A coating thermal noise interferometer for the AEI 10m Prototype facility

24 04/2015

Friday, 24 Apr. 2015, 12:00 - 13:00

Presenter: Tobias Westphal; Max-Planck Institut für Gravitationsphysik (Albert-Einstein-Institut) und Institut für Gravitationsphysik der Leibniz Universität Hannover, Germany
Host: M. Aspelmeyer
Where: Schrödingerroom, 4th Floor, Boltzmanngasse 5, 1090 Wien

Coating thermal noise (CTN) is getting a more and more significant noise source as the sensitivity of interferometry is pushed to its limits. It arises from inherent mechanical loss of thin films in dielectric coatings. Deeper understanding and verification of its theory such as frequency dependence of losses requires direct (off-resonant) observation. The AEI 10 m Prototype facility is probably the best suited environment for this kind of experiment in a frequency range of special importance for earth bound gravitational wave detectors. A pre-isolated platform shows three to four orders of magnitude attenuated seismic noise inside ultra-high vacuum. Up to 10 W highly stabilized (frequency as well as amplitude) laser power at 1064 nm will be available for experiments. In this talk the CTN- interferometer being in the construction phase will be presented. The range solely limited by CTN is designed to reach from 10 Hz to about 50 kHz, limited by seismic noise at low frequencies and shot noise (photon counting noise) at high frequencies. The first of three identical suspensions has been set up. Digitally controlled actuation as well as active damping were successfully demonstrated on air.