This Tuesday, October 6, the 2026 Nobel Prize was announced. The laureate turned out to be particle physicist Francis Halzen, a scientist closely linked to the Institute of Corpuscular Physics (IFIC), a joint center of the Spanish National Research Council (CSIC) and the University of Valencia (UV). Halzen has collaborated with several researchers at the institute and is a pioneer in the study of neutrinos. Professor Halzen visited IFIC in 2024 to talk about his groundbreaking experiments at the IceCube Neutrino Observatory (see his talk here), which have made it possible to detect high-energy neutrinos and identify their astrophysical origins. He is also a member of the IFIC Scientific Advisory Committee, which oversees the scientific activity of our center, ensuring that it maintains the highest standards of research excellence.

Neutrino physics

Neutrinos are fundamental subatomic particles with an extremely small mass, close to zero, and no electric charge, making them unaffected by electromagnetic fields. This is why highly advanced instrumentation is required to detect them. The IceCube Neutrino Observatory is a particular type of telescope designed to observe these elusive particles. From deep beneath the ice at the South Pole, IceCube's detectors look toward the North Pole to detect neutrinos passing through the entire Earth. This location offers particular advantages, as the Antarctic ice is free from various types of interference and the region is geologically stable, with no earthquakes.

Thanks to its innovative configuration, in 2013 IceCube successfully detected 28 neutrinos of cosmic origin. The discovery was featured on the cover of the prestigious journal Science. Juan José Hernández Rey, CSIC Research Professor, highlights Professor Halzen's determination and perseverance, stressing that “he did not merely propose the idea; with extraordinary leadership and great perseverance, he worked for more than two decades to make it a reality.”

For his part, Juan de Dios Zornoza, Associate Professor at the University of Valencia, says that Halzen has also been instrumental in promoting the projects being developed in Europe, first ANTARES, which operated for several years in the Mediterranean Sea and demonstrated the feasibility of this type of project on the seafloor, and later KM3NeT. IFIC researchers are part of this collaboration, whose observations complement those of IceCube. KM3NeT was featured on the cover of the prestigious journal Nature following the detection of the highest-energy neutrino ever observed by a similar experiment.

First reactions

The first reactions from IFIC staff were not long in coming. In the words of IFIC Director and CSIC Research Scientist Sergio Pastor: “The award given to Francis Halzen is a major recognition not only of his standing in neutrino astrophysics, as leader of the IceCube collaboration, but also of a field in which IFIC researchers play a very important role through their participation in the KM3NeT project. The detection of extremely high-energy neutrinos from astrophysical sources opens a new window onto astronomy, allowing us to study the universe not only through the detection of light at different wavelengths, but also through the measurement of neutrinos and gravitational waves.”

Likewise, Nuria Rius, former IFIC Director and Professor at the University of Valencia, says: “Francis is an excellent and tenacious researcher who has succeeded in opening a new window onto the universe: neutrino astrophysics, which complements our view of space through electromagnetic radiation and gravitational waves.”

The recognition of Francis Halzen with the 2026 Nobel Prize in Physics highlights the importance of neutrino research and its ability to expand our understanding of the universe. The advances made possible by observatories such as IceCube and KM3NeT allow scientists to study extremely energetic cosmic phenomena and open up new possibilities for understanding the secrets of the cosmos. The award also underscores the importance of international scientific collaboration and the development of technologies capable of observing the universe with ever greater precision.