Low frequency double electron muon resonance (Demur) in fused quartz

Double electron muon resonance was studied with comparable amplitudes of the static and rf magnetic fields. The experiments were carried out in fused quartz and employed a resonant linearly-polarized rf field and a small static field. For small amplitudes of the rf field a three-line frequency spectrum was obtained consisting of a central line at the rf frequency and two weaker lines of equal amplitude symmetrically positioned about the central line. A symmetrical three line spectrum is predicted for muonium using the rotating wave approximation (RWA). For large rf fields the amplitudes of the three lines were not symmetric and depended on whether positrons were observed parallel or perpendicular to the beam. For very large rf fields the total amplitude of all the lines was less than for lower rf fields. These results do not agree with the theory using the RWA and no satisfactory theory currently exists.