Testing Gravity Below 50 micrometers

Searches for violations of the gravitational inverse square law at small separations constrain proposed phenomena such as large extra spatial dimensions and the chameleon mechanism. Our Fourier-Bessel torsion-pendulum measures gravitational torques on test masses with 18-fold and 120-fold symmetric wedge patterns cut from 50µm thick platinum foils. The total masses of the 120-fold patterns are only 0.6 g, but yield highly resolved signals. I will present preliminary results obtained at separations between 5 mm and 50 µm.