Vacuum-compatible vibration isolation stack for an interferometric gravitational wave detector TAMA300

Abstract

Design of an isolation system to a medium size spherical resonant gravitational wave detector AIP Conf.Interferometric gravitational wave detectors require a large degree of vibration isolation. For this purpose, a multilayer stack constructed of rubber and metal blocks is suitable, because it provides isolation in all degrees of freedom at once. In TAMA300, a 300 m interferometer in Japan, long-term dimensional stability and compatibility with an ultrahigh vacuum environment of about 10 Ϫ6 Pa are also required. To keep the interferometer at its operating point despite ground strain and thermal drift of the isolation system, a thermal actuator was introduced. To prevent the high outgassing rate of the rubber from spoiling the vacuum, the rubber blocks were enclosed by gas-tight bellows. Using these techniques, we have successfully developed a three-layer stack which has a vibration isolation ratio of more than 10 3 at 300 Hz with control of drift and enough vacuum compatibility.

Measurement of optical losses in a high-finesse 300 m filter cavity for broadband quantum noise reduction in gravitational-wave detectors

“…Four magnets have been glued to the back of the mirrors, allowing to move them by coil actuators. The double pendulum is placed on a vibration isolation multilayer stack made of rubber and metal blocks [19]. The mirror position is sensed using optical levers with lenses which decouples shifts and tilts motion [20].…”

Operational status of TAMA300 with the seismic attenuation system (SAS)

“…The plan is to upgrade the isolation system for the four test-mass mirrors. In the former isolation system, the mirror was suspended by a doublependulum which was placed on an optical table supported by a three-layer stack [10] and an active isolation system with pneumatic actuators [11]. The new isolation system consists of a horizontal 5-layer pendulum and a 3-layer vertical isolation.…”

Frequency-Dependent Squeezed Vacuum Source for Broadband Quantum Noise Reduction in Advanced Gravitational-Wave Detectors

“…The filter cavity is hosted in one of the 300 m arms of the former TAMA interferometer, and uses the already existing vacuum system. The 10 cm diameter cavity mirrors are suspended with a double pendulum system [28] placed on a vibration isolation multilayer stack [29], initially developed for TAMA and re-commissioned for this experiment. Mirror motion is sensed by optical levers and coil-magnet actuators are used to align the cavity and to damp suspension mechanical resonances [30].…”