Stanford Program in Support of LIGO – Seismic Isolation and Controls

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This award supports research in relativity and relativistic astrophysics and it addresses the priority areas of NSF's "Windows on the Universe" Big Idea. The LIGO team at Stanford works to improve the performance and reliability of the Laser Interferometer Gravitational-wave Observatories (LIGO) by developing technology and techniques to reduce the impact of ground motion on the detectors. This grant supports the study of new techniques to reduce the noise that limits the sensitivity of the LIGO detectors by implementing new sensing technology in the ground motion isolation systems, and also by increasing the ability of the detectors to operate in challenging environmental conditions such as wind storms and earthquakes. Under good conditions, the LIGO observatories can operate 24 hours a day, but challenging environmental conditions limit the observatories' stable operation. The improved technology and control schemes funded by this grant will help maximize the scientific output of these premier facilities. This grant also supports research to enable the next generation of detectors which may operate at low temperature, by demonstrating ways to cool the sensitive optics without compromising the extremely low-vibration conditions in which they operate.This grant supports development of several complementary approaches to improving Advanced LIGO. In the short term, the implementation of improved earthquake warning schemes will enable the operators at the sites to better utilize information from the realtime USGS earthquake early warning systems so that the detectors can change from a low-noise to a robust configuration before the increased motion from teleseismic (i.e., distant) earthquakes can affect operations. The grant also supports the study of the new wind protection fences which were developed in the previous funding cycling and constructed recently at the LIGO Hanford Observatory. In the medium term, this grant supports the building and testing of a Seismic Platform Interferometer (SPI) in the test facility at Stanford. This SPI is designed to be used to interferometrically connect the various isolation systems at the Observatories so as to dramatically reduce the relative motion at frequencies below 1 Hz. This integration should reduce the control noise and also improve robustness of the LIGO detectors. In the long term, this grant supports the development of new cryogenic heat transport systems, both dilute nitrogen gas and nitrogen thermo-siphons for the test facility at Stanford. These systems will be used to measure how to remove heat quickly from next generation detectors.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.