Super-Kamiokande Captures First Sign of the "Diffuse Supernova Neutrino Background"

Explanation

Super-Kamiokande, the neutrino observation facility located in Gifu Prefecture, has captured, for the first time in the world, a sign of the "diffuse supernova neutrino background"—the accumulated neutrinos released from every supernova explosion in the universe. Analyzing about 5,000 days' worth of data, combining pure-water operation data since 2008 with data made more sensitive by the addition of gadolinium since 2020, researchers found the signal's statistical significance reached 99.5% (2.6σ). However, a confidence level of 5σ or higher is required to declare a definitive "discovery," so at this stage it remains a strong "sign." This provides a clue to understanding how stars have been born and exploded throughout the universe, scattering elements such as iron and oxygen.