Thermal Noise in Test Masses and Suspensions for Gravitational Wave Interferometers

根据涨落耗散定理，任何耗散机械能的机制都会产生热噪声。这意味着，引力波干涉仪测试质量及其悬浮液将工作得越好，耗散程度越低。锡拉丘兹小组将对各种测试质量和悬架设计进行研究，根据它们的耗散水平来表征它们。实现这一点的一种方法是测量系统中各种机械共振的品质因数。锡拉丘兹小组新开发的一种新方法，涉及到仔细测量系统在释放稳定应力后的反应。这两种方法都将用于寻找建立和暂停LIGO测试质量块的最佳方法。为了成功地搜索引力波，探测器必须不受干扰，这种干扰可以模仿或掩盖微弱的引力波信号。热噪声，也称为布朗运动，是最需要减少的噪声源之一。

According to the Fluctuation-Dissipation Theorem, thermal noise arises from any mechanism that dissipates mechanical energy. This means that a gravitational wave interferometer test mass and its suspension will work better, the lower is the level of dissipation. The Syracuse group will carry out studies of various test mass and suspension designs, characterizing them by their dissipation levels. One means of doing this is to measure the quality factors of the various mechanical resonances in the system. A novel method, newly developed by the Syracuse group, involves careful measurement of the response of the system after a steady stress has been released. Both methods will be employed in the search for the best ways to build and suspend test masses for LIGO. In order for the search for gravitational waves to succeed, it is necessary that detectors be free from disturbing influences that can mimic or mask the weak gravitational wave signal. Thermal noise, also known as Brownian motion, is among the noise sources most in need of reduction. The aim of the research program of the Syracuse University group is to understand the sources of thermal noise in interferometric detectors of gravitational waves (such as those of the LIGO Project), and to thereby learn ways of minimizing its strength. In addition to its main goal of improving the performance of LIGO and other gravitational wave detectors, this work may stimulate progress in understanding the structure of noncrystalline solids, such as the fused silica from which test masses are made.