A CMOS Frontend for Scintillators Readout by Photodiodes for Nuclear Physics Experiments

We designed a CMOS frontend for the readout of scintillators coupled with silicon photodiodes for nuclear physics experiments. The preamplifier features a continuous-reset feedback and an input pMOS transistor. The designed input dynamic range is 90-MeV silicon equivalent. The frontend has been integrated in single channel and multichannel versions up to 16-channel application specific integrated circuits (ASICs) in the C35B4C3 AMS technology. The measured integral-non-linearity over the whole dynamic range is below 0.5%. The intrinsic rise time (10%-90%) of the preamplifier is of the order of 3 ns over the entire dynamic range and is below 50 ns when coupled with a 130-pF photodiode. We qualified the spectroscopic performance by acquiring spectra of a mixed nuclei α source and of different γ sources (137Cs and60Co) with a CsI(Tl) scintillator crystal 3.2 × 3.2 × 6 coupled with a 18mm × 18mm silicon p-i-n diode 300-μm -thick readout by the developed ASIC.