Francis Halzen to receive 2026 Nobel Prize in Physics for cosmic neutrino detection

The Royal Swedish Academy of Sciences announced today that Francis Halzen of the University of Wisconsin–Madison will receive the 2026 Nobel Prize in Physics “for decisive contributions to the IceCube Neutrino Observatory and the discovery of high-energy neutrinos of astrophysical origin.”

In his speech after the announcement, Halzen, principal investigator of IceCube, said, “This was the kind of adventure where success was not guaranteed and we got lucky.”

The highest-energy neutrinos are flung from mysterious astrophysical particle accelerators outside our solar system—and they may carry useful information about their cosmic sources. In the rare instances when neutrinos collide with an atomic nucleus, they can produce a flash of light. Halzen and others realized that the large volume of clear glacial ice below the surface of Antarctica could provide a natural lab on the scale necessary to observe those bursts of light.

By 2011, 86 holes had been drilled several kilometers into the ice cap and strings of photodetectors lowered to capture those flashes. Two years later, the facility detected the rare high-energy neutrinos it was built to find. An international collaboration of more than 400 scientists operates the cubic-kilometer observatory today.

When asked after the announcement what he would be doing with the rest of his day, Halzen replied, “I’m working on a proposal; I hope this prize will help get it approved.”

Halzen received his PhD in 1969 from KU Leuven in Belgium for research on broken symmetries of hadrons. He was a scientific associate at CERN until 1971, when he moved to a visiting position at the University of Wisconsin–Madison. He joined the faculty the following year. He has been the principal investigator of IceCube since 2001.

This is a developing story and will be updated.

Physics Today articles by Francis Halzen

• Astronomy and astrophysics with neutrinos , by Francis Halzen and Spencer Klein (May 2008).

Other selected articles in Physics Today

• IceCube expands neutrino search to spot fainter signals (March 2026).
• Record-setting cosmic neutrino breaks in a new telescope (April 2025).
• Cosmic tau neutrinos uncovered (June 2024).
• High-energy neutrinos originate in our own galaxy (September 2023).
• Neutrino messengers originate within our own galaxy (July 2023).
• A star’s demise is connected to a neutrino outburst (August 2022).
• The elusive Glashow resonance was observed deep within Antarctic ice (April 2021).
• Neutrinos reveal Earth’s inner structure (November 2018).
• Astrophysical high-energy neutrinos (October 2018).
• IceCube pinpoints an extragalactic neutrino source (July 2018).
• Sterile neutrinos give IceCube and other experiments the cold shoulder (October 2016).
• More ice, more neutrinos (June 2014).
• Gigantic IceCube tightens limits on theories that predict dark-matter particles (May 2013).

Other resources

• AIP Oral History Interview with Francis Halzen
• South Pole experiment traps neutrinos from beyond the galaxy , by Francis Halzen (Scientific American, December 2015).

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