Calorimetry with Nonequilibrium Phonon Sensors for Dark Matter Direct Detection

Low-temperature calorimetric particle detectors are applied to the problem of dark matter detection. These semiconductor crystal-based devices operate at sub-Kelvin temperatures. Nuclear-recoil interactions can be distinguished from electron-recoils by comparing the thermal energy yield with that in another channel, such as ionization or scintillation, essential in the search for dark matter and potentially quite useful in measuring neutrino-nucleus scattering cross-sections. The Cryogenic Dark Matter Search collaboration has demonstrated in phase two (CDMS II) that athermal phonon sensors instrumented with direct-current SQUID arrays achieve additional background rejection encoded in the pulse shape, particularly associated with leading edge features. This talk will present the general ideas of applying calorimetry to dark matter detection. It will also present CDMS II detector design and performance, and discuss future plans for dark matter direct detection with this approach