The Royal Swedish Academy of Sciences has awarded the Nobel Prize in Physics to Francis Halzen for his pivotal contribution to the establishment of the IceCube Neutrino Observatory.

The IceCube Neutrino Experiment is a unique experiment that utilises a cubic kilometre of ice at the South Pole. Ninety-one deep holes have been drilled into IceCube, each containing detectors that record the blue glow (Cherenkov radiation) produced when neutrinos collide with water molecules.

Neutrinos are tiny elementary particles capable of passing through the earth, rock and water. They are electrically neutral and interact very weakly with matter, which is why they are so difficult to study. Both the geologically stable location of the experiment and the enormous volume of the “detector” make IceCube capable of detecting collisions with very high-energy neutrinos.

– The main aim of the experiment is to record high-energy neutrinos and trace their sources on a sky map. The energy of these particles reaches 10¹⁸ electronvolts (eV). This is therefore much greater than the energies achievable even in the world’s largest accelerator, the Large Hadron Collider (LHC), – explains Prof. Ewa Rondio from the High-Energy Physics DIvision at the National Centre for Nuclear Research.

The IceCube Neutrino Observatory enables the study of processes occurring in the Universe. Detecting neutrino interactions provides scientists with new insights into violent phenomena in which high-energy neutrinos may be produced. It may also lead to the discovery of previously unknown cosmic phenomena.

– We do not yet fully understand the mechanism by which such high-energy neutrinos are produced. The aim of the IceCube experiment is therefore to measure their energy spectrum, compare it with various theoretical models, and determine which mechanism best fits the data – says Dr Justyna Łagoda, Professor at the National Centre for Nuclear Research (NCBJ) and Head of the High-Energy Physics Division.

Francis Halzen first presented his idea for building a neutrino detector at the South Pole in 1988 at a conference in Poland. Construction of IceCube began in 2005 and was completed five years later. The physical results obtained in the experiment were presented by Prof. Halzen at various events, including a workshop on water Cherenkov detectors co-organized by the NCBJ in 2025. 

Polish groups forming a consortium led by the National Center for Nuclear Research are participating in a neutron experiment being conducted in Japan – the massive international neutrino observatory known as Hyper-Kamiokande. The underground detector uses the same technique – the Cherenkov effect – to detect charged particles produced by neutrinos and measure their energy.

A team composed of experts from nine institutions in Poland, led by Prof. Ewa Rondio, is responsible, among other things, for the design and construction of a linear electron accelerator for the precise calibration of the detector, the construction of light detectors and electronics, as well as the development of tools for the analysis and reconstruction of neutrino interactions and theoretical modeling (the NuWro generator).