Status of Japanese gravitational wave detectors Arai, K; Takahashi, R; Tatsumi, D ...
Classical and quantum gravity,
10/2009, Letnik:
26, Številka:
20
Journal Article, Conference Proceeding
Recenzirano
The Large-scale Cryogenic Gravitational wave Telescope (LCGT) is planned as a future Japanese project for gravitational wave detection. A 3 km interferometer will be built in an underground mine at ...Kamioka. Cryogenic sapphire mirrors are going to be employed for the test masses. For the demonstration of LCGT technologies, two prototype interferometers, TAMA300 and CLIO, are being developed. This paper describes the current status of the LCGT project and the two prototype interferometers.
Next generation gravitational wave detectors, such as an advanced LIGO, will generally require improved sensitivity at low frequency. One of the principal challenges for low-frequency sensitivity is ...isolation from seismic motion.
A mechanical seismic isolation filter specifically studied for the next generation of the LIGO detectors, based on a geometric anti-spring concept, has been developed with the aim to provide thermal noise limited sensitivity to frequencies of
10
Hz
.
The design and the performance of the isolation filter, mainly for the vertical degree of freedom are discussed.
The achievement of low resonance frequency in vertical action oscillators is the most difficult of the basic ingredients for seismic noise attenuation filters. These oscillations are achieved by ...means of “anti-springs” systems coupled with more classical suspension springs. Magnetic anti-springs have been used so far. Geometric anti-springs have been studied and the concept tested in this work, opening the way to a simpler and better performance seismic attenuation filters.
The Horizontal Access Module Seismic Attenuation System (HAM-SAS) is a mechanical device expressly designed to isolate a multipurpose optical table and fit in the tight space of the LIGO HAM ...Ultra-High-Vacuum chamber. Seismic attenuation in the detectors' sensitivity frequency band is achieved with state of the art passive mechanical attenuators. These devices should provide an attenuation factor of about 70dB above 10Hz at the suspension point of the Advanced LIGO triple pendulum suspension. Automatic control techniques are used to position the optical table and damp rigid body modes. Here, we report the main results obtained from the full scale prototype installed at the MIT LIGO Advanced System Test Interferometer (LASTI) facility. Seismic attenuation performance, control strategies, improvements and limitations are also discussed.
A new seismic isolation system, TAMA Seismic Attenuation System (TAMA-SAS), was installed to TAMA300 in order to improve the sensitivity at low frequencies. Inertial damping is one of the ...hierarchical control systems of the TAMA-SAS which are employed to give full play to its ability. We have established two servo loops to control the Inverted Pendulum (IP) which composes the SAS. One is the servo loop using LVDT position sensors to keep the position of the IP. The other is the inertial damping which uses accelerometers to control the inertial motion of the IP for the horizontal direction. The fluctuation of the IP was reduced using our servo system. In addition, reduction of angular and longitudinal fluctuation of the mirror was also confirmed. These results indicate that the control for the IP properly works and the isolation performance of the TAMA-SAS was improved.
Monolithic geometric anti-spring blades Cella, G.; Sannibale, V.; DeSalvo, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2005, Letnik:
540, Številka:
2
Journal Article
Recenzirano
Odprti dostop
In this article we investigate the principle and properties of a vertical passive seismic noise attenuator conceived for ground based gravitational wave interferometers. This mechanical attenuator ...based on a particular geometry of cantilever blades called monolithic geometric anti springs (MGAS) permits the design of mechanical harmonic oscillators with very low resonant frequency (below 10
mHz).
Here we address the theoretical description of the mechanical device, focusing on the most important quantities for the low-frequency regime, on the distribution of internal stresses, and on the thermal stability. In order to obtain physical insight of the attenuator peculiarities, we devise some simplified models, rather than use the brute force of finite element analysis. Those models have been used to optimize the design of a seismic attenuation system prototype for LIGO advanced configurations and for the next generation of the TAMA interferometer.
A small fixed-mirror Michelson interferometer has been built in Frascati to experimentally study the alignment method that has been suggested for VIRGO. The experimental results fully confirm the ...adequacy of the method. The minimum angular misalignment that can be detected in the present setup is
10
nrad/
Hz
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