Characterizing the Performance of a SiPM Scintillator Detector for Low Radioactivity Measurements

A detector that can measure positron emitters at low radioactivity levels is crucial for understanding different molecular processes at the single-cell level. To that end, we have developed a βeta particle detector by coupling a 0.5 mm thick plastic scintillator (EJ-212) to a 3.86 x 3.86 mm
²
silicon photomultiplier (SiPM). We have characterized the detector in terms of background scintillation rate, absolute detection efficiency, and minimum detectable activity (MDA) at room temperature. The measured background scintillation rate per detector was 6×10
^-4
bcps/mm
²
(9×10
^-3
bcps/detector channel). The absolute detection efficiency using
¹⁸
F as the positron emitter is 42.5 ± 0.4%, mainly attributed to the hemispheric available solid angle. The MDA of the detector was calculated to be 0.06 Bq for a 10 min acquisition. Using the timing output of BROADCOM’s AFBR-S4E001 evaluation kit, we obtained energy spectra for
¹⁸
F (EJ-212) and
²²
Na (LYSO). This makes it possible to eliminate most of the dark counts using energy discrimination. Together, these results show the feasibility of using this detector to measure positron emitters at low radioactivity levels. Work is ongoing to develop an array of many channels with this detector and the aim of measuring the metabolic heterogeneity found within a cell population using different radiotracers.