Development of the full-chain cryogenic readout electronics for the point-contact HPGe detectors

摘要

The paper presents the development of the full-chain cryogenic readout electronics for HPGe detectors for dark matter and neutrino physics experiments. It consists of an ultra-low noise CMOS charge sensitive preamplifier, CR-RC shapers with multiple gains, and a 100 MS/s 10 bits SAR ADC. The preamplifier and ADC ASICs were fabricated in CMOS 350 nm and 65 nm processes respectively, and the shapers were implemented with commercial CMOS components. The integral non-linearly of the cryogenic readout system was measured to be less than 0.09%. An energy resolution of 550 eV +/- 20 eV FWHM has been achieved at 122 keV energy peak of Co-57 radiation source with optimum DPLMS area-balanced digital filter. The resolution for the pulser signals was also monitored to be 243 eV +/- 6 eV FWHM, corresponding to 34 electrons (r.m.s.) ENC noise. Different pulse shapes were captured from the single-site/multi-site events and bulk/surface events The pedestal noise with CR shaper obtained by filtering the baseline signals was measured to be 525 eV +/- 23 eV FWHM. The energy threshold for Bulk/Surface discrimination was estimated to be about 2 keV.