Solar Neutrinos with Borexino: First evidence of CNO fusion cycle

The prime energy producer in the sun is the fusion of hydrogen to formhelium. However, there is more than one way for this fusion to takeplace: for stars the size of the sun or smaller, the proton-proton (pp)chain reactions dominate (~99%), while in heavier stars, thecarbon-nitrogen-oxygen (CNO) cycle is expected to play a more importantrole. Not only these fusion reactions would not have been possiblewithout the emission of neutrinos, neutrinos are the only way todirectly access the processes in the core of the sun.Borexino experiment, located at the Laboratori Nazionali del Gran Sasso,was built with a primary goal of the Be7 solar neutrinos (part of ppchain) detection. In more than a decade of data taking, Borexino has notonly demonstrated the unprecedentedly high sensitivity towards Be7 solarneutrinos (