Atmospheric Neutrino Charged-Current Interactions at Large Liquid-Scintillator Detectors: I. Physics of Neutrino-Antineutrino Discrimination

Abstract

In this work, we present a systematic study of the event characteristics and physics of neutrino-antineutrino discrimination associated with atmospheric neutrino charged-current interactions in large liquid scintillator detectors. This study encompasses the primary neutrino interactions, the sequential second interactions of final-state particles, and the final neutron captures. We carefully investigate the properties of final-state charged leptons and hadrons, providing distinct distributions of inelasticity and captured neutron multiplicity for both neutrino and antineutrino interactions. These distributions are employed to assess the quantitative performance of neutrino-antineutrino discrimination. Our findings lay the groundwork for atmospheric neutrino oscillation studies in large liquid scintillator detectors, particularly in the determination of neutrino mass ordering.

Figures (15)

• Figure 1: The schematic diagram for the atmospheric neutrino interactions in LS, including the charged current interactions, the sequential secondary interactions, and final neutron captures.
• Figure 2: Typical examples of charged current interaction between $\nu_e$ (left panel) or $\nu_\mu$ (right panel) and $\rm{^{12}C}$. The solid lines show the tracks of final-state particles and their secondary particles, and the dashed shows the incoming atmospheric neutrinos. The triangles represent the positions of neutrons capture.
• Figure 3: PMT hit-time distributions in different angular regions ($\alpha$), where $\alpha$ is the angle between the PMT position and the charged-particle momentum. Lines show electrons, muons, protons and pions with momenta of at 3 GeV (a) and 1 GeV (b).
• Figure 4: Mollweide projections of the PMT-level observables for electrons, muons, protons and pions with 3 GeV momentum. Columns from left to right show Slope, FHT and NPE. All particles originate perpendicular to the plane, pointing outward.
• Figure 5: Mollweide projections of the PMT-level observables for electrons, muons, protons and pions with 1 GeV momentum. Columns from left to right show Slope, FHT and NPE. All particles originate perpendicular to the plane, pointing outward.