Innovative Flexible Systems and Integrated Charge-Sensitive Pre-Amplifiers for Modern HPGe Detectors

Segmented high-purity germanium detectors play a key-role in advanced gamma spectroscopy. However, their technical and manufacturing details are proprietary and not publicly disclosed by industry. To address this gap, Italy's National Institute for Nuclear Physics launched the N3G Project, aimed at designing new segmented high-purity germanium detectors and developing the technical know-how to independently operate and maintain them. In this framework, the current paper offers novel contributions. The innovative system designed to electrically connect the electrodes of the detector to the front-end electronics will be described and its low impact on the detector leakage current will be shown. Specifically, a reduction in leakage current exceeding several orders of magnitude compared to conventional contact methodologies was demonstrated. Moreover, the architecture of a new integrated charge sensitive pre-amplifier will be reported and its validation will be presented. It features low power consumption and a wide dynamic range, and is available in two variants: a single-ended version and one with differential output. The circuit demonstrated excellent linearity and low noise. An integral non-linearity factor of 0.04 % was found and an optimum equivalent noise charge of 108 root-mean-square electrons was measured for a 15 pF equivalent electrode capacitance and 1 MeV equivalent energy events.