First Observation of the Ground-State Hyperfine-Structure Resonance of the Muonic Helium Atom

H. Orth; K. -P. Arnold; P. O. Egan; M. Gladisch; W. Jacobs; J. Vetter; W. Wahl; M. Wigand; V. W. Hughes; G. zu Putlitz

doi:10.1103/PhysRevLett.45.1483

First Observation of the Ground-State Hyperfine-Structure Resonance of the Muonic Helium Atom

H. Orth, K. -P. Arnold, P. O. Egan, M. Gladisch, W. Jacobs, J. Vetter, W. Wahl, M. Wigand, V. W. Hughes, and G. zu Putlitz

Phys. Rev. Lett. 45, 1483 – Published 3 November 1980; Erratum Phys. Rev. Lett. 45, 1984 (1980)

Abstract

The first measurement of the hfs interval $Δ ν$ for the muonic helium atom ${({}^{4}{He}^{+ +} μ^{-} e^{-})}^{0}$ is reported. In terms of its electronic structure, it is a heavy isotope of hydrogen. Polarized atoms are formed by stopping polarized negative muons in a helium-gas target at 19.4 atm with a 1.5% admixture of Xe. The ground-state hfs splitting $Δ ν$ was measured through observation of a microwave magnetic-resonance transition at zero magnetic field. After correction for the hfs pressure shift, we determine $Δ ν = 4464.95 (6)$ MHz (13 ppm).