New Experimental Constraints on Non-Newtonian Forces below 100 microns

TL;DR

The authors' data eliminate from consideration mechanisms of deviation that posit strengths approximately 10(4) times Newtonian gravity at length scales of 20 microm, which is 3 orders of magnitude more sensitive than others that provide constraints at similar length scales.

Abstract

We have searched for large deviations from Newtonian gravity by means of a microcantilever-based Cavendish-style experiment. Our data eliminate from consideration mechanisms of deviation that posit strengths ~10^4 times Newtonian gravity at length scales of 20 microns. This measurement is 3 orders of magnitude more sensitive than others that provide constraints at similar length scales.

Figures (4)

• Figure 1: Schematic top and side views of test mass on cantilever and drive mass below, showing alternating gold and silicon drive mass bars. Drive mass motion was in the $Y$ direction.
• Figure 2: (a) Actuator voltage (left axis), raw cantilever displacement (right axis), and averaged cantilever displacement (right axis, $10$ min averaging time) as a function of time over one period of actuator motion. (b) Averaged data for one period of actuator motion for five values of dc current through the drive mass meander.
• Figure 3: Background and experimental signal, as well as theoretical thermal noise, as a function of averaging time. The experimental signal levels off at a force of $8.9\times 10^{-17}$ N.
• Figure 4: Strength versus length scale parameter space [ see Eq. (\ref{['potential']})] for non-Newtonian effects showing area excluded by present (darker shaded region bounded by signal plus 2$\sigma$-level error) and previous (lighter shaded region) experiments. Lines labeled Lamoreaux, UWashington, UColorado, and Irvine are from lamoreaux, adel, price, and irvine, respectively. Theoretical predictions (dashed lines) are adapted from dilaton_refscalar (dilaton and moduli) and from addsavas (gauge bosons).