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Sensitivity ofTh229nuclear clock transition to variation of the fine-structure constant
Physical Review A ( IF 2.9 ) Pub Date : 2020-11-30 , DOI: 10.1103/physreva.102.052833
Pavel Fadeev , Julian C. Berengut , Victor V. Flambaum

Peik and Tamm [Europhys. Lett. 61, 181 (2003)] proposed a nuclear clock based on the isomeric transition between the ground state and the first excited state of thorium-229. This transition was recognized as a potentially sensitive probe of possible temporal variation of the fine-structure constant, α. The sensitivity to such a variation can be determined from measurements of the mean-square charge radius and quadrupole moment of the different isomers. However, current measurements of the quadrupole moment are yet to achieve an accuracy high enough to resolve nonzero sensitivity. Here we determine this sensitivity using existing measurements of the change in the mean-square charge radius, coupled with the ansatz of constant nuclear density. The enhancement factor for α variation is K=(0.82±0.25)×104. For the current experimental limit, δα/α1017 per year, the corresponding frequency shift is 200 Hz per year. This shift is six orders of magnitude larger than the projected accuracy of the nuclear clock, paving the way for increased accuracy of the determination of δα and interaction strength with low-mass scalar dark matter. We verify that the constant-nuclear-density ansatz is supported by nuclear theory and propose how to verify it experimentally. We also consider a possible effect of the octupole deformation on the sensitivity to α variation and calculate the effects of α variation in a number of Mössbauer transitions.

中文翻译:

Th229核时钟跃迁对精细结构常数变化的敏感性

佩克和塔姆[Europhys 。来吧 61,181(2003)]提出了基于地面状态和钍229的第一激发态之间的同质异能跃迁核时钟。这种转变被认为是精细结构常数可能随时间变化的潜在敏感探针,α。可以通过测量不同异构体的均方电荷半径和四极矩来确定对这种变化的敏感性。但是,目前对四极矩的测量尚未达到足以解决非零灵敏度的高精度。在这里,我们使用均方电荷半径变化的现有测量值以及恒定核密度的ansatz来确定这种灵敏度。的增强因子α 变化是 ķ=-0.82±0.25×104。对于当前的实验极限,δα/α10-17 每年相应的频移是 200 每年Hz。该偏移量比核时钟的预计精度大六个数量级,为提高确定频率的准确性铺平了道路。δα以及与低质量标量暗物质的相互作用强度。我们验证核理论支持恒定核密度的ansatz,并提出如何通过实验进行验证。我们还考虑了八极形变对灵敏度的可能影响。α 变化并计算 α 多个Mössbauer过渡的变化。
更新日期:2020-12-01
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