Test of a composition-dependent force by a free-fall interferometer

Abstract

We have obtained an experimental null result for a possible composition-dependent force by a newly developed Galilean method in which we measured the acceleration difference between two objects freely falling simultaneously in a vacuum chamber. The data on two pairs of objects, an aluminum-copper pair and an aluminum-carbon pair, indicate \ensuremath{\Vert}\ensuremath{\xi}\ensuremath{\Vert}\ensuremath{\lambda}<9m if baryon coupling and a simple model of the Earth is assumed.