A Compact 4-Decade Dynamic Range Readout Module for Gamma Spectroscopy and Imaging

Abstract

A miniaturized 16-channel readout system for portable γ-ray spectroscopy and imaging is presented. It features the combination of a microcontroller with a novel CMOS ASIC for analog processing of the currents of planar SiPM solid-state photodetectors coupled to large scintillators. The adoption, in the gated-integrator shaper, of a doublewindow time-based automatic gain control offers an 84 dB dynamic range (3 μΑ to 30 mA) combining single-photon sensitivity with an extended energy range (50 keV – 10 MeV). Sensitivity (SNR ∼7dB for 1 photoelectron), linearity of 4%, gain switching among 3 integrator capacitors, 3.8% energy resolution (at 662 keV) and imaging capability with an array of 144 selectively-merged pixels are experimentally demonstrated.