Preliminary tests of a newly developed superconducting gravity gradiometer

We have recently completed a series of tests on a newly developed superconducting gravity gradiometer consisting of two 400 g niobium proof masses separated by a distance of 15 cm. The resonance frequency of the proof mass suspension systems is 25 Hz. The sensitivity of this gradiometer obtained during these tests was 1 to 2 Eötvös Hz^-1/2(1 Eötvös = 10^-9s^-2 E) below 1Hz, and 0.2 E Hz^-1/2between 15 and 20 Hz. Using this gradiometer, a prototype experiment has been performed to demonstrate a new source-independent null test of the inverse square law of gravitation. The result, assuming a potential of the form , is α = + 0.024 ± 0.036 at μ^-1= 1m.