An inter-comparison between calculated solid angle for different geometrical correlations of source-detector through analytical and Monte Carlo approaches

Calculation of solid angle (Ω) is of particular importance in radiation detection purposes. Nevertheless, determining the Ω value by analytical methods is a difficult procedure in complicated geometry conditions. The current study evaluates the capability of the Monte Carlo simulation approach in Ω calculation at different geometrical correlations between the source and detector by comparing the obtained results with those of the analytical method. Ω values were calculated for four different geometrical correlations between the source and detector (point and disk source/circular and rectangular detector apertures) through both analytical (Ω_th) and Monte Carlo simulation (Ω_sim) approaches. The MCNPX code was used for Monte Carlo-based calculations. For all studied geometrical correlations, a good agreement was observed between Ω_th and Ω_sim values such that the maximum difference between the results was less than 4%. A better accordance between Ω_th and Ω_sim was found for a point source in comparison with the disk source. Finally, it is concluded that Monte Carlo simulation can be considered a fast and reliable alternative to the analytical method in determining the solid angle for a radiation detector, especially in complicated geometry conditions, where applying the analytical approach may fail to result in an accurate Ω value.