Belgian astrophysicist Francis Halzen has won the 2026 Nobel Prize in Physics for his work on ghostly cosmic particles called neutrinos.

The Royal Swedish Academy of Sciences announced the award on Tuesday. It honoured Halzen for his decisive contributions to the IceCube Neutrino Observatory and the discovery of high-energy neutrinos from deep space.

Halzen, 82, is a professor at the University of Wisconsin-Madison. He first proposed building a giant neutrino detector in Antarctic ice back in 1988. The observatory uses thousands of light sensors buried about two kilometres under the South Pole to catch tiny flashes of light made when neutrinos hit atoms in the ice.

Nobel committee chair Mark Pearce said Halzen had led an international team that built a fantastic instrument. He added that Halzen’s tenacity and scientific vision had paved the way for a new kind of astronomy.

Halzen told the Nobel news conference by phone from Italy that the win was a great surprise. The prize is worth 12 million Swedish kronor, about 1.2 million dollars. The chemistry prize will be announced on Wednesday.