A. Bertolini et al., Recent progress on the R&D program of the seismic attenuation system (SAS)proposed for the advanced gravitational wave detector, LIGO II, NUCL INST A, 461(1-3), 2001, pp. 300-303
High-performance Seismic Isolation Systems in gravitational wave interferom
eters are needed not only to increase the sensitivity of the detectors but
also to guarantee long periods of stable operation. SAS is essentially a sy
stem which produces the required in-band seismic isolation by use of passiv
e mechanical filters and actively reduces the out of band seismic noise usi
ng inertial damping. The passive isolation is achieved for all the 6 degree
s of freedom, with an Inverted Pendulum and a chain of single wire pendula
whose masses are the Geometrical Anti-Spring Filters (GASF). The active con
trol is applied to reduce mainly the noise below 4 Hz and to damp the reson
ances of the chain acting from the inverted pendulum table. Here we present
a brief overview of SAS and recent results achieved from the full scale SA
S prototype. (C) 2001 Elsevier Science B.V. All rights reserved.