Muon transfer to sulphur dioxide

A systematic study of muon capture and muon transfer has been performed in seven different H2+SO2 gas mixtures. From the single-exponential time structure of the muonic sulphur X-rays, one determines the lifetime of the mu p atoms under the given experimental conditions. The reduced muon transfer rates to the sulphur dioxide molecule, deduced from these lifetimes, all agree well with each other. The muonic oxygen time spectra show an additional structure as if mu p atoms of another kind were present. Comparable time structures are observed in a D2+SO2 mixture. For lack of a reliable theory, the data were analysed in the framework of the models of 'black and white' and 'ephemeral' muonic hydrogen atoms. The systematic study revealed an unexplained concentration dependence of the ratio of prompt muonic X-ray events between sulphur and oxygen.