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Description
ETpathfinder is a research and development facility for the future Einstein Telescope, located in Maastricht, the Netherlands. One of its primary objectives is the testing of a newly developed cryogenic system, designed to cool silicon test masses to 15K without introducing additional seismic or thermal noise. This system is based on a modular cryochain design, consisting of multiple sorption compressors and Joule-Thomson cold stages, and is being developed by the University of Twente, Demcon and Cooll. Prior to its installation at the ETpathfinder facility, a full prototype is assembled at the University of Twente, where it undergoes extensive validation against system requirements.
In order to achieve the sensitivity goals for future low-frequency gravitational wave detectors, the setup must maintain a vibration level below 32 nm peak-to-peak, while reaching a cold platform temperature of 8K to enable a mirror temperature of 15K. Additionally, the total cooldown time must not exceed 4 weeks. This work focuses on validating these key performance requirements for the cryogenic test setup intended for ETpathfinder.
The prototype is equipped with an array of seismic and temperature sensors, enabling detailed characterization of vibrations and thermal behavior throughout both the cooldown phase and steady-state operation. Seismic measurements will be conducted using a combination of geophones, cryogenic piezoelectric accelerometers and Trillium sensors, providing coverage of a broad frequency range. Temperature monitoring will be performed using Cernox and PT1000 sensors, ensuring accurate measurements across the full system. This poster shows an assessment of the achieved cooldown time and the temperature of the dummy test mass, along with a first characterisation of the system’s seismic noise performance.