Muonium. I. Muonium Formation and Larmor Precession

A complete quantitative discussion is given of the experiments in which muonium was discovered through studies of the depolarization of muons in gases and of the Larmor precession of muonium in argon in a static magnetic field. Also described are the observation of the hfs interval $\Delta \nu$ of muonium in its ground state and the determination of $\Delta \nu$ to an accuracy of about 50% through the use of a static magnetic field. A theoretical discussion is given of muonium formation in gases, including polarization effects. The experimental results on the Larmor precession of muonium prove that close to 100% of the muons stopping in pure argon gas form muonium. The experimental results on muon depolarization in other gases, together with the theoretical considerations, suggest that abundant muonium formation should occur when muons are stopped in most gases; the case of S${\mathrm{F}}_6$ appears anomalous in that, at most, only small formation of muonium is indicated. A discussion of the energy levels and decay characteristics of muonium is given. This is the first in a series of papers on the muonium atom and on its interactions in gases.