High-Precision Determination of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>g</mml:mi></mml:math> Factors and Masses of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>Ne</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>20</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow><mml:mrow><mml:mn>9</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>Ne</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>22</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow><mml:mrow><mml:mn>9</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>
F. Heiße, Menno Door, Tim Sailer, P. Filianin, Jost Herkenhoff, C. M. König, Kathrin Kromer, Daniel Lange, Jonathan Morgner, Alexander Rischka, Christoph Schweiger, B. Tu, Yu. N. Novikov, S. Eliseev, S. Sturm, K. Blaum
Abstract
We present the measurements of individual bound electron $g$ factors of ${^{20}\mathrm{Ne}}^{9+}$ and ${^{22}\mathrm{Ne}}^{9+}$ on the relative level of 0.1 parts per billion. The comparison with theory represents the most stringent test of bound-state QED in strong electric fields. A dedicated mass measurement results in $m(^{20}\mathrm{Ne})=\phantom{\rule{0ex}{0ex}}19.992\text{ }440\text{ }168\text{ }77(9)\text{ }\text{ }\mathrm{u}$, which improves the current literature value by a factor of 18, disagrees by 4 standard deviations, and represents the most precisely measured mass value in atomic mass units. Together, these measurements yield an electron mass on the relative level of 0.1 ppb with ${m}_{\mathrm{e}}=5.485\text{ }799\text{ }090\text{ }99(59)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}\text{ }\text{ }\mathrm{u}$ as well as a factor of seven improved $m(^{22}\mathrm{Ne})=21.991\text{ }385\text{ }098\text{ }2(26)\text{ }\text{ }\mathrm{u}$.