Test of the equivalence principle using a rotating torsion balance

S Schlamminger; K-Y Choi; T A Wagner; J H Gundlach; E G Adelberger

doi:10.1103/PhysRevLett.100.041101

Test of the equivalence principle using a rotating torsion balance

Phys Rev Lett. 2008 Feb 1;100(4):041101. doi: 10.1103/PhysRevLett.100.041101. Epub 2008 Jan 28.

Authors

S Schlamminger¹, K-Y Choi, T A Wagner, J H Gundlach, E G Adelberger

Affiliation

¹ Center for Experimental Nuclear Physics and Astrophysics, University of Washington, Seattle, Washington 98195, USA.

PMID: 18352252
DOI: 10.1103/PhysRevLett.100.041101

Abstract

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 Deltaa(N),(Be-Ti)=(0.6+/-3.1)x10(-15) m/s2 improves limits on equivalence-principle violations with ranges from 1 m to infinity by an order of magnitude. The Eötvös parameter is eta(Earth,Be-Ti)=(0.3+/-1.8)x10(-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 eta(DM,Be-Ti)=(-4+/-7)x10(-5). Space-fixed differential accelerations in any direction are limited to less than 8.8x10(-15) m/s2 with 95% confidence.