Overview of KAGRA: Calibration, detector characterization, physical environmental monitors, and the geophysics interferometer

Abstract KAGRA is a newly built gravitational wave observatory, a laser interferometer with a 3 km arm length, located in Kamioka, Gifu, Japan. In this series of articles, we present an overview of the baseline KAGRA, for which we finished installing the designed configuration in 2019. This article describes the method of calibration (CAL) used for reconstructing gravitational wave signals from the detector outputs, as well as the characterization of the detector (DET). We also review the physical environmental monitors (PEM) system and the geophysics interferometer (GIF). Both are used for characterizing and evaluating the data quality of the gravitational wave channel. They play important roles in utilizing the detector output for gravitational wave searches. These characterization investigations will be even more important in the near future, once gravitational wave detection has been achieved, and in using KAGRA in the gravitational wave astronomy era.

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Detector Characterization and Mitigation of Noise in Ground-Based Gravitational-Wave Interferometers

Galaxies ◽

10.3390/galaxies10010012 ◽

2022 ◽

Vol 10 (1) ◽

pp. 12

Author(s):

Derek Davis ◽

Marissa Walker

Keyword(s):

Data Quality ◽

Gravitational Wave ◽

Impact Analysis ◽

Instrumental Performance ◽

Successful Operation ◽

Detector Performance ◽

Detector Characterization ◽

Gravitational Wave Detectors ◽

Quality Issues

Since the early stages of operation of ground-based gravitational-wave interferometers, careful monitoring of these detectors has been an important component of their successful operation and observations. Characterization of gravitational-wave detectors blends computational and instrumental methods of investigating the detector performance. These efforts focus both on identifying ways to improve detector sensitivity for future observations and understand the non-idealized features in data that has already been recorded. Alongside a focus on the detectors themselves, detector characterization includes careful studies of how astrophysical analyses are affected by different data quality issues. This article presents an overview of the multifaceted aspects of the characterization of interferometric gravitational-wave detectors, including investigations of instrumental performance, characterization of interferometer data quality, and the identification and mitigation of data quality issues that impact analysis of gravitational-wave events. Looking forward, we discuss efforts to adapt current detector characterization methods to meet the changing needs of gravitational-wave astronomy.

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Key technologies analysis and design of ultra-clean & ultra-stable spacecraft for gravitational wave detection

International Journal of Modern Physics A ◽

10.1142/s0217751x21400212 ◽

2021 ◽

pp. 2140021

Author(s):

Kun Chen ◽

Xiaofeng Zhang ◽

Tong Guo ◽

Zhi-Ming Cai ◽

Keyword(s):

Gravitational Wave ◽

Measurement Accuracy ◽

Laser Interferometer ◽

Gravitational Interaction ◽

Thermal Control ◽

Theory Of Relativity ◽

Gravitational Wave Detection ◽

Analysis And Design ◽

Wave Detection ◽

Key Technologies

The observation of gravitational wave enables human to explore the origin, formation and evolution of universe governed by the gravitational interaction and the nature of gravity beyond general theory of relativity. The groundbreaking discovery of Gravitational Wave by Laser Interferometer Gravitational-Wave Observatory provides a brand-new observation way. While detecting gravitational wave on ground is limited by noises and test scale, space detection is an optimized alternative to learn rich sources in range of 0.1 mHz–1 Hz. Considering the great significance of space gravitational wave detection, ESA proposed LISA project, CAS also proposed Taiji project. Due to the extremely weak gravitational wave signal and high measurement accuracy requirement, the spaceborne GW observation antenna is accomplished by three spacecrafts constitute isosceles triangle formation intersatellite interferometer. The arm length of the interferometer reaches millions of kilometers between them, and the measurement accuracy reaches pico-meter magnitude. There are many key technologies including pm magnitude space laser interferometer metrology, drag-free control using TM of Gravity Reference Sensor, [Formula: see text]N micro thruster, ultra-clean & ultra-stable spacecraft, etc. This paper focuses on key technologies of the ultra-clean & ultra-stable spacecraft, analyzing the design of mechanical, thermal control and magnetic clean. Moreover, it reports the preliminary results of the technological breakthrough.

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The Calibration Home Base for Imaging Spectrometers

Journal of large-scale research facilities JLSRF ◽

10.17815/jlsrf-2-137 ◽

2016 ◽

Vol 2 ◽

Cited By ~ 3

Author(s):

Johannes Felix Simon Brachmann ◽

Andreas Baumgartner ◽

Peter Gege

Keyword(s):

Wavelength Range ◽

Stray Light ◽

Third Party ◽

Home Base ◽

Geometric Calibration ◽

Wide Range ◽

Along Track ◽

Near Future

The Calibration Home Base (CHB) is an optical laboratory designed for the calibration of imaging spectrometers for the VNIR/SWIR wavelength range. Radiometric, spectral and geometric calibration as well as the characterization of sensor signal dependency on polarization are realized in a precise and highly automated fashion. This allows to carry out a wide range of time consuming measurements in an ecient way. The implementation of ISO 9001 standards in all procedures ensures a traceable quality of results. Spectral measurements in the wavelength range 380–1000 nm are performed to a wavelength uncertainty of +- 0.1 nm, while an uncertainty of +-0.2 nm is reached in the wavelength range 1000 – 2500 nm. Geometric measurements are performed at increments of 1.7 µrad across track and 7.6 µrad along track. Radiometric measurements reach an absolute uncertainty of +-3% (k=1). Sensor artifacts, such as caused by stray light will be characterizable and correctable in the near future. For now, the CHB is suitable for the characterization of pushbroom sensors, spectrometers and cameras. However, it is planned to extend the CHBs capabilities in the near future such that snapshot hyperspectral imagers can be characterized as well. The calibration services of the CHB are open to third party customers from research institutes as well as industry.

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