For the first time, physicists have detected rare and ghostly particles produced by a strange type of fusion within the sun.
The particles, called neutrinos produced by CNO, traveled from the sun to a detector buried deep in a mountain in Italy. This discovery takes humans one step closer to understanding the blazing nuclear reactions that fuel our star of origin.
“With this result,” physicist Gioacchino Ranucci, a physicist at the Italian National Institute of Nuclear Physics in Milan, told Live. “Borexino has completely unraveled the two processes that feed the sun.”
Two types of nuclear fusion reactions occur in the nucleus of the sun. The first, and most common, is proton-proton fusion, where protons fuse to transform. hydrogen inside helium. Scientists predict that such reactions generate 99% of the sun’s energy. Rarely, nuclear fusion occurs through a six-step process, called the CNO cycle, where hydrogen is fused with helium using Coal (C), nitrogen (N) and oxygen (O) The proton-proton fusion and CNO cycle create different types of neutrinos, subatomic particles that have almost no mass and can pass through ordinary matter without an indication of their presence, at least most of the time. Physicists routinely detect neutrinos created during the proton-proton process. However, on June 23, in the Neutrino 2020 virtual meeting, researchers at Italy’s Borexino detector announced that they had detected solar neutrinos produced by CNO for the first time.
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The Borexino underground experiment, at the Laboratori Nazionali del Gran Sasso, near the city of L’Aquila, Italy, was designed to study these extremely rare interactions with neutrinos. The Borexino detector consists of a tank approximately 60 feet (18 meters) high that contains 280 tons (254 metric tons) of scintillating liquid, which blinks when the electrons in the liquid interact with a neutrino. A bright flash, indicating more energy, is more likely to come from neutrinos produced by CNO.
Buried underground and enclosed in a water tank, Borexino’s inner tank is lined with sensitive detectors that are extremely isolated from the background radiation of cosmic rays present on Earth’s surface. Without this shield, other signals would drown out the rare signals coming from CNO. neutrinos.
Ranucci also credits the “unprecedented purity” of the scintillating liquid with much of the experiment’s success.
Comparing the observed observation of CNO neutrinos to the number of proton-proton neutrinos observed will help reveal how much of the sun is made up of elements heavier than hydrogen, such as carbon, nitrogen, and oxygen. The current results, although not yet peer reviewed and published in a scientific journal, showed a significance greater than 5 sigma with a confidence level greater than 99%, which means that there is only a probability of 1 in 3.5 Millions of random signal fluctuations, rather than the CNO process.
Borexino’s international collaboration is comprised of researchers from Italy, France, Germany, Poland, Russia, and three universities in the United States, Princeton, Virginia Tech, and the University of Massachusetts at Amherst.
Originally published in Live Science.
