A search for the electron electric dipole moment ${\mathit{d}}_{\mathit{e}}$ is carried out with two counterpropagating beams of ground-state ${}_{}{}^{205}{}_{}{}^{}\mathrm{Tl}$. The experiment employs atomic-beam magnetic resonance with separated oscillatory fields combined with laser state selection and fluorescence detection. Extensive tests were made for possible systematic effects. The result for the atomic electric dipole moment is ${\mathit{d}}_{\mathit{a}}$=(1.6 ±5.0)×${10}^{\mathrm{-}24}$ e cm, where the uncertainty includes equal statistical and systematic contributions. This yields ${\mathit{d}}_{\mathit{e}}$=(-2.7±8.3) ×${10}^{\mathrm{-}27}$ e cm, assuming the ratio ${\mathit{d}}_{\mathit{a}}$/${\mathit{d}}_{\mathit{e}}$=-600.

• Received 31 August 1990

DOI:https://doi.org/10.1103/PhysRevLett.65.2347