On Wednesday, a group of scientists revealed that they experienced a remarkable breakthrough. They are constructing a neutrino detector on the seabed of the Mediterranean, designed to capture the infrequent instances when a neutrino interacts with the surrounding seawater. Surprisingly, despite the detector being only 10 percent of its final size, it successfully recorded the highest energy neutrino ever observed.

For context, the Large Hadron Collider, the most powerful particle accelerator accessible, boosts protons up to an energy level of 7 Tera-electronVolts (TeV). In contrast, the neutrino detected displayed an energy of at least 60 Peta-electronVolts, potentially reaching as high as 230 PeV, which far exceeds previous records that were around 10 PeV.

Efforts to trace the origin of the neutrino have indicated that it was emitted from outside our galaxy, with several potential sources located in the distant universe.

Investigating Neutrinos

Neutrinos are notably elusive, which is part of what makes them so fascinating. These particles are known for their reluctance to interact with other matter. It is estimated that blocking a bright neutrino source would require a substantial amount of lead, equivalent to about a light-year. In fact, while trillions of neutrinos pass through each of us every second, fewer than five interact with the matter in our bodies over an entire lifetime.

Detection becomes possible because neutrinos are generated in vast quantities through nuclear processes, such as the fusion occurring in the Sun or within nuclear reactors. Additionally, detector designs incorporate significant amounts of matter to increase the chances of neutrino interactions.

A prime example of this “abundance of matter” strategy is the IceCube detector, located in Antarctica. This detector capitalizes on the principle that neutrinos striking the Antarctic ice generate numerous particles and light. Researchers drilled into the ice and installed arrays of detectors to capture this light, enabling them to reconstruct the arrival of neutrinos.