Regensburg 2022 – scientific programme

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VA: Fachverband Vakuumphysik und Vakuumtechnik

VA 2: Vacuum technology: New developments and applications

VA 2.3: Talk

Monday, September 5, 2022, 13:50–14:30, H12

Outgassing rate studies and Monte Carlo simulations for the design of the cryogenic vacuum system of the Einstein Telescope — •Katharina Battes, Stefan Hanke, Xueli Luo, and Christian Day — Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany

The Einstein Telescope (ET) is a third-generation underground gravitational wave observatory, currently under development in Europe. It is designed as an equilateral triangle with 10 km long arms and detectors in each corner. Two interferometers will be used to detect both low-frequency (LF) and high-frequency gravitational wave signals.

In order to reduce thermal noise, the main optics will partly be cooled to cryogenic temperatures below 20 K for ET-LF. The integral ET vacuum system requires high to ultra-high vacuum conditions and comprises three different parts: (i) the beamline vacuum characterised by outgassing from the pipe walls, (ii) the tower vacuum characterised by outgassing from the suspension arrangement, and (iii) the cryogenic vacuum systems around the LF mirror.

In this paper, the outgassing behavior of potential materials such as mild steel is studied at the Outgassing Measurement Apparatus OMA. Using this input, a Test Particle Monte Carlo model has been established with the KIT in-house code ProVac3D, to allow for a system analysis of the cryogenic vacuum area. It assesses the impinging rate of residual gas on the cryogenic mirror, depending on the particle sources. With that, the expected speed of frost formation is estimated, which is critical due to degradations of the optical performance.