The composition of the solar core is nonexistent. But Borexino Collaboration recently reported that they had detected solar neutrinos, produced by the nuclear-fusion reaction cycle known as the carbon-nitrogen-oxygen cycle. If we can measure this neutrino, we can potentially resolve the uncertainties about the solar core composition. We can have an insight into the formation of massive stars.
Now, what are neutrinos?
Wolfgang Pauli in 1930, discovered Neutrinos are subatomic particles. These are the massless particle that can carry any fraction of the energy emitted during β-decay. Decades of research have yielded enough information about Pauli’s “ghost particle,” including the ‘Nobel’ prize-winning discovery that neutrinos have mass but are so small that it is beyond measurements.
The fusion reaction in the Sun produces an astounding number of neutrinos. Because of their weak interaction, they are barely deterred from their path even when they must pass the entire body of Earth.
Therefore, neutrinos are very challenging to observe. In the solar center, the energy produced is in photons, takes tens of thousands of years to escape. But a neutrino can escape the Sun and reach the Earth in just eight minutes.
Homestake Mine, South Dakota, performed the first experiment to detect neutrinos using a detector. After decades of Nobel-prize winning results from the Sudbury Neutrino Observatory in Ontario, Canada explained that neutrinos change flavor when it comes to their detection and production.
From this Nobel-prizewinning experiment, the Borexino Collaboration reported another achievement: detecting neutrinos from the CNO cycle. Now, this offers a chance to resolve the mystery of the Sun’s core elemental composition. Because the exact metal content of a star affects the rate of the CNO cycle.
The main problem in making these measurements is low energy, CNO neutrinos’ flux, and difficulty separating neutrinos signal. The Borexino experiment uses a medium that produces light in response to the passage of charged particles known as a scintillator.
A precise measurement of detected light’s energy and time profile allows the scintillation caused to differentiate from other light sources.
The experiment results are not precise enough to solve solar metallicity, but still, it offers a path towards this subject. Learning from the previous experiments will improve and would most likely achieve future investigations in the coming years.