Site and infrastructure

• Applicant: Dr. Sebastian Lindemann
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 561595909

DELight is a new particle physics experiment to search for light dark matter (LDM) particles with masses well below 1 GeV/c2 by detecting elastic LDM scattering off a cryogenic liquid helium (LHe) target. Its low mass number, the low threshold achievable with large-area magnetic microcalorimeters (MMCs), its intrinsic radiopurity and the availability of several signal channels render LHe an ideal target for LDM searches. DELight can only be realized through the confluence of its six projects. Each project plays a fundamental and unique role, where this project (P4) is responsible preparing the underground site at the Vue-des-Alpes (VdA) laboratory, providing the infrastructure for autonomous operation and remote control of the experiment, and for the mechanical realization of the external shield for the experiment. If dark matter exists in the form of LDM, it interacts extremely weakly with ordinary matter, so the expected number of signal events is small. Therefore, backgrounds from cosmic radiation or radioactivity must be minimized. This can only be achieved in an underground laboratory with an additional radiation shield. The Vue-des-Alpes laboratory located in the Swiss Jura Mountains is a small, medium-depth underground laboratory offering 620 meters of water equivalent rock overburden. Access to the laboratory is provided via the UFR group which is currently the main user of the laboratory. Preliminary studies show that operating DELight at this site will reduce muon-induced cosmogenic backgrounds by several orders of magnitude compared to operating above ground, which will allow achieving the background goals of DELight phase-I. This project will establish the infrastructure necessary to safely operate DELight at the VdA laboratory and will ensure efficient use of the available space, allowing good access to the various detector systems and providing optimal operating conditions. The high-Z material shield enclosing the experiment may include layers of high-density polyethylene or water to mitigate the impact of neutrons. Additionally, muon veto detectors might be integrated into the design, depending on the simulation results. This project will contribute to the design and will lead the technical realization of the external shield for DELight. Operation of the DELight detector in the underground laboratory requires access to live detector performance data and the possibility for remote control. This is mandatory to promptly and safely respond to unforeseen events, such as equipment failures or power outages. Within this project we will develop a Slow Control system to continuously monitor the various detector systems and ambient conditions, with the capability to control them when necessary. All monitored parameters will be stored in a database in order to be easily accessible for data analysis.

• DFG Programme: Research Units
• Subproject of: FOR 6006: DELight: Direct Search Experiment for Light Dark Matter with Superfluid Helium
• Co-Investigators: Dr. Klaus Eitel; Professor Dr. Marc Schumann