Seismic isolation enhancements for initial and Advanced LIGO

R. Abbott, California Institute of Technology
R. Adhikari, LIGO, Massachusetts Institute of Technology
G. Allen, Ginzton Laboratory
D. Baglino, Ginzton Laboratory
C. Campbell, Ginzton Laboratory
B. Coyne, California Institute of Technology
E. Daw, Louisiana State University
D. DeBra, Stanford University
J. Faludi, Ginzton Laboratory
P. Fritschel, LIGO, Massachusetts Institute of Technology
A. Ganguli, Ginzton Laboratory
J. Giaime, Louisiana State University
M. Hammond, LIGO Livingston
C. Hardham, Ginzton Laboratory
G. Harry, LIGO, Massachusetts Institute of Technology
W. Hua, Ginzton Laboratory
L. Jones, California Institute of Technology
J. Kern, LIGO Livingston
B. Lantz, Ginzton Laboratory
K. Lilienkamp, LIGO, Massachusetts Institute of Technology
K. Mailand, California Institute of Technology
K. Mason, LIGO, Massachusetts Institute of Technology
R. Mittleman, LIGO, Massachusetts Institute of Technology
S. Nayfeh, LIGO, Massachusetts Institute of Technology
D. Ottaway, LIGO, Massachusetts Institute of Technology
J. Phinney, LIGO, Massachusetts Institute of Technology
W. Rankin, LIGO, Massachusetts Institute of Technology
N. Robertson, Ginzton Laboratory
R. Scheffler, Ginzton Laboratory
D. H. Shoemaker, LIGO, Massachusetts Institute of Technology
S. Wen, Louisiana State University
M. Zucker, LIGO Livingston
L. Zuo, LIGO, Massachusetts Institute of Technology

Abstract

A seismic isolation system for the proposed 'Advanced LIGO' detector upgrade is under development. It consists of a two-stage in-vacuum active isolation platform that is supported by an external hydraulic actuation stage. A full-scale preliminary-design technology demonstrator of the in-vacuum platform has been assembled and is being tested at Stanford's engineering test facility. Unanticipated excess ground motion from local human activity at LIGO Livingston has prompted accelerated development of the external stage for installation and use in the initial Livingston detector. As an interim measure, active external isolation in the laser beam direction is implemented using existing PZT external actuators.