SPICE stands for Sub-ev Polar Interactions Cryogenic Experiment. Single crystals are uses as DM interaction targets. The crystals can be sapphire (a polar crystal) or GaAs cubes, instrumented on one face with athermal phonon sensors. The primary goal for polar crystal detectors is to search for single optical phonons produced by electromagnetically interacting DM via scattering (3keV< M DM <1MeV) and via absorption (100meV< M DM <1eV). These detectors have complementary sensitivity to GaAs detectors for electromagnetically interacting DM at higher masses and overlapping sensitivity with the He detector for nucleonic interacting DM via scattering off oxygen nuclei. GaAs crystals produce both scintillation and phonons. The possibility to use the same detector to measure both scintillation and phonons can give an important background discrimination handle. The images show a 3″ sapphire wafer patterned with detectors on one side, and laser calibration peaks (form a different prototype device) showing single photons resolution in two laser wavelengths.
