DESIGN OF SUSPENSION SYSTEMS FOR MEASUREMENT OF HIGH-Q PENDULUMS

Laser interferometer gravitational wave detectors require the use of massive ultra-high-Q test mass pendulums to minimize thermal noise. The verification of ultra-high Q-factors in pendulums is difficult due to the coupling of support structure recoil losses into the pendulum stage. We present a numerical analysis of three different pendulum suspension systems to assess their performance. We show that conventional two-stage and three-stage suspension systems cannot be expected to verify Q-factors beyond 10(8) due to recoil losses, but that a twin pendulum system can allow Q-factors of 10(10) to be observed.