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Japan gravitational wave detector revealed to media, set to debut at end of year

Part of a 3-kilometer-long vacuum duct is seen inside the KAGRA large-scale cryogenic gravitational wave telescope tunnel in this image taken in Hida, Gifu Prefecture, on Sept. 30, 2019. (Mainichi/Koji Hyodo)

HIDA, Gifu -- KAGRA, the large-scale cryogenic gravitational wave telescope, built underground in this central Japan city and used to observe gravitational waves emitted by mergers and collisions between black holes, opened to the press on Sept. 30 following its completion.

The facility, which is underneath the Kamioka neighborhood in Hida, Gifu Prefecture, houses two tunnels that intersect in an L shape some 200 meters below ground. The tunnels house a vacuum duct 3 kilometers long and 80 centimeters in diameter. A high-power laser beam that passes through the duct is observed with precision accuracy to detect small distortions caused by gravitational waves.

The existence of gravitational waves was predicted by Albert Einstein. The first team to successfully observe them was the U.S.-based Laser Interferometer Gravitational-Wave Observatory (LIGO). The discovery won them the Nobel Prize in physics in 2017.

There are three facilities able to observe gravitational waves -- Europe's Virgo and LIGO's two installations. But KAGRA is expected to greatly improve the accuracy of readings.

The project started in 2010. Observations are set to commence by the end of the year, and there are plans to carry out coordinated observations with other facilities. A ceremony to celebrate the completion of KAGRA will take place on Oct. 4.

(Japanese original by Takayo Hosokawa, Nagoya News Center)

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