A new super-spring for ultra-quiet experiments
Physicists and instrument makers in Leiden have succeeded to optimise a spring that almost completely filters out vibrations at temperatures near the absolute zero. This breakthrough opens the door to a new generation of highly sensitive experiments.
‘Our new special spring reduces the disruptive vibrations down to 0.185 hertz. Which is a major improvement,’ says PhD candidate Louw Feenstra. Instrument makers Kees van Oosten and Hugo van Bohemen designed and built the new instrument in their workshop and tested it in the lab together with Feenstra.
Today, many – if not all - modern physics experiments are based on extremely precise measurements. Such measurements are often carried out inside a cryostat: a device that cools materials to temperatures as close as possible to absolute zero (0 Kelvin equals -273.15 °C). Until now, cryostats had one major drawback. Their cooling systems generate strong vibrations, particularly around 1 hertz — roughly one vibration per second. For sensitive experiments, this can seriously affect the results.
Inspired by gravitational wave research
‘Our design - a geometric anti-spring - was inspired by techniques used in gravitational wave research,’ instrument maker Kees van Oosten explains. ‘The collaboration with Alberto Bertolini from Nikhef really allowed us to hit the ground running. Our instrument is based on a special, extremely ‘soft’ suspension system that works at low temperatures without the need for a structure several metres in size.
Precision engineering at the micrometre scale
‘Building such a system turned out to be an enormous technical challenge’, says instrument maker Hugo van Bohemen. ‘Each of the springs had to be adjusted with a precision of just a few tens of micrometres, while the entire system also had to operate reliably at extremely low temperatures’.
‘This project simply would not have been possible without the combining of expertise and excellent collaboration,’ says physicist Milan Allan.
We build the tools to study the foundations of quantum and space
For hundreds of years, studying the big questions of our Universe and making the instruments required to answer them have gone hand in hand for physicists in Leiden.
Towards quieter quantum experiments
The researchers see many potential applications for their new setup: ultra-stable microscopes, quantum experiments, and future gravitational-wave detectors. In addition, there are opportunities to further improve the design. While the current system primarily suppresses vertical vibrations, future versions will also aim to reduce vibrations in the horizontal direction.
For now, however, the most important milestone has been achieved: proof that a geometric anti-spring can also function in a cryogenic environment. This brings a new generation of ultra-quiet experiments one step closer.
This article is based on the paper in Measurement Science and Technology:
‘Cryogenic geometric anti-spring vibration isolation system’
L. Feenstra, S. Domínguez-Calderón, K. van Oosten, H.S.M. Bohemen, T. Benschop, M. Brinkman, M. Li, E. Hennes, R. Cornelissen, B.J. Hensen, A. Bertolini en M.P. Allan.