| Abstract: | Muonium is an exotic atom consisting of a positive muon and an electron. As it comprises two leptons, it lacks contributions from hadronic interactions or corrections due to the finite size of the nucleus, while still resembling hydrogen in its theoretical simplicity. Therefore, comparing measured and calculated energy levels in muonium provides a clean test of QED. Here, I report a new microwave spectroscopy measurement of the 2S(1/2)–2P(3/2) transition in Muonium using a costume-made waveguide optimized in the range of 8-11 GHz. The measured value agrees with the calculated value and improves upon the previous measurement by a factor of 5. I will also present the design of the second-generation waveguide system that harbors lower reflections and a simpler field. |