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

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

来源：Physical Review D - Particles, Fields, Gravitation and Cosmology, 2010, 82(2): 022001.

DOI：10.1103/PhysRevD.82.022001

• FUNDAMENTAL PHYSICAL CONSTANTS
• CODATA RECOMMENDED VALUES
• TORSION PENDULUM
• THERMAL NOISE
• EXPERIMENTAL TESTS
• BALANCE
• FIBER
• REDETERMINATION
• SEPARATION
• DENSITY

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 +/- 0.000 18) x 10(-11) m(3) kg(-1) s(-2) with a relative uncertainty of 26 ppm.

• 出版日期2010-7-1
• 单位华中科技大学