Equivalence principle and experimental tests of gravitational spin effects

We study the possibility of experimentally testing the manifestations of the equivalence principle in spin-gravity interactions. We reconsider the earlier experimental data and get the first experimental bound on the anomalous gravitomagnetic moment. The spin coupling to the Earth's rotation may also be explored at the extensions of neutron electric-dipole-moment and g-2 experiments. The spin coupling to terrestrial gravity produces a considerable effect which may be discovered at the planned deuteron electric-dipole-moment experiment. The Earth's rotation should also be taken into account in optical experiments in search of axionlike particles.