Solar neutrinos with the JUNO experiment

Abstract

The JUNO liquid scintillator-based experiment, construction of which is on-going in Jiangmen (China), will start operations in 2020 and will detect anti-neutrinos from nearby reactors; but also solar neutrinos via elastic scattering on electrons. Its physics goals are broad; its primary aim to measure the neutrino mass ordering demands to collect large statistics, which requires JUNO's 20 kt sensitive mass, and achieve an unprecedented energy resolution (3$\%/\sqrt{E}$). Thanks to these characteristics, JUNO is in a very good position to contribute to the solar neutrino studies in the line of previous experiments of similar technology. It will collect a large sample of neutrinos from $^7$Be and $^8$B. In particular, for $^7$Be the target energy resolution will provide a powerful tool to isolate the electron energy end point from backgrounds like $^{210}$Bi and $^{85}$Kr. At the same time, challenges will have to be faced mainly related to the reduction and estimation of the backgrounds. While a thorough LS purification campaign is being planned, the desired level of purification is less aggressive than e.g. in Borexino. Also, cosmogenic backgrounds such as cosmic ray muons traversing the relatively thin layer of ground above JUNO (700 m) and crossing the detector will need to be vetoed with dedicated techniques for the extraction of $^8$B. In my talk I reviewed JUNO's preliminary analysis strategy and challenges in the solar neutrino sector; and provided the current estimates of its solar neutrino and background yields, with related energy spectra, assuming two benchmark scenarios of scintillator radio-purity.