Belgian-born American physicist Francis Halzen has won the 2026 Nobel Prize in Physics for his decisive contributions to the IceCube Neutrino Observatory.

The Royal Swedish Academy of Sciences announced the prize on October 6. It honours Halzen’s work on the discovery of high-energy neutrinos of astrophysical origin.

Halzen, 82, is a professor at the University of Wisconsin-Madison. His crucial insight was to use a huge volume of exceptionally clear Antarctic ice as the detector itself.

IceCube contains 5,160 light sensors spread through roughly a cubic kilometre of ice beneath the South Pole. In November 2013, it reported 28 very high-energy neutrino events, the first solid evidence of cosmic neutrinos.

The collaboration spans about 450 scientists from 58 institutions in 14 countries. An upgrade adding more than 600 new sensors is expected to yield its first science data later in 2026.

Halzen’s proposal began in the 1980s and required scientists and funding agencies to accept substantial scientific risk. The US National Science Foundation supported the project for over two decades.

The Nobel recognises the creation of a new investigative capability. Researchers are now pursuing IceCube Gen2, which would expand the detector to eight times its current volume.