DEVELOPMENT OF 100 G SI AND 250 G GE DETECTORS FOR A DARK-MATTER SEARCH

Over tile last two years we have proposed and implemented a new phonon sensing scheme for Cryogenic elementary particle detectors based upon Transition Edge Sensors (TES) operated in the (negative) Electrotherm al-feedback (ETF) mode, and utilizing large Al collection pads for the initial phonon absorption. We have also implemented an ionization ele ctrode, in addition to the phonon sensors, to allow the simultaneous m easurement of ionization and phonon signals in Si and Ge absorbers. Ou r progress to date include successfully discriminating between electro n and nuclear recoils down to a threshold of 4 keV recoil energy for a 4 g Si detector. Our first 100 g Si detectors have been fabricated, a nd initial work on Ge detectors indicates that our phonon sensing sche me will also work on large mass Ge absorbers.