[论文解读] Full Data Release of the Daya Bay Reactor Neutrino Experiment

Daya Bay collaboration, F. P. An+199 more|arXiv (Cornell University)|Nov 28, 2022

Neutrino Physics Research被引用 4

一句话总结

本论文利用大亚湾实验在千米量级基线上采集的数据，对反应堆反中微子振荡进行了高精度测量，采用基于Geant4的模拟方法建模系统误差。分析结果得到 ${\rm sin}^{2}2\theta_{13} = 0.0851 \pm 0.0024$ 和 $\Delta m^{2}_{ee} = (2.519 \pm 0.060) \times 10^{-3}\ \text{eV}^2$，其中 $\theta_{13}$ 的精度达到2.8%，为迄今最精确的测量结果，支持三中微子框架。

ABSTRACT

Full Data Release of the Daya Bay Reactor Neutrino Experiment Summary The repository contains the full Daya Bay data set of inverse-beta-decay (IBD) candidates (reactor electron antineutrino interactions) with the final-state neutron captured on gadolinium. The dataset and supplementary data are sufficient to reproduce the measurement of neutrino oscillation parameters sin²2θ₁₃ and Δm²₃₂, published in Phys.Rev.Lett. 130 (2023) 16, 161802. The Daya Bay Reactor Neutrino Experiment took data from 2011 to 2020 in China. It obtained a sample of 5.55 million IBD events with the final-state neutron captured on gadolinium (nGd). This sample was collected by eight identically designed antineutrino detectors (AD) observing antineutrino flux from six nuclear power plants located at baselines between 400 m and 2 km. It covers 3158 days of operation. Code is provided elsewhere to read the dataset and produce a measurement of sin²2θ₁₃ and Δm²₃₂, consistent with the publication. Citation statement If you use the dataset, cite the following sources: [1] Daya Bay Collaboration, “Full Data Release of the Daya Bay Reactor Neutrino Experiment”, v1.0.0. Zenodo, DOI:10.5281/zenodo.17587229; 2025. [2] F. P. An et al. (Daya Bay collaboration), “Precision Measurement of Reactor Antineutrino Oscillation at Kilometer-Scale Baselines by Daya Bay”, Phys. Rev. Lett. 130,161802 (2023), DOI: 10.1103/PhysRevLett.130.161802. The dataset organization The data is provided in four different formats and is split into two categories: 1. Full dataset: IBD events in eight ADs, daily livetimes, daily efficiencies, rates of accidental backgrounds, and all the necessary inputs, needed to perform a measurement of sin²2θ₁₃ and Δm²₃₂. The size of the dataset is approximately 200 MB for each format.2. Analysis dataset: all the necessary inputs, needed to perform a measurement of sin²2θ₁₃ and Δm²₃₂, including livetimes and efficiencies. The dataset includes IBD histograms for each data taking period. Its size is around 1 MB for each format. Each category is available in four different formats: hdf5, npz, root and tsv (plain text, compressed). The detailed information on the contents of the files and formats is provided in each archive. Data availability The main storage of the data is Zenodo. A few alternative storage locations are available, including: Full dataset and analysis dataset: Zenodo: https://doi.org/10.5281/zenodo.17587229 NHEPSDC: https://doi.org/DOI:10.12402/opendata/DYB/20251205202440 Analysis dataset: GitHub: https://github.com/dayabay-experiment/dayabay-data-official PYPI: https://pypi.org/project/dayabay-data-official If you host a copy of the dataset, it should be supplemented with the current description. Feedback and contacts It is advised to use discussions and issues of the GitHub dataset repository as a main channel to provide feedback or request additional details related to the dataset itself. If a personal contact is desired, please, contact Zeyuan Yu ([e-mail]) and Maxim Gonchar ([e-mail]). Analysis code A dedicated python module dayabay-model is provided, which is able to read analysis data in any of the formats and provide predicted IBD spectra for each AD, the χ² function, or a result of any intermediate calculation. The module also contains a few minimal examples on how to work with the model and extract data from it. At this moment the latest version of dayabay-model, consistent with the dataset, is v0.4.2. More comprehensive examples of the data analysis are available in dayabay-analysis repository. Commands to perform the oscillation fit to the full Daya Bay dataset is provided as well. The code above depends on a few other Python modules, developed to support the analysis. The dependencies are automatically resolved via pip when the model is installed. Acknowledgements The results published here are in whole or in part based on the data released as Open-Access by the Daya Bay Collaboration supported by the Ministry of Science and Technology of China, the U.S. Department of Energy, the Chinese Academy of Sciences, the CAS Center for Excellence in Particle Physics, the National Natural Science Foundation of China, the New Cornerstone Science Foundation, the Guangdong provincial government, the Shenzhen municipal government, the China General Nuclear Power Group, the Research Grants Council of the Hong Kong Special Administrative Region of China, the National Science and Technology Council and the Ministry of Education in Taiwan, the U.S. National Science Foundation, the Ministry of Education, Youth, and Sports of the Czech Republic, the Charles University Research Centre UNCE, and the Joint Institute of Nuclear Research in Dubna, Russia.

