New Measurement of the Charge Radius of the Neutron

Abstract

The neutron transmission through a thorogenic liquid ${}^{208}\mathrm{Pb}$ sample 2 in. thick has been measured in the neutron energy range between 0.1 and 360 eV at the ORNL neutron source ORELA. Analyzing the shape of the transmission spectra as a function of neutron energy, agreement was found with the predictions by the atomic form factor. With a sensitivity for the mean squared charge radius of the neutron $〈{r}_{n}^{2}〉$ as high as 3%, a very reliable and also accurate result of $〈{r}_{n}^{2}〉\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}0.113\ifmmode\pm\else\textpm\fi{}0.003\ifmmode\pm\else\textpm\fi{}0.004{\mathrm{fm}}^{2}$ was extracted. For the neutron-electron scattering length we obtained ${b}_{\mathrm{ne}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}(\ensuremath{-}1.31\ifmmode\pm\else\textpm\fi{}0.03\ifmmode\pm\else\textpm\fi{}0.04)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}\phantom{\rule{0ex}{0ex}}\mathrm{fm}$.