Precise Determination of Separation Between Spherical Attracting Masses in Measuring the Gravitational Constant

A rotating gauge method is used to measure the span between two spheres with high precision in determination of the gravitational constant G.A rectangular gauge block slightly shorter than the span is located horizontally between two spheres,and the angle between two symmetric bounding points during rotation can be determined by measuring the shift of a laser beam passing through an optical plate fixed on the gauge block.Experimental results show that the uncertainty in the determination of the span between the two spheres is less than 0.5μm.

Thermoelastic Correction in the Torsion Pendulum Experiment

The thermoelastic effect of the suspension fibre in the torsion pendulum experiment with magnetic damping was studied.The disagreement in the oscillation periods was reduced by one order of magnitude through monitoring the ambient temperature and thermoelastic correction.We also found that the period on uncertainty due to noise increases with the amplitude attenuation after thermoelastic correction.

Proposed Test of the Equivalence Principle with Rotating Cold Polar Molecules

We propose a novel scheme for testing the equivalence principle with rotating cold polar molecules whose angular momenta are polarized at different states.Molecules in specific rotational states are selected out via the hexapole state-selection technique and the gravitational acceleration g of molecules is measured by measuring the Doppler shift of the molecules free falling in the gravitational field.Some other possible methods of rotating molecules and measuring g are also mentioned.Molecules,as the test masses,have higher rotating speed and smaller dimension in comparison with mechanical gyroscopes and may open a new way for testing the equivalence principle and the possible coupling between rotation and gravity.

Determination of the Unperturbed Period of a Torsion Pendulum in the Time-of-Swing Method

A symmetric disc-shaped torsion pendulum was designed to study the nonlinear effects of the torsion fiber. It was showed that the period of the pendulum decreases with the amplitude of the oscillation. Determination of the unperturbed period through a fit to measured data of the period variation with amplitude shows that this systematic error in the measurement of Newtonian gravitational constant G by the time-of-swing method can be reduced by an order of the magnitude at least.

小型化原子重力仪及应用

重力场是地球基本物理场之一,随时间变化,随空间分布。精密重力测量在资源勘探、地质调查、导航制导、地球物理及基础科学研究等领域都具有重要意义。重力仪是高精度测量重力加速度不可或缺的仪器,可分为绝对和相对重力仪两类。基于物质波干涉技术的原子重力仪是一种新型绝对重力仪,经过30多年的发展,目前已进入小型化研究和实用化演示阶段。首先,简要介绍了精密重力测量的意义、高精度重力测量现状、原子干涉重力测量的基本原理以及高精度原子干涉重力测量的研究现状。然后以应用场景分类详细介绍了当前国内外小型化原子重力仪的研制及应用情况,重点介绍了华中科技大学在小型化原子重力仪研制及应用测试方面所做的工作。最后,对小型化原子重力仪的发展及应用前景进行了展望。