Test of the Equivalence Principle Using a Rotating Torsion Balance

We used a continuously rotating torsion balance instrument to measure the acceleration difference of beryllium and titanium test bodies towards sources at a variety of distances. Our result Δa_N,Be-Ti=(0.6±3.1)×10^-15m/s² improves limits on equivalence-principle violations with ranges from 1 m to ∞ by an order of magnitude. The Eötvös parameter is η_Earth,Be-Ti=(0.3±1.8)×10^-13. By analyzing our data for accelerations towards the center of the Milky Way we find equal attractions of Be and Ti towards galactic dark matter, yielding η_DM,Be-Ti=(-4±7)×10^-5. Space-fixed differential accelerations in any direction are limited to less than 8.8×10^-15m/s² with 95% confidence.