Borexino is listed in 2014 Top Ten of Physics World “for being the first to detect neutrinos from the main nuclear reaction that powers the Sun”.
The top-10 breakthroughs were chosen by a panel of six Physics World editors and reporters, and the criteria for judging the top 10 included:
- fundamental importance of research;
- significant advance in knowledge;
- strong connection between theory and experiment; and
- general interest to all physicists.
Among the finalists listed in the Physics World 2014 Breakthrough of the Year Top Ten there is the Borexino collaboration, “for being the first to detect neutrinos from the main nuclear reaction that powers the Sun”.
Nearly all of the energy generated in the Sun involves a chain of nuclear reactions that begins with two protons fusing together to form deuterium along with a positron and a low-energy neutrino. Calculations predict that about 60 billion of these neutrinos pass through a square centimetre on Earth every second, but low-energy neutrinos are particularly difficult to detect and so the theory could not be verified. Now, deep under the Gran Sasso mountain in Italy, some of these neutrinos have been detected by spying the flashes of light that occur when the neutrinos collide with electrons in a giant tank of liquid. The Borexino team was not actually expecting to see these neutrinos, but its detector was so well built that the researchers managed to measure a flux of 66±7 billion neutrinos per square centimetre, confirming the long-established theory of solar fusion.