Sensors for Low-Frequency Improvements in Advanced LIGO

去年2月，Advanced LIGO首次探测到引力波，打开了一扇新的宇宙之窗。该奖项支持在华盛顿州汉福德和洛杉矶利文斯顿的LIGO站点部署新设备的开发。这包括一个高精度的惯性倾斜传感器，可以独立于水平加速度测量水平倾斜，这将改善先进的LIGO地震隔离，使干涉仪在恶劣的环境条件下能够稳定运行。对倾斜传感器的研究将在地震学和地球物理学等领域产生更广泛的影响，因为它能以低至10兆赫的频率测量远震倾斜和无倾斜地面加速度。为这些倾斜传感器开发的高精度角度读数在计量和精密实验中有着广泛的应用。该奖项不仅支持先进LIGO设备的开发，而且还有助于维持和加强这个桌面重力组与引力波探测社区的协同活动。重要的是，这项STEM研究将培养本科生、研究生和博士后建造精密机械仪器。在LIGO从探测器到天文台的过渡过程中，保持高占空比是一个关键挑战。强风、微震和地震等环境条件是第一次观测运行期间显著限制工作周期的主要原因。这是由于地震仪无法区分低频倾斜和平移，称为倾斜-水平耦合。该小组开发的地面倾斜传感器已被证明可以改善LIGO的低频地震隔离。通过使它们更小和更灵敏的干涉仪读数的进一步改进，将允许它们直接安装在悬挂LIGO反射镜的隔离平台上，从而使反射镜的低频差分运动具有更强和直接的益处。此外，它们可能被证明在5-30 Hz之间的引力波信号频带中测量地震倾斜是有用的，可以消除牛顿噪声，这预计会限制alIGO和未来探测器的灵敏度。

Last February, Advanced LIGO detected gravitational waves for the first time, opening a new window to the universe.This award supports the development of new equipment to be deployed at the LIGO sites in Hanford, WA, and Livingston, LA. This consists of a high precision inertial tilt sensor to measure horizontal tilt independently from horizontal acceleration, which will improve Advanced LIGO seismic isolation, enabling robust operation of the interferometer under adverse environmental conditions. Research on tilt sensors will have a broader impact in areas such as seismology and geophysics by enabling measurement of tele-seismic tilts and tilt-free ground acceleration at frequencies as low as 10 mHz. The high precision angle readouts developed for these tilt sensors have a wide variety of applications in metrology and precision experiments. This award not only supports the development of a device for Advanced LIGO, but it also serves to maintain and strengthen synergistic activities of this table-top gravity group with the gravitational wave detection community. Importantly, this STEM research will train undergraduate and graduate students, and postdocs in building precision mechanical instruments.In LIGO's transition from Detector to Observatory, maintaining high duty cycles is a key challenge. Environmental conditions such as high wind, microseism and earthquakes were primarily responsible for significantly limiting the duty cycle during the first observing run. This is due to the inability of seismometers to distinguish between low-frequency tilt and translation, known as tilt-horizontal coupling. The ground-tilt sensors the group has developed have been demonstrated to improve the low-frequency seismic isolation in LIGO. Further improvement by making them smaller and more sensitive with interferometric readouts, would allow them to be mounted directly on the isolated platforms from which the LIGO mirrors are suspended, enabling a stronger and direct benefit to low-frequency differential motion of the mirrors. In addition, they may prove useful in measuring seismic tilts in the gravitational wave-signal band between 5-30 Hz, allowing cancellation of Newtonian noise, which is expected to limit sensitivity of aLIGO and future detectors.