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arXiv 1303.6733hep-exhep-ph
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用反应堆中微子确定中微子质量等级

Unambiguous Determination of the Neutrino Mass Hierarchy Using Reactor Neutrinos

Yu-Feng Li, Jun Cao, Yifang Wang, Liang Zhan

摘要:

本文讨论了中基线反应堆中微子实验中中微子质量分级的确定。通过观察Δm^2_{31}和Δm^2_{32}振荡之间的干涉效应,可以进行不依赖于绝对质量平方差的相对测量。大亚湾Ⅱ号实验在距离总热功率为36 GW的反应堆50 km处,采用能量分辨率为3%/ \sqrt{E(MeV)}的20 kton液体闪烁探测器,在考虑堆芯实际空间分布的情况下,可以在6年内确定出置信水平为Δχ^2_{MH} \sim(10-12)(3-3.5 σ)的质量等级。我们发现,未知的剩余能量的非线性液体闪烁体探测器的灵敏度,由于小的振荡峰的自校准的影响有限。此外,通过包括来自正在进行的长基线μ子中微子消失实验的预期相对误差1.5%(1%)的有效质量平方差Δm^2_{μμ}的精确测量,可以获得Δχ^2_{MH} \simeq 4(9)的额外增加。干扰和绝对测量的灵敏度可以交叉检查。当结合这两者时,可以在6年内以Δχ^2_{MH} \sim(15-20)(4 σ)的置信水平确定质量等级。

英文摘要:

Determination of the neutrino mass hierarchy in a reactor neutrino experiment at medium baseline is discussed. Observation of the interference effects between the Δm^2_{31} and Δm^2_{32} oscillations enables a relative measurement independent of the knowledge of the absolute mass-squared difference. With a 20 kton liquid scintillator detector of 3%/\sqrt{E(MeV)} energy resolution, the Daya Bay II Experiment at a baseline of \sim 50 km from reactors of total thermal power 36 GW can determine the mass hierarchy at a confidence level of Δχ^2_{MH} \sim (10-12) (3-3.5 σ) in 6 years after taking into account the real spatial distribution of reactor cores. We show that the unknown residual energy non-linearity of the liquid scintillator detector has limited impact on the sensitivity due to the self-calibration of small oscillation peaks. Furthermore, an extra increase of Δχ^2_{MH} \simeq 4(9) can be obtained, by including the precise measurement of the effective mass-squared difference Δm^2_{μμ} of expected relative error 1.5% (1%) from ongoing long-baseline muon neutrino disappearance experiments. The sensitivities from the interference and from absolute measurements can be cross checked. When combining these two, the mass hierarchy can be determined at a confidence level of Δχ^2_{MH} \sim (15-20) (4 σ) in 6 years.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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