Investigation of Suspension Upgrades for Advanced LIGO

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Abstract:: Detection of gravitational waves, produced by asymmetric acceleration of mass, can provide a powerful tool to study energetic astrophysical systems since gravitational waves have weak interaction with matter, and thus carry relatively undistorted information about their sources. To increase the sensitivity of the current interferometric gravitational wave detectors, an upgrade plan for the US based detectors, or "Advanced LIGO," is being studied. As part of this upgrade, changing the mass, stress, and length of the suspension for the mirrors in the interferometers is considered to improve noise sources such as seismic noise, radiation pressure noise, and suspension thermal noise. However, these changes have to be carefully investigated considering as many different noise sources as possible, since the change can improve one noise source but also bring disadvantages for other sources. In this talk, the impact of different mass, stress, and length conditions for the mirror suspensions on seismic, suspension thermal, and coating Brownian noise will be discussed to allow evaluation of the overall performance of different possible suspension designs. Suspension conditions were investigated, including: 80kg and 160kg test mass, 0.6m and 1.1m of final stage fibre, 770MPa and 1.54GPa of stress in the fibre.

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LIGO Document G1500696-v1