The electrical neutrality of atoms

An atomic beam deflection experiment is described which establishes upper limits to the electrical charges of potassium and cesium atoms ofq(K)<2.4×10^?18 q _e andq(Cs)<3.0×10^?18 q _e at the 90% confidence level, in whichq _e is the electron charge magnitude. If we assume that the electron neutrino charge is zero and that charge conservation holds in neutron beta decay, then the difference δq in the electron and proton charge magnitudes has the upper limit δq<1.3×10^?20 q _e at the 90% confidence level. The possibility of a more sensitive atomic beam deflection experiment using a laser-cooled atomic beam is suggested. A brief review of the topic of the electrical neutrality of atoms is given.