{"id":3719,"date":"2023-04-05T15:57:00","date_gmt":"2023-04-05T06:57:00","guid":{"rendered":"https:\/\/atc.mtk.nao.ac.jp\/?page_id=3719"},"modified":"2024-10-16T13:12:43","modified_gmt":"2024-10-16T04:12:43","slug":"gravitationalwave","status":"publish","type":"page","link":"https:\/\/atc.mtk.nao.ac.jp\/en\/gravitationalwave\/","title":{"rendered":"Gravitational Wave Observations"},"content":{"rendered":"\n

Gravitational-wave astronomy pioneered by advanced technology development<\/h2>\n\n\n\n

Observing extremely weak gravitational waves from space can unveil new aspects of the Universe inaccessible by conventional astronomy. The Advanced Technology Center is in charge of designing and manufacturing key components such as optical equipment and vibration isolators for KAGRA, a large-scale cryogenic gravitational-wave telescope in Japan.<\/p>\n\n\n\n

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KAGRA<\/h3>\n\n\n\n
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KAGRA is an international gravitational-wave observatory hosted by the Institute for Cosmic Ray Research, University of Tokyo, together with the National Astronomical Observatory of Japan and High Energy Accelerator Research Organization, as well as numerous other international institutes and universities. It is the first large-scale gravitational-wave telescope in Japan, being located under Mt. Ikenoyama, Kamioka-cho, Hida, Gifu prefecture. Unlike conventional \"telescopes,\" this is a large-scale Michelson interferometer having two 3-km long arms installed within a vacuum vessel in an L-shaped tunnel excavated under the mountain.<\/p>\n\n\n\n

Gravitational waves are propagating, periodic, weak space-time distortions. In order to achieve sufficient sensitivity to such tiny signals, we need to isolate the optics in the interferometer from noise of all kinds. For this reason, we have constructed the interferometer at a stable site with low ground vibrations (less than one-100th that of Tokyo) and suspended the mirrors from vibration isolators made of multi-stage pendulums. The most significant mirrors are cooled to nearly -250\u2103 to suppress thermal noise.<\/p>\n\n\n\n

The Advanced Technology Center applied technological capabilities accumulated during the development of other types of telescopes and detectors to the design, production, and installation of various components that enabled the KAGRA interferometer to become what it is today. These components include opto-mechanical systems to monitor the 3-km-long laser optical beam axes, stray light countermeasures, and vibration isolators. We also contribute to developing new sapphire mirrors, which will be necessary for KAGRA's next goal of improving performance.<\/p>\n\n\n\n

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KAGRA Observatory<\/span><\/i><\/div><\/a><\/div>\n<\/div>\n\n\n\n
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Transmission Monitors<\/h2>\n\n\n\n
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Systems to detect mis-alignment of the optical axes in the 3-km-long laser cavities. The Advanced Technology Center has been involved in the entire process from design to assembly, testing, and onsite installation.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n

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Optics<\/h3>\n\n\n\n

The design is based on a transmission telescope. The optical axis is folded to achieve a reduction ratio of 1\/10 within a 1-m diameter vacuum vessel.<\/p>\n<\/div>\n\n\n\n

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Vibration Isolator Part<\/h3>\n\n\n\n

This part is a combination of passive vibration isolation using a pendulum and active vibration damping using various onboard sensors and actuators.<\/p>\n<\/div>\n<\/div>\n<\/div><\/div><\/div>