We report a fourfold improvement in the determination of nuclear magnetic moments for neutron-deficient francium isotopes 207–213, reducing the uncertainties from 2% for most isotopes to 0.5%. These are found by comparing our high-precision calculations of hyperfine structure constants for the ground states with experimental values. In particular, we show the importance of a careful modeling of the Bohr-Weisskopf effect, which arises due to the finite nuclear magnetization distribution. This effect is particularly large in Fr and until now has not been modeled with sufficiently high accuracy. An improved understanding of the nuclear magnetic moments and Bohr-Weisskopf effect are crucial for benchmarking the atomic theory required in precision tests of the standard model, in particular atomic parity violation studies, that are underway in francium.

中文翻译：

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来自精密超细比较的Franc207-213的核磁矩。

我们报告说，中子缺陷is同位素207-213的核磁矩测定提高了四倍，将不确定性从大多数同位素的2％降低到0.5％。这些是通过将我们对基态的超精细结构常数的高精度计算与实验值进行比较而发现的。特别是，我们显示了仔细建模Bohr-Weisskopf效应的重要性，这是由于有限的核磁化分布而产生的。在Fr中，这种影响特别大，直到现在还没有以足够高的精度建模。更好地了解核磁矩和玻尔-魏斯科普夫效应对于基准标准模型（尤其是atomic中正在进行的原子平价违规研究）的精密测试所需的原子理论进行基准测试至关重要。