An underground site and cryogenic mirrors are the hallmarks of Japan’s planned gravitational-wave detector. In June the Japanese government approved about two-thirds of the estimated ¥15.5 billion ($190 million) tab for building the Large-scale Cryogenic Gravitational-wave Telescope (LCGT).
The funding granted so far covers construction, but not the equipment to cool the interferometer’s four mirrors. Money for that and for digging perpendicular tunnels some 200 m below ground to accommodate the 3-km-long arms of the interferometer will be sought in the next few years, says project principal investigator Takaaki Kajita of the University of Tokyo’s Institute for Cosmic Ray Research.
Tests using a prototype detector with 100-m-long arms found that seismic noise from wind, human activities, and other sources was attenuated about two orders of magnitude underground compared with on the surface, Kajita says. The LCGT will share the Kamioka Mountain location some 250 km northwest of Tokyo with the...
