A MEASUREMENT OF THE 1S-2S TRANSITION FREQUENCY IN MUONIUM

Abstract Doppler-free two-photon laser spectroscopy has been employed to measure the 1 2 S 1 2 −2 2 S 1 2 transition in the muonium atom ( μ + e − ). A value of 2 455 529 002(33) (46) MHz has been obtained, which agrees with QED calculations within two standard deviations. The Lamb shift contributions are tested to the level 8×10 −3 . The corresponding measurements in hydrogen and deuterium using the same apparatus and laser system provide a test of the applied systematic corrections and have verified the systematic error of 46 MHz quoted. The mass of the positive muon has been derived from the isotope shift in this transition and yields a value of 105.65880(29)(43) MeV c 2 .