Seismic Isolation in Earth-Based Interferometers
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Video Lecture 46 of 69
Copyright Information: This video is taken from a 2002 Caltech on-line course on "Gravitational Waves", organized and designed by Kip S. Thorne, Mihai Bondarescu and Yanbei Chen. The full course, including this and many other lecture videos, exercises, solutions to exercises, and lists of relevant reading, are available on the web at http://elmer.caltech.edu/ph237/
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Date Added: July 21, 2010

### Lecture Description

Seismic Isolation in Earth-Based Interferometers - Week 13, Lecture 24, Part 2  [by Riccardo De Salvo]

1. Seismic attenuation requirements
2. Principals of seismic attenuation
1. Pendulum or oscillator as an example; its transfer function
2. Chain of oscillators; net transfer function

The Virgo isolation system as an example

The need for seismic attenuation in all six degrees of freedom:

1. All feed into horizontal noise that interferometer measures
2. How to achieve such attenuation

Vertical attenuation: the most serious problem

1. A solution: cantilever blades, radially compressed
1. Their transfer function
2. Example in Virgo

Creep in stressed elements of isolation system

1. Mechanism of creep
2. Reduction of creep with time after stress was applied
3. How to control creep: special materials; freezing dislocations; glassy materials in final attentuation stages

Mechanical resonances in isolation system

1. Must damp them because of  interferometer's limited dynamic range
2. Damping techniques: inertial, viscous; active, passive

### Course Description

Caltech's Physics 237-2002: Gravitational Waves
A Web-Based Course organized and Designed by Kip S. Thorne, Mihai Bondarescu and Yanbei Chen.

This course contains all the materials from a graduate-student-level course on Gravitational Waves taught at the California Institute of Technology, January through May of 2002. The materials include Quicktime videos of the lectures, lists of suggested and supplementary reading, copies of some of the readings, many exercises, and solutions to all exercises. The video files are so large that it may not be possible to stream them from most sites, but they can be downloaded. Alternatively, the course materials on DVD's can be borrowed via Interlibrary Loan from the Caltech Library (click on CLAS, then on Call Number, then enter QC179.T56 2002 ).

Questions and issues about this course and website can be directed to Mihai Bondarescu or Yanbei Chen.