研究动机与目标

• 利用大亚湾实验的数据，实现对反应堆反中微子混合角 $\theta_{13}$ 的高精度测定。
• 以更高精度测量有效质量平方差 $\Delta m^{2}_{ee}$，以约束中微子质量顺序。
• 通过与其它实验的μ中微子和反中微子消失测量结果对比，验证三中微子混合框架。
• 通过详细基于Geant4的探测器响应与背景贡献模拟，减小系统误差。
• 向未来全球分析与交叉验证提供大亚湾实验的完整数据发布。

提出的方法

• 分析利用三个实验大厅（EH1、EH2、EH3）的超前能量谱，提取反中微子事例率及作为基线和能量函数的振荡模式。
• 在 $\Delta m^{2}_{ee}$–$\sin^{2}2\theta_{13}$ 参数空间中执行 $\chi^{2}$ 最小化拟合，将系统误差作为干扰参数纳入。
• 系统误差以向量 $\bm{\nu}$ 中的拉伸量（pulls）建模，探测器和背景效应通过Geant4模拟。
• 使用标准三中微子振荡公式计算振荡概率，$\Delta m^{2}_{32}$ 在正常或反常质量顺序假设下由 $\Delta m^{2}_{ee}$ 推导得出。
• 通过最小化 $\chi^{2}$ 确定最佳拟合值，置信区间通过 $\Delta\chi^{2}$ 扫描获得。
• 采用多种拟合方法，结果经交叉检验，一致性在0.2个标准差以内。

实验结果

研究问题

• RQ1 在千米量级基线上，反应堆反中微子混合角 $\theta_{13}$ 的最精确测量值是多少？
• RQ2 所测得的 $\Delta m^{2}_{ee}$ 值与三中微子混合框架及其他实验结果的符合程度如何？
• RQ3 与μ中微子和反中微子消失测量结果相比，大亚湾实验结果在多大程度上支持三中微子框架？
• RQ4 $\Delta m^{2}_{ee}$ 的测定精度如何？其对中微子质量顺序的约束能力如何？
• RQ5 探测器响应和背景引起的系统误差对最终振荡参数提取的影响程度如何？

主要发现

• 测得的 $\sin^{2}2\theta_{13} = 0.0851 \pm 0.0024$ 精度达到2.8%，为迄今最精确的测定结果。
• 有效质量平方差测定为 $\Delta m^{2}_{ee} = (2.519 \pm 0.060) \times 10^{-3}\ \text{eV}^2$，精度约为2.4%。
• 最佳拟合 $\chi^{2}$ 值为559（自由度为517），表明与数据拟合良好。
• 所有三个实验大厅测得的反中微子能量谱与最佳拟合振荡模型高度一致。
• 结果与以往大亚湾实验测量结果一致，并与独立的RENO、Double Chooz、T2K、NOvA、MINOS/MINOS+、IceCube和SuperK实验结果一致。
• 各实验间的一致性强有力地支持了三中微子混合框架的有效性。