ETpathfinder: a cryogenic testbed for interferometric gravitational-wave detectors

TL;DR

ETpathfinder is a cryogenic testbed designed to simulate third-generation gravitational-wave detectors, focusing on noise analysis and subsystem development for future observatories like ET and Cosmic Explorer.

Contribution

It introduces a full interferometer test facility with cryogenic technologies and noise budget analysis for two configurations at different wavelengths and temperatures.

Findings

Noise contributions identified and analyzed.

Full noise budgets for two configurations established.

Guidance for design and development of third-generation detectors.

Abstract

The third-generation of gravitational wave observatories, such as the Einstein Telescope (ET) and Cosmic Explorer (CE), aim for an improvement in sensitivity of at least a factor of ten over a wide frequency range compared to the current advanced detectors. In order to inform the design of the third-generation detectors and to develop and qualify their subsystems, dedicated test facilities are required. ETpathfinder prototype uses full interferometer configurations and aims to provide a high sensitivity facility in a similar environment as ET. Along with the interferometry at 1550 nm and silicon test masses, ETpathfinder will focus on cryogenic technologies, lasers and optics at 2090 nm and advanced quantum-noise reduction schemes. This paper analyses the underpinning noise contributions and combines them into full noise budgets of the two initially targeted configurations: 1) operating with 1550 nm laser light and at a temperature of 18 K and 2) operating at 2090 nm wavelength and a temperature of 123 K.