Design and performance of the Majorana low-noise low-background front-end electronics
ORAL
Abstract
The Majorana Demonstrator will search for the neutrinoless double beta decay ($\beta\beta$(0$\nu$)) of the isotope $^{76}$Ge. In view of the next generation of tonne-scale germanium-based $\beta\beta$(0$\nu$)-decay searches, a major goal of the Majorana Demonstrator is to demonstrate a path forward to achieving a background rate at or below 1 cnt/(ROI-t-y) in the 4 keV region of interest (ROI) around the 2039-keV Q-value of the $^{76}$Ge $\beta\beta$(0$\nu$)-decay. Such a requirement on the background level significantly constrains the design of the readout electronics which is further driven by noise performances. We present here the low-noise low-background front-end electronics developed for the low-capacitance P-type point-contact (PPC) germanium detectors of the Majorana Demonstrator. This resistive-feedback front-end, specifically designed to have low mass, is fabricated on a radioactivity-assayed fused silica substrate where the feedback resistor consists of a sputtered thin film of high purity amorphous germanium and the feedback capacitor is based on the capacitance between circuit Au traces. Performance studies of the front-end and associated back-end electronics in single and multi-detector systems, as well as on-site performances are reported.
*We acknowledge support from the Office of Nuclear Physics in the DOE Office of Science, the Particle Astrophysics Program of the National Science Foundation, the Russian Foundation for Basic Research, and the Sanford Underground Research Facility.
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