Seismic Isolation of Einstein Telescope

ended

With the first direct detection of gravitational waves on the 14th of September 2015, a new window has been opened on the Universe. This was the starting point of new science, complementary to the measurement of electromagnetic signals by optical telescopes. Since that date, several detections have been made, offering wonderful validation of Einstein’s theory of general relativity, and extraordinary insight on the dynamics of heavy black hole binaries and binaries of neutron stars. The exploration of the Universe through this new window using Earth-based instruments will continue with more sensitive instruments, but will ultimately depend on our capability to isolate them from the two main sources of low-frequency disturbances on Earth: seismic activity and fluctuations of gravity field (Newtonian noise). Due to the extremely small amplitude of gravitational waves, it is a prior concern to carefully isolate the detector from any type of disturbance. In order to address the aforementioned limitations, this project proposes to develop a completely novel platform, controlled by optical seismometers, liquid inclinometers and a gravimeter. It will virtually float in the inertial space, decoupled from ground motion for periods at least as large as 100 seconds. The controlled platform will be the most stable ever build on Earth. Such performance will be obtained thanks to a revolutionary approach, combining three major innovations: (1) Novel optical inertial sensors, (2) Efficient controllers, combining sensor fusion methods, and dedicated mechatronic architectures, (3) Direct measurement of Newtonian noise. This project will contribute to prepare the third generation of low-frequency gravitational wave detectors. The outcomes will be also applicable to a large class of other instruments (e.g. particle colliders, atomic force microscopes, lithography machines, medical imaging instruments), ensuring a generic character to this project, and a major scientific impact.