Cryogenic suspension design for a kilometer-scale gravitational-wave detector
Abstract
We report the mirror suspension design for Large-scale Cryogenic Gravitational wave Telescope, KAGRA, during bKAGRA Phase 1. Mirror thermal noise is one of the fundamental noises for room-temperature gravitational-wave detectors such as Advanced LIGO and Advanced Virgo. Thus, reduction of thermal noise is required for further improvement of their sensitivity. One effective approach for reducing thermal noise is to cool the mirrors. There are many technical challenges that must be overcome to cool the mirrors, such as cryocooler induced vibrations, thermal drift in suspensions, and reduction in duty cycling due to the increased number of potential failure mechanisms. Our mirror suspension has a black coating that makes radiative cooling more efficient. For conduction cooling, we developed ultra high purity aluminum heat links, which yield high thermal conductivity while keeping the spring constant sufficiently small. A unique inclination adjustment system, called moving mass, is used for aligning the mirror orientation in pitch. Photo-reflective displacement sensors, which have a large range, are installed for damping control on marionette recoil mass and intermediate recoil mass. Samarium cobalt magnets are used for coil-magnet actuators to prevent significant change of magnetism between room temperature and cryogenic temperature. In this paper, the design of our first cryogenic payload and its performance during bKAGRA Phase 1 are discussed.
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Cite
@article{arxiv.2010.01889,
title = {Cryogenic suspension design for a kilometer-scale gravitational-wave detector},
author = {Takafumi Ushiba and Tomotada Akutsu and Yoichi Aso and Sakae Araki and Rishabh Bajpai and Dan Chen and Kieran Craig and William Creus and Yutaro Enomoto and Yoshinori Fujii and Masashi Fukunaga and Ayako Hagiwara and Sadakazu Haino and Kunihiko Hasegawa and Yuki Inoue and Kiwamu Izumi and Nobuhiro Kimura and Keiko Kokeyama and Rahul Kumar and Ettore Majorana and Yuta Michimura and Takahiro Miyamoto and Shinji Miyoki and Iwao Murakami and Yoshikazu Namai and Masayuki Nakano and Toshiro Ochi and Masatake Ohashi and Koki Okutomi and Yoshio Saito and Takaharu Shishido and Ayaka Shoda and Kentaro Somiya and Toshikazu Suzuki and Suguru Takada and Masahiro Takahashi and Ryutaro Takahashi and Hiroki Tanaka and Shinichi Terashima and Takayuki Tomaru and Flavio Travasso and Ayako Ueda and Helios Vocca and Tomohiro Yamada and Kazuhiro Yamamoto and Simon Zeidler},
journal= {arXiv preprint arXiv:2010.01889},
year = {2021}
}
Comments
18 pages, 9 figures