Formation of Muonium in the2SState and Observation of the Lamb Shift Transition

Abstract

Muonium in the $2S$ state has been produced by the beam-foil method with a ${\mu }^{+}$ beam of 10 MeV/c. The metastable $2S$ state of muonium has been detected by a static electric field quenching method, and the transition $2S_{\frac{1}{2}}$, $F=1\mathrm{}\to 2P_{\frac{1}{2}}$, $F=1\mathrm{}$ induced by a radio-frequency electric field has been observed with an event rate of about 4/h.