http://en.wikipedia.org/wiki/G-factor
Measured g-factor values
Elementary Particle g-factor Uncertainty
Electron ge ?2.0023193043622 0.0000000000015
Neutron gn ?3.82608545 0.00000090
Proton gp 5.585694713 0.000000046
Muon gμ ?2.0023318414 0.0000000012
Currently accepted NIST g-factor values[1]
The electron g-factor is one of the most precisely measured values in physics, with its uncertainty beginning at the twelfth decimal place
