New determination of the gravitational constant G with time-of-swing method

Liang-Cheng Tu, Qing Li, Qing-Lan Wang, Cheng-Gang Shao, Shan-Qing Yang, Lin-Xia Liu, Qi Liu, and Jun Luo
Phys. Rev. D 82, 022001 – Published 1 July 2010

Abstract

A new determination of the Newtonian gravitational constant G is presented by using a torsion pendulum with the time-of-swing method. Compared with our previous measurement with the same method, several improvements greatly reduced the uncertainties as follows: (i) two stainless steel spheres with more homogeneous density are used as the source masses instead of the cylinders used in the previous experiment, and the offset of the mass center from the geometric center is measured and found to be much smaller than that of the cylinders; (ii) a rectangular glass block is used as the main body of the pendulum, which has fewer vibration modes and hence improves the stability of the period and reduces the uncertainty of the moment of inertia; (iii) both the pendulum and source masses are placed in the same vacuum chamber to reduce the error of measuring the relative positions; (iv) changing the configurations between the “near” and “far” positions is remotely operated by using a stepper motor to lower the environmental disturbances; and (v) the anelastic effect of the torsion fiber is first measured directly by using two disk pendulums with the help of a high-Q quartz fiber. We have performed two independent G measurements, and the two G values differ by only 9 ppm. The combined value of G is (6.67349±0.00018)×1011m3kg1s2 with a relative uncertainty of 26 ppm.

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  • Received 25 March 2010

DOI:https://doi.org/10.1103/PhysRevD.82.022001

©2010 American Physical Society

Authors & Affiliations

Liang-Cheng Tu, Qing Li, Qing-Lan Wang, Cheng-Gang Shao, Shan-Qing Yang, Lin-Xia Liu, Qi Liu, and Jun Luo*

  • Department of Physics, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of China

  • *junluo@mail.hust.edu.cn

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Vol. 82, Iss. 2 — 15 July 2010

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