New Measurements ofGUsing the Measurement Standards Laboratory Torsion Balance

Abstract

This Letter presents the results of a series of measurements of the Newtonian gravitational constant $G$ using the compensated torsion balance developed at the Measurement Standards Laboratory. Since our last published result using the torsion balance in the compensated mode of operation [Meas. Sci. Technol. 10, 439 (1999)], several improvements have been made to reduce the uncertainty in the final result. The new measurements have used both stainless steel and copper large masses. The values of $G$ for the two sets of masses are in good agreement. After combining all of the measurements we get a value of $G=6.67387(0.00027)\times {10}^{-11}{\mathrm{m}}^3{\mathrm{k}\mathrm{g}}^{-1}{\mathrm{s}}^{-2}$. This new value is 5 parts in ${10}^5$ smaller than our previous published values.