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Monte Carlo based approach to the LS-NaI ß-γ anticoincidence extrapolation and uncertainty



Ryan P. Fitzgerald


The β-γ anticoincidence method is used for the primary standardization of β-, β+, electron capture (EC), α, and mixed-mode radionuclides. Efficiency extrapolation using one or more γ ray coincidence gates is typically carried out by a low-order polynomial fit. The approach presented here is to use a Geant-based Monte Carlo simulation of the detector system to analyze the efficiency extrapolation. New code was developed to account for detector resolution, direct γ ray interaction with the PMT, and implementation of experimental β-decay shape factors. The simulation was tuned to 57Co and 60Co data, then tested with 99mTc data, and used in measurements of 18F, 129I, and 124I. The analysis method described here offers a more realistic activity value and uncertainty than those indicated from a least-squares fit alone.
Applied Radiation and Isotopes


beta-gamm, anticoincidence, coincidence, Monte Carlo


Fitzgerald, R. (2015), Monte Carlo based approach to the LS-NaI ß-γ anticoincidence extrapolation and uncertainty, Applied Radiation and Isotopes, [online], (Accessed April 23, 2024)
Created November 1, 2015, Updated November 10, 2018