Measurement of the Neutron-Electron Interaction by the Scattering of Neutrons by Lead and Bismuth

Abstract

The atomic scattering length of lead and the nuclear scattering lengths of lead and bismuth were measured with high accuracy. From the results we obtained ${b}_{c}(\mathrm{Pb}\mathrm{atom})=9.4003\ifmmode\pm\else\textpm\fi{}0.0014$ fm, ${b}_{N}(\mathrm{Pb}\mathrm{nucleus})=9.5121\ifmmode\pm\else\textpm\fi{}0.015$ fm, ${b}_{N}(\mathrm{Bi}\mathrm{nucleus})=8.6412\ifmmode\pm\else\textpm\fi{}0.015$ fm, and from the previously reported ${b}_{c}(\mathrm{Bi}\mathrm{atom})$ we obtained two new values for the neutron-electron scattering length: ${b}_{n,e}=\ensuremath{-}(1.364\ifmmode\pm\else\textpm\fi{}0.025)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ fm from the Pb experiment, and ${b}_{n,e}=\ensuremath{-}(1.393\ifmmode\pm\else\textpm\fi{}0.025)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ fm from the Bi data.