SEARCH FOR SPONTANEOUS CONVERSION OF MUONIUM TO ANTIMUONIUM

An experimental search for the spontaneous conversion of muonium to an timuonium is described. A 10 MeV/c mu+ beam of average intensity 3 X 1 0(5) s-1 was used to produce muonium atoms in vacuum by charge capture in a thin foil. The novel method applied here for detection of an ant imuonium atom was a triple coincidence of two muonic x-ray photons fro m the atomic capture of its mu- by a high-Z target and a secondary ele ctron ejected from the target upon the impact of the antimuonium atom. No antimuonium events were observed and the resulting 90% confidence level upper limit on the coupling constant leading to the conversion, G(MMBAR), is 6.9G(F), where G(F) is the Fermi coupling constant.