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A gettering procedure using phosphorus doped glass is shown to remove lithium-ion precipitation sites from p-type Floating-Zone (FZ) silicon. A model involving interaction between grown-in vacancies and oxidation-injected silicon interstitials is proposed to explain the gettering procedure. Examples of silicon lithium-drifted detectors fabricated on ungettered and gettered FZ silicons are presented.

We present new results from a cryogenic detector instrumented to measure both the phonon and ionization signals. The detector is a 60 g Ge disk operated at 30 mK. We have made significant improvements in the electronics noise, threshold, and energy resolution of the device. The baseline FWHM, corresponding to the total system noise, is 1.55 keV in the phonon channel and 1.59 keV in the ionization channel. At 60 keV the FWHM are 1.9 keV and 1.7 keV in the phonon and ionization channels, respectively. We have demonstrated for the first time a discrimination between electron recoils and nuclear recoils at low energy.