Correction of the TRUE summations in volume sources.

ABSTRACT

The correction factors for volume sources may be approximated using average efficiencies determined by experiment or by Monte Carlo methods in the same way as for point sources. This simple technique does not take into account properly the absorption of photons in the source, nor the change of the effective solid angle. A more precise method must take into account for the spatial distribution of products of efficiencies η(peak)*η(total) (for summing-out) or η(peak)*η(peak) (for summing-in) over the volume of the source. The differences between the approximate and the more precise method are discussed.