Energy Spectrum of Charged Particles Emitted Following Muon Capture inSi28

Results of a high-resolution study of the charged-particle energy spectrum resulting after ${\mu }^{-}$ capture in ${\mathrm{Si}}^{28}$ are presented. The spectrum, attributed mainly to proton emission, exhibits a low-energy cutoff at 1.4 MeV and a maximum at about 2.5 MeV from which it decreases approximately exponentially with a decay constant of 4.6 MeV. A branching ratio of 0.15±0.02 charged particle per capture was determined.