The solid angle subtended by a well-type detector and a cylindrical source.
A Monte Carlo approach, based on total variance reduction, was presented in order to evaluate the solid angle subtended between a well-type NaI detector and a cylindrical source within the well. The results obtained, in the form of the geometrical efficiency εg, were within 0.7% of those in the literature, for a point and a volumetric radioactive source within the well. The effect of self-absorption on the geometrical efficiency was investigated for different gamma-ray energies emitted by the volumetric source, different source matrices and radii. Self-absorption is found to be particularly significant for gamma-ray energies below 300keV regardless the source matrix and radius. Furthermore, self-absorption becomes significant, in the case of the larger radius volumetric source, for the gamma-ray energies up to 1MeV considered. Hence, the effect of self-absorption on the geometrical factor should be considered in the absolute quantification of radioactivity of volumetric sources.
Demokritus University of Thrace, School of Engineering, Department of Electrical and Computer Engineering, Laboratory of Nuclear Technology, Kimmeria Campus, Xanthi, Greece. nicolaou@ee.duth.gr
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