A new modification of gamma-gamma coincident activity measurement method was used for characterization of Co-60. Two-dimensional analysis of coincident events allows carefully calculating the fraction of Compton scattered gammas for each of two gammas emitted by Co-60 and for each of two NaI(Tl) detectors. A modification of standard formulas that were used before for absolute calibration of I-125 (Eldridge formulas) was done. These modified Eldridge formulas were applied for absolute calibration of Co-60 samples with two NaI(Tl) detectors. Measurements were done for three sources of different activities and for two positions of each source between NaI(Tl) detectors. Results are compared with measurements performed by beta-gamma coincidence method.
Citation: Nuclear Instruments & Methods
Pub Type: Journals
absolute standardization, direct activity measurement, gamma-gamma coincidence, NaI(Tl) detector.