Experimental Limit for the Neutron Charge

Abstract

A microscopic measurement of the charge on a free, monoenergetic neutron has led to the value of (-1.9\ifmmode\pm\else\textpm\fi{}3.7)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}18}$ electron charges. This is consistent with the usual view that neutrons are electrically neutral. The experiment has exploited the very high angular sensitivity of a double-crystal spectrometer in assessing the angular deflection of a monoenergetic neutron beam under electrostatic deflection conditions. An improvement of about six orders of magnitude in the upper limit of the charge over previously published values obtained by direct experimentation has been attained.