Probing Neutrino Oscillations with Reactor Antineutrinos in JUNO

Abstract

The Jiangmen Underground Neutrino Observatory (JUNO) is a multi-purpose neutrino experiment currently under construction in South China, in an underground laboratory with approximately 650 m of rock overburden (1800 m.w.e.). The detector consists of a 20 kton liquid scintillator target, contained inside a 35.4-meter-diameter spherical acrylic vessel. The central detector (CD) is equipped with 17,612 20-inch and 25,600 3-inch Photomultipliers Tubes (PMTs), providing more than 75% total photocathode coverage. JUNO's main goal is the determination of the neutrino mass ordering with reactor antineutrinos, emitted from two adjacent nuclear power plants on a ~52.5 km baseline from the experimental site. JUNO's strategic location at a baseline corresponding to the first solar oscillation maximum, where the kinematic phase $\Delta_{21} \simeq \frac{\pi}{2}$, grants it the unique capability to simultaneously probe the effects of oscillations on both solar and atmospheric scales; moreover, it stands out as the first experiment to address the unresolved NMO question through vacuum-dominant oscillations. The oscillated energy spectrum in JUNO changes subtly depending on the neutrino mass ordering, which manifests as an energy-dependent phase shift, thus providing sensitivity to this parameter. Furthermore, the unparalleled size and energy resolution will enable to achieve a sub-percent precision on three parameters: $\Delta m_{21}^{2}$, $\Delta m_{31}^{2}$, and $\sin^2\theta_{12}$. This contribution will focus on JUNO's oscillation physics potential with reactor antineutrinos, with a particular emphasis on its crucial role in inaugurating a new era of precision within the neutrino sector.