Abstract
The Jiangmen Underground Neutrino Observatory (JUNO) features a 20 kt multi-purpose underground liquid scintillator sphere as its main detector. Some of JUNO's features make it an excellent location for B solar neutrino measurements, such as its low-energy threshold, high energy resolution compared with water Cherenkov detectors, and much larger target mass compared with previous liquid scintillator detectors. In this paper, we present a comprehensive assessment of JUNO's potential for detecting B solar neutrinos via the neutrino-electron elastic scattering process. A reduced 2 MeV threshold for the recoil electron energy is found to be achievable, assuming that the intrinsic radioactive background U and Th in the liquid scintillator can be controlled to 10 g/g. With ten years of data acquisition, approximately 60,000 signal and 30,000 background events are expected. This large sample will enable an examination of the distortion of the recoil electron spectrum that is dominated by the neutrino flavor transformation in the dense solar matter, which will shed new light on the inconsistency between the measured electron spectra and the predictions of the standard three-flavor neutrino oscillation framework. If eV , JUNO can provide evidence of neutrino oscillation in the Earth at approximately the 3 (2 ) level by measuring the non-zero signal rate variation with respect to the solar zenith angle. Moreover, JUNO can simultaneously measure using B solar neutrinos to a precision of 20% or better, depending on the central value, and to sub-percent precision using reactor antineutrinos. A comparison of these two measurements from the same detector will help understand the current mild inconsistency between the value of reported by solar neutrino experiments and the KamLAND experiment.
Highlights
Solar neutrinos, produced during the nuclear fusion in the solar core, have played an important role in the history of neutrino physics, from the first observation and appearance of the solar neutrino problem at the Homestake experiment [1], to the measurements at Kamiokande [2], GALLEX/GNO [3, 4], and SAGE [5], and to the precise measurements at Super-Kamiokande [6], SNO [7, 8], and Borexino [9]
In this paper we present a more comprehensive study with the following updates
Solar neutrinos were detected via the neutrino electron elastic scattering (ES) process in water Cherenkov or liquid scintillator detectors, which are predominantly sensitive to νe with lower cross sections for νμ and ντ
Summary
Solar neutrinos, produced during the nuclear fusion in the solar core, have played an important role in the history of neutrino physics, from the first observation and appearance of the solar neutrino problem at the Homestake experiment [1], to the measurements at Kamiokande [2], GALLEX/GNO [3, 4], and SAGE [5], and to the precise measurements at Super-Kamiokande [6], SNO [7, 8], and Borexino [9]. Solar neutrinos were detected via the neutrino electron elastic scattering (ES) process in water Cherenkov or liquid scintillator detectors, which are predominantly sensitive to νe with lower cross sections for νμ and ντ. The heavy water target used by SNO allowed observations of all the three processes, including ν − e ES, CC, and neutral-current (NC) interactions on deuterium [10]. The NC channel is sensitive to all active neutrino flavors allowing a direct measurement of the 8 B solar neutrino flux at production. After combining with the 8 B neutrino flux from the SNO NC measurement, the ∆m221 precision is expected to be similar to the current global fitting results [24].
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