Charlotte Bragard, Giacomo Bruno, Ricardo Cabrita, Pavel Demin, Swapnil Dhage, Rodney Eckler, Vito Garzone, Aaron Goodwin-Jones, Alexander Moncello, Nicolas Szilasi, Morgane Zeoli, Jue Zhang

Gravitational wave detectors based on Michelson interferometry (such as LIGO, Virgo, ET) use very high laser powers and quantum-optics to overcome fundamental noises associated with the Heisenberg Uncertainty Principle. However, these high optical powers present a number of challenges including:
- Themoelastically driven changes in the mirror radii of curvature. This leads to:
+ Reduced optical power, therefore reduced sensitivity,
+ Modifications to the phase of optical control fields, limiting the operational time and power of the detectors
+ Quantum hyperloss, leading to reduced sensitivity
- Parametric instability - an optomechanical coupling that degrades interferometer sensitivity
- Angular instability, such as siggs-sidles.

ET-OPT is a next-generation high-power interferometry platform being developed at UCLouvain to advance optical technologies for future gravitational-wave observatories such as the Einstein Telescope and Virgo. The project focuses on developing real-time optical mode control loops in a prototype scale infrastructure. This unlocks the following possibilities:
- Increase optical power in today's gravitational wave detectors (such as Virgo)
- A concrete route towards the 3 MW of optical power targeted by ET
- New possibilities, such as the use of higher order modes for coating brownian noise reduction
- Dynamic control of gouy phase, without causing hyperloss, thus facilitating PI suppression

The work is carried out in close collaboration with Virgo and ET scientific consortia.

External collaborators: Nicolas Letendre (Laboratoire d'Annecy de Physique des Particules), Alain Masserot (Laboratoire d'Annecy de Physique des Particules), Emmanuel Pacaud (Laboratoire d'Annecy de Physique des Particules), Carl Blair (University of Western Australia), Haochen Zhu (University of Western Australia), Chunnong Zhao (University of Western Australia), Liu Jian (University of Western Australia), Christophe Collette (ULiege), Matteo Tacca (Nikhef), Martin van Beuzekom (Nikhef), Sebastian Steinlechner (ETpf), André Füzfa (UNamur).

Giacomo Bruno, Nicolas Szilasi

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.

External collaborators: S. Hild (Maastricht), A. Bertolini (Nikhef), Conor Mow-Lowry (Nikhef), Ken Strain (and other LIGO HRTS designers) and ETpathfinder collaboration.

Hamid Basiri, Alice Biolchini, Eduardo Cortina Gil, Pavel Demin, Khalil El Achi, Andrea Giammanco, Sumaira Ikram, Gábor Nyitrai, Aitor Orio, Nicolas Szilasi, Ayman Youssef, Zahraa Zaher

The general goal of this project is to develop muon-based radiography or tomography (“muography”), an innovative multidisciplinary approach to study large-scale natural or man-made structures, establishing a strong synergy between particle physics and other disciplines, such as geology and archaeology.
Muography is an imaging technique that relies on the measurement of the absorption of muons produced by the interactions of cosmic rays with the atmosphere.
Applications span from geophysics (the study of the interior of mountains and the remote quasi-online monitoring of active volcanoes) to archaeology and mining.

We are using the local facilities at CP3 for the development of high-resolution portable detectors based on Resistive Plate Chambers.

We also participate to the MURAVES collaboration through simulations (including the coordination of the Monte Carlo group), data-analysis developments (an example of the latter is the implementation and in-situ calibration of time-of-flight capabilities), and development of a new database.

We have contributed the EU projects SilentBorder / SilentBorder2, aiming at developing new muon scanners at border controls. Our role in this project is to develop a parametric simulation and a ML-based detector optimization procedure, and of KINETIKA where our task is to apply muography to cultural heritage preservation.

External collaborators: EU projects INTENSE, SilentBorder/SilentBorder2, KINETIKA.

Anna Benecke, Agni Bethani, Laurent Bruniaux, Jérôme de Favereau, Christophe Delaere, Noemie Deplechin, Majid Hussain, Paul Malek, Nicolas Szilasi, Semra Turkcapar

Development of the "phase II" upgrade for the CMS silicon strip stracker.

More precisely, we are involved in the development of the uTCA-based DAQ system and in the test/validation of the first prototype modules. We take active part to the various test-beam campaigns (CERN, DESY, ...)

This activity will potentially make use of the cyclotron of UCL, the probe stations and the SYCOC setup (SYstem de mesure de COllection de Charge) to test the response to laser light, radioactive sources and beams.

The final goal is to take a leading role in the construction of part of the CMS Phase-II tracker.

External collaborators: CRC and CMS collaboration.