The proton magnetic moment in nuclear magnetons is measured to be μp/μN≡g/2=2.792846±0.000007
Nearby in the stack
, 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