Measurement of the 1s-2s Energy Interval in Muonium

[[abstract]]The 1s-2s interval has been measured in the muonium (μ+e-) atom by Doppler-free two photon pulsed laser spectroscopy. The frequency separation of the states was determined to be 2 455 528 941.0(9.8) MHz in good agreement with quantum electrodynamics. The result may be interpreted as a measurement of the muon-electron charge ratio as -1-1.1(2.1)×10-9. We expect significantly higher accuracy at future high flux muon sources and from CW laser technology[[fileno]]2010112010020[[department]]物理