Large area detector of low-energy gamma radiation

Abstract

Detectors for registration of low-energy gamma radiation based on plastic scintillator UPS-923A with composite YSO:Ce and CsI:Tl layers were developed. Size and concentrations of granules in the composite scintillators were determined experimentally. Additional composite layer in the detector design allowed reducing the gamma radiation registration threshold down to 20 keV. It was shown that registration efficiency of 59.5 keV gamma-quanta (Am²⁴¹) of the detector with YSO:Ce composite layer was 4 times higher than that of UPS-923A. The detector with CsI:Tl composite layer had 1.5 times higher sensitivity and almost 2 times lower minimum detectable activity in comparison to UPS-923A under Am²⁴¹ irradiation.