The “Physics World” magazine has called researches of solar neutrinos fluxes, performed by an international team of scientists, united in collaboration “Borexino”, as the most important scientific achievement of the outgoing year. The collaboration includes physicists from several research centers in Europe, Russia and the United States. The Russian side is represented by scientists from the Kurchatov Institute, National Research Nuclear University “MEPhI”, Joint Institute for Nuclear Research, Lomonosov Moscow State University.
Unique flow measurements of the so-called PP-neutrinos, which were formed in the Sun’s interior in the main thermonuclear reaction of fusion of two hydrogen nuclei with the formation of deuterium nucleus, made it possible to determine the energy of the Sun directly by the neutrino flux. This work, published in the prestigious interdisciplinary journal “Nature”, was among the 10 most important scientific results in physics, received in 2014.
Up to the present moment all measurements of solar energy were based on radiation of the solar photosphere, produced in thermonuclear processes around 100,000 years ago, what is the average diffusion time from the central regions of the Sun to its surface. Comparison between measurements of the “Borexino” collaboration and light radiation of the Sun proves that the energy release of the Sun has not changed for a historically long period of time.
Neutrino detector “Borexino”, installed in the underground laboratory “Gran Sasso” of the National Institute for Nuclear Physics (INFN), Italy, was created for almost 17 years; and experimental studies has started in 2007. Unprecedented low level of background was achieved in the Borexino detector, which gives the opportunity to perform unique measurements not only of neutrinos emitted by the Sun, but also neutrinos formed in the Earth’s interiors, and even neutrinos from distant astrophysical sources. Studies also had its own scientific importance to understand the fundamental properties of neutrinos – elusive members of the family of elementary particles.
