Absolute Ag108 Characterization Based on Gamma-Gamma Coincident Detection by Two NaI (TI) Detectors

A two-dimensional analysis of three coincident gamma-rays in ¹⁰⁸Ag^m decay, detected by two NaI(Tl) scintillation detectors, allows a direct measurement of the source activity

A modification of Eldridge - Crowther formulas derived originally for ¹²⁵I was done recently for the case of two coincident gamma-rays in ⁶⁰Co decay. A similar approach is applied to a more complicated case of three coincident gamma-rays in the¹⁰⁸Ag^m decay.  The large number of experimental quantities, measured both in coincidence and anticoincidence modes, allows the determination of both detector efficiencies for all three x-ray photo-peaks and the source activity.  Results are compared with measurements of the activity of the same source with HPGe detectors.