Japanese Underground Gravitational Wave Detector

A laser interferometer gravitational wave antenna with a baseline length of 20 m (LISM) was developed at a site 1000 m underground, near Kamioka,
Japan. This project was a unique demonstration of a prototype laser interferometer for gravitational wave observation located underground. The extremely stable environment is the prime motivation for going underground. In their paper (S Sato et al. 2004 http://arXiv.org/abs/gr-qc/0403080), S. Sato et al. demonstrated ultra-stable operation of the interferometer and reported a well-maintained antenna sensitivity.