The Borexino detector. Credit: Borexino
A team of researchers working on the Borexino project have announced that they have observed carbon / nitrogen / oxygen (CNO) fusion neutrinos from the sun for the first time. Group spokesman Gioacchino Ranucci, a physicist at the University of Milan, announced the observation at this year’s Neutrino 2020 virtual conference.
The Borexino solar neutrino project is an experiment being conducted underground at the Gran Sasso National Laboratories in Italy. It has been in operation since 2007. Its mission is to observe neutrinos that are emitted from the sun through two types of fusion reactions. The laboratory is located under a kilometer of rock to filter noise. Inside, it houses a huge balloon made of nylon and filled with 278 tons of liquid hydrocarbons surrounded by water in a tank. The temperature inside the tank is kept constant by heat exchangers and a blanket cover. Photon sensors line the tank. Neutrinos can be observed when they collide with electrons inside the globe, creating a small flash. The researchers determine the characteristics of the flashes, information that can be used to isolate their source.
Project researchers observed neutrinos from a type of fusion reaction called the proton-proton chain in 2012: They are believed to account for 99 percent of the energy released by the sun. Detecting neutrinos produced during CNO reactions has presented a greater challenge because there are far fewer. In both cases, the hydrogen fuses into helium. The elements that are part of the reaction are called chains because they allow such reactions to continue. In his presentation, Ranucci stated that the team had “… untangled the two processes that feed the sun.”
Scientists have pointed out over the years that studying neutrinos from the sun could ultimately lead to a better understanding of their mechanics: A specific goal is to discover how much of the sun is made up of elements that are heavier than helium. and hydrogen.
Neutrino observations have not yet been peer-reviewed; therefore, the finding has yet to be considered official. Once that happens, the Borexino project will end and the laboratory will be closed, fulfilling its mission.
A first ‘snapshot’ of the full spectrum of neutrinos emitted by the sun
First detection of solar neutrinos from the CNO cycle with Borexino (PDF) (Video)
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Citation: CNO fused neutrinos from the sun first observed (2020, June 25) recovered on June 25, 2020 from https://phys.org/news/2020-06-cno-fusion-neutrinos-sun.html
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