A HEMT-based cryogenic charge amplifier with sub-100 eVee ionization resolution for massive semiconductor dark matter detectors.

We present the measured baseline ionization resolution of a HEMT-based cryogenic charge amplifier coupled to a CDMS-II detector. The amplifier has been developed to allow massive semiconductor dark matter detectors to retain background discrimination at the low recoil energies produced by low-mass WIMPs. We find a calibrated baseline ionization resolution of σ E = 91 eV e e. To our knowledge, this is the best direct ionization resolution achieved with such massive (≈ 150 pF capacitance) radiation detectors. [ABSTRACT FROM AUTHOR]