Readout Electronics for Gamma-Ray Astronomy

Gamma-ray astronomy explores a wide range of photon energies (0.1 MeV–1 PeV) and leverages different types of detectors, based on different technologies and coping with a variety of installation constraints, spanning from ground to satellite telescopes. Common aspects across instrumentation are a multiplicity of channels and very weak signals, often requiring photodetectors with internal gain such as photomultiplier tubes (PMTs) and silicon photomultipliers (SiPMs). Here we review the key concepts in the design of the readout electronics, with special focus on the latter class of solid-state detectors and on modern integrated microelectronic implementations, allowing unprecedented miniaturization. The different strategies in the readout of signals (voltage, charge and current mode, negative and positive feedback circuits) are compared and illustrated with reference to the most relevant literature.