Measurement and Analysis of Uncertainty in Mechanical Quality Factor and Implications for LIGO Thermal-Noise Estimation*

With the continued push for more-sensitive gravitational wave interferometers, reducing coating Brownian thermal noise becomes increasingly essential. We report on the uncertainty in quality factor experiments, which are key measurements for predicting the thermal noise of the optics in gravitational wave detectors. Through repeated measurements, we investigate the distribution associated with quality factor measurements. We estimate these uncertainties in mechanical loss measurements and discuss their possible causes. Finally, we comment on the implications of our results for the Laser Interferometer Gravitational-Wave Observatory, LIGO.