First observation of electron antineutrinos from nuclear reactors at Super-Kamiokande

By Abe, Asaoka, Harada +197Oct 2, 2026

Score████░░░░░░4.3

VerdictWorth a reader's time today.

Abstract

In 2020, Super-Kamiokande entered the SK-Gd phase, improving its sensitivity to low-energy electron antineutrinos through the detection of neutrons captured on gadolinium dissolved in the detector water. An analysis of reactor electron antineutrino data has been carried out using data from SK-Gd, with a total exposure of 411.52 live days. The observed prompt energy spectra and monthly event rates are consistent with the oscillated reactor antineutrino prediction after accounting for accidental, geoneutrino, and spallation backgrounds. The no-reactor hypothesis is disfavored with a reactor-antineutrino signal significance of approximately $6σ$. The oscillation parameters are measured to be sin²θ₁₂ = 0.500±0.155 and Δm²₂₁ = (9.08_-0.54⁺0.55) × 10⁻⁵ eV². A comparison with Super-Kamiokande solar neutrino measurements shows a statistical compatibility between the two datasets at the $1.9σ$ level. A combined solar and reactor fit in Super-Kamiokande yields best-fit values of sin²θ₁₂ = 0.332_-0.026⁺0.028 and Δm²₂₁ = (8.94_-0.47⁺0.46) × 10⁻⁵ eV².

K. Abe, Y. Asaoka, M. Harada, Y. Hayato, K. Hiraide, T. H. Hung, K. Ieki, M. Ikeda, J. Kameda, Y. Kataoka, S. Mine, M. Miura, S. Moriyama, K. Nakagiri, M. Nakahata, S. Nakayama, Y. Noguchi, G. Pronost, K. Sato, H. Sekiya, R. Shinoda, M. Shiozawa, Y. Suzuki, A. Takeda, Y. Takemoto, H. Tanaka, S. Chen, Y. Itow, T. Kajita, R. Nishijima, et al.

The editor's rubric

Heuristic review

Dimension	Level	Weight	What that level means
Leverage	███░░ 3	18%	A method or resource many groups across the field will adopt within a year.
Magnitude	███░░ 3	20%	Large gain: roughly 2x, or a clear new state of the art on a hard, unsaturated problem.
Evidence	███░░ 3	22%	Solid: multiple benchmarks or cohorts, ablations, fair baselines, released code or data.
Novelty	███░░ 3	22%	A genuinely new approach to an open problem.
Trajectory	██░░░ 2	10%	Some room to improve with obvious engineering.
Stakes	██░░░ 2	8%	Benefits a professional community (practitioners, clinicians, engineers).

Editor’s rationale

Heuristic triage from title and abstract text only, not a reading of the paper. Cues found: breadth (many tasks); firsts (first); novelty (discovery); verification (multiple benchmarks); stakes (energy).

How the score was computed

rank-2026-09-29

Score████░░░░░░4.3

Score = 10 × (75% × adjusted merit / 10 + 15% × attention + 10% × freshness)

Merit: 5.6 / 10; Weighted rubric, evidence-gated.
Adjusted merit: 4.7 / 10; Shrunk toward the desk prior by editor confidence (40%).
Attention: 0%; Citations, upvotes, points, mentions.
Freshness: 75%; Half-life decay since publication.

No attention signals recorded yet.

The record

Reviewed by heuristic-v2 on Oct 5, 2026, 07:29 UTC. Paper type: empirical.
Categories: hep-ex
BRIEF, No.7 in the Physics edition of October 5, 2026.