Direct Measurement of the Proton Magnetic Moment

TL;DR

This paper reports a highly precise direct measurement of the proton magnetic moment using a Penning trap, paving the way for similarly precise measurements of the antiproton magnetic moment, which has remained largely unchanged for two decades.

Contribution

It introduces a novel direct measurement method with high precision that can be applied to antiprotons, significantly improving measurement accuracy.

Findings

Proton magnetic moment measured with 2.5 ppm uncertainty

Method applicable to antiprotons for the first time

Potential to improve antiproton magnetic moment measurement by 1000 times

Abstract

The proton magnetic moment in nuclear magnetons is measured to be $\mu_p/\mu_N \equiv g/2 = 2.792\,846 \pm 0.000\,007$, a 2.5 ppm (parts per million) uncertainty. The direct determination, using a single proton in a Penning trap, demonstrates the first method that should work as well with an antiproton as with a proton. This opens the way to measuring the antiproton magnetic moment (whose uncertainty has essentially not been reduced for 20 years) at least $10^3$ times more precisely.