Improved energy resolution for scintillator based gamma-ray detectors obtained using a CsI(Tl)/Si-PIN detector

This note reports improved energy resolution measured using a gamma-ray detector consisting of a 2 mm×2 mm×4 mm long CsI(Tl) scintillator coupled to a 2 mm×2 mm photodiode. Energy resolution of 7.5% full width at half-maximum (FWHM) was obtained for the 122 keV photopeak of Co-57. Energy resolution of 35% FWHM was obtained for the 5.9 keV photopeak of Fe-55.