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科学家测量出中微子至今最精确质量上限 0.45 eV
#科学

KATRIN(Karlsruhe Tritium Neutrino,卡尔斯鲁厄氚中微子)实验的研究人员报告了迄今为止对中微子质量上限的最精确测量结果:设定为 0.45 电子伏特 (eV) ,不到电子质量的百万分之一。该发现为宇宙中最难以捉摸的基本粒子设置了更严格的质量范围,使得其物理学适用边界超越了“标准模型”(Standard Model)。中微子(一种电中性基本粒子)是宇宙中数量最多的粒子,它以三种不同类型或“味”存在:电子中微子、μ 中微子和 τ 中微子。这些味态的摆荡意味着单个中微子在传播时可转变为三种味态中的每一种类型;该现象提供了确凿的证据:中微子具有质量;这与“标准模型”最初假设的中微子无质量相矛盾。然而,它们的确切质量仍是粒子物理学的一大谜团。KATRIN 实验通过分析氚的 β 衰变来确定中微子的质量。在此衰变过程中,中子会转变为质子,同时会释放一个电子和一个电子反中微子——后者是中微子的反粒子。通过分析发射的电子和电子反中微子间的总衰变能量分布便可推算中微子的质量。在 2019 年至 2021 年间的 259 天中,KATRIN 合作团队测量了约 3600 万个电子的能量——这一数据集比之前的运行规模要大 6 倍。这些发现确定了电子中微子有效质量的最严格实验室上限:将其置于 < 0.45 eV (置信水平为 90%)。
Science: DOI 10.1126/science.adq9592
EurekAlert KATRIN 实验确立了中微子质量的最精确上限:0.45 eV



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科学家测量出中微子至今最精确质量上限 0.45 eV
#科学

KATRIN(Karlsruhe Tritium Neutrino,卡尔斯鲁厄氚中微子)实验的研究人员报告了迄今为止对中微子质量上限的最精确测量结果:设定为 0.45 电子伏特 (eV) ,不到电子质量的百万分之一。该发现为宇宙中最难以捉摸的基本粒子设置了更严格的质量范围,使得其物理学适用边界超越了“标准模型”(Standard Model)。中微子(一种电中性基本粒子)是宇宙中数量最多的粒子,它以三种不同类型或“味”存在:电子中微子、μ 中微子和 τ 中微子。这些味态的摆荡意味着单个中微子在传播时可转变为三种味态中的每一种类型;该现象提供了确凿的证据:中微子具有质量;这与“标准模型”最初假设的中微子无质量相矛盾。然而,它们的确切质量仍是粒子物理学的一大谜团。KATRIN 实验通过分析氚的 β 衰变来确定中微子的质量。在此衰变过程中,中子会转变为质子,同时会释放一个电子和一个电子反中微子——后者是中微子的反粒子。通过分析发射的电子和电子反中微子间的总衰变能量分布便可推算中微子的质量。在 2019 年至 2021 年间的 259 天中,KATRIN 合作团队测量了约 3600 万个电子的能量——这一数据集比之前的运行规模要大 6 倍。这些发现确定了电子中微子有效质量的最严格实验室上限:将其置于 < 0.45 eV (置信水平为 90%)。
Science: DOI 10.1126/science.adq9592
EurekAlert KATRIN 实验确立了中微子质量的最精确上限:0.45 eV

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