A comparison of different analytical methods of determining the solid angle of a circular coaxial source-detector system

In this work, seven different analytical expressions for the solid angle subtended by a circular detector for a coaxial circular source are compared. These expressions-which have been published by different investigators over the course of the last half century-are compared for previously published geometries, and for geometries planned in future experimental work. As compared to benchmark Monte Carlo calculations, the expressions published by Segre, Knoll, and Ruby, were the most accurate and exhibited the highest degree of self-correlation.