Belgian-American particle physicist Francis Halzen has been awarded the 2026 Nobel Prize in Physics by the Royal Swedish Academy of Sciences for his pioneering work on the IceCube Neutrino Observatory. The $1.2 million prize recognizes his decisive contributions to the observatory and the discovery of high-energy neutrinos of astrophysical origin.

Born on March 23, 1944, in Tienen, Belgium, Halzen earned an MSc in Physics in 1966 and a PhD in 1969 from the Catholic University of Leuven, later passing his Agrégé de l'Enseignement Supérieur in 1972. He worked as a scientific associate at CERN between 1969 and 1971 before joining the University of Wisconsin-Madison in 1972, where he serves as the Hilldale and Gregory Breit Distinguished Professor.

In 1988, Halzen suggested using the vast, clear ice at the South Pole to detect neutrinos, or "ghost particles," that pass through the Earth without a trace. Following early work on the AMANDA project starting in 1987, he secured international funding to begin construction in 2005 on the IceCube Neutrino Observatory, which spans one cubic kilometer of ice near the Amundsen-Scott South Pole Station and became fully operational in 2010.

In 2013, IceCube made the first clear observation of high-energy cosmic neutrinos originating from outside our galaxy, particles about 100 times more energetic than those produced by the Large Hadron Collider. Because neutrinos are electrically neutral and undeflected by magnetic fields, their arrival direction points directly back to their source, effectively opening the new field of neutrino astronomy.

Halzen serves as Principal Investigator of IceCube and Director of the Institute for Elementary Particle Physics at UW-Madison, and co-authored the standard textbook Quarks and Leptons. His previous honors include the Balzan Prize in 2015, the Bruno Pontecorvo Prize in 2018, the Yodh Prize in 2019, election to the National Academy of Sciences in 2024, and the APS Medal for Exceptional Achievement in Research in 2026.