TESTING THE INVERSE-SQUARE LAW OF GRAVITY - A NEW CLASS OF TORSION PENDULUM NULL EXPERIMENTS

We discuss two null experiments designed to test the inverse-square la w of gravity in the critical range between 10 cm and 100 m with higher precision than earlier work. To do so, we have devised a torsion pend ulum detector whose mass distribution is specifically configured to pr ovide high-sensitivity detection of a uniquely non-Newtonian derivativ e of the potential (the horizontal derivative of the Laplacian), rathe r than looking for a small deviation from the expected power-law depen dence on distance of a Newtonian field derivative. This method provide s a stronger null test of the gravitational inverse-square law force b ecause it is less sensitive to imperfections in the source mass. We di scuss the design of these experiments and estimate their performance r elative to currently established experimental limits on inverse-square law violation.