NIST logo

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


A two-dimensional analysis of three coincident gamma-rays in 108Agm 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 the108Agm 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.
Absolute Ag108 Characterization Based on Gamma Gamma Coincident detection
Contour plot for a two-dimensional histogram of coincident events. Six coincident peaks and six coincident summation peaks are clearly seen.

Lead Organizational Unit:



Radioactivity Group

Peter Volkovitsky