Digital pulse processing and optimization of the front-end electronics for nuclear instrumentation

International audienceThis article describes an algorithm developed for the digital processing of signals provided by a high efficiencywell-type NaI(Tl) detector used to apply the 4$\pi \gamma$ technique. In order to achieve a low-energythreshold, a new front-end electronics has been specifically designed to optimize the coupling to ananalog-to-digital converter (14 bit, 125 MHz) connected to a digital development kit produced byAltera (c) . The digital pulse processing is based on an IIR (Infinite Impulse Response) approximation ofthe Gaussian filter (and its derivatives) that can be applied to the real-time processing of digitizedsignals. Based on measurements obtained with the photon emissions generated by an $^{241}$Am source, theenergy threshold is estimated to be equal to ~2 keV corresponding to the physical threshold of the NaI(Tl) detector. An algorithm developed for a Silicon Drift Detector used for low-energy x-ray spectrometryis also described. In that case, the digital pulse processing is specifically designed for signals provided bya reset-type preamplifier (${55}$Fe source)