Orateur
Description
The nature of dark matter is one of the most important unsolved puzzles in fundamental physics, driving searches beyond the Standard Model. Current theories suggest that this matter primarily interacts via gravitation, but also weakly with ordinary matter. However, due to the very low interaction cross-sections, it is very hard to observe and detectors sensibilities need to be increased.
The TESSERACT (Transition Edge Sensors with Sub-EV Resolution And Cryogenic Targets) international collaboration aims at pushing back these limits and increase the resolution of current detectors (Billard Julien et al., Nuclear Physics B, 2024). To achieve this, teams are developing cryogenic detectors coupled with superconducting Transition Edge Sensors (TES) through several technologies (such as liquid helium, semiconductor crystals and others).
At IJCLab (Orsay), our focus is on the Cryosel detector, a germanium (Ge) crystal paired with TES sensors, optimized for phonon collection via the Neganov-Trofimov-Luke (NTL) effect. By applying a non-linear electric field, even small interactions as small as a single electron-hole pair can be detected (Marnieros Stefanos et al. (2026), To be published). Moreover, the final objective is to measure both the ionisation of an interaction but also its calorimetry, allowing discrimination between the different kinds of particles. Current efforts prioritize TES design refinement and phonons simulations with G4CMP to optimize detector performance and background discrimination.
By 2028, Cryosel and other TESSERACT detectors will be deployed at the Modane Underground Laboratory (LSM), leveraging its ultra-low-radioactivity environment for the first direct dark matter searches. This project also aligns with RICOCHET, targeting coherent elastic neutrino-nucleus scattering (CEνNS) at the ILL reactor, further advancing quantum-limited calorimetry and low-energy particle physics.
This presentation will provide an overview of the TESSERACT collaboration, then dive in the Cryosel germanium detector developed at the IJCLAB. The quantum physics processes will be explained and discussed, linked with experimental results and simulations.