Search for Gravity-Like Forces at Sub-100 microns Scale

该奖项支持一项实验计划，该计划旨在探测基本粒子相互作用标准模型之外的物理理论所预测的距离约为25微米的牛顿引力偏差。已经建造了一个低温探测器来测量预计在这些距离上的微小作用力。力传感器是一个微机械加工的硅悬臂梁。悬臂梁的末端粘着一块金色的试块。金条和硅条的交替图案在测试质量下方振荡；测试质量和移动驱动质量的变化重力场之间的耦合激发了悬臂的共振。光纤干涉仪测量悬臂梁的运动，并由该测量结果推导出质点之间的力。由于驱动质量的几何形状，当驱动质量的纵向平衡位置不同时，任何引力都会表现出明显的周期性。将测量的力与有限元分析的预测进行比较，得出了可能预示新物理的新的类似重力的力的界限。尽管标准模型成功地统一了电磁、强相互作用和弱相互作用，但它忽略了重力。这在基础物理学中提出了一个巨大的谜团：为什么即使是这种最弱的亚原子力，即弱力，也比引力强得多？试图回答这个问题的现代理论预测，牛顿定律的修正将在更长的尺度上进行，最大可达1毫米。这项实验中使用的技术处于微制造设备的前沿。

This award supports an experimental program to probe deviations from Newtonian gravity at distances on the order of 25 microns as predicted by theories of physics beyond the Standard Model of fundamental particle interactions. A low temperature probe has been built to measure tiny forces expected at these distances. The force sensor is a micromachined silicon cantilever. A gold test mass is glued to the end of the cantilever. An alternating pattern of gold and silicon bars is oscillated below the test mass; the coupling between the test mass and the varying gravitational field of the moving drive mass excites the cantilever on resonance. A fiber interferometer measures the cantilever motion and from this measurement, the force between the masses is deduced. Due to the geometry of the drive mass, as the longitudinal equilibrium position of the drive mass is varied, any gravitational force will show a distinct periodicity. Comparison of the measured force to predictions from finite element analysis yields bounds on new gravity-like forces which could signal new physics.While the Standard Model successfully unifies the electromagnetic, the strong and the weak interactions, it ignores gravity. This poses a great mystery in fundamental physics: why is even this most feeble subatomic force, i.e. the weak force, so much stronger than gravity? Modern theories that attempt to answer this question predict modifications to Newton's law at much longer length scales, up to 1 millimeter. The technology used in this experiment is at the cutting edge of micro-fabricated devices.