Preliminary determination of Newtonian gravitational constant with angular acceleration feedback method

Abstract

This paper describes the preliminary measurement of the Newtonian gravitational constant G with the angular acceleration feedback method at HUST. The apparatus has been built, and preliminary measurement performed, to test all aspects of the experimental design, particularly the feedback function, which was recently discussed in detail by Quan et al . The experimental results show that the residual twist angle of the torsion pendulum at the signal frequency introduces 0.4 ppm to the value of G . The relative uncertainty of the angular acceleration of the turntable is approximately 100 ppm, which is mainly limited by the stability of the apparatus. Therefore, the experiment has been modified with three features: (i) the height of the apparatus is reduced almost by half, (ii) the aluminium shelves were replaced with shelves made from ultra-low expansion material and (iii) a perfect compensation of the laboratory-fixed gravitational background will be carried out. With these improvements, the angular acceleration is expected to be determined with an uncertainty of better than 10 ppm, and a reliable value of G with 20 ppm or below will be obtained in the near future.

Precision measurement of the Newtonian gravitational constant

“…4 (d). Our group has performed proof-of-principle experiments since 2008 [ 84 , 85 ], redesigning and completely rebuilding the apparatus to reduce several sources of uncertainty that existed in the previous experiment. The pendulum, a gold-coated fused silica block, was suspended from a tungsten fibre in the vacuum chamber supported by an air-bearing turntable.…”

Determination of G with time-of-swing method by using high-Q silica fibers

“…The aim of the present work at HUST has been to measure G with the time-of-swing method and the angular acceleration feedback method [2] at the same period of time. The two methods, with a different set of systematic errors, are used to measure G at two independent apparatus, so that unknown systematic errors in one method would be unlikely to exist in the other.…”

Two Values Of The Constant G Obtained From Inclining-Pull Projection Method

“…Here, we would like to make an analysis on the systematic error of torsion experiment. As shown in Figure 6, when the big ball attracts the small ball on its own side, it should attract the other small one on the opposite side (Xue et al, 2014) (Rosi et al, 2014) (Newman et al, 2014) (Fan et al, 2008) (Quan et al, 2014). This can lead to the notable systematic error.…”