The interaction of spins in a spin-polarized test mass and those in a paramagentic salt, separated by a μ-metal shield and a double-layer superconducting shield, was investigated. Our results set a limit on electron spin interactions and on moments which are not of electromagnetic origin. In terms of a standard dipole-dipole form, the limit is (2.7±2.4)×10−14 of the interaction strength between the magnetic moments of the electrons. Compared to previous results, this is more than a twentyfold improvement.
CONST is the interaction strength between the magnetic moments of the electrons in terms of a standard dipole-dipole form.