PHONON-MEDIATED DETECTORS FOR DARK MATTER SEARCHES AND NEUTRINO EXPERIMENTS

Our group at Stanford is developing a new class of elementary particle detectors capable of sensing weakly interacting particles such as neutrinos. Our detectors are based on the propagation of phonons in silicon crystals at low temperatures. We have developed superconducting transition edge devices to sense the arrival of phonons at the crystal surfaces. During the past two years, we have characterized titanium transition-edge devices operated around 0.3 K and are beginning tests with tungsten transition-edge devices operated below 100 mK. The titanium devices have been operated in coincidence on both sides of silicon crystals up to 2 mm thick and have been used in calibration experiments with x-rays, alpha particles and neutrons. An underground facility is near completion at Stanford which provides 20 meters water equivalent of cosmic-ray shielding. This facility will house a pilot dark matter search which we will undertake collaboratively through the Center for Particle Astrophysics and the facility also will be used for developing our reactor neutrino detector.