Tilt Control System for Tests of Gravity Under 50 Microns

Undergraduate researchers and faculty at Humboldt State University are conducting tests of gravity at distances under 50 microns with the goal of searching for violations of the Inverse Square Law of gravity or the Weak Equivalence Principle. Violations of either of these principles could support models attempting to unify the Standard Model and General Relativity. The short-range gravity tests at Humboldt State University are being conducted using a torsion pendulum with equal masses of aluminum and titanium arranged as a composition dipole and a sinusoidally oscillating copper attractor mass in a parallel-plate arrangement. Due to the sensitivity of these tests, environmental effects such as the thermal conditions of the laboratory, electrical and magnetic fields from the environment and surrounding systems, and the tilt of the building housing the apparatus all must be understood and reduced as much as possible. We have implemented various systems to reduce the noise from each of these sources as much as possible. In this talk we will describe the ways in which the motion of the laboratory building affects our measurements and a system developed to actively level the apparatus to reduce tilt-related effects.