Stanford Program in Support of LIGO - Seismic Isolation and Controls

The team at Stanford works to improve the performance and reliability of NSF's Laser Interferometer Gravitational-wave Observatories (LIGO) by developing technology and techniques to improve the isolation of the optics and reduce the impact of ground motion on the detectors. This award will help LIGO implement a new auxiliary laser sensing technology to improve the control and lower the noise of the ground motion isolation systems. It also supports research to reduce the noise of the suspended optics by developing advanced control techniques to better integrate the isolation and suspension subsystems. The improved technology and control schemes funded by this grant will help maximize the scientific output of these premier facilities. This award also supports the design of new suspensions which will provide a significant upgrade to the astrophysical reach of the existing detectors. This grant supports development of several complementary approaches to improving LIGO. It supports the construction and testing of a Seismic Platform Interferometer (SPI) in the test facility at Stanford. This SPI is designed to interferometrically connect the various isolation systems at the Observatories to dramatically reduce the inertial and the relative motion at frequencies below 1 Hz. These sensors are now running at the lab scale and this award provides the support to move these into a first implementation at a LIGO observatory. This integration should reduce the control noise and improve robustness of the LIGO detectors. In the long term, this grant supports the design effort for the new “Heavy Suspension” for an upgrade for LIGO known as A# (to follow A+ which and now being developed by the LIGO Scientific Collaboration). By increasing the mass of the main mirrors from 40 kg to 100 kg and improving the controllability of the suspension system, this upgrade should allow the detectors to reach fundamental noise sources all the way down to 10 Hz. This low frequency performance improvement will significantly improve the ability of the LIGO detectors to see the inspiral phase of binary neutron stars and measure the merger of black holes which are more than 100 times the mass of our sun. 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.