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International team reports first 'snapshot' of complete spectrum of neutrinos emitted by the sun

About 99 percent of the sun's energy emitted as neutrinos is produced through nuclear reaction sequences initiated by proton-proton (pp) fusion in which hydrogen is converted into helium, say scientists. Now, they report new results from Borexino, one of the most sensitive neutrino detectors on the planet. Their first complete study of all the components of a pp-chain include not only the pp neutrinos, but others called Beryllium-7 (7Be), pep and Boron-8 (8B) neutrinos. The pp fusion reaction of two protons to produce deuteron, nuclei of deuterium, is the first step of a reaction sequence responsible for about 99 percent of the sun's energy output. Shown here: The Borexino instrument located deep beneath Italy's Appenine Mountains detects neutrinos as they interact with the electrons of an ultra-pure organic liquid scintillator at the center of a large sphere surrounded by 1,000 tons of water.

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