Measurement of Parity Nonconservation in Atomic Bismuth

Parity-nonconserving optical rotation has been observed and measured on the 8757-\AA{}A magnetic-dipole absorption line in atomic bismuth vapor. The result, $R\ensuremath{\equiv}\mathrm{Im}(\frac{{E}_{1}}{{M}_{1}})=(\ensuremath{-}10.4\ifmmode\pm\else\textpm\fi{}1.7)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$, is of the approximate size calculated with use of the Weinberg-Salam theory of the weak neutral-current interaction with ${{sin}^{2}\ensuremath{\theta}}_{\mathrm{W}}=0.23$.