Einstein Telescope
The Einstein Telescope (ET) is a future terrestrial gravitational-wave detector based on the laser interferometric technique. ET will open a new window on the Universe through the observation of gravitational waves. Its infrastructure will be buried 300 meters below the surface to reduce human-, wind- and ground-induced vibrations and movements. The border region between Belgium, the Netherlands and Germany is a candidate site for hosting ET. It is called the Euregio Meuse-Rhine region.
The Interreg project E-TEST is a very important step of the Einstein Telescope, as it will be a proof of concept, both on the prototype side and on the geological side.
In addition to the characterisation of the candidate sites, intense Research and Development is currently being performed by research groups all over the world to prepare the ET technology. The GW group at UCLouvain is notably involved in two major ET R&D facilities, E-TEST in Belgium and ETpathfinder in the Netherlands.
E-TEST will build a prototype – a large suspended mirror at cryogenic temperature (10 Kelvin) – to validate the ET technology. E-TEST will also run an underground study to map and model the geology of the Euregio Meuse-Rhine region.
This will allow to define the optimal design and location of the future Einstein Telescope. UCLouvain collaborates with the following institutes:
E-TEST full partners: Université de Liège, RWTH Aachen, UHasselt, Rheinische Friedrich-Wilhelms-Universität Bonn, NMWP Management GmbH, Fraunhofer-Gesellschaft für Förderung des Applied Forschung e.V., KU Leuven, Nikhef, KNMI, Maastricht University.
E-TEST satellite partners : Université Libre de Bruxelles, Vrije Universiteit Brussels, Universiteit Gent, Universiteit Antwerpen, Université de Mons.
The participation of UCLouvain in this project is possible thanks to support from the European Union through its Interreg EMR programme.
Interreg EMR programme website
E-TEST project website
Interreg EMR E-TEST project website
Projects
Click the title to show project description.-
On Feb 1, 2020 the R&D EU Interreg project E-TEST officially started. It involves 11 institutes from Belgium, Germany and Netherlands and will carry on crucial detector developments for the Einstein Telescope (ET) - a 3rd generation antenna of gravitational waves, related mostly to cryogenic operations of large mass mirrors and their suspensions, ultra-precise metrology and sensing, as well as to advanced geological studies in the region (the ET is a deep-underground detector). The CP3 group is a partner in this project and is working on work package 1 : "Ultra-cold vibration control" and in particular on a cryogenic superconducting inertial sensor.
Gravitational wave signals below a frequency of about 10 Hz are obscured by thermal noise in current detectors. Because temperature is the vibration of atoms in some respect, making the distance measurement between the mirror surfaces more challenging, the mirrors of future detectors will need to be cooled down to temperatures around 10 K. We need to control the motion of some of the cold objects, for which we develop inertial sensors that can survive this harsh environment. The interferometric readout of the inertial sensor also serves as to monitor a ringdown or the E-TEST mirror. After it is excited by a tiny hammer strike, the interferometer follows the ringdown and can determine the quality factor. Additionally, we are investigating an alternative suspension technique, where instead of long fibres under tension, we use short flexures under compression in combination with long, fat rods so we obtain good thermal conductivity and low stiffness suspension.
CP3 members collaborate mostly with KU Leuven (we are collaborating to develop cryogenic readout electronics for the sensor) and ULiège (we align our sensor efforts), RWTH Aachen (they are preparing a cryostat where we will test the inertial sensor). -
The ETpathfinder is an R&D infrastructure for testing and prototyping innovative concepts and enabling technologies for the Einstein Telescope, the European concept for a new class of future gravitational wave observatories. ETpathfinder is funded by the interreg program of the EU. The ETpathfinder project broadly consists of six vacuum towers. Four towers are cryogenic and hold suspensions for the mirrors (or test masses) of the experiment. Two towers are operated at room temperature. They hold suspensions for optical tables which hold smaller optics that prepare the beams to be shot into both arms (mode cleaning, frequency stabilisation etc.) and hold the beamsplitters and detection optics.
Many of these optics are suspended individually with small bench top suspensions so they can be steered and additionally seismically isolated. This project concerns the design, prototyping and partial fabrication of >10 suspensions of order 75cm high.