Nobel Prize in Physics awarded to Francis Halzen

Francis Halzen, a Belgian physicist, has been awarded the 2026 Nobel Prize in Physics for his decisive contributions to the IceCube observatory and the discovery of high-energy neutrinos of astrophysical origin. The Royal Swedish Academy of Sciences announced the award on October 6.

IceCube's massive scale

The IceCube detector occupies a 1 km³ volume of ice at the South Pole and contains 5,160 sensors distributed across 86 cables, or 60 sensors per cable. This scale is necessary because high-energy cosmic neutrinos are rare, requiring a large volume of ice to observe enough collisions. The final size of the detector was reached in 2011.

Origins of the IceCube idea

The idea for IceCube was first presented in 1988 and was inspired by a Soviet project for radio detection in Antarctica. Halzen described it as a "cute idea." The first tests of sensor deployment in the South Pole's glacier took place in 1992. AMANDA, the predecessor of IceCube, was built until January 2000.

Challenges and breakthroughs

Initial tests were disappointing due to air bubbles in the ice, but below 1,400 m, the ice is so pure that light can pass through. A flash travels 300 m before being absorbed. On Christmas Eve 1993, Halzen was waiting with a computer on his knees for confirmation of the installation of the first cable. 33 years later, the same man received the Nobel.

Discoveries and significance

Researchers first detect high-energy neutrinos in 2013 and publish the discovery of neutrinos that must originate from well beyond our solar system a few years later. The Nobel committee believes that IceCube elevates neutrino astronomy to a new level, providing information on cosmic phenomena hidden behind dust clouds or distant objects such as black holes.

Neutrinos and their detection

The neutrino passes through everything without stopping. According to the Academy, 65 billion neutrinos from the Sun pass through the fingernail of your little finger every second, approximately eight times the population of the planet, without you feeling anything. The detector therefore does not wait for those that pass through, but for the infinitesimal minority that collides with an ice atom and causes a flash of light recorded by the sensors.

Francis Halzen's background

Francis Halzen was born in 1944 in Tirlemont, Belgium. He has been a doctor from KU Leuven since 1969 and now teaches at the University of Wisconsin-Madison. During the press conference that followed the announcement, he said he hoped the prize would reflect on the courageous people who had joined him at the beginning of the project.

European collaboration and funding

Europe has its share: Halzen contributed to ASTRONU (2005-2008), a project supported by the EU and funded with 255,188 euros through Marie Skłodowska-Curie actions, according to the European Commission. The commissioner for research, Ekaterina Zaharieva, praised the award, also citing the European neutrino telescopes installed in the depths of the sea.