Cryogenic suspension design for a kilometer-scale gravitational-wave detector

Present status of large-scale cryogenic gravitational wave telescope

The large-scale cryogenic gravitational wave telescope (LCGT) is the future project of the Japanese gravitational wave group. Two sets of 3 km arm length laser interferometric gravitational wave detectors will be built in a tunnel of Kamioka mine in Japan. LCGT will detect chirp waves from binary neutron star coalescence at 240 Mpc away with a S/N of 10. The expected number of detectable events...

Force measurements of a superconducting-film actuator for a cryogenic interferometric gravitational-wave detector

We measured forces applied by an actuator with a YBa2Cu3O7 (YBCO) film at near 77 K for the Large-scale Cryogenic Gravitational-wave Telescope (LCGT) project. An actuator consisting of both a YBCO film of 1.6 μm thickness and 0.81 cm area and a solenoid coil exerted a force of up to 0.2 mN on a test mass. The presented actuator system can be used to displace the mirror of LCGT for fringe lock o...

Indium joints for cryogenic gravitational wave detectors

A viable technique for the preparation of highly thermal conductive joints between sapphire components in gravitational wave detectors is presented. The mechanical loss of such a joint was determined to be as low as 2×10 at 20 K and 2×10 at 300 K. The thermal noise performance of a typical joint is compared to the requirements of the Japanese gravitational wave detector, KAGRA. It is shown ...

The Case for a Kilometer - Scale High Energy Neutrino Detector ∗

Doing astronomy with photons of energies in excess of a GeV has turned out to be extremely challenging. Efforts are underway to develop instruments that may push astronomy to wavelengths smaller than 10 −14 cm by mapping the sky in high energy neutrinos instead. Neutrino astronomy, born with the identification of thermonuclear fusion in the sun and the particle processes controlling the fate of...

Induced current damping for the suspension system of a gravitational-wave detector