Excited state muon transfer in hydrogen/deuterium mixtures.

We report the first direct observation of excited state muon transfer in hydrogen/deuterium mixtures by direct measurement of q1s, the probability that a μp atom, which is initially formed in an excited state, reaches the 1s ground state. The dependence of q1s on deuterium concentration cd was measured for two different densities at cryogenic temperatures using charge coupled devices (CCDs) to detect the muonic X rays. First results based on the analysis of the Kα-lines of the two isotopes are presented.