Abstract
LEGEND, the Large Enriched Germanium Experiment for Neutrinoless ββ Decay, is a ton-scale experimental program to search for neutrinoless double beta (0νββ) decay in the isotope 76Ge with an unprecedented sensitivity. Building on the success of the low-background 76Ge-based GERDA and \ extsc{Majorana Demonstrator} experiments, the LEGEND collaboration is targeting a signal discovery sensitivity beyond 1028 yr on the decay half-life with approximately 10 t⋅yr of exposure. Signal readout electronics in close proximity to the detectors plays a major role in maximizing the experiment's discovery sensitivity by reducing electronic noise and improving pulse shape analysis capabilities for the rejection of backgrounds. However, the proximity also poses unique challenges for the radiopurity of the electronics. Application-specific integrated circuit (ASIC) technology allows the implementation of the entire charge sensitive amplifier (CSA) into a single low-mass chip while improving the electronic noise and reducing the power consumption. In this work, we investigated the properties and electronic performance of a commercially available ASIC CSA, the XGLab CUBE preamplifier, together with a p-type point contact high-purity germanium detector. We show that low noise levels and excellent energy resolutions can be obtained with this readout. Moreover, we demonstrate the viability of pulse shape discrimination techniques for reducing background events.
Highlights
: LEGEND, the Large Enriched Germanium Experiment for Neutrinoless ββ Decay, is a ton-scale experimental program to search for neutrinoless double beta (0νββ) decay in the isotope 76Ge with an unprecedented sensitivity
Signal readout electronics based on application-specific integrated circuit (ASIC) technology are ideally suited for low-background 0νββ decay experiments like LEGEND
While not being inferior to discrete readout systems, Application-specific integrated circuit (ASIC) technology could allow for a lower electronic noise, a lower perchannel power consumption, and a higher per-channel radiopurity
Summary
The LEGEND collaboration has been formed to pursue a ton-scale 76Ge-based 0νββ decay experiment utilizing the best technologies from the GERDA (GERmanium Detector Array) and. The overall background is estimated to improve by a factor of more than two compared to the background achieved in the GERDA experiment to a level below 2 · 10−4 counts/(keV · kg · yr), with a targeted signal discovery sensitivity of T10/ν2 > 1027 yr. In the final stage of LEGEND, LEGEND-1000, the collaboration plans to operate 1000 kg of HPGe detectors for a time period of about 10 years. This requires a completely new infrastructure and a more ambitious background goal of less than 1 · 10−5 counts/(keV · kg · yr) to reach the targeted signal discovery sensitivity on the half-life of T10/ν2 > 1028 yr
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