Angle vs. LabSOCS for HPGe efficiency calibration

The quantitative determination of radionuclides by gamma ray spectrometry requires a high accuracy of detection efficiency determination. Different software codes for efficiency determination are available. The aim of this work was to compare different methods and software used for efficiency calibration modeling and analyses. For that purpose, same samples of vegetation and soil of known activities were measured using HPGe detectors in two laboratories which are employing different software for mathematical efficiency calibrations and analyses, LabSOCS which is based on purely mathematical calculations and Angle which uses a semi-empirical approach. The codes were also tested on samples with unknown reference values (different geometries and matrices). The main advantages and disadvantages of both software were compared. Both Angle and LabSOCS gave comparable and consistent results for different detectors, matrices and geometries used. Deviations of the order of 10% or less obtained from the comparison of different sets of parameters are acceptable and imply that Angle and LabSOCS can be considered reliable for gamma ray detector efficiency calibrations. The main limitation of LabSOCS is in its inability to be used on newly installed detectors (factory characterization needed first), as for Angle the main drawback is in its demand for reference materials which can be costly as well as the need for plenty detector characteristics which are not always provided by the manufacturer.