Improving Short Range Gravity Limits With Cylinders

Some unification theories and extensions to the standard model predict a non-Newtonian interaction between two point masses separated by distance r. In both cases the interaction is Yukawa-like, V(r) = αe^-r/λ/r, with strength α and characteristic length λ. At separations below 1 μm the parameters that characterize the interaction are poorly bounded. Previous experiments have used a spherical test mass in front of a plane to place upper bound limits on the interaction strength.

Our estimates show that cylindrical test masses will reduce upper bounds by ∼2 orders of magnitude. To this end a system implementing a cylindrical test mass is under development. The cylinders will be 500 μm long with radius of 150 µm. They will be created using maskless grayscale lithography techniques to place them directly onto a high-Q oscillator. The success of future measurements, however, depends on the ability to align the cylinder's longitudinal axis perpendicular to the normal of the plane. We are developing a scheme that uses capacitance to align the cylinder-plane system and determine their separation. A scaled up version of our system has been constructed to verify if capacitance is a viable indicator of alignment and separation. The results will be compared to COMSOL simulations.