Full-energy peak efficiency and response function of 1 cm3 CdZnTe detectors

The energy dependence of the full-energy peak (FEP) efficiency and response function of 1 cm3 CdZnTe detectors that use gamma rays were investigated in the present study. Specifically, full-energy peaks from 60 keV to 1.3 MeV were evaluated. 214Am, 133Ba, 137Cs, 54Mn, and 60Co radionuclides with good source activities were employed. The results showed that the absolute peak efficiencies decreased at higher energies, and the calculated (EGS5 code) efficiencies were nearly 70% greater than the experimental values when above 100 keV photon. Below 100 keV, disagreement is within 35%. The measured and calculated peak efficiencies peak agreed within 5% in a wide energy range when the “effective” of the crystal area was down to 0.8 x 0.8 cm2. Agreement corresponding to response function curve at the region of interest (full-energy peak) and Compton plateau region for 137Cs achieved once considering the 0.8 x 0.8 cm2 effective area of the crystal and the source plastic casing. The results of the present study provided important insights on the calibration of the FEP efficiency as a function of the gamma ray energy. The detectors must be individually calibrated to obtain reliable results.