Extremely high-energy neutrino detected in the Mediterranean Sea

Using the Kilometer Cubic Neutrino Telescope (KM3NeT), an international team of researchers has detected the most energetic neutrino ever detected on Earth. At 220 PeV, it beats the previous record by a factor of 22 and is orders of magnitude higher than the particle energies that can be produced at the LHC particle accelerator at CERN.

Neutrinos are nearly massless, electrically neutral particles that can pass through matter unimpeded. Since they are not deflected by electromagnetic fields and hardly interact with matter, they have the useful property that their straight-line trajectory always points to their place of origin. This makes it possible to draw conclusions about their place of origin. Neutrinos are produced, for example, in black holes or in cosmic collisions.

The extremely energetic neutrino was detected by the KM3NeT telescope, which is located 3,500 meters deep in the Mediterranean Sea. It is still under construction, but is already partially operational. It works like this: When a neutrino passes through the rock or water near the detector, it can create charged leptons. If these leptons move fast enough through the water, they produce electromagnetic radiation that is detected by KM3NeT. In this way, neutrinos can be detected despite their minimal interaction with matter.

This discovery contributes to the understanding of the astrophysical processes that produce such extremely energetic particles. It also provides insight into the nature of the universe at extremely high energies. The measurement dates back to February 2023, but it took two years of analysis to confirm it. The fact that KM3NeT registered such an unusual event during the construction phase was a surprise.

PROPOSAL54 and TAUSIC55 were used to simulate the neutrino propagation. This software was developed with the participation of our chair.

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