KAGRA
The Kamioka Gravitational Wave Detector (KAGRA), formerly the Large Scale Cryogenic Gravitational Wave Telescope (LCGT), is a project of the gravitational wave studies group at the Institute for Cosmic Ray Research (ICRR) of the University of Tokyo. It became operational on 25 February 2020, when it began data collection. It is Asia's first gravitational wave observatory, the first in the world built underground, and the first whose detector uses cryogenic mirrors. The design calls for an operational sensitivity equal to, or greater than, LIGO and Virgo. KAGRA is located in the Kamioka Observatory in Gifu Prefecture, Japan. The  observatory specializes in the detection of neutrino, dark matter and gravitational waves, and possesses other important instruments, including Super Kamiokande, XMASS and NEWAGE. The collaboration of LIGO, Virgo and KAGRA plans to start the next observation run (O4) in mid-December, 2022 (KAGRA ended its latest observation run on 21 April 2020; that was also the first observation run for KAGRA ). Overview. The ICRR was established in 1976 for cosmic ray studies. The LCGT project was approved on 22 June 2010. In January 2012, it was given its new name, KAGRA, deriving the "KA" from its location at the Kamioka  mine and "GRA" from gravity and gravitational radiation. The word KAGRA is also a homophonic pun of Kagura (神楽), which is a ritual dance dedicated to Gods in Japanese Shinto shrines. The project is led by Nobelist Takaaki Kajita who had a major role in getting the project funded and constructed. The project was estimated to cost about 200 million US dollars. Two prototype detectors were constructed to develop the technologies needed for KAGRA. The first, TAMA 300, was located in Mitaka, Tokyo and operated 1998-2008, demonstrating the feasibility of KAGRA. The second, CLIO, started operating in 2006 underground  near the KAGRA site. It was used to develop cryogenic technologies for KAGRA. KAGRA has two arms, long, which form a laser interferometric gravitational wave detector. It is built in the Kamioka Observatory near the neutrino physics experiments. The excavation phase of tunnels was started in May 2012 and was completed on 31 March 2014. The construction of KAGRA was completed 4 October 2019, with the construction taking nine years. However, further technical adjustments were needed before it could start observations. The "baseline" planned cryogenic operation ("bKAGRA") was planned to follow in 2020. After the initial adjustment operations, the first  observation run started on 25 February 2020. Because of COVID-19, the observation run was ended 21 April 2020. The first detections were made in collaboration with LIGO and Virgo and were reported 11 November 2021.