Interferometric Measurements and Analysis of Thermal Noise in Solids

To be added laterThermal noise is one of the main noise sources contributing to the noise budget of current and upcoming gravitational wave interferometers. It is currently possible to model thermal noise in thermodynamic equilibrium using the equipartition theorem, but there is no good model for modeling thermal noise outside of thermodynamic equilibrium. The goal of this thesis work is to try to establish that the non-equilibrium thermal noise (NETN) experiment is capable of accurately measuring thermal noise using a quadrature phase differential interferometer that uses a monolithic oscillator as one of the mirrors. We investigated the response of this oscillator to thermal fluctuations by isolating it from as much other noise as possible, and using the interferometer to measure the displacement induced by thermal noise as a response in its first longitudinal mode. Upgrades needed to be made to the experiment before data collection at equilibrium temperatures above room temperature could be performed. We found that as compared to previous work on this project, the variation of effective temperature \(T_{eff}\) was significantly decreased. Additionally, it was found that the behavior of \(T_{eff}\) as compared to thermodynamic temperature was a good fit for the expected theoretical behavior within a \(2\sigma\) variation.