Level crossing resonance detection of a muonic radical in sulphur

Detection of a level crossing resonance establishes that a molecular radical is created in elemental sulphur following the implantation of positive muons. Formally this is the product of the reaction of atomic muonium with the S₈ rings and must serve as a model for the fate of interstitial atomic hydrogen in this element. The isotropic component of the muon-electron hyperfine interaction is determined to be 233 ± 5 MHz. Preliminary data for the temperature dependence of the resonance linewidth indicates a substantial motional narrowing of the anisotropic components.