In a surprising discovery, physicists have detected a rare, ghostly particle previously thought to be only produced inside the sun - under a mountain in Italy.
The Quest to Understand The Sun's Fusion Processes
Nuclear fusion processes, where hydrogen is transformed into helium, is predicted to be behind 99 percent of the sun's energy. Aside from the rarer CNO cycle, the other fusion reaction process is the more common proton-proton fusion. While both are nuclear fusion processes for turning H to He, they produce different types of neutrinos--almost massless, elusive subatomic particles that pass through most materials at nearly the speed of light.
In CNO, the carbon, nitrogen, and oxygen isotopes serve as catalysts as four protons undergo nuclear fusion. It creates an alpha particle, two positrons, as well as two neutrinos. Meanwhile, proton-proton reactions occur when the kinetic energy of protons reach a point above their mutual electrostatic repulsion.
The discovery of the CNO-produced neutrinos is a step towards understanding one of the nuclear reactions that keep the sun burning.
Physicists will be using the data from the CNO produced neutrino with existing proton-proton neutrinos. This comparison will provide scientists an idea on the concentration of elements called the CNO--carbon, nitrogen, and oxygen--in relation to the abundant hydrogen.
The result of the subterranean neutrino detection has already displayed a significance above 5 sigma, with confidence levels exceeding 99%. It translates to a one in 3.5 million probability that the detected signal was from random fluctuations instead of the actual CNO produced neutrino passing through. However, the findings are still awaiting peer review as of this writing. Ranucci first presented the results at the virtual incarnation of the Neutrino 2020 conference.
Congratulations to Borexino on "Quest of the CNO neutrinos has finally produced the first observation of the signal" #solarneutrinos #borexino @INFN_ #nu2020 #congratulations pic.twitter.com/WOnimhrDwT — Neutrino2020 (@nu2020_chicago) June 23, 2020
RELATED: Hydrogen Is The Most Common Element: Here's The Reason Why
The Borexino Observatory
Physicist Gioacchino Ranucci from the National Institute for Nuclear Physics in Milan, Italy, shared their discovery in an interview with Live Science. Ranucci said that with the discovery, "Borexino has completely unraveled the two processes powering the sun."
Ranucci was referring to the Borexino project, an extensive experimental setup for particle physics specifically designed for the detection and study of low energy solar neutrinos. The 16.9x18-meter (55.4x59-ft) detector weighs approximately 278 tons. It is mostly filled with scintillating liquid that flashes light when the electrons in the fluid interact with a neutrino. A brighter flash, corresponding to higher energy, is mainly believed to be indicative of the presence of CNO-produced neutrinos.
Borexino sits at the Laboratori Nazionalli del Gran Sasso (LNGS). The LGNS established back in 1985, is the largest underground center, situated underneath the Gran Sasso mountain. Its name, Borexino, is taken from BOREX or Boron solar neutrino experiment.
Without the natural shielding offered by its deep underground location, other signals would easily drown out the CNO neutrinos, which are still in the sub-MeV range. Also, Ranucci credited the "unprecedented purity" of the scintillating liquid, improves the Borexino's capability to detect the CNO neutrino.
