Laser spectroscopy of muonic atoms

Laser spectroscopy of muonic atoms is well suited for testing the Quantum Electrodynamics of bound states, for precise measurements of fundamental constants, for investigating properties of hadronic nuclei, and for searching for anomalous muon interactions. Successful experiments have been reported for the 2S-2P transitions in muonic helium ion and for the 1S-2S two-photon transition in muonium. Experiments on muonic hydrogen are coming up. A source of very slow positive muons is being developed which employs laser photoionization of muonium. Polarized muonic helium was obtained by spin transfer from laser polarized Rubidium. The field is open for addressing a variety of interesting physics problems.