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Ho Jung Paik
University of Maryland
Improved Determination of Gravitational Constant G Using a Laboratory Planetary System
The Earth-Moon system gives the product GME accurate to better than one part in 108. Unfortunately, G cannot be determined from this since the mass of the Earth ME cannot be measured independently. We discuss a cryogenic experiment in which four magnetically levitated test masses form a planetary system around a heavy source mass. The test masses are coupled by superconducting circuits to form a sensitive two-axis superconducting gravity gradiometer. The entire apparatus is rotated about the vertical to precisely balance the gravitational field with centrifugal acceleration. This brings in numerous benefits: (1) the experiment is free from anelasticity associated with a mechanical support; (2) the gradiometer is used as a null detector, alleviating the need for its calibration and eliminating errors associated with scale-factor nonlinearity; (3) the angular velocity can be calibrated to high precision unambiguously by measuring the time it takes to make a complete turn; and (4) the source mass can be shaped to alleviate the stringent metrology requirements for the test masses. This experiment aims at determining G with an uncertainty < 10 ppm.
Paik教授是国际上超导重力测量领域的权威，发明的超导加速度计和超导重力梯度仪仍是目前国际上精度最高的超导重力测量仪器。主要研究工作是利用此新型精密测量仪器进行最前沿的引力物理实验和相关应用。Paik 教授在精密测量与引力实验领域的研究成果丰硕，已发表学术论文150余篇，技术报告数十篇，获得专利4项，各类学术奖项共10项。此外，Paik 教授还参与多个 NASA 和 ESA 的空间任务研究计划，并获得NASA杰出贡献奖。
Center for Gravtitational Experiments, School of Physics
Huazhong University of Science and Technology, 1037 Luoyu Road, Whuan, 430074, P. R. China.