Design of a low background cryostat for a 1.3 kg low-noise, high purity germanium gamma-ray spectrometer

Recent progress on the development of very-low-energy threshold high-purity germanium ionization spectrometers has produced an instrument of 1.3 kg mass and noise performance of less than 100 eV full-width half-maximum for a peak generated with an electronic pulser as input. The detector was installed in a low-background cryostat intended for use in a low-mass WIMP dark-matter search. The integrated detector and low-background cryostat achieved noise performance of 98 eV full-width half-maximum for an electronic pulser-generated peak and gamma-ray energy resolution of 1.9 keV full-width half-maximum at the 60Co gamma-ray energy of 1332 keV. This presentation describes the low-noise and low-background design considerations employed, the thermal characterization of the low-background cryostat, the specifications of the newly prepared 1.3 kg p-type point contact germanium detector, and the baseline performance of the integrated detector and cryostat.