Efficiency and energy resolution of gamma spectrometry system with HPGe detector depending on variable source-to-detector distances

The high-purity germanium (HPGe) detectors, which are one of the basic instruments in the experimental nuclear physics, are widely used in many areas such as the environmental radioactivity, neutron activation analysis and geology. This study reports the results of energy calibration, energy resolution and efficiency calculations for an HPGe detector (ORTEC), which are necessary to determine the quality of the measurement results obtained from a gamma spectrometry system. For the purpose of examining the effects of gamma-ray energy and the distance between the source and the detector on the detector efficiency, measurements were made at six different source-detector distances for a total of about fourteen energies of the point sources (133Ba, 109Cd, 137Cs, 57Co, 60Co, 152Eu, 22Na, and 65Zn). Basic data were obtained with this detector system for later studies.