JUNO models atmospheric neutrino singles
A study characterizes single-signal events from atmospheric neutrino neutral-current interactions in large liquid scintillator detectors, identifying the
Researchers have systematically investigated the model dependence of single-signal events, or 'singles', generated by atmospheric neutrinos in large liquid scintillator detectors. The work, detailed in a paper submitted to arXiv on August 28, 2026, focuses on events with a prompt MeV-to-GeV scale energy deposit and no delayed signal.
Neutral-current interactions of atmospheric neutrinos produce these singles. The study breaks down the contributions from three physical processes: the primary neutrino-nucleus interaction, the subsequent de-excitation of the residual nucleus, and secondary interactions within the scintillator medium. According to the authors, the dominant model dependence stems from the primary interaction, particularly for neutral-current processes on carbon nuclei.
Sources of Model Dependence
De-excitation of the residual nucleus is identified as vital for selecting singles events. However, its impact on the energy spectrum is relatively small when comparing different realistic models. The effects of secondary interactions, such as those involving neutrons or gamma rays produced in the initial interaction, are also found to be subdominant overall.
These findings clarify which theoretical components require the most precise modeling for accurate analysis. The primary interaction's outsized role suggests that future improvements in neutrino-nucleus cross-section calculations will be most beneficial.
Event Rates and Spectra
The paper presents event rates and prompt-energy spectra specifically for neutral-current singles. It also details the contribution from charged-current interactions, which can mimic the single-signal signature under certain conditions. Separately, the researchers provide an estimate for a low-energy contribution from a different process: elastic scattering of sub-100 MeV atmospheric neutrinos on free protons.
Implications for Current and Future Experiments
The results highlight the physics potential of existing and planned large liquid scintillator detectors. The authors highlight facilities like the Jiangmen Underground Neutrino Observatory (JUNO) as beneficiaries. The characterization of atmospheric-neutrino singles serves multiple purposes.
It provides a new channel to study neutrino-nucleus interaction models directly. Also, a precise understanding of these events is critical for improving background estimates in searches for rare processes, such as proton decay or neutrinoless double-beta decay. The study concludes that this avenue offers a fresh opportunity for discovery and precision measurement in neutrino physics. For instance, precise stats on event rates will be key for these searches, and understanding the squad of interaction processes helps model backgrounds.
