Consistency of photon emission intensities for efficiency calibration of gamma-ray spectrometers in the energy range from 20 keV to 80 keV

Highlights: • Efficiency calibration of four HPGe detectors using standard radioactive sources. • Accurate processing of the full-energy peaks and Monte Carlo simulation. • Absolute photon emission intensities derived for Ba-133. • Absolute K X-ray emission measured for Sr-85, Y-88, Cd-109, Eu-152 and Ho-166 m. - Abstract: The efficiency calibration for different high-purity germanium detectors in the low-energy range was established by the conventional method, using standard radioactive sources. The peak shapes were carefully analysed taking account of natural linewidth, full-energy width at half maximum and scattering. Complementary information was obtained by Monte Carlo simulation using the PENELOPE code, after optimization of the geometrical parameters. This was used to measure photon emission intensities of some low-energy emitting radionuclides, including ¹³³Ba, and compared to the tabulated values.