LIGO Document T1600433-v1
- The Advanced Laser Interferometer Gravitational-Wave Observatory (aLIGO) first detected gravitational waves (GW) from a binary black hole merger on September 14, 2015 at both the Hanford and Livingston aLIGO sites. The transition from initial LIGO to aLIGO enhanced sensitivity across the frequency band of the detectors. One such change was increasing a one stage mirror suspension system to a multilevel system in order to improve isolation to seismic ground motion and thermal noise. The goal to improve aLIGO is to understand the sources of noise that decreases the sensitivity of the detectors. Thermal noise in the coatings and suspensions of the test masses is one of the main sources of noise that limits detector sensitivity within the suspension systems. Thermal noise results from the thermal energy of atoms and molecules in the mirrors and their suspensions (Saulson, 1990). Using the program known as ANSYS, Finite Element Analysis (FEA) is performed on different models of the mirror suspension systems. FEA allows the analysis of realistic features of the suspensions and using Levin's formalism can be used to calculate thermal noise in the detectors.
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