Active, Low-Frequency Vibration Isolation System

一个系统的基础上的三个级联的阶段，每个能够提供约两个数量级的隔离在六个自由度，正在开发中。 每一级都利用主动和被动隔离来实现性能目标。 初步阶段已经开始运作，两个主要阶段正在建设中。 第一个主要阶段的早期测量已经完成。 初步的单级隔振系统在1 Hz时提供的隔振效果比任何其他研究或商业隔振系统都要好。 建成后，三级系统将提供有史以来最安静的地面环境。 悬挂式望远镜中的连续热噪声，就像那些计划用于引力波干涉仪的连续热噪声一样，将通过将一对匹配的热噪声悬挂在超安静的第二主级上并确定它们的相对运动来测量。 正在开发这种先进的主动隔振系统，以保护敏感的测量仪器免受频率低至1 Hz的地震和人为振动噪声的影响。 这项工作的目的是开发技术，可以帮助减少地面运动和其他振动的直接机械耦合的引力波干涉仪的测试质量的影响下降到干扰的引力耦合的测试质量在尽可能宽的频率范围内的水平。 在第三年的工作中，将为可用于先进低频LIGO探测器的主动隔振系统开发概念设计。 这将包括预期性能的数字模型。 在低至1Hz的频率下的改进性能将允许搜索终止于10Hz或更低频率的信号。

A system based on three cascaded stages, each capable of providing about two orders of magnitude of isolation in six degrees of freedom, is being developed. Each stage utilizes active and passive isolation to achieve the performance goals. The preliminary stage is operational, and the two main stages are under construction. Early measurements have been made on the first main stage. The preliminary, single stage, vibration isolation system provides more isolation at 1 Hz than any other research or commercial isolation system. When complete, the three-stage system will provide the quietest terrestrial environment ever achieved. The continuum thermal noise in suspension pendulums, like those planned for gravitational wave interferometers, will be measured by hanging a matched pair of them from the ultra quiet second main stage and determining their relative motion. This advanced active vibration isolation system is being developed to shield sensitive measurement instruments from the effects of seismic and man-made vibration noise at frequencies down to 1 Hz. The objective of this work is to develop techniques which can help reduce the effects of the direct mechanical coupling of ground motions and other vibration on the test masses of gravitational wave interferometers down to the level of the gravitational coupling of disturbances to the test masses over as wide a frequency range as possible. During the third year of work, a conceptual design will be developed for an active vibration isolation system which could be used in advanced low-frequency LIGO detectors. This will include a numerical model of the expected performance. Improved performance at frequencies down to 1 Hz would permit searches for signals which terminate at frequencies of 10 Hz or less.