Tests of Newtonian Gravitation and the Equivalence Principle and Cryogenic Torsion Pendulum Development

在继续发展低温扭摆作为引力物理学研究的一般工具的同时，将继续和扩大引力实验室实验方案。 这项工作的大部分将与华盛顿大学的保罗·博因顿教授的引力物理小组合作完成。 拟开展的研究包括：在第一年完成了引力常数G的精确测量，目标精度为15 ppm。与博因顿教授的小组合作，测试了质量分离在15厘米量级时引力与平方反比距离的关系。与博因顿小组合作，测试了各种距离范围内的等效原理，引力场源包括实验室质量、附近的山脉、这些项目将在一个地下实验室中进行，该实验室是在太平洋西北国家实验室的支持下准备的，该实验室位于一个孤立的环境保护区内，靠近华盛顿的里奇兰。 结合这些项目，将通过开发和改进地震隔离、倾斜控制、温度控制以及纤维选择和制备技术，逐步提高低温扭转摆的性能。 正在开发的低温扭摆对引力或其他需要测量极小的缓慢变化的力的领域的任何研究都具有潜在价值。该项目为本科生和研究生以及博士后研究人员提供各种广泛适用技术的研究经验和培训。

A program of laboratory experiments in gravitation is to be continued and expanded, in parallel with continued development of the cryogenic torsion pendulum as a general tool for research in gravitational physics. Much of this work will be done in collaboration with the gravitational physics group of Professor Paul Boynton at the University of Washington. Research to be conducted includes:Completion in the first year of a precision measurement of the gravitational constant G, withtarget accuracy of 15 ppm.Jointly with Professor Boynton's group, a test of the inverse square distance dependence of the gravitational force for mass separation on the order of 15 centimeters.Jointly with Boynton's group, tests of the equivalence principle over various distance ranges,for gravitational field sources which include laboratory masses, a nearby mountain, and thesun.These projects will be conducted in an underground laboratory that has been prepared with support from the Pacific Northwest National Laboratory in a former Nike missile bunker on an isolated environmental preserve nearRichland, Washington. In conjunction with these projects, the performance of the cryogenic torsionpendulum will be progressively improved through development and refinement of seismic isolation, tilt control, temperature control, and fiber choice and preparation techniques. The cryogenic torsion pendulum being developed is of potential value to any research in gravitation or other fields which requires the measurement of extremely small slowly varying forces.This project provides research experience and training in a variety of widely applicable technologies, to undergraduate and graduate students as well as to a postdoctoral researcher.