Magnetic neutrality of the neutron

Present interest in the possible existence of isolated magnetic charges has raised questions about the degree of magnetic neutrality in magnetic dipole systems. For the free neutron case, past experiments dealing with the spatial deflection of neutron beams in extended magnetic fields have been analyzed by Ramsey to set an upper limit of 10-12 for the fractional unbalance of poles separated by the neutron radius. This limit has been lowered by about six orders of magnitude in present experiments of deflection effects in crystals of silicon wherein the anomalously small effective mass of neutrons provides greatly enhanced sensitivity. (orig.)