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 $\alpha $ source and of different $\gamma $ sources (137Cs and 60Co) with a CsI(Tl) scintillator crystal $3.2~\text {cm}\times 3.2~\text {cm}\times 6~\text {cm}$ coupled with a $18~\text {mm}\times 18~\text {mm}$ silicon p-i-n diode 300- $\mu \text{m}$ -thick readout by the developed ASIC.