Current status of Japanese detectors

Abstract

The current status of the TAMA and CLIO detectors in Japan is reported in this paper. These two interferometric gravitational wave detectors are being developed for the large cryogenic gravitational wave telescope (LCGT) which is a future plan for detecting gravitational wave signals at least once per year. TAMA300 is being upgraded to improve the sensitivity in a low-frequency region after the last observational experiment in 2004. To reduce the seismic noises, we are installing a new seismic isolation system, called the TAMA seismic attenuation system, for the four test masses. We confirmed stable mass locks of a cavity and improvements of length and angular fluctuations by using two SASs. We are currently optimizing the performance of the third and fourth SASs. We continue TAMA300 operation and R&D studies for the LCGT. The next data taking is planned for the summer of 2007. CLIO is a 100 m baseline length prototype detector for LCGT to investigate interferometer performance in cryogenic condition. The key features of CLIO are that it locates the Kamioka underground site for a low-seismic noise level, and adopts cryogenic Sapphire mirrors for low-thermal noise level. The first operation of the cryogenic interferometer was successfully demonstrated in February 2006. Current sensitivity at room temperature is close to the target sensitivity within a factor of 4. Several observational experiments at room temperature have been done. Once the displacement noise reaches the thermal noise level of room temperature, its improvement by cooling test mass mirrors should be demonstrated.

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