Scientists announce the highest-energy neutrino ever detected

 

On February 13, 2023, the ARCA detector of the KM3NeT (Cubic Kilometre Neutrino Telescope) project, located deep beneath the Mediterranean Sea near Sicily, Italy, detected the most energetic neutrino ever observed. This neutrino, designated KM3-230213A, possessed an estimated energy of approximately 220 petaelectronvolts (PeV), or 220 million billion electronvolts. 

Detection Details

The ARCA detector identified this extraordinary event by observing a high-energy muon produced from the interaction of the neutrino with matter near the detector. The muon's trajectory was reconstructed using the recorded times and positions of the initial hits on the photomultiplier tubes within the optical modules. The muon's measured energy was approximately 120 PeV, with an uncertainty ranging from +110 PeV to −60 PeV. Given the muon's near-horizontal trajectory—0.6 degrees above the horizon—and its immense energy, it is inferred that it originated from a cosmic neutrino of even higher energy, estimated at 220 PeV.

Implications and Significance

This groundbreaking detection provides the first evidence that neutrinos of such ultra-high energies are produced in the universe. Neutrinos are subatomic particles with extremely low mass and weak interactions with matter, making them challenging to detect. Their ability to traverse vast cosmic distances unimpeded allows them to serve as "cosmic messengers," offering insights into the most energetic and catastrophic events in the cosmos.

The discovery of KM3-230213A suggests that these ultra-high-energy neutrinos may originate from different cosmic accelerators than their lower-energy counterparts. Alternatively, this event could represent the first detection of a cosmogenic neutrino, produced from interactions between ultra-high-energy cosmic rays and background photons in the universe.

Scientific Significance

• This is the first evidence of neutrinos at such extreme energies in the universe.
• Neutrinos are nearly massless, elusive particles that rarely interact with matter, allowing them to travel across the cosmos unimpeded.
• Detecting ultra-high-energy neutrinos helps scientists trace the most energetic cosmic events, such as:
  • Supermassive black holes
  • Active galactic nuclei (AGN)
  • Gamma-ray bursts
  • Exploding stars (supernovae)
• Scientists suspect this neutrino might be a cosmogenic neutrino, produced when ultra-high-energy cosmic rays interact with cosmic background radiation.

 The KM3NeT Project

KM3NeT is a European research infrastructure currently under construction, designed to host a network of neutrino detectors in the deep waters of the Mediterranean Sea. The project comprises two main detectors: ARCA (Astroparticle Research with Cosmics in the Abyss) and ORCA (Oscillation Research with Cosmics in the Abyss). ARCA, situated near Sicily, is optimized for detecting high-energy neutrinos, while ORCA, located off the coast of France, focuses on low-energy neutrinos. These detectors consist of numerous optical modules arranged in vertical detection lines, designed to observe the Cherenkov light emitted when neutrinos interact with the surrounding water.

As of the end of 2024, ARCA had 33 detection lines installed, with more than 10% of the detector operational and actively collecting data. The successful detection of KM3-230213A underscores the potential of KM3NeT to advance our understanding of high-energy astrophysical phenomena and the origins of cosmic rays.

This landmark observation opens new avenues for research in neutrino astronomy and provides a unique perspective on the most energetic processes occurring in the universe.

Website: popularscientist.com

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