LIGO Publication Abstract
Issues in the Detection of Gravitational Radiation
Stephens, M.
PhD Thesis, MIT (1992)

The experimental and analytic work done as part of the effort to detect gravitational radiation with laser interferometric detectors is presented. In particular the seismic isolation issues for such detectors and the techniques for setting upper limits on the numbers of the transient signals are discussed. A double pendulum suspension system is presented as a partial solution to the seismic isolation requirements of an interferometric detector. The results of a series of tests performed on a prototype suspension system are presented. The vibration transfer function of the suspension demonstrates the f^-4 isolation expected of a double pendulum. The results of the tests were compared with a numerical model of the system. An interferometric accelerometer developed for use in characterizing isolation systems under development for interferometric antennas is described. A Nd:Yag laser is frequency locked to a Fabry-Perot cavity in which one mirror is flexibly mounted. At 100 Hz the sensitivity is 1.0x10E-14 m/rHz, one hundred times more sensitive than the piezoelectric accelerometers usually used for such measurement. The analytic work presented is a comparison of the coincidence technique to the correlation technique for setting upper limits on the rate as a function of strength of transient signals arriving at two interferometry antennas. Specific waveforms for transient signals, corresponding to waveforms predicted by theorists, were chosen. The techniques were applied to predict the sensitivities of proposed detectors. Analytic predictions agreed with numerical simulations.


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