A STUDY OF INCOMPLETE CHARGE COLLECTION IN CRYOGENIC DETECTORS USING A SEGMENTED 60 GRAM GERMANIUM PHONON AND IONIZATION DETECTOR

We have tested a new 60 gram germanium phonon and ionization detector to study incomplete charge collection effects in cryogenic detectors. An understanding of such effects is necessary to further improve the n uclear vs. electronic recoil discrimination capability of cryogenic de tectors. The detector is operated at almost-equal-to 20 mK. If has thr ee concentric ionization channels, and four electric field shaping str uctures on its sides. Phonons are sensed using NTD Ge thermistors. Fir st results obtained using this device and moveable radioactive sources of Am-241 and Co-57 will be presented