A new determination of the Newtonian constant of gravity using the free fall method

We report on a recent determination of the Newtonian constant of gravity, G , using a new 'free fall' method. This method uses a freely falling test ob ject to sense the gravitational field of a ring-shaped mass placed alternat ely above and below the drop region. The measurement of the changes in acce leration of the test object allow determination of G. Because the test mass is unsupported, systematic errors associated with the free fall method are significantly different from those of the traditional torsion experiments that constitute the great majority of G measurements. This characteristic m akes this method potentially valuable in the context of today's uncertainty about the value of G. The raw data have been examined in a variety of ways. We describe our metho ds which allow us to extract, besides G, information about various experime ntal parameters and possible systematic errors. A number of sources of syst ematic errors have been investigated, including magnetic and vibratory sign als arising from the dropping action of our apparatus. We outline the steps we have taken to ascertain the magnitude of errors introduced by these eff ects. Using the free fall method, we have completed a determination of G, obtaini ng a result of G = (6.6873 +/- 0.0094) x 10(-11) m(3) kg(-1) s(2).