Physics potential for detecting solar neutrinos with the JUNO experiment

The Jiangmen Underground Neutrino Observatory (JUNO) is a next-generation neutrino experiment located in China. Although the main goals of JUNO are to determine the neutrino mass ordering (NMO) and to perform sub-percent precision measurements of oscillation parameters with reactor antineutrinos, its physics program is broader and includes studies on solar neutrinos. The JUNO central detector is an acrylic sphere 35.4 meters in diameter filled with 20 kt of liquid scintillator (LS). It is equipped with photomultiplier tubes (PMTs) of two types: 17,612 20-inch PMTs and 25,600 3-inch PMTs. The central detector is designed to provide an unprecedented energy resolution of 3% at 1 MeV. Although the target level of radiopurity of LS for performing the NMO analysis is set at 10⁻¹⁵ g/g of ²³⁸U and ²³²Th, the solar neutrino analysis targets a level below 10⁻¹⁶-10⁻¹⁷ g/g. The exceptional radiopurity of JUNO will enable the detection of neutrinos produced in the Sun in the pp chain — ⁸B, ⁷Be, pep neutrinos — as well as neutrinos from the CNO cycle. Depending on the exact achieved background level, JUNO will set stringent limits on the fluxes of ⁷Be, pep and CNO neutrinos, potentially exceeding the limits of Borexino in a few years of data-taking. The primary detection channel for solar neutrinos in JUNO is the neutrino-electron elastic scattering process. However, JUNO's large target mass of ¹³C nuclei makes possible the first model-independent measurement of ⁸B solar neutrinos via charged-current and neutral-current interactions on ¹³C, complementing the elastic scattering channel.