A novel approach to the analysis of HPGe spectra—Part I

A new approach to spectrum analysis in gamma-ray spectrometry is proposed. For each of the radionuclides in a context-sensitive radionuclide library, a corresponding synthetic spectrum is created, containing the peaks that would appear in the measured spectrum if the radionuclide were present in the sample. A search is then made for the linear combination of these single-radionuclide spectra that matches the measured spectrum best, and the resulting coefficients in this combination are the desired activities of the radionuclides in the sample. Very precise energy and peak-shape calibrations need to be in place for the approach to work. The parameters of the two calibration functions are therefore optimized so that the global minimum in the difference between the channel contents of the measured and calculated spectrum is reached. In order to avoid the need to model the background below the peaks in the synthetic spectra, smoothed first derivatives of the spectra are used throughout, rather than their original shapes.