Short Range Test of the Gravitational Inverse Square Law using the Fourier Bessel Torsion Pendulum

For this experiment, we removed pie shaped wedges from 50 micron thick tungsten foils to create 120-fold rotationally symmetric attractor and detector masses. The detector mass is hung from a thin tungsten fiber. The attractor mass is rotated continuously beneath it, providing a gravitational drive signal at 120 times the rotational frequency which is recorded via an autocollimator. Comparing the angular deflection of the detector to a precise Newtonian calculation, we are able to place new limits on range-dependent, non-Newtonian physics below 50 microns.