Control strategy to limit duty cycle impact of earthquakes on the LIGO gravitational-wave detectors

Improving the Robustness of the Advanced LIGO Detectors to Earthquakes

Teleseismic, or distant, earthquakes regularly disrupt the operation of ground--based gravitational wave detectors such as Advanced LIGO. Here, we present \emph{EQ mode}, a new global control scheme, consisting of an automated sequence of optimized control filters that reduces and coordinates the motion of the seismic isolation platforms during earthquakes. This, in turn, suppresses the differential motion of the interferometer arms with respect to one another, resulting in a reduction of DARM signal at frequencies below 100\,mHz. Our method greatly improved the interferometers' capability to …

Limiting the effects of earthquakes on gravitational-wave interferometers

Ground-based gravitational wave interferometers such as the Laser Interferometer Gravitational-wave Observatory (LIGO) are susceptible to high-magnitude teleseismic events, which can interrupt their operation in science mode and significantly reduce the duty cycle. It can take several hours for a detector to stabilize enough to return to its nominal state for scientific observations. The down time can be reduced if advance warning of impending shaking is received and the impact is suppressed in the isolation system with the goal of maintaining stable operation even at the expense of increased …

Global Feed-Forward Vibration Isolation in a km scale Interferometer

Using a network of seismometers and sets of optimal filters, we implemented a feed-forward control technique to minimize the seismic contribution to multiple interferometric degrees of freedom of the LIGO interferometers. The filters are constructed by using the Levinson-Durbin recursion relation to approximate the optimal Wiener filter. By reducing the RMS of the interferometer feedback signals below \sim10 Hz, we have improved the stability and duty cycle of the joint network of gravitational wave detectors. By suppressing the large control forces and mirror motions, we have dramatically red…

External environmental noise influences on Virgo during O3

Sources of geophysical noise, such as wind, sea waves and earthquakes, can have an impact on gravitational wave interferometers causing sensitivity worsening and gaps in data taking. During the 1-year long O3 run (April 1st 2019 to March 27th 2020), the Virgo Collaboration collected a statistically significant dataset to study the response of the detector to a variety of environmental conditions. We used these data to correlate environmental parameters to global detector performance, such as observation range, duty cycle and control losses. Where possible, we identified weaknesses in the detec…

Advanced LIGO 探测器在第四次观测运行中的性能

Advanced LIGO detector performance in the fourth observing run

本文介绍了 Advanced LIGO 探测器在第四次观测运行中的性能提升，通过 A+ 升级计划（包括激光系统、核心光学器件改进及引入 300 m 滤波腔）实现了宽带量子噪声降低与前所未有的灵敏度，并详细分析了仪器升级、噪声源及调试挑战。

用于引力波天文台的六轴地震仪的设计与灵敏度

Design and sensitivity of a 6-axis seismometer for gravitational wave observatories

本文设计了一种由单根熔融石英纤维悬挂质量块、采用紧凑型 Michelson 干涉仪读数的六轴地震仪，其角自由度灵敏度比商用设备高一个数量级以上，可服务于引力波探测及多种基础物理实验。