A High-Rate Direct-Coupled Preamplifier for High Energy Ge Detector Systems

The fast counting of high energy gamma events with excellent resolution is made possible by the design of a recycling preamplifier and a direct-coupled spectrometer system. Measurements were performed with a 40 cc Ge(Li) coaxial detector. Data were observed with and without pile-up rejection for count rates up to 150,000 counts/s. Resolution without pile-up rejection for 60Co was 2.50 keV FWHM at 75,000 counts/s (1.5-¿s shaping). The exceptional performance of this direct-coupled system is mainly attributed to the preamplifier which requires no pole-zero compensation. After single differentiation the pulses return precisely to the baseline.