arXiv subjects

Obada Nairat

Publications and source records attributed to Obada Nairat.

4 recordsLinked to original sources

arXiv2026

Towards First Detection of the Solar MSW Transition With JUNO

Matter-induced neutrino flavor mixing (the Mikheyev-Smirnov-Wolfenstein, or MSW, effect) is a central prediction of the neutrino mixing framework, but it has not been conclusively observed. Direct observation of the energy-dependent MSW transition in the solar electron-neutrino survival probability would solve this, but backgrounds have been prohibitive. We show that our new technique for suppressing muon-induced spallation backgrounds will allow JUNO to measure the MSW transition at $>$4$σ$ significance in 10 years. This would strongly support upcoming multi-\$1B next-generation experiments and their goals in cementing the neutrino mixing framework.

hep-ph↗

arXiv2026

New Spallation Background Rejection Techniques to Greatly Improve the Solar Neutrino Sensitivity of JUNO

While the potential of the Jiangmen Underground Neutrino Observatory (JUNO) to measure solar neutrinos is known, realizing this potential requires new techniques to reduce detector backgrounds. One of the most serious backgrounds is due to the beta decays of unstable nuclei produced through muon breakup (spallation) of nuclei. This background is much more significant in JUNO compared to Super-Kamiokande due to JUNO's shallower depth and its lack of directional information. We present the first detailed theoretical calculations of spallation backgrounds in JUNO, showing the underlying physical processes and new ways to cut backgrounds while preserving signals. A key point is showing the importance of neutron tagging to identify hadronic showers, which are rare but produce almost all of the dangerous isotopes. With our new techniques, JUNO will be able to reduce deadtime (signal loss) by a factor of about 4.5 and to reduce the running time needed to meet sensitivity goals by a factor of two. This will give JUNO greatly improved sensitivity to $^8$B and $hep$ solar neutrinos, as we will explore in a separate paper.

hep-ph↗

arXiv2026

Self-Calibration of the Neutrino-Argon Cross Section with Solar Neutrinos

The success of DUNE's MeV physics program depends upon high-precision knowledge of the charged-current (CC) $ν_e+\mathrm{^{40}Ar}$ cross section. While there are indirect constraints at the 10% level for the nuclear transitions that constitute this cross section, the only direct measurement in the MeV range has an uncertainty of $\sim$50%. We show, surprisingly, that the cross section can be precisely measured using the solar-neutrino data themselves. This is possible because of independent knowledge of the $^8$B flux and survival probability, plus the distinctive angular distributions of the Fermi and Gamow-Teller transitions that comprise the cross section. We propose new methods to extract the transition strengths, considering both intuitive groupings and a Principal Component Analysis. Under pessimistic assumptions about detection, but taking detector uncertainties to be controlled, we demonstrate that a precision of $\lesssim$2% on the cross section can be achieved in the 9-15 MeV energy range. These results will be an important foundation for studying the cross section up to several tens of MeV, where the complexity increases significantly due to nuclear breakup channels but where reducing uncertainties is critical for supernova and atmospheric neutrino studies.

hep-ph↗

arXiv2025

Neutron Tagging Can Greatly Reduce Spallation Backgrounds in Super-Kamiokande

Super-Kamiokande's spallation backgrounds - the delayed beta decays of nuclides following cosmic-ray muons - are nearly all produced by the small fraction of muons with hadronic showers. We show that these hadronic showers also produce neutrons; their captures can be detected with high efficiency due to the recent addition of dissolved gadolinium to Super-Kamiokande. We show that new cuts based on the neutron tagging of showers could reduce spallation backgrounds by a factor of at least four beyond present cuts. With further work, this could lead to a near-elimination of detector backgrounds above about 6 MeV, which would significantly improve the sensitivity of Super-Kamiokande. These findings heighten the importance of adding gadolinium to Hyper-Kamiokande, which is at a shallower depth. Further, a similar approach could be used in other detectors, for example, the JUNO liquid-scintillator detector, which is also at a shallower depth.

hep-ph↗