Studying how to improve the control system of seismic section of LIGO with the use of Capacitive Position Sensors (CPS)

I worked on this project during my stay at LIGO Hanford site: the seismic isolation control and reduction is a crucial matter of concern on site, because seismic motion affects the performance of the detector. Since the detector is an interferometer in which cavities there is a laser travelling 4 km back and forth, the platforms hosting the optics are affected by the seismic motion in a different way and the control systems of each platform act independently. The idea is to connect the platforms to each-other via position sensors in order to minimize the differential motion and reduce the control efforts to apply. This would make the platforms move in sync, assuring also more stability in the cavities and a longer time in resonance. This work was carried on also after my stay on site and it implied a deep study of the control system in order to modify it suitably. The idea is currently in use on LIGO sites and under study for further developments. A paper in under writing with the LIGO lab collaboration. Several reports and a preprint have been stored on the LIGO Document Control Center Portal.