Speaker
Description
Segmented high-purity germanium (HPGe) detectors are essential tools in advanced gamma spectroscopy. However, many of their technical and manufacturing details remain proprietary to industry. To overcome this limitation, the Italian Institute for Nuclear Physics funded the N3G Project, aimed at developing new segmented HPGe detectors while building in-house expertise for their design, production, operation and maintenance.
This work presents two key outcomes of the project. The first is the development and validation of an innovative electrical interconnection system between the detector electrodes and the front-end electronics, designed to ensure minimal impact on detector leakage current. The solution relies on flexible PCBs fabricated on a 36 $\mu m$ polyimide substrate and shaped to conform to the detector geometry. Its performance was benchmarked against a conventional micro-spring contact scheme with an indium interlayer, demonstrating a reduction in leakage current of more than four orders of magnitude.
The second outcome is a newly designed integrated charge-sensitive preamplifier and its experimental validation. The device is based on a custom Application-Specific Integrated Circuit (ASIC) developed for HPGe signal read-out and implemented in the AMS C35B4C3 technology, a mature and reliable 350 nm CMOS process from Austria Microsystems. Experimental characterization demonstrated excellent performance, including strong linearity (integral non-linearity below 0.03 %) and low noise, with an equivalent noise charge of 108 RMS electrons for a 1 MeV equivalent event and 15 pF electrode capacitance.