Sensitivity to neutrinos from the solar CNO cycle in Borexino
Neutrinos emitted in the carbon, nitrogen, oxygen (CNO) fusion cycle in the Sun are a sub-dominant, yet crucial component of solar neutrinos whose flux has not been measured yet. The Borexino experiment at the Laboratori Nazionali del Gran Sasso (Italy) has a unique opportunity to detect them directly thanks to the detector's radiopurity and the precise understanding of the detector backgrounds. We discuss the sensitivity of Borexino to CNO neutrinos, which is based on the strategies we adopted to constrain the rates of the two most relevant background sources, $pep$ neutrinos and $^{210}$Bi beta decays. Finally, the relevance of a detection of CNO neutrinos is extensively discussed in the context of the solar metallicity problem.
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