DELight Demonstrator
Technological proof of concept and sensitivity studies for a new dark matter experiment
The nature of dark matter is one of the greatest mysteries of modern physics. Experiments worldwide are searching for direct interactions of potential dark matter particles with the detector material. An established candidate for these direct searches is the so-called WIMP, with a mass between a few GeV and several tens of TeV. The fact that this particle has not yet been found shifted the focus in recent years to lighter particles, known as light dark matter (LDM). However, previous experiments have struggled to probe the LDM parameter space due to significantly weaker expected signals compared to WIMPs, necessitating new concepts. Scientists at KIT and the Universities of Heidelberg and Freiburg are therefore developing the new DELight experiment to achieve a milestone in the worldwide search for DM-nucleus scattering: high sensitivity down to DM masses below 100 MeV. In the first phase of the experiment, DELight will use up to 10 L of superfluid helium-4, whose nuclear mass is small compared to that of conventional detector materials, which leads to a particularly high sensitivity for light particles. Additionally, superfluid helium-4 has no long-lived radioisotopes, is self-cleaning and enables the classification of events thanks to its photon, excimer and quasiparticle signal channels.
For precise energy measurements, highly sensitive cryogenic calorimeters are designed with the latest quantum sensor technology: large-area magnetic microcalorimeters (MMCs) with an energy threshold of a few eV:
Since DELight is based on innovative technologies and detector concepts, a key to success is the careful testing and optimization of all relevant elements of the experiment. This is made possible by the DELight Demonstrator, an approximately 400 mL helium cell with infrastructure for testing different microcalorimeter designs and individual elements of the cryogenic infrastructure.
Team
The DELight Collaboration, consisting of students and scientists from KIT, Heidelberg University and the University of Freiburg:
