How to reduce the suspension thermal noise in LIGO without improving the Q's of the pendulum and violin modes

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dc.creatorBraginsky, Vladimir B.
dc.creatorLevin, Yuri
dc.creatorVyatchanin, Sergey
dc.date1998-05-09
dc.date1998-11-04
dc.date.accessioned2026-07-07T10:51:49Z
dc.date.available2026-07-07T10:51:49Z
dc.descriptionThe suspension noise in interferometric gravitational wave detectors is caused by losses at the top and the bottom attachments of each suspension fiber. We use the Fluctuation-Dissipation theorem to argue that by careful positioning of the laser beam spot on the mirror face it is possible to reduce the contribution of the bottom attachment point to the suspension noise by several orders of magnitude. For example, for the initial and enhanced LIGO design parameters (i.e. mirror masses and sizes, and suspension fibers' lengths and diameters) we predict a reduction of $\sim 100$ in the "bottom" spectral density throughout the band $35-100\hbox{Hz}$ of serious thermal noise. We then propose a readout scheme which suppresses the suspension noise contribution of the top attachment point. The idea is to monitor an averaged horizontal displacement of the fiber of length $ l$; this allows one to record the contribution of the top attachment point to the suspension noise, and later subtract it it from the interferometer readout. For enhanced LIGO this would allow a suppression factor about 100 in spectral density of suspension thermal noise.
dc.descriptiona few misprints corrected; submitted to Classical and Quantum Gravity
dc.identifierhttps://arxiv.org/abs/gr-qc/9805031
dc.identifierhttp://arxiv.org/abs/gr-qc/9805031
dc.identifierMeasur.Sci.Tech.10:598-606,1999
dc.identifierdoi:10.1088/0957-0233/10/7/305
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/184948
dc.subjectGeneral Relativity and Quantum Cosmology
dc.titleHow to reduce the suspension thermal noise in LIGO without improving the Q's of the pendulum and violin modes
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