Fast procedures for coincidence-summing correction in gamma-ray spectrometry

Simplified and fast procedures for coincidence-summing correction in gamma-ray spectrometry were investigated. These procedures are based on the usual theoretical expressions of the correction factors, but differ in the determination of the total efficiency curve based on the following approximations: (a) replacement, below the knee efficiency value, of the total efficiency by the full-energy peak efficiency; and (b) use of linear interpolations (in log-log plot) between only two experimental points above the knee efficiency value; or (c) assumption of a peak-to-total efficiency ratio independent on the counting geometry; or (d) assumption of a constant relation between the peak-to-total efficiency ratios and the photoelectric-to-total cross section ratios. The above approximations were separately assumed for determination of the coincidence-summing correction factors for nuclides with complex decay scheme (133Ba, 134Cs, 152Eu) and for 60Co and 88Y measured on a 15% relative efficiency p-type coaxial HPGe detector, for three source-detector geometries: point source placed on top of and at 10 cm from the detector window, and 1 l Marinelli beaker filled with aqueous solution. The results were compared with those based on more accurate experimental determinations of the total efficiency curve from measurements of standard sources of eight different single-gamma-ray emitters. The usefulness of each simplified procedure is evaluated with respect to its accuracy and to the reduction of the number of standard sources and measurement time.