Search Results (7 total)

An experimental search for the spontaneous conversion of muonium to antimuonium is described. A 10 MeV/c μ⁺ beam of average intensity 3×10⁵ 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 antimuonium atom was a triple coincidence of two muonic x-ray photons from the atomic capture of its μ^- by a high-Z target and a secondary electron 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_MM̅ , is 6.9G_F, where G_F is the Fermi coupling constant.

To search for spontaneous conversion of muonium to antimuonium with very low background, a new signature was implemented that required the coincident detection of the decay products of the antimuonium atom, the energetic e^- and the atomic e⁺. No conversion events were seen, which sets an improved upper limit of 6.5×10^-7 (90% C.L.) on the conversion probability. The corresponding limit on the coupling constant, using a V-A form for the conversion Hamiltonian, is G_MM¯<0.16G_F (90% C.L.), where G_F is the Fermi coupling constant.

The negative muonium ion, Mu^-≡μ⁺e^-e^-, has been produced by double electron pickup as a beam of positive muons passes through thin foils of various materials. The Mu^- ions were detected by electrostatically accelerating and analyzing the ions in a magnetic time-of-flight spectrometer. Yields of Mu^-, Mu and μ⁺ as well are reported when μ⁺ with kinetic energies from 380 to 800 keV impinge on thin Be, Al, and Au foils. A Monte Carlo simulation provides good agreement with the experimental results.

The results of an experimental search with a new method for the spontaneous conversion of muonium to antimuonium are reported. The upper limit for G_MM̅ , the coupling constant characterizing the strength of the interaction leading to the conversion, is measured to be G_MM̅ <7.5G_F (90% confidence level), where G_F is the Fermi coupling constant. This result is about a factor of 3 lower than the previous limit and begins to probe predictions of the left-right-symmetric theory with a doubly charged Higgs triplet.

The negative muonium ion Mu^-≡μ⁺e^-e^- has been produced by double electron pickup as a beam of positive muons passes through a foil. A clean signal was detected by electrostatically accelerating and analyzing the ions in a magnetic time-of-flight spectrometer. The Mu^- beam at the focal plane of our spectrometer had an intensity 1.4×10^-5 times that of the incident μ⁺ beam or 2 s^-1, which corresponds to a Mu^-/μ⁺ conversion probability of 0.5×10^-4 at the foil in agreement with the calculated value. The kinetic energies of Mu^- at the foil are less than several keV as expected.