发表机构
Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo; Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, University of Tokyo（神冈观测站，宇宙线研究所，东京大学; 汤川理论物理与宇宙学研究所（WPI），东京大学高等研究院，东京大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
Super-Kamiokande在SK-Gd阶段首次观测到反应堆电子反中微子，信号显著性约6σ，并精确测量了振荡参数，与太阳中微子数据在1.9σ水平相容。
AI 中文摘要
2020年，Super-Kamiokande进入SK-Gd阶段，通过探测溶解在探测器水中的钆所俘获的中子，提高了对低能电子反中微子的灵敏度。利用SK-Gd的数据进行了反应堆电子反中微子分析，总曝光时间为411.52活天。在考虑偶然、地球中微子和散裂本底后，观测到的瞬发能谱和月事件率与振荡后的反应堆反中微子预言一致。无反应堆假设被否定，反应堆反中微子信号显著性约为6σ。振荡参数测量结果为sin²θ₁₂=0.500±0.155和Δm²₂₁=(9.08₋₀.₅₄⁺⁰.⁵⁵)×10⁻⁵ eV²。与Super-Kamiokande太阳中微子测量结果的比较显示，两个数据集在1.9σ水平上统计相容。在Super-Kamiokande中联合太阳和反应堆拟合得到的最佳拟合值为sin²θ₁₂=0.332₋₀.₀₂₆⁺⁰.₀₂₈和Δm²₂₁=(8.94₋₀.₄₇⁺⁰.₄₆)×10⁻⁵ eV²。
英文摘要
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 $\sin^2θ_{12} = 0.500\pm0.155$ and $Δm^2_{21} = (9.08_{-0.54}^{+0.55}) \times 10^{-5} \mathrm{eV}^2$. 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 $\sin^2θ_{12} = 0.332_{-0.026}^{+0.028}$ and $Δm^2_{21} = (8.94_{-0.47}^{+0.46}) \times 10^{-5} \mathrm{eV}^2$.
Comments9 pages, 5 figures, 5 tables; submitted to Physical Review Letters
