近日，德国马克斯-普朗克核物理研究所的Christoph Schweiger及其研究团队取得一项新进展。经过不懈努力，他们利用潘宁势阱实现了用于确定电子中微子质量的¹⁶³Ho中的电子捕获Q值测量。相关研究成果已于2024年4月19日在国际知名学术期刊《自然—物理学》上发表。

本文报道了在潘宁势阱实验PENTATRAP中的一项重要成果：通过测量¹⁶³Ho和¹⁶³Dy高电荷离子的自由空间回旋频率比，研究人员直接、独立地确定了Q值。研究人员结合原子物理计算的电子结合能，得出的Q值为2,863.2±0.6eVc^-2，这一结果相较于现有技术水平提升了50多倍。这将使从¹⁶³Ho的电子捕获分析中确定亚电子伏特水平上的电子中微子质量成为可能。

据悉，粒子物理学的标准模型中，中微子与已知粒子的相互作用微弱，因此确定有效中微子质量绝对尺度的研究仍然面临挑战。目前，卡尔斯鲁厄氚中微子实验（KATRIN）通过对氚β衰变的深入分析，已经给出了电子反中微子质量的最精确且模型依赖最小的上限。同时，另一种备受瞩目的方法是利用¹⁶³Ho的电子捕获过程，这一方法正由钬电子捕获（ECHo）和HOLMES协作项目通过微热法进行研究。独立测量这一过程的Q值对于评估中微子质量测定中的系统不确定度至关重要。

附：英文原文

Title: Penning-trap measurement of the Q value of electron capture in ¹⁶³Ho for the determination of the electron neutrino mass

Author: Schweiger, Christoph, Bra, Martin, Debierre, Vincent, Door, Menno, Dorrer, Holger, Dllmann, Christoph E., Enss, Christian, Filianin, Pavel, Gastaldo, Loredana, Harman, Zoltn, Haverkort, Maurits W., Herkenhoff, Jost, Indelicato, Paul, Keitel, Christoph H., Kromer, Kathrin, Lange, Daniel, Novikov, Yuri N., Renisch, Dennis, Rischka, Alexander, Schssler, Rima X., Eliseev, Sergey, Blaum, Klaus

Issue&Volume: 2024-04-19

Abstract: The investigation of the absolute scale of the effective neutrino mass remains challenging due to the exclusively weak interaction of neutrinos with all known particles in the standard model of particle physics. At present, the most precise and least-model-dependent upper limit on the electron antineutrino mass is set by the Karlsruhe Tritium Neutrino Experiment (KATRIN) from the analysis of the tritium β-decay. Another promising approach is the electron capture in ¹⁶³Ho, which is under investigation using microcalorimetry by the Electron Capture in Holmium (ECHo) and HOLMES collaborations. An independently measured Q value for this process is vital for the assessment of systematic uncertainties in the neutrino mass determination. Here we report a direct, independent determination of this Q value by measuring the free-space cyclotron frequency ratio of highly charged ions of ¹⁶³Ho and ¹⁶³Dy in the Penning-trap experiment PENTATRAP. Combining this ratio with atomic physics calculations of the electronic binding energies yields a Q value of 2,863.2±0.6eVc^-2, which represents a more than 50-fold improvement over the state of the art. This will enable the determination of the electron neutrino mass on a sub-electronvolt level from the analysis of the electron capture in ¹⁶³Ho.

DOI: 10.1038/s41567-024-02461-9

Source: https://www.nature.com/articles/s41567-024-02461-9