Laboratori Nazionali del Gran Sasso

node · earth

The INFN underground laboratory beneath the Gran Sasso massif in Abruzzo, between L'Aquila and Teramo, with roughly 1.4 km of rock overhead. It housed Borexino, the liquid-scintillator detector that in 2020 reported the first detection of neutrinos from the CNO fusion cycle in the Sun - the secondary hydrogen-burning route that accounts for only about one per cent of solar energy output and had never before been observed directly. The measurement mattered beyond the Sun: the CNO cycle dominates in stars more massive than about 1.3 solar masses, so confirming it in the one star we can measure closely validates the assumed energy source of the majority of luminous stellar mass in the Galaxy.