A CsI(Tl)-PIN photodiode gamma-ray probe

We characterize two single elements consisting of 10×10×5 and 5×5×5 mm3 scintillator crystals read out by 10×10 mm2 PIN silicon photodiode. The photodiode signal is amplified by an ultra-low-noise preamplifier and a pulse shape amplifier. The photodiode has a low leakage current (<1 nA) and a small capacitance for electronic noise minimization. This probe demonstrates, at room temperature, an energy resolution of 15% for 140 keV gamma rays and 8.38% for 365 keV. Detection efficiency of a 57Co source placed at a distance of 1 cm is 250 counts s−1 μCu−1. Furthermore, the detector compactness, its low sensitivity to magnetic fields and the low-voltage power supply are very useful features for per-operative use.