Scott Hertel

The SPICE and HeRALD experiments for sub-GeV dark matter direct detection

Abstract:
The SPICE and HeRALD experiments aim to probe dark matter (DM) masses down to 10 MeV in the near term, with upgrade paths to sub-MeV masses. The project is currently in a preparatory R&D phase focused on pushing Transition Edge Sensor (TES) recoil energy thresholds into the sub-eV regime, and then applying this next generation of sensors to a variety of well-motivated target materials. The HeRALD portion of the effort employs a novel active target material: superfluid 4He. Helium's nuclear recoil sensitivity benefits from both a low-mass target nucleus and a unique quantum evaporation phonon readout method. The complementary SPICE effort employs polar crystal target materials, motivated by their low-momentum phonon states and strong couplings to dark photon-mediated DM.