He/Xe Clock Comparison Experiment: Search for Spin-Dependent Short-Range Interaction

We report on the search for a new spin–dependent interaction ~σ·r̂ which causes a shift in the precession frequency of nuclear spin polarized gases. Therefore we use a comagnetometer that is based on the detection of freely precessing nuclear spins from He and Xe gas samples using SQUIDs as low–noise magnetic flux detectors. As result we could improve the upper bounds of the dimensionless product gsgp of the monopole–dipole coupling of an axion to the spin of a bound neutron in the mass range between 2 μeV and 500 μeV (corresponding to force ranges between 3 · 10−4 m and 10−1 m) by up to 4 orders of magnitude.