Doctor of Philosophy (PhD)


Physics and Astronomy

Document Type



General relativity predicts the existence of gravitational waves as ripples in spacetime propagating at the speed of light. They couple to matter weakly, which implies only cataclysmic cosmic events generating such waves can be detected. Binary neutron star coalescences are, for example, one of the most promising detectable source. Their weak coupling also implies that very sensitive instruments are needed to detect them, and the most sensitive so far have been laser interferometers with km-scale arms. The Laser Interferometric Gravitational wave Observatory (LIGO) is exactly such an instrument, and the most sensitive in the world to the date of this dissertation. It operates two identical interferometers, one in Hanford, WA and one in Livingston, LA. I will present noise studies on two different topics.First, studies of environmental effects in the enhanced LIGO detector era (2008-2010) for both sites, showing that stationary ambient environmental noise did not limit the sensitivity at the time. After enhanced LIGO, advanced LIGO began installation, where all hardware was replaced except the enclosing vacuum system. The expected improvement in sensitivity is designed to be tenfold, which results in a factor of a thousand in the volume of space from where a source could be detected. This dissertation then focuses on a sub-configuration of advanced LIGO, the dual-recycled Michelson interferometer (DRMI), which is the LIGO instrument without the 4km arms. I will expose in detail the length sensing and control scheme which is the cornerstone of LIGO's ability to provide a linear gravitational wave readout. We model the behavior of the instrument in order to identify key commissioning targets. I will present models and measurements I performed at the Livingston Observatory for assessing two main topics: the sensing performance and the noise couplings in the DRMI. This work has only been possible with the support from the NSF grants NSF-PHY 0905184 and 1205882.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Gonzalez, Gabriela