Resonance line narrowing in a precision muonium experiment

An experiment is in progress at LAMPF to measure δν and μμ/μp in the ground state of muonium to a higher precision than they are presently known by the microwave magnetic resonance method at a strong magnetic field of 1.7T. An important aspect of this measurement is the line-narrowing possible by the open-quotes oldclose quotes muonium technique using a chopped muon beam. Indeed the authors have observed this resonance line narrowing up to 1/2 of the natural linewidth of 145 kHz. The resonance lines ν12[(Mj,Mμ) = (1/2,1/2) → (1/2,-1/2)] and ν34[(-1/2,1/2)→(-1/2,-1/2)] were induced and resonance lines were obtained both by varying the microwave frequency with fixed magnetic field and by varying the microwave frequency with fixed magnetic field. Extensive data have been obtained with Kr target gas pressures of 0.5 and 1.0 atm, and data analysis is in progress