Feedforward Seismic Noise Cancellation at the 40m Interferometer

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Abstract:: The interferometers used by Laser Interferometer Gravitational Wave Observatory (LIGO) are subject to a multitude of noise sources. These noise sources, if not properly accounted for, will eliminate the possibility of gravitational wave detection. Seismic noise and the self-noise of devices used are two main noise sources that can be filtered out using a variety of physical and mathematical filters. The goal of this project was to develop mathematical filters to reduce self-noise of our seismometers and accelerometers, both of which are used to measure seismic noise. I used both FIR and IIR Wiener filters, in combination with pre-filtering, to account for these noise sources. The main pre-filter explored was an elliptic bandpass filter, focusing on a region of lower frequencies, where we expect the instruments’ self-noise interferes most with the interferometer signal. Combining such a pre-filter with a Wiener filtered out a significant amount of instrument self-noise.

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LIGO Document T1500194-v1