DELight: Direct Search Experiment for Light Dark Matter with Superfluid Helium

The DM-nucleon scattering parameter space of Light Dark Matter (LDM) has been barely experimentally probed, as it requires an energy detection threshold down to a few tens of eV. The “Direct search Experiment for Light dark matter” (DELight) aims at using superfluid helium-4 as target, particularly suited because of its low nuclear mass and radiopurity, while providing both photon and quasiparticle signal channels valuable for event classification. DELight will deploy Magnetic Micro-Calorimeters (MMCs) operating at a temperature of 20 mK, promising high resolution and a threshold of a few eV. With an exposure of only 1 kg×d and an energy threshold of 20 eV, in its first phase DELight will be able to probe unexplored regions of the parameter space for LDM masses below 100 MeV with an expected sensitivity lower than 10−39 cm2 at 20 MeV.

In this talk we will present the working principle of the detector technologies as well as an overview of the ongoing R&D towards the realization of DELight.