从大亚湾到江门中微子实验

From Daya Bay experiment to Jiangmen Underground Neutrino Observatory experiment

中微子振荡现象是当前粒子物理领域的研究热点.中微子振荡的发现确认了中微子具有微小的质量,这也成为探索超出标准模型新物理的重要途径.大亚湾反应堆中微子实验是研究短基线反应堆中微子振荡的地下实验,其利用远近点全同探测器对反应堆中微子事例率及能谱进行相对测量,以降低探测器关联误差及反应堆中微子流强预期误差.大亚湾反应堆中微子实验在2018年使用1958天的数据公布了中微子振荡参数sin^(2)2θ_(13)与|△m_(32)^(2)|的最新结果,其中sin^(2)2θ_(13)参数为目前最高的测量精度,达到了3.4%,|△m_(32)^(2)|的精度为2.8%,其与MINOS, NoνA及T2K等基于加速器中微子的实验测量精度相当.θ13的精确测量将有利于下一代中微子实验确定中微子质量顺序以及测量CP破坏相角等未知的中微子振荡参数,其中包括了我国正在建设的江门中微子实验.它的主要科学目标是通过在中等基线下精确测量反应堆中微子能谱来确定中微子质量顺序.探测器可以实现3%的超高能量分辨率和小于1%的能标误差,从而在6年的取数时间内以3–4σ的置信度测量中微子质量顺序.此外江门中微子实验也将精确测量中微子振荡参数,同时将在超新星中微子、太阳中微子、大气中微子、地球中微子、核子衰变等物理研究领域做出重要的贡献.

Currently, the neutrino oscillation phenomenon is of research interest in particle physics. The discovery of the neutrino oscillation phenomenon confirmed that neutrinos have a minute mass, which is an important way to explore new physics beyond the standard model. The Daya Bay reactor neutrino experiment is an underground experiment that studies shortbaseline reactor neutrino oscillations. It uses the far and near-identical detectors to reduce the detector uncertainty and the reactor neutrino expected flux uncertainty to measure the anti-neutrino rate and energy spectrum. The Daya Bay experiment released the latest neutrino oscillation parameters sin^(2)2θ_(13) and |△m_(32)^(2)| in 2018, which used 1958 days of data.The sin^(2)2θ_(13) had the highest measurement precision to date, which reached 3.4%, and the precision of |△m_(32)^(2)| was 2.8%,which was comparable with that of the accelerator-based experiments, such as MINOS, NoνA and T2K. The accurate measurement of θ13 will be helpful to the next-generation of neutrino experiments that will determine the neutrino mass ordering and measure the CP-violating phase. Jiangmen Underground Neutrino Observatory(JUNO) is a multipurpose neutrino experiment that is under construction. The main scientific aim of JUNO is to determine the neutrino mass ordering by measuring the neutrino energy spectrum with a resolution of 3% at 1 MeV and a ≥ 1% energy linearity. The neutrino mass ordering can be measured with a significance 3–4σ based on six years of data that has been collected. In addition,JUNO will make a significant contribution to the precise measurement of neutrino oscillation parameters and the study of supernova neutrinos, solar neutrinos, atmospheric neutrinos, geoneutrinos, and nucleon decay.