Francis Halzen wins physics Nobel for cosmic neutrino find

University of Wisconsin–Madison physicist Francis Halzen won the Nobel Prize in physics on Tuesday, Oct. 6, for the discovery of high-energy neutrinos of astrophysical origin. The Royal Swedish Academy of Sciences announced the award in Stockholm, the Associated Press reported.local10+1

Halzen leads the IceCube Neutrino Observatory, a detector buried in the ice at the South Pole. The citation recognized "decisive contributions to the IceCube Neutrino Observatory," and his work established that particles from far beyond our galaxy can be detected and studied.wikipedia

Listening for ghost particles

Neutrinos are abundant, nearly massless elementary particles. Because they rarely interact with matter, they are often called "ghost particles." IceCube was built to catch the few that do interact so astrophysicists can learn about the cosmic objects that produce them. To build it, the project melted 86 holes 2.5 kilometers deep into the Antarctic ice sheet, creating the largest neutrino detector ever built.icecube.wisc+1

Halzen came up with the idea in the 1980s. The observatory began operating in 2010. He has said that building such a detector in Antarctica was once just a "cute" idea.gssi+1

"After one and a half decades of development, and another decade of construction, there was no guarantee we would ever see anything," Halzen said in a University of Wisconsin profile published last December. "Many people thought we wouldn't, but we did. After two years of data, there were neutrinos from way beyond — not from the atmosphere, not from our own galaxy, but reaching us from across the universe with enormous energies".icecube.wisc

Those first observations of high-energy cosmic neutrinos earned IceCube the Physics World Breakthrough of the Year Award for 2013. In September 2017, the observatory produced the first evidence of a source of high-energy cosmic rays. The origins of those particles had been hard to pin down for more than a century.nasonline

A string of honors

Halzen was born in Tienen, Belgium, in 1944 and is a U.S. citizen. Before the Nobel, he won the 2015 Balzan Prize. He was also named the 2026 recipient of the American Physical Society's Medal for Exceptional Achievement in Research, the society's largest prize. The IceCube collaboration now includes more than 450 researchers from institutions in 14 countries.balzan+2

The prize comes with 12 million Swedish kronor, about $1.2 million. Last year's physics prize went to three scientists for research on quantum tunneling. On Monday, the medicine prize went to three scientists whose work led to a light-based tool for studying how the brain works.dallasnews

The chemistry prize will be announced Wednesday and the literature prize Thursday. The peace prize follows on Friday, and the economics prize will be announced Oct. 12.dallasnews