Gravitational Wave Group

LISM Project.

Motivation

MACHO is proposed as one of missing matter sources of a galaxy. Some scientists guess that MACHO is a super compact massive object and that there are many MACHOs in our galaxy. Some of them form binary systems and are estimated to coalesce one event per 20 years. MACHO is so compact massive object and so near the Earth that its coalescence may radiate detectable gravitational wave if MACHO is true oblect. Induced strain on the Earth is within the 20m gravitational wave interferometer's sensitivity. It's a exciting GW source!!
To perform long observation for MACHO coalescence survey, Tokyo where the 20m interferometer is now constructed is not proper because the seismic noise level for the low frequency range (less than 100Hz) is high. Then, we will move it in the kamioka mine where the seismic noise level under 100 Hz is 10-3 - 10-2 smaller than in Tokyo. This project name is LISM.



Where is LISM

LISM facilities was established near world-famous 50k-ton water Cherenkov neutrono detector known as Super-Kamiokande, Kamioka. The site is about 3000m inside from the entrance to Mozumi-mine, which corresponds to 1000m depth underground. As this mine yields lead and zinc, the mining industry is in still operation. The facilities was completed by excavating a tunnel, so the whole laboratry is surrounded by very hard rock.



LISM NOW

The tunnel view of primary arm direction. Hight, width and depth of the arm tunnel are about 3.5, 4.0 and 23.0m respectively. The roof and side wall were reinforced with mortar-spraying and floor was completed with mortar finishing. Whole surface of this laboratry will be spray-coated with acrylic resin paint as a measures for dust production.



The center room view. This space is about 12m square wide and 4m high. Mortar finishing of floor have been already completed and partition wall is now being built.