A semi-empirical method for calculation of true coincidence corrections for the case of a close-in detection in γ-ray spectrometry

Abstract

In this paper, a semi-empirical method is proposed to determine true coincidence-summing (TCS) correction factors for high resolution γ-ray spectrometry. It needs the knowledge of both full energy peak (FEP) efficiency and total-to-peak (TTP) efficiency curves. The TTP efficiency curve is established from the measurements with a set of coincidence-free point sources. Whereas for a volume source, the coincidence-free FEP efficiency curve is obtained iteratively by using the peaks from almost the coincidence-free nuclides and those from the coincident nuclides in the mixed standard sources. Then the fitting parameters obtained for both TTP and FEP efficiency curves are combined in a freely-available TCS calculation program called TrueCoinc, which yields the TCS correction factors required for any nuclide. As an application, the TCS correction factors were determined for the particular peaks of 238U, 226Ra and 232Th in the reference materials, measured in the case of a close-in detection geometry using a well-type Ge detector. The present TCS correction method can be applied without difficulty to all Ge detectors for any coincident nuclide.