Measurement of parity nonconserving neutron spin rotation in lanthanum

Abstract

The rotation, ${\ensuremath{\varphi}}_{\mathrm{pnc}}$, of a neutron beam polarization vector due to parity nonconserving forces is measured in a lanthanum target. It is found that $\frac{{\ensuremath{\varphi}}_{\mathrm{pnc}}}{l}=\ensuremath{-}(21.9\ifmmode\pm\else\textpm\fi{}2.9)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ rad/cm, where the negative sign corresponds to a left-handed rotation of the neutron spin about its momentum.