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Useful for much more than the Einstein Telescope

Demcon Kryoz, Cooll and the University of Twente are developing a vibration-free cooling technique for the Einstein Telescope with a grant from the Dutch National Growth Fund. This should help get the mirrors of the future detector for gravitational waves as quiet as possible, says founder of Demcon Kryoz Pieter Lerou.

Why is vibration-free cooling so important for the Einstein Telescope?

“The Einstein Telescope needs to become ten times more sensitive than existing detectors for gravitational waves. To achieve that, you need incredibly quiet measuring equipment. Not only the mirrors must be stationary: even the atoms in the mirror layers must barely move. You can only achieve that by cooling the equipment to around -260 degrees Celsius, close to absolute zero.”

Pieter Lerou (Demcon Kryoz)
Pieter Lerou (Demcon Kryoz)
And that is tricky?

“There are all kinds of cooling methods to cool equipment that far, but that technology itself generates vibrations. The suspension point of the mirrors, where the cooling pipes arrive, may only move nanometres: a billionth of a metre. But in most cooling technology, there are compressors that create vibrations as much as a thousand times worse.”

How do you address that?

“Basically, our refrigeration technology works the same as the domestic refrigerator: you take a gas at high pressure and let it expand, so that it takes up more volume and drops in temperature. The difference is in the types of gas we use and how we build up that pressure. We use a tube full of activated carbon instead of a mechanical pump. Activated carbon takes up gases easily – sorption, for the experts. A small temperature pulse, and the gas is released again from the material, so that you build up pressure. In four consecutive steps, we cool with different gases from two hundred degrees below zero – the temperature of liquid nitrogen – to 263 degrees below freezing.”

Will that work?

“This cooling technique has been working for years, which is the basis of the company Kryoz that I founded 2008 based on my PhD research at the University of Twente. Research on vibration-free compressor technology has also been done there for years, commercialised by the company Cooll. Whether we can also get the performance low-vibration enough for the Einstein Telescope, we now want to find out. There are several approaches in the race; we will develop these now and test them at the ETpathfinder facility in Maastricht in 2026.”

Ontwikkelaars van de trillingsvrije koeling bij de ETpathfinder-faciliteit
Developers of the vibration-free cooling technology at the ETpathfinder-facility
What makes this assignment interesting for you?

“It’s obviously exciting to be able to contribute to such a demanding project as the Einstein Telescope. In doing so, you show what kind of performance you can achieve with your product. And good, vibration-free cooling has all kinds of applications. For instance, this approach is already quite similar to the cooling technology we are developing for sensitive electron microscopes. That enables better analyses of cooled biological samples such as coronavirus with electron microscopes, or better cooling of sensors in satellites. Low-vibration cooling is interesting for all kinds of applications, far beyond the Einstein Telescope.”

R&D scheme for high-tech companies

To encourage innovation and accelerated development of new technologies for the Einstein Telescope, an R&D scheme for high-tech companies was launched in the Netherlands in autumn 2023. That scheme is part of the Einstein Telescope valorisation programme and will be implemented by Dutch-Limburg development company LIOF. The scheme is open to individual companies and partnerships around five technology domains relevant to the Einstein Telescope.

More information? Visit the R&D scheme website.

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