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.