Sub-millimeter tests of the gravitational inverse-square law: A search for "large" extra dimensions

TL;DR

The gravitational 1/r(2) law is tested at separations ranging down to 218 microm using a 10-fold symmetric torsion pendulum and a rotating 10- fold symmetric attractor to improve previous short-range constraints and find no deviations from Newtonian physics.

Abstract

Motivated by higher-dimensional theories that predict new effects, we tested the gravitational 1/r^2 law at separations ranging down to 218 micrometers using a 10-fold symmetric torsion pendulum and a rotating 10-fold symmetric attractor. We improved previous short-range constraints by up to a factor of 1000 and find no deviations from Newtonian physics.

Figures (5)

• Figure 1: Scale drawing of the torsion pendulum and rotating attractor. The active components are shaded. For clarity, we show an unrealistically large 1.5 cm vertical separation between pendulum and attractor, and omit the BeCu membrane and the attractor drive mechanism. The 4 horizontal screws were adjusted to make the pendulum precisely level.
• Figure 2: Autocollimator data for one complete revolution of the attractor, taken at $\zeta = 237~\mu$m. The curve is a fit to Eq. \ref{['eq: fit']}
• Figure 3: $T_{10}$, $T_{20}$ and $T_{30}$ torques, and the $10\omega$ torque from the upper attractor alone. Each point contains at least 36 individual measurements; the $1\sigma$ error bars are derived from the scatter of the individual measurements. The upper panel shows the measured torques; the solid line is the Newtonian prediction. The $T_{10}$ sign change at $z=2.2$ mm is due to cancellation from the bottom set of holes. The lower panel displays the Newtonian fit residuals; the solid curve shows the effect on $T_{10}$ of an interaction with $\alpha=3$ and $\lambda=250~\mu$m.
• Figure 4: 95% confidence upper limits on $1/r^2$-law violating interactions of the form given by Eq. \ref{['eq: potential']}. The region excluded by previous workho:85mi:88la:98 lies above the heavy lines labeled Irvine, Moscow and Lamoreaux, respectively. The data in Fig. \ref{['fig: b10']} imply the constraint shown by the heavy line labeled Eöt-Wash. Constraints from previous experiments and the theoretical predictions are adapted from Ref. pr:99, except for the dilaton prediction which is from Ref. ka:00.
• Figure 5: Capacitance measurements of the separation. The horizontal axis is the reading of the $z$-micrometer. The fit indicated that the pendulum would touch the screen at $z=978 \pm 3~\mu$m.