Monolithic Multi-Element HPGe Detector Equipped With CMOS Preamplifiers: Construction and Characterization of a Demonstrator

Multi-element germanium detectors for X-ray fluorescence are widely used in synchrotron experiments and in particular in XAFS experiments. This paper presents the construction and characterization of a demonstrator built to investigate the viability of multi-element monolithic germanium detectors equipped with CMOS front-end electronics. Semikon Detector GmbH fabricated a germanium sensor segmented with a pad pattern with pad size 1×1 mm². 16 channels were instrumented with the CUBE preamplifiers developed at XGLab Srl. The detector was tested with radioactive sources and with the synchrotron X-ray beam of Diamond. The results showed spectra with energy resolution satisfactory for XAFS experiments but with a considerable tail. The low energy tail was proved to be due to charge sharing. In addition the spectra showed the peak stability as a function of counting rate better than 1% for rate up to 838 kcps. The non-linearity of the peak position vs. energy was estimated to be a maximum of 0.13% No evidence of charge loss in the crystal was identified. This work proved that this technology is a viable option to improve the throughput of germanium fluorescence detectors as long as methods to reduce events leading to charge sharing are in place.