Developments of Cryogenic Laser Interferometer Observatory (CLIO) and Local Suspension Point Interferometer (LSPI) in Kamioka

Abstract

The Cryogenic Laser Interferometer Observatory (CLIO) is a laser interferometric gravitational wave (GW) detector. CLIO is a prototype of the Large-Scale Cryogenic Gravitational Wave Telescope (LCGT). Both CLIO and LCGT use the same cryogenic mirror technique as well as the underground site of Kamioka mine. The cryogenic mirror technique is a method to reduce thermal noises that are fundamental in GW detectors. The most important purpose of CLIO is to demonstrate sensitivity improvement by using the cryogenic mirror technique. During the operation of CLIO with cryogenic mirrors, several unique behaviors in the interferometer systems were found. One of the serious issues that we found was low effectiveness of the magnet damping system for a mirror suspension system at cryogenic temperatures. Thus, we have developed a new damping system, the Local Suspension Point Interferometer (LSPI). In this article, we give a brief introduction to CLIO and recent results of the LSPI experiments in CLIO.