The MAJORANA low-noise low-background front-end electronics

The MAJORANA DEMONSTRATOR will search for the neutrinoless double beta decay (beta beta(0 nu)) of the isotope Ge-76 with a mixed array of enriched and natural germanium detectors. In view of the next generation of tonne-scale germaniumbased 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 Ge-76 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 and energy resolution performances. We present here the low-noise lowbackground front-end electronics developed for the low-capacitance p-type point contact (P-PC) germanium detectors of the Majorana Demonstrator. This resistive-feedback front-end, specifically designed to have low mass, is fabricated on a radioassayed 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 gold conductive traces. (C) 2015 The Authors. Published by Elsevier B.V.