The reaction of muonium with hydrated electrons

Abstract

When positive muons stop in water roughly 60% are incorporated in diamagnetic compounds, and the remainder form muonium. The two fractions can be distinguished by their muon spin rotation (μSR) signals, but the signal amplitudes indicate that part of the initial muon spin polarization is missing. Earlier work showed that the depolarization occurs as a result of encounters between muonium atoms and hydrated electrons formed at the end of the muon track. A reexamination of the field dependence of the muon polarization in the diamagnetic signal has revealed a small increase at low fields, which is consistent with formation of MuH from Mu on the same time-scale as the muonium depolarization process. This has been explored in a variety of experiments at various temperatures, pressures, and concentrations of paramagnetic ions.