Lawrence Berkeley National Laboratory

The observation of neutrinoless double-beta decay would provide evidence for the proposition that neutrinos are their own antiparticle, a property that is not prescribed in the Standard Model. The proposed Large Enriched Germanium Experiment for Neutrinoless double beta Decay (LEGEND) will search for this decay mode in 76Ge by deploying high-purity germanium (HPGe) detectors enriched in this isotope. The signal from two hundred kilograms of HPGe detectors will be fed to low-radioactivity, charge-sensing amplifiers (CSA) deployed in the first phase of the LEGEND experiment: LEGEND-200. We optimized the performance of the CSA in different test conditions by varying the operating parameters (including voltages supplied to the active components of the CSA) and measured the properties of the amplified waveform, such as rise time, dynamic range, and electronic noise. The optimized parameters lead to waveforms with the following characteristics: 90 ns rise time, a dynamic range from 0-10 MeV, and noise of 620 keV (FWHM) at a total power consumption of 156 mW in liquid nitrogen. The optimization process will continue as the circuit is integrated with other components of the experiment.