Duty cycle enhancement of observation using rapid recovery technique for cryogenic mirror performance in the 3rd generation gravitational wave detectors

2023 Fiscal Year Final Research Report

• Project/Area Number: 19H00680
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Medium-sized Section 15:Particle-, nuclear-, astro-physics, and related fields
• Research Institution: The University of Tokyo
• Principal Investigator: Miyoki Shinji 東京大学, 宇宙線研究所, 教授 (20302680)
• Co-Investigator(Kenkyū-buntansha): 都丸 隆行 国立天文台, 重力波プロジェクト, 教授 (80391712)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 重力波 / 低温吸着 / 光学損失 / 光刺激脱離 / 昇温脱離

Outline of Final Research Achievements

A gravitational wave telescope with a cryogenic mirror such as KAGRA requires periodic recovery work of the mirror's low-loss characteristics. However, as a telescope that awaits unpredictable gravitational waves, this work causes a significant opportunity loss in the detection of gravitational waves and also a degradation in the accuracy of the determination of the position of the gravitational wave sources because the LIGO, Virgo, and KAGRA simultaneous observations will be also lost. To solve this problem, first, we aim to achieve instantaneous photo-stimulated desorption of water molecules by concentrated irradiation of ultrashort infrared laser pulses with a wavelength of 3 micrometers without a heating process, and as a backup, we will shorten the heating process by directly heating the substrate material with a CO2 gas laser. The goal was to maintain the mirror's low-loss characteristics.

Free Research Field

重力波物理学

Academic Significance and Societal Importance of the Research Achievements

KAGRAにとどまらず、ヨーロッパやアメリカの次期重力波望遠鏡計画であるEinstein Telescope 計画やCosmic Explorer 計画、及び、その前段階のVoyager計画においても想定されている、低温鏡を用いた重力波望遠鏡計画にかならず付随する、低温鏡へのガス分子吸着とそれによる、鏡の低損失特性の劣化という共通の問題に対する解決策の一端を示すことができ、これらの次期計画の実現性を担保する貢献ができた。