近日，德国马克斯普朗克核物理研究所的Stefan Dickopf及其研究团队取得一项新进展。经过不懈努力，他们发现⁹Be的精密光谱学能够克服原子核结构的限制。相关研究成果已于2024年8月14日在国际权威学术期刊《自然》上发表。

本文聚焦于⁹Be，它提供了独特的可能性，即通过比较彭宁阱中可用于高精度光谱学的不同电荷状态，来检验通常因核结构而模糊不清的理论计算。具体而言，研究人员对类氢⁹Be³⁺的1s超精细结构和塞曼结构进行了高精度光谱学研究。研究人员测定了有效泽马赫半径，其不确定性为500ppm，还测定了裸露核磁矩，其不确定性为0.6ppb——这些不确定性在氢以外是前所未有的。

此外，研究人员将测量结果与在三电子电荷态⁹Be⁺（参考文献5）上进行的测量进行了比较，这使得能够在十亿分之一的水平上检验核磁矩的多电子抗磁屏蔽效应的计算。此外，他们还检验了用于计算超精细分裂的量子电动力学方法。这项研究结果作为将核磁性质的高精度结果转移到不同电子构型的关键基准。

据悉，由于对核性质的了解不足，许多对粒子物理学标准模型的强有力测试以及利用精密原子光谱学寻找新物理的努力都受到了阻碍。理想情况下，这些性质可以通过对最敏感、理论上最易于理解的观测量的精确测量来推导，而这些观测量通常存在于类氢系统中。尽管对核的电性质的测量非常丰富，但对磁性质的测量却很少，而且精确的实验结果仅限于最轻的核。

附：英文原文

Title: Precision spectroscopy on 9Be overcomes limitations from nuclear structure

Author: Dickopf, Stefan, Sikora, Bastian, Kaiser, Annabelle, Mller, Marius, Ulmer, Stefan, Yerokhin, Vladimir A., Harman, Zoltn, Keitel, Christoph H., Mooser, Andreas, Blaum, Klaus

Issue&Volume: 2024-08-14

Abstract: Many powerful tests of the standard model of particle physics and searches for new physics with precision atomic spectroscopy are hindered by our lack of knowledge of nuclear properties. Ideally, these properties may be derived from precise measurements of the most sensitive and theoretically best-understood observables, often found in hydrogen-like systems. Although these measurements are abundant for the electric properties of nuclei, they are scarce for the magnetic properties, and precise experimental results are limited to the lightest of nuclei. Here we focus on ⁹Be, which offers the unique possibility to use comparisons between different charge states available for high-precision spectroscopy in Penning traps to test theoretical calculations typically obscured by nuclear structure. In particular, we perform high-precision spectroscopy of the 1s hyperfine and Zeeman structure in hydrogen-like ⁹Be³⁺. We determine the effective Zemach radius with an uncertainty of 500ppm, and the bare nuclear magnetic moment with an uncertainty of 0.6 parts per billion— uncertainties unmatched beyond hydrogen. Moreover, we compare our measurements with the measurements conducted on the three-electron charge state ⁹Be⁺ (ref.5), which enables testing the calculation of multi-electron diamagnetic shielding effects of the nuclear magnetic moment at the parts per billion level. Furthermore, we test the quantum electrodynamics methods used for the calculation of the hyperfine splitting. Our results serve as a crucial benchmark for transferring high-precision results of nuclear magnetic properties across different electronic configurations.

DOI: 10.1038/s41586-024-07795-1

Source: https://www.nature.com/articles/s41586-024-07795-1