Precision measurement of parity nonconservation in proton-proton scattering at 45 MeV

Abstract

Parity nonconservation in pp scattering has been studied by measuring the helicity dependence of the cross section, ${A}_{z}$=(${\ensuremath{\sigma}}^{+}$-${\ensuremath{\sigma}}^{\ensuremath{-}}$)/(${\ensuremath{\sigma}}^{+}$+${\ensuremath{\sigma}}^{\ensuremath{-}}$), for longitudinally polarized incident protons of 45 MeV. We found ${A}_{z}$=(-1.50\ifmmode\pm\else\textpm\fi{}0.22)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}7}$ for the angular range 23\ifmmode^\circ\else\textdegree\fi{} to 52\ifmmode^\circ\else\textdegree\fi{} (laboratory). The uncertainty is the root square sum of the error of the measured asymmetry (\ifmmode\pm\else\textpm\fi{}0.19\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}7}$), the error of the applied corrections (\ifmmode\pm\else\textpm\fi{}0.05\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}7}$), and of various systematic errors (\ifmmode\pm\else\textpm\fi{}0.09\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}7}$). This is the most accurate result ever obtained on parity nonconservation in the nucleon-nucleon interaction.