first high-energy neutrinos from beyond the solar system. Neutrinos are ghost-like particles that pass through matter almost untouched, so they point straight back to the violent cosmic events that produced them.

Halzen is the first sole physics laureate since 1992. He keeps the full prize of 12 million Swedish kronor, about $1.2 million. He spoke to the Nobel Committee by phone from Italy, where he was travelling. The medals will be presented by Sweden's king in Stockholm on December 10.